Port live instability, writing recovery and Link Modifier controls to 26.3

README.md

@@ -17,10 +17,16 @@ supports authored terrain/biomes, structure and vegetation pages, independent
 Age weather/lighting, seeded and colorable Overworld/Nether/End/Static skies,
 independent Sun/Moon controls, multiple bodies and eclipses, seeded biome and
 feature completion, and random structure selection. Nether/End noise-biome
-materials now follow their native rules. The beta does not yet provide full
+materials now follow their native rules. Books now have Legacy-style spreads,
+animated fallback panels and saved destination labels; lectern stands, open-book
+drops, page collections, stations and basic progression are also ported. The latest
+beta adds Age libraries, crystal portals with animated fallback surfaces, saved
+instability scoring/provider selection, potion providers and four-color decay.
+Full writing recovery, live material profiling and other hazards remain pending.
+The beta does not yet provide full
 1.21.1 gameplay or optional-integration parity.
 See the [26.3 beta guide](ports/mc263/README.md) and
-[latest beta release notes](ports/mc263/RELEASE_NOTES_1.0.1.106-beta.1.md).
+[latest beta release notes](ports/mc263/RELEASE_NOTES_1.0.1.120-beta.1.md).
 Keep the builds and their saves separate, and back up worlds before updating.
 
 ## Getting started

docs/MINECRAFT_26_3_PORT.md

@@ -2021,3 +2021,570 @@ passed again after the 26.3 registry slice.
 On 2026-11-01, the default 1.21.1 GameTest server was rerun and all 93
 required tests passed, including the desk test. Issue #97 was then closed;
 remaining 26.3 parity work stays under #98–#104.
+
+## Progression advancement port
+
+`1.0.1.107-beta.1` reuses seven root progression JSON files and existing
+translations. The Open Portal node remains excluded because its Receptacle icon
+and action are not yet ported. Added server-owned post-commit hooks for Mixer
+normal/shift output, Desk normal/shift copies, Binder assembly and successful
+handheld travel whose destination is a saved runtime Age. Inventory and root
+criteria remain vanilla. Existing saves retain vanilla player advancement data;
+no action history is reconstructed and no protocol/schema change is required.
+
+The build and disposable-server fixtures passed loaded data, preview/empty Mixer
+rejection, both Panel pickup paths, actual Desk copy and Binder assembly awards,
+and registered-Age entry eligibility. NeoForge FakePlayer uses a no-op advancement
+tracker; the fixture player overrides it with vanilla PlayerAdvancements rather
+than changing production awards to accommodate a test double. No client joined;
+GUI tree/toasts, inventory triggers, actual travel and reconnect persistence are
+the user validation. The test server was stopped and its world removed.
+
+## Recipe discovery and advancement background
+
+`1.0.1.109-beta.1` uses the existing Crystal Block texture for the root
+advancement background via the modern asset ID. The .108 stone-path correction
+passed the player's in-game test. Added adapted 1.21.1 discovery advancements
+for Ink Vial, Ink Mixer, Book Binder and Crystal Block, retaining all original
+materials, OR requirements and recipe rewards. The 26.3 recipe-unlocked trigger
+requires `conditions.recipes`, a list. Root 1.21.1 data remains unchanged.
+
+The build and disposable-server `recipe_discovery_probe` passed loaded
+recipe/advancement availability, wrong-material negatives, actual matching-material
+inventory triggers, per-player isolation and direct recipe grants for all six
+crafting unlocks (including Notebook and Writing Desk). No client joined this
+fixture. The test server was stopped and its world removed; crystal background
+and client recipe-book presentation remain manual checks.
+
+## Lectern book stands
+
+`1.0.1.110-beta.1` adapts the root stand block/entity/conversion and final
+renderer transforms to 26.3 extraction/submission. It uses the shared lectern
+blockstate and lectern-drop loot table; no new art or stand item. Storage sync
+and persistence use ValueInput/ValueOutput. preRemoveSideEffects receives the
+old state and handles one stored-item drop; emptying before conversion back to
+vanilla prevents duplicate recovery.
+
+The existing book screens accept a stand source. A separate validated packet
+checks dimension, eight-block distance, loaded chunk, stand identity and exact
+book components before travel. Descriptive travel now shares the same helper
+for handheld/stand routes; only handheld books are detached/dropped. Linking
+travel uses the existing item service. Stand travel retains effects, Return Link
+configuration and Age-entry awards. Live views and exploration remain unported;
+unbound books require removal for handheld binding in this slice.
+
+Build and isolated server checks passed all facing/hand/book/page combinations,
+occupied/unrelated-item rejection, ownership on retrieval/break, stale/distant/
+wrong-dimension requests, serialization and full restart persistence. The test
+server was stopped and world removed. GUI/rendering/actual stand travel and
+modifier effects require the player's in-game check. Root 1.21.1 is unchanged.
+
+## Descriptive Book authored-page GUI
+
+`1.0.1.111-beta.1` adapts the root Legacy cover/front/full-right-page composition
+and page-index rules to GuiGraphicsExtractor. Glyphs use the existing glyph-only
+special item model in a later stratum at 128×128, avoiding the dynamic-blit and
+nested item-outline issues previously fixed in the Binder. Navigation uses SDL
+mouse constants and current KeyEvent helpers, corner hotspots and page-turn sound.
+The destination packet remains confined to the front spread; stand source
+validation is unchanged. Naming widgets stay hidden off the front spread even
+after resize. Screens do not pause the world.
+
+Added the root `book_author` component with persistent string and network codec.
+Binder and handheld descriptive binding assign the authenticated player's profile
+name; the client never supplies author text. Existing books without it use the
+unknown-author translation. Existing book_symbols retain written order, duplicates
+and omitted-controller choices exactly; no Age data or generation behavior changes.
+Random-Age glyph descriptions/live destination rendering remain unported.
+
+Build and disposable server checks passed real assembly, authorship, first/last
+symbol mapping, repeated-symbol and legacy-empty fallbacks, navigation bounds and
+full-restart book author/page persistence. Shared full-page texture was verified
+in the JAR. The temporary server was stopped and world removed. Client visuals,
+turning/input/sound, lectern opening and panel-click travel remain manual checks.
+
+## Animated link-panel fallback
+
+`1.0.1.112-beta.1` reuses the root LegacyDestinationPreviewRenderer spiral/noise
+algorithm in a shared 26.3 GUI extractor helper, removing placeholder labels from
+both book panels. Shared dimensions/hit-testing retain the existing 132×83 panel
+and validated hand/stand travel routes. GUI strata enforce cover -> animation ->
+Legacy frame ordering. Descriptive symbol pages do not expose an active panel.
+No world/network changes, dependencies, remote audio or chunk loads are introduced.
+Default teal is retained until destination metadata/tint is ported; this is a
+fallback, not live destination rendering. Build passed; client visual/click,
+lectern, scale and page-turn checks remain manual. No server run was required.
+
+## Linking Book spreads and artwork consolidation
+
+`1.0.1.113-beta.1` adapts LinkingBookScreen's two spreads, counter, wrapped
+left-page details, Return Link title suppression and input/page-turn behavior.
+The front retains validated hand/stand travel and the animated fallback; the
+final spread has no active destination panel. Vanilla dimension names translate;
+Age display-name metadata remains pending and other dimensions fall back to IDs.
+Block coordinates use floor-based BlockPos conversion, including negative values.
+
+Both screens use PortLegacyBookArtwork adapted directly from the root helper,
+with shared text/counter/corner routines. The descriptive screen retains its
+accepted glyph/author behavior. No networking, persistence or server changes.
+Build and diff checks passed; GUI presentation, controls, long names, lecterns
+and descriptive-page regression are manual checks. No server was started.
+
+## Saved destination names
+
+`1.0.1.114-beta.1` adds optional server-owned Age display metadata and the root
+persistent/networked `link_destination_name` item component. Successful book-driven
+Age creation saves the entered title; Linking Book binding snapshots its source
+Age's title, and automatic Return Links snapshot the departure label. Item tooltip
+and GUI use the same component/vanilla/ID fallback. Negative tooltip coordinates
+now floor correctly rather than truncating toward zero.
+
+The index name map defaults empty for old saves and does not participate in seed,
+folder or dimension identity selection. Names are visible only for active IDs;
+retirement retains metadata for identity/rollback without exposing it as an active
+Age. No catalog packet change, remote chunk load, automatic old-label migration
+or terrain change is introduced.
+
+Build and isolated server checks passed actual Binder name assignment, metadata
+with case/punctuation, named Linking/automatic Return Link components, legacy
+vanilla fallback, unload/reload and full-restart index/book persistence. Temporary
+config restored; server stopped and world removed. Client GUI/tooltip/lectern
+presentation remains manual. New names require a newly created Age and newly
+bound book; old Ages retain their existing fallback label.
+
+## Ordinary dropped books
+
+`1.0.1.115-beta.1` implements the 26.3 half of #114. A server-only queued join
+conversion creates the custom entity before discarding an ordinary book drop,
+preserving toss state and item data through native restoreFrom. It gives the
+replacement a new UUID (the original is still registered), adopts open-book
+lifetime/decay rules and skips already-custom entities. Canceled replacements
+preserve the ordinary source. No force-loading, world scanning or per-tick retry.
+Loaded ordinary book entities are also eligible.
+
+Build and isolated source/state checks passed, including cancellation recovery.
+The no-player fixture required one loaded entity chunk for inspection. The user
+requested to perform further checks; no additional automated restart test was run.
+Server stopped and temporary world removed. Manual checks: Q/inventory toss,
+death/Disarm, broken stand, full-inventory delivery/retrieval, open-book visual
+orientation, motion, ownership/pickup, component preservation and restart. Root
+1.21.1 remains unchanged and #114 stays open until both tracks are complete.
+
+## Handheld Link Panel resource policy
+
+`1.0.1.116-beta.1` adapts root WritingInkService and the configurable
+`writing.link_panel_ink_cost` (2 default, 1–16 allowed). The item delegates the
+server transaction to the service; Writing Desk cost reads also use its shared
+getter. Mixer cost remains independently fixed at one ink per Link Panel.
+Unsynchronized LOCAL config is not consulted for client affordability prediction;
+the server validates both inputs and constructs outputs before mutation.
+
+Build passed. No additional server fixtures were added; the user offered manual
+validation. Check default/custom cost, insufficient ink, final bottle, both hands,
+stacked/full-inventory inputs and dedicated-server cost differing from the client.
+Root 1.21.1 is unchanged; no commit/push/publication was performed.
+
+## Library discovery port
+
+`1.0.1.117-beta.1` ports MystcraftLibraryFeature from the 1.21.1 implementation,
+using the shared schematic/loot table and final five-stand orientation. Natural
+placement runs after all vanilla/authored decoration via the Age feature wrapper,
+with the same bounded footprint, candidate RNG/spacing, slope/footing and obstruction
+rules. The wrapper now applies to every runtime Age; Cave terrain disables libraries
+as in root. Existing chunks are not rewritten and vanilla Overworld generation is
+not modified.
+
+A separate saved writing map holds the original symbol list for AGE_ONLY loot,
+avoiding expansion of the already-large backend index record. Creation stores it
+before constructing/publishing the level; the wrapper captures an immutable list
+and serializes library flags/list in its codec. Reload reconstructs the same pool.
+LEGACY is the default; AGE_ONLY uses known distinct written IDs. Full random-page
+policy integration remains pending. The snapshot list does not alter generation
+traits or the book's original contents.
+
+Added operator placement, session-only spacing override, cheap candidate reporting,
+current-chunk probe/loot inspection and a locator restricted to loaded nearby chunks.
+The locator checks a clear, dry, footed aisle; it never performs a mass remote
+chunk-generation search. Explicit test placement checks empty space and entities.
+
+Build passed; shared schematic/Sealed Notebook loot packaging verified. Dedicated
+server startup passed. The user offered manual testing, so generation/loot checks
+were handed over before running them. Temporary server stopped and world removed.
+No new test fixture, commit or publication. This is a substantial discovery-system
+slice; instability/recovery, crystal portals and remaining optional integrations
+remain the other large parity gaps.
+
+
+## .118 crystal portal gameplay port
+
+The player confirmed .117 library generation and retracted the missing-library report.
+Ported the 1.21.1 Book Receptacle, bounded crystal flood/tension network, portal
+surface ownership and orientation, activation protection checks and rollback, removal
+cleanup, queued transport and cooldown. Reused existing crystal, portal and receptacle
+assets, recipe and progression node. The book renderer retains all final six mounting
+orientations and explicitly clears its extracted presence when the book is removed.
+
+Player traversal uses existing Linking/Descriptive Book paths, with portal audio
+precedence. Descriptive arrival resolution is now shared; no separate portal offset
+or generated exit position is introduced. Existing Intra-Linking, Disarm, momentum,
+client Age acknowledgement, Return Link configuration and progression remain in force.
+Non-player traversal uses modern TeleportTransition, collision/permission checks,
+and the same landing resolver. A shared Disarm helper supports container/horse/mob
+inventory and equipment without requiring the old protected-method mixin.
+
+Book and owner pointers use modern ValueInput/ValueOutput and update packets. Startup
+waits for loaded frame chunks; periodic bounded reconciliation retains root's cleanup
+of disconnected cells, staggered every 200 ticks per holder. The surface remains the
+animated facing-only fallback, tinted to the saved destination sky. Live portal views
+are still optional integration work, not advertised as ported.
+
+Build/resources and dedicated-server startup passed. A command-seeded 3x3 opening
+verified exact-coordinate entity transport, persistence and traversal after restart,
+and support-removal teardown/open-book recovery. Player interaction and client visuals
+are handed over for manual testing. Temporary server stopped/world deleted; no new
+permanent GameTest, commit, push or publication. Version: 1.0.1.118-beta.1.
+
+
+## .119 instability foundation and status-effect gameplay
+
+The player passed .118. Ported the complete five-deck catalog and deterministic
+provider selection from 1.21.1. Separate modern codec SavedData freezes new Ages'
+scoring contributions, seed, selected providers/levels and an enabled flag. Older
+Ages remain neutral. Creation-time scoring currently covers Bright Lighting,
+Accelerated, all three Corrupted sizes, ignored Cave weather/celestial modifiers,
+excess/biome-forced structures and additional suns. Original page indices are retained.
+Corrupted Pages now bind and contribute their Legacy costs; existing redacted rendering
+is reused. The new Abandoned Camps structure follows the same modern-structure costs.
+
+Adapted the bounded occupied-Age scheduler and the 18 local/global/general/hostile
+potion providers, preserving 1.21.1 defaults, effect durations, level-based amplifiers,
+sky exposure and Survival/Adventure targeting. The owned-instance lease system revokes
+only Rivencraft's effects on exit/disable/shutdown, preserving other sources. Runtime
+uses already-loaded chunks and shared per-Age work budgets; failed providers receive
+a temporary quarantine. The config retains server ownership and can disable providers
+without rerolling stored plans.
+
+OP-only `/rivencraft_port instability` supplies status/breakdown, persistent enabled
+control, session-only score override/reset and one-provider pulses. Pulse output tracks
+successful application separately from attempted work so event-cancelled effects are
+not reported as applied. No scoring data is sent to player book/Binder UI. Unimplemented
+hazards stay selected with an explicit status; they are never replaced or rerolled.
+
+Build/startup passed. Temporary dedicated-server checks verified neutral creation,
+provider selection at a test score, Poison application/duration, immediate owned-effect
+revocation, unrelated stronger-effect retention, local-versus-global roof behavior,
+enabled-state persistence and test-score reset across restart. Server stopped/world
+deleted; no new permanent GameTests, commit, push or publication. Manual checks cover
+authored Corrupted/Accelerated/lighting score contributions, automatic player-occupied
+scheduling, Survival/Creative policy, exit cleanup and hostile buffs. Version .119.
+
+Still pending: full writing grammar recovery/penalties, live block abundance, decay,
+lightning/explosions, meteors, burning and erosion, plus optional integration parity.
+
+
+## .120 colored decay gameplay
+
+The player passed .119. Ported the 1.21.1 DecayBlock, four provider handlers and bounded
+frontier persistence. Reused all four active 16x16 block textures/models and the
+protected-block tag. Modern adaptation uses BreakBlockEvent, Value/codec SavedData,
+ChunkPos accessors, loaded-chunk lookup and server-side magic damage for White.
+No decay item/recipe/drop is added.
+
+Provider metadata now distinguishes world-mutating handlers, so world_mutation gates
+decay independently of potion policy. Defaults remain enabled/four neighbor attempts,
+one successful conversion per call under the shared scheduler budget. Conversion
+hardness/air/color odds, infrastructure/BE/fluid/unbreakable protection, positioned
+fake-player claim events and placement rollback are retained from 1.21.1.
+
+The instability record adds an optional first resolved spawn, preserving old records'
+scores/plans and enable flags. Shared Descriptive Book landing resolution records it
+once; decay protects the same +/-4 horizontal and -2..+4 vertical region as root.
+Older Ages record this on the next book/portal arrival; OP status exposes the point.
+Frontiers and attempt counters live in each Age, capped at 1,024 positions per color.
+
+Added OP-only `/rivencraft_port instability decay <color> [1..32 attempts]`, reporting
+actual changes and nearby tracked positions. Existing generic pulses now report block
+as well as entity actions. Invalid input/out-of-Age commands use proper command errors.
+White block contact damage retains root's decay/world_mutation policy; disabling an
+Age scheduler stops spread but does not remove existing decay or alter its block form.
+
+Build/startup passed. All four colors seeded/spread through bounded command pulses.
+A full restart retained each frontier and advanced attempts from 32 to 40 while Red
+continued growing. Bedrock and water generated empty frontiers, and the saved Age
+disable blocked further provider changes. Textures verified 16x16. A stationary NoAI
+sheep did not exercise the stepping hook, so White stepping damage remains a player
+manual check, alongside visuals, arrival protection, normal scheduler/claim integration.
+Server stopped/test world removed; no permanent tests, commit, push or publication.
+Version: 1.0.1.120-beta.1. Other hazards, full writing recovery and live abundance
+profiling remain pending.
+
+
+## .120 release sign-off
+
+The user passed .120 and authorized commit, push and publication of the accumulated
+.116–.120 work. Both target builds passed. Consolidated release notes distinguish
+implemented libraries, fallback crystal portals and partial instability/decay from
+remaining gameplay and optional-integration parity. Tracking issues #98/#102/#104
+remain open; #114 still requires the matching 1.21.1 fix.
+
+
+## .121 lightning/explosion providers
+
+The player passed .120. Adapted the 1.21.1 hazard implementation, independent hazard
+scheduler lane, loaded-only ring candidates, Legacy aggregated rates, bounded explosion
+calculator, entity/Creative policy, protected-block/spawn checks and event guards.
+Modern differences: EntityTypes registry constants, explicit entity spawn reason,
+server damage API, gamerule registry, spatial fire-spread permission, BreakBlockEvent,
+and explosion damage exposure argument. Since Level.explode now returns void, the
+calculator retains its approved positions for bounded post-blast fire and records
+whether an uncancelled explosion actually began. Lightning dispatch also reports
+whether its entity was accepted. Existing optional mods are not required.
+
+Per-Age modern SavedData persists attempt count and separate hazard cooldowns (with
+the meteor field retained for the next provider port). Default config matches 1.21.1.
+Added OP `/rivencraft_port instability hazard lightning|explosions` to skip probability
+without bypassing cooldowns, loaded terrain, Age/config/provider policy or spawn
+exclusion. Console sources may supply dimension/position explicitly. Neither the
+command nor provider registration changes saved instability scores/decks.
+
+Version 1.0.1.121-beta.1 builds and starts a dedicated server. The user offered manual
+damage/block-destruction testing, so the temporary server was stopped before running
+those fixtures and the world removed. Effects, visual/audio behavior, damage/block
+caps and policy/restart checks are handed over; they are not reported as tested.
+No new permanent GameTests, commit, push or publication. Meteor, burning, erosion,
+crumble, full grammar recovery and live material profiling remain pending.
+
+
+## .122 meteor provider
+
+The player passed .121. Extracted the meteor-specific portion of the existing 1.21.1
+AgeEnvironmentalProviders into a focused modern provider. The effect remains the
+30-tick flame/smoke flight and roar followed by a strength-3 bounded impact, without
+inventing a new rendered entity. Natural chance, randomized chunk/central coordinates,
+48-block descent height, headroom/spawn checks, 200-tick cooldown, one active flight
+per Age and 16 active Ages retain the root values.
+
+The selected card uses an independent scheduler pass, sharing the existing hazard
+candidate ring and saved attempt/cooldown data. The impact reuses the .121 blast
+guards with meteor-specific config (24 blocks, eight entities, 12 damage by default).
+Event handlers cancel active flights on disabled policy, absent players, unavailable
+target chunk, Age unload or shutdown; session-only descent state is not replayed.
+Modern changes use loaded ChunkPos accessors, max-Y API and codec SavedData already
+ported for hazards. No optional mod dependency or new asset was introduced.
+
+Added OP `/rivencraft_port instability meteor`, bypassing chance only. Status reports
+meteor config distinctly from potion policy. The original roar is verified in the
+built JAR. Version 1.0.1.122-beta.1 builds; effects, damage/protection, cooldown and
+cancellation/restart behavior are delegated to the player's manual testing as offered.
+No server/test world was launched, no permanent test added, and no commit/publication.
+Burning, erosion/crumble, full grammar recovery and live material profiling remain.
+
+
+## .123 burning and erosion
+
+The player passed .122. Extracted/adapted the 1.21.1 burning/erosion handlers into a
+focused provider class, retaining bounded candidate scans, seeded attempt sequence,
+independent scheduler budgets and protection/event logic. Burning keeps the active
+Legacy card, sky exposure, Survival/Adventure targeting, four targets per pass and
+4..12-second duration. The manual pulse targets the player and uses modern water/rain
+checking rather than the removed isInWaterRainOrBubble API.
+
+Erosion stays absent from the Legacy deck, with the prior requested testing default
+of enabled at >=10,000 current instability. It converts at most one eligible sampled
+block to an adjacent above/horizontal source fluid. Current score resolves creation
+contributions or an explicit session override; live profiling is not yet claimed.
+The pulse requires a real aimed block within six blocks and the same threshold and
+mutation/protection policy. Modern BreakBlockEvent and snapshot placement rollback
+are reused. Provider status distinguishes these controls from potion policy.
+
+Added OP `/rivencraft_port instability environment burning|erosion`. No scores/plans
+are changed by provider registration or test pulses. Config names/defaults match the
+1.21.1 scorching/erosion sections. Version 1.0.1.123-beta.1 builds; visual/damage/fluid,
+exemption, policy and natural scheduling checks are handed to the player. No temporary
+server/world or permanent fixtures were created; no commit/push/publication.
+
+
+## .124 live material profiling
+
+The player passed .123. Crumble has no active 1.21.1 handler, so it remains explicitly
+unavailable. Ported AgeBlockInstability and modern per-dimension profile SavedData,
+using the same 401/500 readiness thresholds, 1,024 sample cap, watched/native/modded
+weights, 5% Overworld allowance, 100,000-point cap and difficulty scaling. Registry
+material eligibility reuses the Page pool rules; common ore/storage tags use modern
+BlockItems tag accessors. Installed content remains optional; exact weight overrides
+retain the existing root syntax and validation.
+
+Deferred chunk-load sampling processes four entries/tick with a bounded queue. Spawn
+completion requests one chunk per second across occupied profiling Ages and their
+baseline, with at most one request in flight. The off-thread getChunkFuture path was
+verified in the local 26.3 source to avoid main-thread managedBlock. Completion checks
+server stop/level identity. Existing sampled chunks are not recounted. Effective
+provider plans now combine live points and frozen writing, cache stable totals/seeds,
+and retain the original saved plan. Old neutral Ages stay excluded. OP status shows
+progress/totals and session override reset restores the live effective plan.
+
+Version 1.0.1.124-beta.1 builds and starts a dedicated server. Real chunk-load sampling
+persisted 25 snapshots and counted a fixture Diamond Block. A bounded restart test
+used synthetic sample records, plus resumed actual loads: 423 Age / 522 baseline
+samples yielded 2,987 live points (independently calculated), a frozen writing score
+of zero and live selected providers. Override reset restored that plan. No hundreds-
+of-chunks generation test was run; occupied-Age background generation and generated
+material/modded/config checks are delegated to the player. Server stopped and world
+removed. No permanent fixtures, commit, push or publication.
+
+
+## .125 ordered controller recovery
+
+The player passed .124. Added semantic-role metadata to the port symbol index and
+a focused recovery pass for singular-controller duplicates/conflicts, category
+order, Native-with-biomes and Single-with-extra-biomes. Last singular choice wins;
+Single retains the first biome; Native drops authored biome choices. Duplicate or
+conflict diagnostics contribute 500 points and order diagnostics 100, following
+the corresponding 1.21.1 grammar rules. Costs retain original page indices.
+
+Binder support and server terrain/environment selection share recovered choices.
+Original book/library pages, color boundaries and celestial-chain indices remain
+intact; raw number/celestial validation and all unimplemented-page guards still
+apply. Missing biome registry entries are checked even if recovery would discard
+the page. Ambient Color has its own stage and is not a singular lighting choice.
+Existing Ages are unchanged. This is the first recovery slice, not completion of
+celestial/dangling/material grammar recovery or season integration.
+
+Version 1.0.1.125-beta.1 builds; 13 temporary focused checks pass, covering recovery,
+costs, preserved chains and rejection boundaries. No server/test world or permanent
+fixtures. In-game last-choice behavior, original-page retention and OP diagnostics
+are delegated to the player. No commit, push or publication.
+
+
+## .126 ordered celestial and number recovery
+
+The player passed .125. Ported the 1.21.1 grammar treatment of pending celestial
+modifiers and numeric adjacency. Repeated Length/Phase/Angle/Size/Direction pages
+before a celestial use the final value of that kind without a duplicate penalty.
+Only the final unconsumed modifier of each kind adds 100 dangling-modifier points.
+A number without an immediately following supported Color/Length/Phase/Angle/Size
+page adds 100 points (misplaced, or dangling at the end). Consecutive numbers leave
+only the last available for the next target. Colors still mix in written order.
+
+These defects no longer block binding. Numbers and celestial compilation retain
+the original page sequence and seeded color indices; controller recovery never
+moves a number next to a new target. A trailing modifier cannot rewrite an earlier
+body, including the optimized single-body compilation path. Missing celestial
+branches retain their existing seeded completion; dangling controls do not apply
+to those generated bodies. All original book/library pages remain. Unsupported
+pages and the ten-sun/ten-moon limit still block binding; existing Ages are unchanged.
+
+Version 1.0.1.126-beta.1 builds. Seventeen temporary focused checks passed, covering
+last-value selection, dangling costs/indices, numeric adjacency, per-body isolation,
+seeded color stability, valid numbered writing, body limits, unsupported pages and
+cycle codec round-trip. No server/world or permanent test fixture was created.
+Manual validation: bind a book with Half Length, Double Length, Sun and verify the
+last length; bind Sun followed by Large Size and confirm it does not resize that
+sun. Test a trailing Number page and inspect the added writing contribution with
+`/rivencraft_port instability status`. Original pages should remain visible.
+No commit, push or publication.
+
+
+## .127 Link Modifier station: title and core link properties
+
+The player passed .126. Started the missing 1.21.1 Link Modifier station port,
+reusing its block model, textures, horizontal facing variants and Legacy 176x166
+single-book GUI. The item is available in the main creative tab or via
+`/give @s rivencraft:link_modifier`; it has no crafting recipe. As in 1.21.1,
+creative acquisition does not impose a new permission restriction on ordinary
+book edits once the station has been placed.
+
+One persistent slot accepts Linking and Descriptive Books, including unbound
+books, with normal and shift-click transfers. The server menu handles renaming
+and Disarm, Maintain Momentum and Intra Linking toggles. Descriptive Books cannot
+toggle Intra Linking, which only governs same-dimension Linking Book travel.
+Existing target, author, symbols and Age identity are retained. Renaming changes
+the item's custom title, not the Age's saved folder/registry identity. Removing
+the title restores the item's normal name. Text editing consumes inventory/hotbar
+shortcuts while focused; Escape closes the screen. Programmatic text refreshes do
+not send rename packets. Menu identity, owner, distance and live station checks
+protect edits; unknown button IDs and non-book inputs are rejected.
+
+The book is saved with modern ValueInput/ValueOutput container serialization.
+Station removal uses block-entity preRemoveSideEffects to release the stored book
+once, including non-player removal. No tick handler or renderer is needed.
+
+This is a station slice, not full Link Modifier parity. Seed editing, Age retirement,
+Relative Link, Intra-Linking Only and platform overrides remain unported and are
+not presented as working controls. Existing core flag behavior is reused unchanged.
+Manual validation: place the station in multiple orientations, insert/shift-click
+both book types, rename using text containing E, toggle each available property,
+remove the book and use it to check travel effects. Confirm Descriptive Book Intra
+Linking is unavailable, restart with a book left in the station, and break a loaded
+station to recover one book. Build and dedicated persistence results are recorded
+below. No commit, push or publication.
+
+Version 1.0.1.127-beta.1 builds. Packaged model, GUI, texture, item definition,
+loot table and localization checks passed; no station recipe is included. A
+fresh dedicated server placed the station and serialized a named Linking Book
+with all three core flags. Restart retained the same book/name/flags and station
+removal completed normally. The first harness run expected the wrong wording
+for vanilla force-load cleanup; the corrected harness completed successfully.
+Both temporary worlds were deleted and servers stopped. No permanent tests were
+added. UI interaction, transfer counts and modifier travel effects await the
+player's in-game check.
+
+
+## .128 six Link Modifier controls
+
+The player reported that .127 exposed only three of 1.21.1's six controls. Added
+the remaining Intra-Linking Only, Relative Link and Generate Platform controls in
+the existing two-column, three-row Legacy layout, with matching bit values and
+server-owned menu actions. Enabling Intra-Linking Only enables Intra Linking too;
+disabling Intra Linking clears Intra-Linking Only. Both intra controls are disabled
+for Descriptive Books. Unknown actions and out-of-range menu edits remain rejected.
+
+Linking Book Intra-Linking Only blocks cross-dimension travel. Relative Link uses
+the traveller's block offset from the source world's spawn, applied to destination
+spawn, preserving destination yaw/pitch. Normal links retain their precise bound
+coordinates. Player and non-player portal travel share the new flags and relative
+coordinate helper. Descriptive relative arrivals still require proper footing.
+
+Generate Platform is off by default for Linking Books. When enabled, a successful
+link fills one missing floor block with cloud platform only if the block two above
+the arrival is air, matching the 1.21.1 helper. Existing floors are retained.
+Descriptive Books instead default to enabled and use Disable Platform internally;
+turning it off prevents fallback platform creation and refuses travel if no footed
+landing is available. Receptacle tint preparation respects that setting too.
+New flags serialize in the shared component and appear in book/panel tooltips.
+Existing three-flag books remain valid. Seed editing and Age retirement remain
+separate, unfinished station work.
+
+Version 1.0.1.128-beta.1 builds. A temporary dedicated-server fixture passed 19
+checks: menu actions/dependencies, descriptive intra rejection, numeric flag codec,
+relative offsets, platform-off/default behavior, platform placement/preservation,
+invalid input and remote edit protection. It did not perform real client travel.
+The test server stopped and its world/fixture sources were removed. The production
+JAR is rebuilt without that fixture. Manual checks: all six buttons and tooltips,
+same/cross-dimension Intra-Linking Only, Relative Link offsets, and platform on/off
+for both book types (including a new Void Age without footing). No commit, push
+or publication.
+
+
+## .129 Link Modifier mouse input repair
+
+The player reported that none of the six controls responded. Confirmed the
+26.3 input constants in the local Minecraft artifact: left/middle/right are
+1/2/3, while the custom Link Modifier handler checked the old left-button value
+0. Its server actions therefore passed the prior direct-menu fixture while
+real mouse clicks never sent an action.
+
+Replaced the manually drawn/clicked areas with six registered Minecraft Button
+widgets at the same Legacy positions. Their callbacks send the existing validated
+menu action IDs, and their custom rendering retains the square controls. Native
+input provides correct mouse mapping, focus, click sound and keyboard activation.
+All six tooltips expose their On/Off state; unavailable Descriptive Book intra
+controls remain disabled. Tooltip objects update only when state changes so their
+hover delay is not reset every tick. Book mutations/travel code is unchanged.
+
+Version 1.0.1.129-beta.1 builds. The native widget's left-button mapping and callback
+dispatch were verified in the local Minecraft bytecode. No client click test or
+new server run was performed; the previous 19 checks covered server actions, not
+client input. Please click each option with an inserted Linking Book and verify
+its selected shading and tooltip/book properties change, then repeat supported
+options with a Descriptive Book. No commit, push or publication.

ports/mc263/README.md

@@ -2,15 +2,18 @@
 
 This is an **experimental beta port** for issues #97–#104, not gameplay parity
 with the Minecraft 1.21.1 release. The 26.3 backend persists separate Ages and
-their seeds. Books, the Book Binder, Ink Mixer, Writing Desk and page collections
+their seeds. Books, lectern book stands, the Book Binder, Ink Mixer, Writing Desk and page collections
 are ported, and the Binder can
 author Standard, Amplified, Island, Flat, Void, or Cave terrain with supported
 biome-distribution pages, selected material/vegetation/structure features, and
 independent Age weather and lighting, multiple authored or seeded celestial
 bodies and eclipses, biome/material completion, and random features/structures.
-Instability, crystal portals, remaining discovery/stations, writing recovery and optional
-integration parity remain unfinished. The latest published beta is
-[1.0.1.106-beta.1](RELEASE_NOTES_1.0.1.106-beta.1.md).
+Crystal portals and libraries are ported. Instability scoring/provider selection,
+status effects, colored decay, lightning, explosions, meteors, burning and erosion,
+ordered writing recovery, live material profiling and all six Link Modifier controls are now ported.
+Link Modifier seed editing/retirement, remaining discovery/configuration and optional
+integrations remain unfinished. The latest published beta is
+[1.0.1.129-beta.1](RELEASE_NOTES_1.0.1.129-beta.1.md).
 Use a test world and keep a backup; do not
 substitute this JAR for the 1.21.1 mod or import 1.21.1 saves.
 
@@ -1646,6 +1649,34 @@ Recipe/advancement data loaded; shared models and atlases were verified in
 the JAR. No client joined these fixtures: visuals, mouse and live catalog
 updates remain the in-game check. The server was stopped and world removed.
 
+### Progression advancements
+
+The local `1.0.1.107-beta.1` slice reuses the 1.21.1 progression tree and
+translations. The root, Page and Linking Book inventory milestones load along
+with action milestones for taking a Link Panel from the Ink Mixer, copying a
+Page at the Writing Desk, binding an Age in the Book Binder and successfully
+travelling by book into a registered Age. Both normal and shift output pickup
+paths award after the server consumes the inputs. Opening a menu, viewing a
+preview or rejected travel does not earn an action milestone. Awards remain
+per-player and use vanilla advancement persistence. No retroactive action
+awards are inferred from existing books. The portal advancement is deferred
+until the Receptacle/portal feature and its icon item are ported.
+
+The build and disposable-server checks passed advancement decoding, empty and
+preview Mixer negative checks, normal/shift Panel pickup, actual Desk copying,
+Binder assembly and registered-Age entry eligibility. Fixtures use vanilla
+PlayerAdvancements because NeoForge FakePlayer deliberately discards awards.
+The temporary server was stopped and its world deleted. Client tree layout,
+toasts, inventory milestones and actual book-travel awards remain manual checks.
+
+For the in-game check, open Advancements and find the Rivencraft tree. Obtain a
+Page and Linking Book; then take a Panel from the Mixer, copy a Page at the Desk,
+bind a Descriptive Book and enter its Age. Check that previews alone do not award
+progress, then reconnect/restart to confirm earned progress remains. If these
+milestones were already earned, revoke the Rivencraft tree with the vanilla
+operator advancement command before retesting. Include shift-click output pickup.
+Nothing has been committed, pushed or published for this slice.
+
 From the repository root:
 
 ```sh
@@ -1667,3 +1698,836 @@ The dedicated development server uses `build/run-server`, with its own world
 and properties. Set a nonconflicting `server-port` there before running if
 another Minecraft server is active. The prototype restores all indexed Ages
 during the Overworld load, before initial chunk preparation completes.
+
+The `1.0.1.108-beta.1` visual correction adapts the advancement root background
+to 26.3's ClientAsset resource identifier (`minecraft:gui/advancements/backgrounds/stone`).
+The older full texture path decoded but resolved to a missing texture. The shared
+1.21.1 root keeps its original path. Check the stone background in the client.
+
+### Crystal advancement background and recipe discovery
+
+The local `1.0.1.109-beta.1` slice switches the progression background to the
+existing blue Crystal Block texture (`rivencraft:block/crystal_block`) using
+the 26.3 ClientAsset identifier format. No new artwork is generated.
+
+The Ink Vial, Ink Mixer, Book Binder and Crystal Block now receive their 1.21.1
+recipe-book discovery advancements. Black Dye unlocks the vial, a Glass Bottle
+unlocks the mixer, an Iron Ingot unlocks the binder, and a Crystal Shard unlocks
+the block. As with the already-ported Notebook and Writing Desk, 26.3's
+`recipe_unlocked` condition uses a `recipes` list instead of the older `recipe`
+field. Recipe ingredients and outputs are unchanged; no Blank Page recipe is added.
+
+Build and disposable-server checks passed all six loaded crafting unlocks:
+wrong material stays locked, obtaining the matching material unlocks the recipe,
+progress remains per-player, and granting the recipe directly completes its
+advancement. The test server was stopped and its temporary world removed.
+The player passed the preceding progression/background correction; this crystal
+background and client recipe-book discovery still need an in-game check. Use
+Survival and a fresh recipe book (or revoke the relevant recipe/advancement)
+when testing the four newly ported unlocks. Nothing is committed or published.
+
+### Lectern book stands
+
+The local `1.0.1.110-beta.1` slice ports the 1.21.1 lectern conversion and
+book/page display. Place a Rivencraft book or Page on an empty vanilla lectern;
+the stand keeps its facing and consumes one item in Survival (Creative retains
+its held stack). Vanilla occupied lecterns are not replaced. Shift-right-click
+with an empty hand retrieves the stored item and restores a vanilla lectern.
+Breaking drops one lectern and its stored item. There is no separate stand item
+or new crafting recipe.
+
+The extracted renderer reuses vanilla lectern geometry, existing book textures
+and the final 1.21.1 Page orientation, including east/west yaw corrections. Books
+show their name above the stand; Pages have no hover label. Empty-hand use opens
+the current port book GUI. Clicking the destination panel travels while leaving
+the book on its stand. Disarm/Maintain Momentum, same-dimension Linking Book
+restrictions, successful-Age advancements and configured Return Links use the
+existing travel logic. Handheld travel still drops the active book at departure.
+Unbound books can be displayed; retrieve and bind them in hand for this slice.
+Live previews and exploration remain later port work.
+
+The stand packet includes the source dimension, position and displayed ItemStack.
+The server checks distance, loaded source chunk, stand identity and exact current
+book contents before travel, rejecting removed/replaced books or stale screens.
+No chunk is loaded just to inspect a remote stand. Book storage uses 26.3
+ValueInput/ValueOutput, update tags and packets. The modern block-entity removal
+hook receives the old state, so the stored item is dropped there once; retrieval
+empties it first to prevent duplicate drops.
+
+Build and disposable-server checks passed conversion/retrieval for all four
+facings, both hands and all three item kinds; occupied-lectern/unrelated-item
+rejection; distant/wrong-dimension/replaced/removed-source rejection; exact break
+drops; component serialization; and named-book persistence across full restart.
+The server was stopped and its world removed. Client checks: display/orientation
+in all facings, names above books only, empty-hand GUI opening, panel-click travel
+for both bound book types, retention at the departure stand, modifier effects,
+Shift retrieval and break drops. Also restart with a loaded stand. Nothing has
+been committed, pushed or published for this slice.
+
+### Descriptive Book author and written pages
+
+The local `1.0.1.111-beta.1` slice brings the authored-book layout closer to
+1.21.1: Legacy gilded cover, front name/author on the left and destination panel
+on the right, followed by one authored glyph page at a time on the right. It
+reuses `bookui_rpage_full.png` and the existing runtime glyph item pipeline;
+no new artwork or per-symbol PNGs are generated. Bottom corners and left/right
+arrow keys turn pages with the vanilla page-turn sound. Only the front page's
+panel activates travel, including when opened from a stand. Escape still closes
+the GUI, and focused naming fields retain text input behavior.
+
+The server records the player's profile name in the persistent/networked
+`book_author` component when binding through the Binder or the temporary handheld
+binding flow. Existing books retain their saved ordered `book_symbols`; older
+books with no author show the shared unknown-author text. Page zero is the front
+spread, followed by each saved symbol in order (including repeated IDs). Books
+with no symbols retain the Legacy blank final spread. Inferred generation pages
+are not inserted into authored contents. The current destination placeholder
+remains; live snapshots and the pageless random-Age glyph description remain
+future port work.
+
+Build and disposable-server checks passed real Binder author assignment, ordered
+symbol indexing, repeated-symbol presentation, navigation bounds, older/panel-only
+fallback and book author/page persistence across full restart. The server was
+stopped and temporary world deleted. Client checks: bind a new book with several
+distinct pages and verify your name, cover/layout, glyph size/no extra item outline,
+corner/arrow turns, sound, Escape, GUI resize and travel only from the front panel.
+Repeat opening the book from a lectern. No commit, push or publication was made.
+
+### Built-in animated link panels
+
+The local `1.0.1.112-beta.1` slice ports the 1.21.1 Legacy fallback animation to
+both book GUIs. Two noisy teal spirals expand into the panel using the shared
+GUI renderer, replacing the static placeholder and instructional text. Rendering
+and clicking share the same panel bounds. Separate GUI strata keep the cover,
+animation and Legacy frame in order. Descriptive Books display the animation only
+on their front page; clicking written pages does not travel. The animation keeps
+running while the book is open and does not pause the world, load destination
+chunks or render/audio-tick a remote world. Lectern books use the same animation.
+
+This is the existing mod-independent fallback, not a live snapshot or a new shader.
+It currently uses the fallback's default teal tint; destination-specific tint and
+live renderer integrations remain unported. The GUI API and outline method were
+adapted; the root spiral/noise math, timing and reveal are unchanged.
+
+The build passed. No server behavior or packet schema changes were made and no
+test server was needed. Check animation/reveal/frame in both books, at different
+GUI scales and on lecterns; panel clicks should still travel, Escape should close,
+and descriptive page turning should keep working. Nothing committed or published.
+
+### Linking Book final spread and shared artwork
+
+The local `1.0.1.113-beta.1` slice adapts the remaining Linking Book layout
+from 1.21.1. Its front spread uses the plain Legacy cover, animated right panel,
+and wrapped/shadow-free text on the left. It shows the bound title, destination
+dimension and floored block coordinates. Vanilla dimensions use translated names;
+other dimensions currently use their registry IDs until saved Age display-name
+metadata is ported. Automatic Return Links suppress the redundant title by its
+translation identity, matching root behavior.
+
+The blank final spread, 0/1 counter, bottom-corner and arrow navigation and
+page-turn sound are now present. Binding widgets hide on the final spread and
+remain hidden after resizing. Escape closes even with naming focused; focused
+text inputs consume inventory/hotbar keys. Only the front panel can travel,
+including books opened from a stand.
+
+Both book screens now share an extractor adaptation of root LegacyBookArtwork,
+plus wrapped-text, counter and corner-hit helpers. The descriptive gilded cover,
+author and symbol pages are retained. This removes duplicated atlas composition
+without changing packets, saved data, Age generation or destination coordinates.
+The build passed; no server run was needed for this client-only change. Check
+long titles, Overworld/Nether/End destination text and negative coordinates,
+front/final turning/sound, resize/Escape/naming, lectern opening and front-only
+travel. Recheck descriptive glyph pages after the shared-artwork refactor.
+Nothing committed, pushed or published.
+
+### Saved Age and Linking Book destination names
+
+The local `1.0.1.114-beta.1` slice ports the root destination-name snapshot.
+New Ages save the entered title, preserving case/spaces/punctuation, separately
+from their existing dimension ID, folder and seed. New Linking Books bound inside
+those Ages store that title in `link_destination_name`; the front GUI and tooltip
+share the same name resolution. Vanilla dimensions keep their familiar names.
+Automatic Return Links capture the departure dimension's saved name when available.
+
+The optional display-name map defaults empty for older indexes. Older books/Ages
+without metadata retain translated vanilla names or raw dimension IDs; no names
+are inferred from inventory books or folder names. This does not rename folders,
+rewrite old book labels, change collision suffixes, or reroll any generation.
+Labels on existing bound books remain snapshots as in root. Names retained with
+retired identities remain unavailable through active-Age lookup and survive a
+failed-retirement rollback. Tooltip coordinates now use floor-based BlockPos
+conversion, matching the GUI for negative values.
+
+Build and disposable-server checks passed real Binder creation/name assignment,
+case/punctuation preservation, Linking/automatic Return Link labels, older vanilla
+fallback, Age unload/reload and full-restart persistence of Age metadata and book
+components. The temporary Return Link test config was restored, and the server
+was stopped/world removed. Client check: create a new named Age, enter it, bind
+a Linking Book there, and inspect its destination in the GUI and tooltip (including
+on a stand). Recheck after restart; optional Return Links should show the departure
+name when enabled. No commit, push or publication was made.
+
+### Universal open-book drops (26.3 half of issue #114)
+
+The local `1.0.1.115-beta.1` slice converts ordinary dropped Linking and
+Descriptive Books into the existing open-book entity, including unwritten
+variants. A server-only join listener queues one conversion after entity/chunk
+registration; it does not scan worlds or force-load chunks. Existing custom
+book entities and non-book items are skipped. The source must actually be
+registered and still present before conversion, and is discarded only after
+replacement succeeds. Rejected replacements leave the ordinary drop intact.
+
+The factory uses native entity-state copying and preserves ItemStack components,
+position, motion, facing, pickup delay, owner/thrower and ordinary entity metadata.
+It does not apply the handheld travel constructor's Y offset or zero velocity.
+The replacement receives a new UUID so both can coexist during the transaction;
+its lifetime switches to the existing open-book decay/weather rules. Existing
+ordinary books loaded from disk also use the join hook. No per-tick retry is used
+if another mod cancels conversion; those drops are eligible on a later reload.
+
+Build and disposable-server checks passed state/component/owner copying and
+ordinary item, player, container and stand-drop conversion, custom-entity recursion
+avoidance, non-book exclusion and cancellation recovery. A no-player fixture's
+entity chunk became unavailable to the first query; temporarily loading that
+single fixture chunk made the checks pass. No storage stall occurred. The player
+offered to perform the remaining validation, so no further automated restart run
+was started. Server stopped and world removed. Shared issue #114 remains open:
+1.21.1 implementation and manual client validation are pending. Nothing committed
+or published.
+
+### Configurable handheld Link Panel ink cost
+
+The local `1.0.1.116-beta.1` slice ports root WritingInkService and its
+`writing.link_panel_ink_cost` option in `config/rivencraft-local.toml`.
+The allowed range is 1–16, default 2. Preparing a baseline Link Panel by hand
+consumes one Paper and that many ink units; insufficient ink changes neither
+input. A drained vial returns a vanilla Glass Bottle. Stacked inputs and
+inventory-full give/drop behavior retain the root transaction rules. The
+Ink Mixer still consumes exactly one ink unit and one Paper per panel, separately
+from this setting. Writing Desk symbol-copy cost uses the shared service getter.
+
+Handheld client prediction checks only eligible item types and a valid nonempty
+vial; the server uses its own configured cost to accept/refuse and consume inputs.
+This avoids relying on unsynchronized LOCAL config for client affordability.
+No new recipe, packet, Page variant or progression award is introduced.
+
+The build passed. Following the player's offer to do testing, no test server
+or new fixtures were started for this small resource-policy port. In game, check
+two ink per panel by default; then set `link_panel_ink_cost = 4` under `[writing]`
+and restart to check four ink per panel, insufficient-ink refusal, last-use bottle,
+both hands and stacked/full-inventory cases. Confirm the Mixer still costs one
+ink. On a dedicated server, change the server's value; the client need not match.
+Nothing committed, pushed or published.
+
+### Age library discovery
+
+The local `1.0.1.117-beta.1` slice ports the 1.21.1 library discovery system:
+the existing 11×11×11 schematic, five stocked lecterns, chest loot, deterministic
+32-chunk-region spread and the terrain/obstruction checks. Libraries generate
+at the end of decoration in newly generated, non-Cave Age chunks. The footprint
+stays inside its candidate chunk. Trees/foliage can be cleared, while fluids,
+block entities, solid obstructions, excessive slopes and absent sturdy footing
+reject placement. Vanilla Overworld generation is unchanged. Old chunks are
+not revisited; existing Ages gain libraries only in eligible new chunks.
+
+`[libraries] loot_mode` in `config/rivencraft-local.toml` defaults to `LEGACY`:
+writing supplies and possible Sealed Notebooks in chests, with random symbol
+Pages on five lecterns. `AGE_ONLY` limits new library chest/lectern Pages to
+known symbols written into that Age, using distinct IDs. Page-free Ages then
+have no symbol loot and the stands display ordinary Books, matching root.
+The original written list is saved independently and copied into the generator
+before generation, then restored on reload. It does not change the book's writing,
+seed, folder or other trait completion. Older Ages without this saved list have
+an empty Age-only pool. The broader random-page eligibility policy remains a
+separate unported system. The Legacy pool may include currently unsupported red
+pages, like the existing Sealed Notebook pool.
+
+Operator tools under `/rivencraft_port library`:
+- `test_place`: place a raised library in clear space ahead, without overwriting
+  existing blocks/entities. A console source may supply position via `execute`.
+- `nearest_loaded`: teleport into the nearest marked library aisle in loaded
+  chunks within 16 chunks. It checks footing/fluids/collision and does not scan
+  or generate remote chunks.
+- `test_spacing 1` through `32`: session-only increased candidate density in an
+  Age, for new chunks only. `32` restores normal spacing; restart clears overrides.
+- `candidate`: report the closest deterministic candidate without loading it;
+  eligibility is still required and a library is not guaranteed.
+- `probe`: identify a marked library or explain current-chunk placement rejection.
+- `inspect_loot`: materialize the current chunk's library chest as opening it would,
+  then print contents and the number of stands in that chunk.
+
+Build passed and the schematic/loot resources were verified in the JAR. A local
+dedicated server started with the data; at the player's request it was stopped
+before generation/loot tests. Its world was deleted. The player will check actual
+natural placement, five lectern pages and orientation/retrieval, chest loot/Sealed
+Notebook opening, both loot modes, locator/test tools and persistence after restart.
+No new GameTest fixtures were added. No commit, push or publication was made.
+
+
+## Beta .118 — crystal portals and Book Receptacles
+
+The player confirmed natural library generation in .117; the earlier missing-library
+report was withdrawn. .118 adapts the complete fallback crystal network from 1.21.1:
+
+- Book Receptacles mount on any of the six faces of Crystal Blocks, with the final
+  1.21.1 model/book orientations. Eight Crystal Blocks surrounding an empty crafting
+  square craft one receptacle; its recipe unlocks on obtaining a Crystal Block.
+- Insert a bound Linking or Descriptive Book into a valid connected crystal frame.
+  The Legacy tension/flood algorithm accepts supported irregular openings, using
+  the same 16-block radius, 2,048-crystal and 1,024-surface limits. Placement respects
+  NeoForge protection events and rolls back rejected activation.
+- Empty-hand interaction removes the book and closes the portal. Breaking its
+  support or holder closes it and drops the book as the recoverable open-book entity.
+- Player travel delegates to the existing book transport, catalog acknowledgement,
+  safe landing, Link Panel effects and configured Return Link handling. Descriptive
+  Books share the exact same landing resolver with portals. Linking Books retain
+  their exact coordinates, facing and same-dimension Intra-Linking requirement.
+- Non-player transport uses the same target rules, collision checks and momentum
+  rotation. Disarm refuses loose items and leaves container contents/eligible mob
+  equipment behind. The shared Disarm helper also replaces the player-only loop.
+- Queued collision travel waits until the entering movement packet is complete.
+  A 40-tick session-only cooldown prevents repeated traversal. Portal owner pointers,
+  the one stored book, and destination sky tint persist and synchronize to clients.
+  Startup waits for required frame chunks before repair. Loaded networks receive a
+  staggered bounded maintenance pass every 200 ticks, without generating chunks.
+- The animated fallback only renders its two facing surfaces. Its tint follows the
+  destination sky, including authored colors and the 1.21.1 Nether/End palette.
+  Optional live destination views remain part of the integration port; installing
+  another portal mod alone does not hide this fallback.
+- Successful activation awards the restored Open Portal advancement.
+
+Validation: build and dedicated-server startup passed. A small command-seeded
+crystal ring verified persisted book/owner data, entity collision travel to exact
+saved coordinates before and after a full server restart, and removal/drop cleanup
+when the support was broken. This was not a substitute for player-driven activation:
+the player should test book insertion/removal, the six model orientations, both book
+types and their Link Panel effects, survival/creative item handling, frame edits,
+reopening after restart, and travel with destination chunks initially unloaded.
+The temporary server was stopped and its world deleted. No new permanent GameTests,
+commit, push or publication.
+
+
+## Beta .119 — saved instability and status-effect providers
+
+The player passed .118 crystal portal testing. This slice begins the major instability
+port using the 1.21.1 scoring rules, complete Legacy card catalog, deterministic deck
+selection, bounded scheduler and potion-provider implementation.
+
+New Ages save creation-time contributions and selected provider IDs/levels in separate
+Overworld SavedData (`rivencraft/instability`), alongside an independent enabled flag.
+Creation saves this with the Age identity before catalog publication. Reload and
+configuration changes do not reroll the frozen plan. Older Ages remain neutral rather
+than being rescored. No score or provider detail is added to player books or Binder UI.
+
+The first scoring set includes Bright Lighting (+500, also when seed-completed),
+Accelerated (+1,000 each), Corrupted Medium (+1,000), Small (+2,000) and Large (+0),
+Cave-ineffective weather/celestial modifiers (+100 each), structure occurrences after
+the first three (+100 each), authored structures forced into non-native biomes (+100
+per occurrence), and growing costs for the third and later suns (+1,000, +2,000, ...).
+The same structure policy includes the new 26.3 Abandoned Camps page. Corrupted Pages
+are now implemented in authoring/creative availability; they retain animated redacted
+text and supply instability rather than a terrain decoration.
+
+All five Legacy decks and card costs/copy counts are retained. Scoring rounds down to
+500 before selecting/shuffling from the Age seed. Unported hazard cards remain selected
+and are reported as unavailable; no replacement reroll biases the deck toward potions.
+Writing-recovery penalties, live valuable-material profiling, decay, lightning,
+explosions, meteors, burning and erosion remain later slices. This is not yet full
+instability parity, and the existing authoring validation rules still apply.
+
+Implemented providers: local/global Blindness, Mining Fatigue, Hunger, Nausea, Poison,
+Slowness, Weakness and Wither, plus global hostile Regeneration and Resistance. Local
+variants require visible sky; global variants work under cover. Harmful general effects
+can affect Survival/Adventure players and non-player living entities; Creative and
+Spectator are exempt. Hostile buffs target monsters. Duration follows the 1.21.1 values:
+60 ticks Blindness/Nausea, 80 Fatigue/Hunger/Poison/Slowness/Weakness, 30 Wither, and 200
+hostile buffs. Provider level raises amplifier, not duration; default effective cap is 3.
+
+The scheduler runs only in occupied runtime Ages, selecting already-loaded nearby
+chunks. Defaults match 1.21.1: 20-tick interval, four Ages, two providers and one action
+per run, at most 16 chunks. Status leases cap at 32 per Age, eight candidates per attempt,
+and 200 ticks per effect. A failed handler is quarantined temporarily. Owned effects
+are revoked on departure/logout/disable/shutdown without deleting replacements or
+stronger/extended effects from another source. Config entries are under `[instability]`
+and `[instability_status_effects]` in the server's `rivencraft-local.toml`; provider
+exclusions accept `poison` or `rivencraft:poison`.
+
+Operator commands, used inside a runtime Age:
+
+- `/rivencraft_port instability status`: frozen score/contributions, saved or test
+  provider levels, enabled/availability information.
+- `/rivencraft_port instability enabled false` (or `true`): persistently pause/resume
+  this Age; pausing immediately clears owned effects without changing its saved plan.
+- `/rivencraft_port instability test_score 5000`: session-only deterministic provider
+  selection at a test score, leaving creation-time contributions unchanged.
+- `/rivencraft_port instability clear_test_score`: restore saved selection. Restart
+  also clears the test override.
+- `/rivencraft_port instability pulse poison_global`: attempt one implemented level-1
+  effect on an eligible living entity in the current already-loaded chunk. The command
+  respects config, enabled state, target policy and effect ownership; it reports when
+  no effect was applied. Existing effects are not replaced. Other catalog providers
+  are suggested too, with unavailable handlers explicitly reported.
+
+Validation: build and fresh dedicated-server startup passed. A small temporary Age
+confirmed neutral scoring, deterministic test deck selection, exact Poison duration,
+owned-effect cleanup on disable, retention of a stronger command-supplied Weakness,
+local shelter versus global effects, saved enabled state after restart and session
+score reset. The server was stopped and its world deleted. No permanent test fixtures
+were added. Player authoring/scoring, automatic occupied-Age scheduling, Survival versus
+Creative behavior, departure cleanup, hostile buffs and multiplayer fairness remain
+manual checks. No commit, push or publication.
+
+
+## Beta .120 — colored decay
+
+The player passed .119. This slice ports the four active 1.21.1 colored decay cards,
+the block and all four existing 16x16 textures, per-Age frontier persistence, surface
+seeding and six-neighbor conversion. Decay is selected by the existing saved Legacy
+decks; older saved provider selections are not rerolled.
+
+Blue, Red and Purple use the same hardness-dependent conversion odds as 1.21.1.
+White converts eligible solid blocks without a hardness roll. Air conversion remains
+rarer (Blue/Red 1-in-20, Purple 1-in-8, White 1-in-50). Other decay colors can be
+converted; White wins that conversion immediately and others use a 1-in-5 roll.
+White also deals one point of magic damage on stepping contact, using the modern
+server damage API. All decay variants are solid, hardness 5/resistance 10, have no
+item form or drops, and do not spread through autonomous/random block ticks.
+
+A provider call samples at most four six-neighbor targets by default and changes at
+most one block, sharing the existing scheduler's Age/provider/action budgets. It only
+examines supplied already-loaded player-nearby chunks. Per-Age SavedData retains a
+monotonic attempt sequence and at most 1,024 frontier coordinates per color; no chunk
+or entity references are persisted. Destroyed/recolored stale sources are discarded.
+
+Protection matches 1.21.1: fluids, unbreakable/critical blocks, block entities,
+portals and Rivencraft infrastructure resist conversion. Data packs can add entries
+to `rivencraft:decay_protected`. A positioned fake player supplies modern NeoForge
+BreakBlockEvent and placement events, with rollback for cancelled placement.
+
+The first resolved Descriptive Book landing is saved as a protected spawn without
+changing scoring or provider selection. It protects +/-4 blocks horizontally and
+Y-2 through Y+4. Portals and hand-held books share that resolver. For an Age entered
+before .120, re-enter it once to record this point; OP status reports whether it is
+recorded. Cloud Platforms and Rivencraft infrastructure remain protected independently.
+
+`[instability] world_mutation` and `[instability_decay] enabled` default to true,
+matching 1.21.1. `max_attempts_per_call` defaults to 4 (range 1–6). Per-Age enable,
+global enable and provider exclusions also gate seeding/spread. Disabling does not
+remove existing decay. As in 1.21.1, existing White block contact damage follows the
+decay/world-mutation toggles rather than the Age provider scheduler toggle.
+
+Operator testing, inside an Age and preferably away from its protected arrival:
+
+- `/rivencraft_port instability decay blue 32` makes up to 32 bounded provider
+  attempts in your current loaded chunk. Use `purple`, `red` or `white` too. It prints
+  the number of actual changes and up to four nearby tracked coordinates, without
+  changing score/selection. A failed roll or protected location can yield no change.
+- The existing `/rivencraft_port instability pulse decayblue` (and other colors)
+  attempts one call. Its output now describes successful actions for either blocks
+  or living entities.
+- `/rivencraft_port instability test_score 50000` allows natural deck selection for
+  observation; inspect `status` for the selected colors, then use `clear_test_score`
+  to restore the saved plan. Merely placing decay does not register an active card.
+
+Validation: build and fresh dedicated-server startup passed. Bounded pulses seeded
+and spread all four colors. On restart, the saved attempt sequence advanced from
+32 to 40 and the original frontiers persisted, with further Red growth. Bedrock and
+water seeding produced no conversions/frontier entries; disabling the Age blocked
+further changes. All packaged textures are 16x16. The temporary server was stopped
+and world deleted. Manual checks remain for visual variants, White stepping damage,
+protected arrival, normal occupied-Age spreading, claim-mod cancellation and controls.
+No permanent test fixtures, commit, push or publication.
+
+
+## .116–.120 release validation
+
+The player passed every slice, including .120 colored decay, and authorized commit,
+push and publication as 1.0.1.120-beta.1. Both Minecraft targets build successfully.
+See the consolidated release notes for the published scope and remaining parity gaps.
+
+
+## Beta .121 — lightning and explosions
+
+The player passed .120. This slice ports the 1.21.1 lightning/explosion providers,
+their separate scheduling lane, persisted per-Age attempt sequence/cooldowns,
+loaded-chunk candidate selection and existing damage/protection settings.
+
+Each selected hazard receives a roll on each admitted Age scheduler pass, independent
+of rotating potion/decay providers. Legacy per-chunk/per-tick odds are aggregated as
+`1 - (1 - 1/denominator)^(loadedChunks * interval * effectiveCopies)`. Denominators
+remain 100,000 for clear-weather lightning, 5,000 during rain plus thunder, and 1,000
+for explosions. Candidate chunks are already-loaded rings around Age players, capped
+at 81 by default; no chunks are generated for hazards. Lightning uses the motion-blocking
+surface; natural explosions choose a random Y across the dimension's modern height.
+
+Defaults match 1.21.1: hazards/block damage/player damage/fire enabled, 20-tick minimum
+gap per hazard type, strength-3 blasts, at most 16 distinct destructible blocks and
+eight damaged entities, and at most 12 damage per entity (lightning itself caps at 5).
+Creative/Spectator are excluded. Spawn columns within eight blocks horizontally are
+excluded as targets; protected infrastructure, block entities, TNT, portals and
+unbreakable blocks resist blasts. Break and placement cancellation checks remain.
+World mutation and mobGriefing gate block damage; entity damage and visual/audio
+feedback can remain active when block mutation is disabled.
+
+The modern API no longer returns an explosion/block list. The damage calculator
+retains its bounded approved positions for post-blast ignition, only where the block
+is now air and fire placement is allowed. Cancelled explosion startup does not count
+as dispatch or generate follow-up fire. NeoForge's renamed BreakBlockEvent and 26.3's
+`canSpreadFireAround` replace the old break event and doFireTick query respectively.
+Vanilla explosion networking and lightning entities provide existing visuals/sounds.
+The `instability_hazards` config section retains the 1.21.1 setting names/defaults.
+
+Operator checks inside an Age:
+
+- `/rivencraft_port instability hazard lightning`
+- `/rivencraft_port instability hazard explosions`
+
+These skip random probability only, retaining loaded-chunk, cooldown, Age/config/provider
+and protected-spawn checks. They target a nearby loaded chunk center, using its surface
+for lightning and the command's Y for explosions, rather than the player's exact feet.
+Move away from the arrival area and allow at least one second between repeats of the
+same hazard. The command reports no dispatch when blocked/cancelled. It also works with
+an explicitly positioned console source. Generic `pulse lightning`/`pulse explosions`
+retain their natural probability roll; `test_score`/`status` exercise normal selection.
+The saved score/plan and catalog protocol are unchanged.
+
+Build and dedicated-server startup passed. The user offered to validate damage and
+block destruction manually, so the server was stopped before effect/terrain fixtures
+were run and its temporary world was removed. Manual checks include lightning/thunder,
+explosion visuals/sound, damage caps and Creative immunity, block/protected-block limits,
+spawn exclusion, world-mutation/mobGriefing/fire settings, cooldown/restart persistence,
+and natural rates in occupied Ages. No permanent tests, commit, push or publication.
+
+
+## Beta .122 — meteor flight and impacts
+
+The player passed .121 lightning/explosion testing. Meteors now reuse the 1.21.1
+particle descent, roar sound, selected Legacy provider card, independent scheduling
+lane and bounded blast helper. They are not a new falling-block/entity model: a
+flame/smoke trail descends for 30 ticks (1.5 seconds) from up to 48 blocks above a
+captured surface target, followed by the impact. The existing meteor roar is bundled.
+
+Natural scheduling aggregates the Legacy 1-in-50,000 per-chunk/per-tick odds across
+loaded chunks, scheduler interval and effective card copies, as in 1.21.1. Targets
+are randomized among already-loaded nearby candidate chunks; X/Z vary within the
+safe central area of each chunk. Up to 16 candidate chunks are considered per
+schedule attempt. Target selection rejects protected spawn columns and surfaces
+without headroom. No terrain is loaded or generated by the provider.
+
+The shared hazard SavedData preserves the meteor cooldown (200 game ticks) and random
+attempt sequence. At most one meteor can descend per Age and 16 Ages can have active
+flights. A pending descent is session-only: server stop, Age unload, no players,
+unloaded target chunk, or disabled Age/global/provider/meteor policy cancels it.
+Interrupted flights never replay after restart; the saved cooldown remains. The
+flight is removed before impact dispatch so a failed impact cannot repeat.
+
+The independent `[instability_meteor]` settings match 1.21.1: enabled/block damage/
+player damage/fire default true, maximum 24 impact blocks, eight damaged entities,
+and 12 damage per entity, strength 3. Impact reuses protected block/BE/infrastructure,
+claim events, Creative/Spectator immunity, world-mutation/mobGriefing and modern fire
+permission checks. Disabling block mutation still permits descent, sound and eligible
+entity damage. Generic instability status reports meteor availability separately
+from potion policy; saved scores/decks and catalog protocol are unchanged.
+
+Test inside an Age, away from its arrival area:
+
+`/rivencraft_port instability meteor`
+
+This skips the natural probability roll, retaining cooldown, loaded target, active
+flight and all policy checks. It uses randomized nearby impact locations, unlike
+the deliberately fixed chunk-center lightning/explosion test commands. Wait at
+least ten seconds before repeating. `/rivencraft_port instability pulse meteors`
+keeps the natural chance roll; test-score/status tools exercise saved deck selection.
+
+The build passed and JAR sound/class packaging was verified. Following the player's
+manual validation preference, particle/audio presentation, impacts/damage/protection,
+repeat cooldown, disabling/leaving during flight and restart cancellation are handed
+over for in-game testing. No server or new world was launched for this slice. No new
+permanent tests, commit, push or publication.
+
+
+## Beta .123 — burning and erosion
+
+The player passed .122 meteor testing. This slice adapts the remaining burning and
+erosion portions of 1.21.1 AgeEnvironmentalProviders, using the existing hazard
+candidate selection, saved attempt sequence, protection helpers and independent
+provider scheduling. No new textures, entities, sounds or optional mods are required.
+
+Burning remains an active Legacy deck card. Sky-exposed eligible living entities
+outside protected spawn can ignite; Survival/Adventure players are included by
+default and Creative/Spectator are excluded. Natural processing inspects at most
+eight loaded chunks/eight eligible candidates per chunk, ignites at most one per
+inspected chunk and four entities per pass by default. The old 1-in-10 per-tick gate
+is aggregated over the scheduler interval. Fire lasts four seconds per effective
+provider level, capped at twelve. Vanilla water/rain extinguishing and fire immunity
+remain in force. Disabling the provider stops new ignitions; existing fire follows
+vanilla behavior rather than the potion lease cleanup mechanism.
+
+Erosion remains outside Legacy's saved card deck. As requested for testing in 1.21.1,
+its config defaults enabled and natural attempts run in admitted occupied Ages at a
+current score of at least 10,000. Current score uses the frozen creation total or an
+explicit session test-score override; live material profiling remains pending.
+At most eight random positions are sampled in already-loaded candidate chunks per
+pass, with at most one conversion. An eligible block next to a source fluid above or
+on a horizontal side is replaced with that fluid's source block; fluid below does
+not grow upward. Normal fluid ticks can subsequently spread it.
+
+Erosion requires world_mutation and mobGriefing, and reuses decay's protection against
+spawn/infrastructure, block entities, fluids, critical/unbreakable blocks and protected
+tags. Modern break/place claim events and rollback remain. Its `instability_erosion`
+enabled toggle does not add a new saved card or alter the Age score. Burning uses
+`instability_scorching`: enabled/affect_players default true and max_targets_per_pass
+is 4 (range 0–16), matching 1.21.1.
+
+Operator manual checks inside an Age:
+
+- On dry ground under open sky, outside arrival protection and in Survival, run
+  `/rivencraft_port instability environment burning`. It targets the player directly
+  for four seconds, skips the chance roll, and explicitly reports water/rain that
+  would immediately extinguish the fire.
+- Place ordinary Stone beside or below source water/lava, outside protected arrival.
+  Use `/rivencraft_port instability test_score 10000`, look at the Stone within six
+  blocks, and run `/rivencraft_port instability environment erosion`. The aimed
+  block should become that adjacent source fluid. Existing policies still apply.
+  End with `/rivencraft_port instability clear_test_score` to restore the saved plan.
+- Automatic burning needs a selected burning card; natural erosion uses the enabled
+  test policy/threshold. `status` exposes both config/threshold information when
+  inspecting the respective provider, without adding scores to ordinary books.
+
+Build passed. The player is performing visual/effect testing, so no server/world or
+new permanent fixtures were created. Manual validation covers burning/fire damage,
+Creative/shelter/spawn exclusion, wet extinguishing feedback, source-fluid conversion,
+protected blocks, mobGriefing/world-mutation/config switches and natural scheduling.
+No commit, push or publication. Crumble, full writing recovery and live abundance
+profiling remain major instability work.
+
+
+## Beta .124 — live material-abundance instability
+
+The player passed .123. This slice ports 1.21.1's Legacy-style generated-block
+profiling and live effective provider selection. Crumble remains a catalog entry
+without a registered handler in 1.21.1; no new Crumble behavior is invented here.
+
+Overworld and runtime-Age chunk loads enqueue bounded sampling work, rather than
+accessing SavedData during chunk-storage callbacks. Four snapshots are processed
+per server tick, with a queue cap of 2,048. Paletted section counts record watched
+block IDs efficiently. Each chunk is sampled once, up to 1,024 per dimension, and
+samples/totals persist in per-dimension `rivencraft/block_profile` SavedData. Subsequent
+player edits or chunk reloads do not replace or double-count a stored snapshot.
+
+Live points remain zero until at least **401 Age samples and 500 Overworld baseline
+samples** exist, matching 1.21.1. For each watched material, positive excess blocks
+per Age chunk above 1.05 times the Overworld average are multiplied by that material's
+weight. The total rounds to an integer and caps at 100,000. The watched list retains
+Legacy ores/quartz/glowstone/crystal and the existing modern/storage extensions,
+including Diamond Blocks, Ancient Debris and Netherite Blocks.
+
+Recognized ores, mineral storage blocks and source-fluid block types from installed
+mods participate automatically via current NeoForge common tags, names and the same
+full-block/fluid material eligibility used for Pages. No content mod/API is required.
+Unknown ore/storage forms use the 1.21.1 fallback weights; known minerals retain its
+named weights. `[instability_modded_materials] block_weight_overrides` accepts exact
+`modid:block_id=points` entries, including zero to exclude a modded block. This is
+installation-based optional support, not a required mod or per-mod opt-in switch.
+
+While a profiling-enabled Age is occupied, missing spawn-area samples are requested
+gradually: at most one chunk request per second, one in flight across the server,
+round-robin between active Ages and the Overworld baseline. Existing samples are
+skipped. The modern getChunkFuture API still blocks when invoked on the server
+thread, so requests use its off-thread scheduling path and completion returns to
+the server thread. Closed levels and stopped-server callbacks are discarded. No
+permanent force-load tickets or generation while no Age is occupied are introduced.
+Natural exploration also fills the sample pool and can reach readiness sooner.
+
+Writing contributions and the original saved provider plan remain frozen. The live
+score is added only at runtime, and the effective deck is reselected deterministically
+from the same saved seed as the total changes. Providers can therefore appear or
+change as abundance is measured. Unchanged totals/seeds reuse a cached plan rather
+than reshuffling on each query. Older Ages predating instability records remain
+neutral; saved neutral arrivals/enable flags do not opt them into new scoring.
+
+`[instability] difficulty` matches 1.21.1: 0=quarter, 1=half, 2=normal (default),
+3=1.75x. It scales writing plus live points without rewriting saved contributions.
+A session `test_score` remains an explicit final-score override and is cleared on
+restart; clearing it now restores the live effective plan. Erosion threshold checks
+use this same effective score.
+
+Use `/rivencraft_port instability status` inside an Age to inspect frozen/live/effective
+scores, difficulty, profile eligibility and both sample counts. Normal book/Binder
+screens receive no score/profiler data. Zero live points before both thresholds are
+ready are expected. To validate, create/explore an Age with Diamond Block Rocks or
+another abundant watched material, watch progress, then confirm live points and
+providers change while the frozen writing contribution remains unchanged. Reopen the
+world to check sample persistence; repeated reloads should not duplicate counts.
+
+Build and temporary dedicated-server checks passed. Real loaded snapshots saved 25
+samples per test dimension and captured one deliberately placed fixture Diamond Block.
+A restart with synthetic profile records exercised scoring/decoding without generating
+hundreds of chunks: resumed real chunk samples produced 423 Age and 522 baseline
+samples, with the expected 2,987 live points, frozen score zero and effective providers.
+Clearing a session override restored the same live result. This verifies save/scoring
+plumbing, not natural bulk generation. The player will check background progress,
+actual generated material distribution, modded recognition and difficulty/config
+changes. Test server stopped/world deleted; no permanent tests, commit or publication.
+
+
+## .125 ordered controller recovery
+
+The player passed .124. New authored Ages now recover repeated singular terrain,
+biome-distribution, weather, lighting and sky choices: the last choice wins, with
+500 instability per duplicate or conflict. Supported category-order mistakes add
+100 points instead of blocking binding. Native distribution discards authored
+biome choices with a 500-point conflict; Single retains the first authored biome
+with a 500-point conflict when extras exist. These diagnostics use the 1.21.1
+writing rules. Season pages remain unsupported until their integration is ported.
+
+The original pages remain in the book and library source list. Generation receives
+recovered choices without rearranging material/feature or per-celestial modifier
+chains. Existing Ages are not rescored. OP instability status shows the writing
+contributions; normal book/Binder screens do not expose the score or new warnings.
+Unknown/unported pages and other unsupported combinations still prevent binding.
+Celestial, number and dangling-modifier recovery is a later slice: their existing
+validation still applies to the original page sequence, before controller recovery.
+
+Version 1.0.1.125-beta.1 builds. Thirteen temporary focused checks passed for
+last-choice selection, duplicate/conflict/order costs, Native/Single recovery,
+unimplemented pages, raw numeric guards, celestial-chain preservation, intentional
+feature repeats and Ambient Color ordering. No server/world was launched. In-game
+validation: bind books with conflicting terrain/weather choices and confirm the
+last choice takes effect; test Native with biome pages and Single with two biomes;
+check that all original pages remain and OP status reports the writing costs.
+No commit, push or publication.
+
+
+## .126 ordered celestial and number recovery
+
+The player passed .125. Ported the 1.21.1 grammar treatment of pending celestial
+modifiers and numeric adjacency. Repeated Length/Phase/Angle/Size/Direction pages
+before a celestial use the final value of that kind without a duplicate penalty.
+Only the final unconsumed modifier of each kind adds 100 dangling-modifier points.
+A number without an immediately following supported Color/Length/Phase/Angle/Size
+page adds 100 points (misplaced, or dangling at the end). Consecutive numbers leave
+only the last available for the next target. Colors still mix in written order.
+
+These defects no longer block binding. Numbers and celestial compilation retain
+the original page sequence and seeded color indices; controller recovery never
+moves a number next to a new target. A trailing modifier cannot rewrite an earlier
+body, including the optimized single-body compilation path. Missing celestial
+branches retain their existing seeded completion; dangling controls do not apply
+to those generated bodies. All original book/library pages remain. Unsupported
+pages and the ten-sun/ten-moon limit still block binding; existing Ages are unchanged.
+
+Version 1.0.1.126-beta.1 builds. Seventeen temporary focused checks passed, covering
+last-value selection, dangling costs/indices, numeric adjacency, per-body isolation,
+seeded color stability, valid numbered writing, body limits, unsupported pages and
+cycle codec round-trip. No server/world or permanent test fixture was created.
+Manual validation: bind a book with Half Length, Double Length, Sun and verify the
+last length; bind Sun followed by Large Size and confirm it does not resize that
+sun. Test a trailing Number page and inspect the added writing contribution with
+`/rivencraft_port instability status`. Original pages should remain visible.
+No commit, push or publication.
+
+
+## .127 Link Modifier station: title and core link properties
+
+The player passed .126. Started the missing 1.21.1 Link Modifier station port,
+reusing its block model, textures, horizontal facing variants and Legacy 176x166
+single-book GUI. The item is available in the main creative tab or via
+`/give @s rivencraft:link_modifier`; it has no crafting recipe. As in 1.21.1,
+creative acquisition does not impose a new permission restriction on ordinary
+book edits once the station has been placed.
+
+One persistent slot accepts Linking and Descriptive Books, including unbound
+books, with normal and shift-click transfers. The server menu handles renaming
+and Disarm, Maintain Momentum and Intra Linking toggles. Descriptive Books cannot
+toggle Intra Linking, which only governs same-dimension Linking Book travel.
+Existing target, author, symbols and Age identity are retained. Renaming changes
+the item's custom title, not the Age's saved folder/registry identity. Removing
+the title restores the item's normal name. Text editing consumes inventory/hotbar
+shortcuts while focused; Escape closes the screen. Programmatic text refreshes do
+not send rename packets. Menu identity, owner, distance and live station checks
+protect edits; unknown button IDs and non-book inputs are rejected.
+
+The book is saved with modern ValueInput/ValueOutput container serialization.
+Station removal uses block-entity preRemoveSideEffects to release the stored book
+once, including non-player removal. No tick handler or renderer is needed.
+
+This is a station slice, not full Link Modifier parity. Seed editing, Age retirement,
+Relative Link, Intra-Linking Only and platform overrides remain unported and are
+not presented as working controls. Existing core flag behavior is reused unchanged.
+Manual validation: place the station in multiple orientations, insert/shift-click
+both book types, rename using text containing E, toggle each available property,
+remove the book and use it to check travel effects. Confirm Descriptive Book Intra
+Linking is unavailable, restart with a book left in the station, and break a loaded
+station to recover one book. Build and dedicated persistence results are recorded
+below. No commit, push or publication.
+
+Version 1.0.1.127-beta.1 builds. Packaged model, GUI, texture, item definition,
+loot table and localization checks passed; no station recipe is included. A
+fresh dedicated server placed the station and serialized a named Linking Book
+with all three core flags. Restart retained the same book/name/flags and station
+removal completed normally. The first harness run expected the wrong wording
+for vanilla force-load cleanup; the corrected harness completed successfully.
+Both temporary worlds were deleted and servers stopped. No permanent tests were
+added. UI interaction, transfer counts and modifier travel effects await the
+player's in-game check.
+
+
+## .128 six Link Modifier controls
+
+The player reported that .127 exposed only three of 1.21.1's six controls. Added
+the remaining Intra-Linking Only, Relative Link and Generate Platform controls in
+the existing two-column, three-row Legacy layout, with matching bit values and
+server-owned menu actions. Enabling Intra-Linking Only enables Intra Linking too;
+disabling Intra Linking clears Intra-Linking Only. Both intra controls are disabled
+for Descriptive Books. Unknown actions and out-of-range menu edits remain rejected.
+
+Linking Book Intra-Linking Only blocks cross-dimension travel. Relative Link uses
+the traveller's block offset from the source world's spawn, applied to destination
+spawn, preserving destination yaw/pitch. Normal links retain their precise bound
+coordinates. Player and non-player portal travel share the new flags and relative
+coordinate helper. Descriptive relative arrivals still require proper footing.
+
+Generate Platform is off by default for Linking Books. When enabled, a successful
+link fills one missing floor block with cloud platform only if the block two above
+the arrival is air, matching the 1.21.1 helper. Existing floors are retained.
+Descriptive Books instead default to enabled and use Disable Platform internally;
+turning it off prevents fallback platform creation and refuses travel if no footed
+landing is available. Receptacle tint preparation respects that setting too.
+New flags serialize in the shared component and appear in book/panel tooltips.
+Existing three-flag books remain valid. Seed editing and Age retirement remain
+separate, unfinished station work.
+
+Version 1.0.1.128-beta.1 builds. A temporary dedicated-server fixture passed 19
+checks: menu actions/dependencies, descriptive intra rejection, numeric flag codec,
+relative offsets, platform-off/default behavior, platform placement/preservation,
+invalid input and remote edit protection. It did not perform real client travel.
+The test server stopped and its world/fixture sources were removed. The production
+JAR is rebuilt without that fixture. Manual checks: all six buttons and tooltips,
+same/cross-dimension Intra-Linking Only, Relative Link offsets, and platform on/off
+for both book types (including a new Void Age without footing). No commit, push
+or publication.
+
+
+## .129 Link Modifier mouse input repair
+
+The player reported that none of the six controls responded. Confirmed the
+26.3 input constants in the local Minecraft artifact: left/middle/right are
+1/2/3, while the custom Link Modifier handler checked the old left-button value
+0. Its server actions therefore passed the prior direct-menu fixture while
+real mouse clicks never sent an action.
+
+Replaced the manually drawn/clicked areas with six registered Minecraft Button
+widgets at the same Legacy positions. Their callbacks send the existing validated
+menu action IDs, and their custom rendering retains the square controls. Native
+input provides correct mouse mapping, focus, click sound and keyboard activation.
+All six tooltips expose their On/Off state; unavailable Descriptive Book intra
+controls remain disabled. Tooltip objects update only when state changes so their
+hover delay is not reset every tick. Book mutations/travel code is unchanged.
+
+Version 1.0.1.129-beta.1 builds. The native widget's left-button mapping and callback
+dispatch were verified in the local Minecraft bytecode. No client click test or
+new server run was performed; the previous 19 checks covered server actions, not
+client input. Please click each option with an inserted Linking Book and verify
+its selected shading and tooltip/book properties change, then repeat supported
+options with a Descriptive Book. No commit, push or publication.

ports/mc263/RELEASE_NOTES_1.0.1.115-beta.1.md

@@ -0,0 +1,88 @@
+# Rivencraft 26.3 beta 1.0.1.115-beta.1
+
+Collects the player-validated port slices .107–.115 since 1.0.1.106-beta.1.
+Minecraft 26.3, NeoForge 26.3.0.99 and Java 25. This remains a beta with
+incomplete Minecraft 1.21.1 gameplay and optional-integration parity.
+
+## Book stands and dropped books
+
+- Place a Linking Book, Descriptive Book or Page on an empty vanilla lectern
+  to convert it into a Rivencraft book stand, preserving facing. Occupied
+  vanilla lecterns are left alone.
+- Books use the existing open-book model and textures and show their name
+  above the stand. Pages use their item artwork without a hover label,
+  retaining the 1.21.1 orientation corrections.
+- Open a bound book with an empty hand, then click its destination panel to
+  travel while leaving the book on its stand. Existing link modifiers,
+  same-dimension rules, Return Link configuration and Age-entry awards apply.
+- Shift-right-click with an empty hand retrieves the stored item and restores
+  a vanilla lectern. Breaking returns one lectern and its contents. Unwritten
+  books can be displayed; retrieve them to bind in hand in this beta.
+- Ordinary dropped Linking/Descriptive Books now become recoverable open-book
+  entities, including unwritten books, inventory/player drops, container and
+  stand drops, death/Disarm drops and ordinary book entities loaded from disk.
+- Conversion preserves the stack and components, position, motion, facing,
+  pickup delay and ownership/thrower metadata. It uses the existing open-book
+  lifetime, slow decay and water/rain behavior. Already-custom books and
+  non-book items are skipped.
+- Conversion runs after registration without world scans or force-loading.
+  The original is removed only after replacement succeeds; a canceled
+  replacement leaves the ordinary item intact and eligible on a later reload.
+- Stand travel validates source dimension, distance, loaded chunk and the exact
+  currently stored book, rejecting stale screens after removal/replacement.
+
+## Book GUIs and names
+
+- Descriptive Books reuse the Legacy gilded cover, name/author front spread,
+  and one authored symbol at a time on following right-hand pages. Saved page
+  order and repetitions are retained, with runtime glyphs and no extra item outline.
+- New Descriptive Books record their author server-side. Older books without
+  that metadata use the unknown-author label.
+- Linking Books use the plain Legacy cover, wrapped title, destination name
+  and block coordinates, plus the blank final spread. Return Links suppress
+  the redundant title. Bottom corners or arrow keys turn pages with sound.
+- Both GUIs share the Legacy artwork/text/counter/corner helpers. Naming
+  controls hide on later pages and remain correct after resizing. Escape closes
+  even with naming focused; normal text input does not trigger inventory keys.
+- Ported the existing 1.21.1 fallback's animated teal spiral panel to both GUIs,
+  including lecterns. Removed placeholder labels. The Legacy frame draws over
+  the animation; travel is active only on the front panel.
+- The animated fallback is not a live destination view. Destination tint,
+  snapshot renderer integrations and random-Age glyph descriptions remain pending.
+- New Ages save their entered display name independently of their ID, folder
+  and seed. Newly bound Linking Books and automatic Return Links capture their
+  destination/departure label for both GUI and tooltip. Older Ages/books retain
+  vanilla-name or dimension-ID fallbacks; existing labels are not rewritten.
+- Corrected negative tooltip coordinates to floor consistently with the GUI.
+
+## Progression and recipe discovery
+
+- Ported the Rivencraft advancement tree: root, obtaining a Page/Linking Book,
+  taking a Link Panel from the Ink Mixer, copying a Page, binding an Age and
+  successfully travelling into an Age. Action awards occur after committed
+  server actions, including normal and shift pickup; previews earn nothing.
+- The advancement background uses the existing blue Crystal Block texture,
+  with the corrected 26.3 resource-path format. The portal node waits for the
+  Receptacle/portal port.
+- Added recipe-book discovery for Ink Vials (Black Dye), Ink Mixers (Glass
+  Bottle), Book Binders (Iron Ingot) and Crystal Blocks (Crystal Shard), alongside
+  the Notebook and Writing Desk unlocks. Three-by-three recipes appear in a
+  Crafting Table's recipe book, not the inventory's two-by-two book.
+- Ingredients and costs are unchanged. Blank Pages remain uncraftable.
+
+## Validation and remaining work
+
+- Player in-game checks passed each slice and the final dropped-book changes.
+- The 26.3 and independent 1.21.1 builds passed. Gradle test tasks have no
+  standalone test sources; targeted disposable-server fixtures covered real
+  station actions, advancements/recipe unlocks, stand ownership/drops and
+  persistence, book author/page/name persistence, and drop conversion/state.
+- Temporary test servers were stopped and their worlds deleted. A no-player
+  entity fixture required one loaded fixture chunk for inspection; further
+  visual/restart validation was handed to the player.
+- 1.21.1 gameplay code is unchanged. Shared issue #114 remains open for its
+  matching universal dropped-book fix; Writing Desk model placement stays in #113.
+- Instability, full writing recovery, discovery/library loot, crystal portals,
+  remaining stations/progression and optional integrations still need port work.
+
+Keep 26.3 and 1.21.1 instances/saves separate and back up beta worlds before updating.

ports/mc263/RELEASE_NOTES_1.0.1.120-beta.1.md

@@ -0,0 +1,85 @@
+# Rivencraft 26.3 beta 1.0.1.120-beta.1
+
+Collects the player-validated .116–.120 port slices since 1.0.1.115-beta.1.
+For Minecraft 26.3, NeoForge 26.3.0.99 and Java 25. The independent 1.21.1
+release is unchanged; full gameplay and optional-integration parity remain incomplete.
+
+## Libraries and writing
+
+- Ported Legacy library generation, shared schematic, chest loot and five correctly
+  oriented book/page stands. Libraries generate after decoration in eligible new
+  non-Cave Age chunks, using the 1.21.1 spacing, terrain and clearance checks.
+- Library loot defaults to `LEGACY`; optional `AGE_ONLY` limits new library Pages
+  to known symbols originally written into that Age. Original writing is saved
+  separately and restored on reload. Older Ages without it have an empty Age-only
+  pool. Ordinary Books replace stand Pages when that pool is empty.
+- Added operator library placement, candidate/probe/loot diagnostics, session-only
+  test spacing and a locator limited to nearby already-loaded chunks.
+- Hand-prepared Link Panel ink cost is server-configurable (default two). The
+  Ink Mixer still consumes one ink unit and one paper per panel. Writing Desk
+  ink handling now uses the shared service.
+
+## Crystal portals
+
+- Ported craftable Book Receptacles with all six mounting orientations and the
+  existing 1.21.1 model/book transforms. A bound Linking or Descriptive Book
+  activates a valid connected crystal frame, including supported irregular frames.
+- Reused the bounded crystal flood/tension algorithm, placement protection events,
+  rollback, owner persistence, restart repair, frame cleanup and traversal cooldown.
+- Empty-hand removal closes the portal and returns the book. Breaking the holder
+  or its crystal support closes it and drops a recoverable open-book entity.
+- Player and non-player travel reuse book destinations, safe arrival, Intra-Linking,
+  Disarm and momentum rules. Descriptive Books share the same landing resolver
+  with portals; no separate portal exit offset is added. Player Return Link policy
+  and progression remain in force.
+- The animated fallback surface renders its facing sides and uses destination sky
+  tint. The Open Portal advancement and receptacle recipe unlock are restored.
+  Live destination views are still pending optional integration work.
+
+## Instability and colored decay
+
+- New Ages save operator-only creation-time score contributions and deterministic
+  provider selections using all five Legacy decks. Existing Ages remain neutral;
+  reloads/config changes do not reroll stored plans.
+- Initial scoring covers Bright Lighting, Accelerated, Corrupted Pages, ineffective
+  Cave sky/weather modifiers, excess and biome-forced structures, and extra suns.
+  Corrupted Pages now bind successfully and retain their animated redacted text.
+- Ported 18 potion providers: local/global Blindness, Fatigue, Hunger, Nausea,
+  Poison, Slowness, Weakness and Wither, plus hostile Regeneration/Resistance.
+  General effects affect eligible Survival/Adventure players and living entities;
+  Creative/Spectator remain exempt. Local variants require sky exposure.
+- Added a bounded occupied-Age scheduler, owned-effect cleanup, provider controls
+  and operator score/status, enable/disable, session test-score and pulse commands.
+  Effects supplied or extended by another source are preserved.
+- Ported Blue, Purple, Red and White decay with the existing 16x16 textures,
+  hardness/air conversion odds, saved per-color frontiers and attempt sequence.
+  White retains stepping-contact magic damage. Decay has no item form or drops.
+- Spread uses only already-loaded candidate chunks, bounded attempts and action
+  budgets. Fluids, block entities, critical/unbreakable blocks, infrastructure,
+  protected tags and claim events prevent conversion.
+- The first resolved book/portal arrival is saved for spawn protection. Re-enter
+  an older Age once to record it. Global/Age/provider and world-mutation controls
+  gate spread; existing decay blocks remain when spreading is disabled.
+- Test a color with `/rivencraft_port instability decay blue 32` (also `purple`,
+  `red`, `white`); output includes actual changes and nearby tracked coordinates.
+  Scores are not added to ordinary book or Binder displays.
+
+## Validation and remaining work
+
+Player in-game checks passed .116–.120. Both the 26.3 and 1.21.1 builds passed;
+Gradle has no standalone test sources. Targeted disposable dedicated-server checks
+covered library placement, portal entity travel and restart ownership/cleanup,
+potion application/cleanup and persistence, all four decay colors, saved spread
+continuation, and bedrock/fluid protection. Test servers were stopped and their
+worlds removed.
+
+Full writing recovery/penalties, live material-abundance profiling, other instability
+hazards, remaining discovery/stations and optional integrations still need port work.
+Unported hazard cards remain saved and are reported as unavailable, rather than
+being replaced with different cards. Book previews remain the animated fallback.
+Machine acceleration (#112), Writing Desk model placement (#113), and the matching
+1.21.1 universal dropped-book fix (#114) remain tracked separately.
+
+Use matching client/server beta builds (catalog protocol 10). Keep Minecraft tracks
+and saves separate, back up beta worlds, and do not downgrade saves containing new
+blocks or data to earlier betas.

ports/mc263/RELEASE_NOTES_1.0.1.129-beta.1.md

@@ -0,0 +1,68 @@
+# Rivencraft 26.3 beta 1.0.1.129-beta.1
+
+Collects the player-validated .121–.129 port slices since 1.0.1.120-beta.1.
+For Minecraft 26.3, NeoForge 26.3.0.99 and Java 25. The independent Minecraft
+1.21.1 release is unchanged. Full parity and optional integrations remain in progress.
+
+## Instability hazards and live profiling
+
+- Ported lightning, explosions, falling meteor effects, burning and erosion with
+  bounded loaded-chunk scans, spawn protection, claim events and configurable
+  world/entity damage. Meteor flight uses the existing sound and particle effects.
+- Natural hazards choose randomized locations; operator test commands provide
+  targeted checks with independent cooldowns. Erosion retains its requested testing
+  default of enabled above 10,000 effective instability, outside the Legacy deck.
+- Ported persistent live material profiling, including native ores, valuable blocks,
+  recognized installed-mod materials and configurable modded block weight overrides.
+  No content mod is required. Profiling starts scoring after 401 Age and 500
+  Overworld baseline samples, with bounded gradual background sampling while an
+  eligible Age is occupied. A chunk snapshot is counted once.
+- Effective instability and deterministic provider selection now update as material
+  abundance is measured; the original writing contribution remains frozen. Added
+  difficulty scaling and operator-only sampling/score diagnostics. Older neutral
+  Ages remain neutral. Normal book/Binder screens do not reveal scores.
+
+## Ordered writing recovery
+
+- Repeated singular terrain, distribution, weather, lighting and sky controllers
+  use the last choice, adding 500 instability per duplicate/conflict. Category-order
+  mistakes add 100. Native distribution ignores supplied biomes; Single retains the
+  first biome when too many are supplied, with conflict penalties.
+- Repeated celestial modifiers use the final pending value of each kind. Dangling
+  modifiers and misplaced/trailing numbers allow binding and add 100 instability.
+  Numbers only attach to the immediately following supported target.
+- Preserved original book/library pages, ordered color mixing and independent
+  celestial chains. A trailing modifier cannot change an earlier sun or moon.
+  Unported pages, unsupported combinations and body limits remain enforced.
+
+## Link Modifier station
+
+- Added the creative-only Link Modifier with its existing model, textures and
+  Legacy single-book GUI. There is no crafting recipe.
+- Books can be renamed and edited through all six controls: Disarm, Intra-Linking,
+  Intra-Linking Only, Maintain Momentum, Relative Link and Generate Platform.
+- Intra-Linking Only enables Intra-Linking and prevents cross-dimension Linking
+  Book travel. Both intra controls are unavailable for Descriptive Books.
+- Relative Link preserves the traveller's offset from the source dimension spawn
+  at the destination spawn. Linking Book platform generation defaults off;
+  Descriptive Book fallback platforms default on and can be disabled.
+- Player and non-player portal paths share the new properties. Book contents and
+  flags persist in the station. Removal releases its stored book.
+- Fixed the controls ignoring real clicks: 26.3 left-click is button 1, not 0.
+  Registered native button widgets now handle input, focus, sound and state tooltips.
+
+## Validation and remaining work
+
+The player passed every included slice, including the six controls and click fix.
+Both Minecraft builds pass (no standalone Gradle test sources). Targeted temporary
+checks covered grammar/celestial recovery, component serialization, station actions,
+platform rules and dedicated-server save/restart behavior. Live profiling was checked
+with real snapshots plus synthetic threshold records; natural gameplay was validated
+by the player. Temporary servers were stopped and their test worlds removed.
+
+Link Modifier seed editing/retirement, remaining discovery/config policy and optional
+integrations are not complete. Live previews remain unavailable; books and portals
+use the animated fallback. Crumble has no active 1.21.1 handler and is not invented
+in this port. The dual-version follow-up issues and full multiplayer/parity gate
+remain open. Use matching client/server beta builds and keep Minecraft version
+tracks and their saves separate.

ports/mc263/build.gradle

@@ -193,6 +193,10 @@ tasks.named('processResources', ProcessResources).configure {
         include 'data/rivencraft/worldgen/structure_set/bastions.json'
         include 'assets/rivencraft/models/block/star_fissure.json'
         include 'assets/rivencraft/blockstates/star_fissure.json'
+        include 'assets/rivencraft/blockstates/decay.json'
+        include 'assets/rivencraft/models/block/decay_*.json'
+        include 'assets/rivencraft/textures/block/decay_*.png'
+        include 'data/rivencraft/tags/block/decay_protected.json'
         include 'assets/rivencraft/sounds.json'
         include 'assets/rivencraft/sounds/**/*.ogg'
         include 'assets/rivencraft/textures/item/crystal_shard.png'
@@ -220,6 +224,8 @@ tasks.named('processResources', ProcessResources).configure {
         include 'assets/rivencraft/models/block/writing_desk_extension.json'
         include 'assets/rivencraft/blockstates/writing_desk.json'
         include 'data/rivencraft/loot_table/blocks/writing_desk.json'
+        include 'data/rivencraft/advancement/progression/*.json'
+        exclude 'data/rivencraft/advancement/progression/root.json'
         include 'assets/rivencraft/textures/item/ink_vial.png.mcmeta'
         include 'assets/rivencraft/models/item/ink_vial.json'
         include 'assets/rivencraft/models/item/crystal_shard.json'
@@ -231,12 +237,19 @@ tasks.named('processResources', ProcessResources).configure {
         include 'assets/rivencraft/textures/gui/bookui_cover.png'
         include 'assets/rivencraft/textures/gui/notebook_pages.png'
         include 'assets/rivencraft/textures/gui/bookui_pager.png'
+        include 'assets/rivencraft/textures/gui/bookui_rpage_full.png'
         include 'assets/rivencraft/textures/block/crystal_block.png'
         include 'assets/rivencraft/textures/entity/linking_book.png'
         include 'assets/rivencraft/textures/entity/descriptive_book.png'
         include 'assets/rivencraft/textures/block/book_binder.png'
         include 'assets/rivencraft/textures/block/book_binder_press.png'
         include 'assets/rivencraft/textures/gui/book_binder_legacy.png'
+        include 'assets/rivencraft/textures/gui/link_modifier_legacy.png'
+        include 'assets/rivencraft/textures/block/link_modifier_*.png'
+        include 'assets/rivencraft/models/block/link_modifier.json'
+        include 'assets/rivencraft/models/item/link_modifier.json'
+        include 'assets/rivencraft/blockstates/link_modifier.json'
+        include 'data/rivencraft/loot_table/blocks/link_modifier.json'
         include 'assets/rivencraft/textures/gui/ink_mixer_legacy.png'
         include 'assets/rivencraft/textures/block/inkwell_base.png'
         include 'assets/rivencraft/textures/block/inkwell_cup.png'
@@ -249,6 +262,19 @@ tasks.named('processResources', ProcessResources).configure {
         include 'assets/rivencraft/models/block/book_binder.json'
         include 'assets/rivencraft/models/item/book_binder.json'
         include 'assets/rivencraft/blockstates/book_binder.json'
+        include 'assets/rivencraft/blockstates/book_receptacle.json'
+        include 'assets/rivencraft/blockstates/crystal_portal.json'
+        include 'assets/rivencraft/models/block/book_receptacle.json'
+        include 'assets/rivencraft/models/block/crystal_portal.json'
+        include 'assets/rivencraft/models/item/book_receptacle.json'
+        include 'assets/rivencraft/textures/block/book_receptacle.png'
+        include 'assets/rivencraft/textures/block/crystal_portal.png'
+        include 'assets/rivencraft/textures/block/crystal_portal.png.mcmeta'
+        include 'data/rivencraft/loot_table/blocks/book_receptacle.json'
+        include 'assets/rivencraft/blockstates/book_stand.json'
+        include 'data/rivencraft/loot_table/blocks/book_stand.json'
+        include 'data/rivencraft/loot_table/chests/mystcraft_library.json'
+        include 'data/rivencraft/structure/mystcraft_library.nbt'
         include 'data/rivencraft/loot_table/blocks/book_binder.json'
         include 'assets/rivencraft/models/block/crystal_block.json'
         include 'assets/rivencraft/blockstates/crystal_block.json'

ports/mc263/gradle.properties

@@ -7,4 +7,4 @@ neo_version=26.3.0.99
 mod_id=rivencraft
 mod_name=Rivencraft
 mod_license=LGPL-3.0-or-later
-mod_version=1.0.1.106-beta.1
+mod_version=1.0.1.129-beta.1

ports/mc263/src/main/java/net/dnorberg/rivencraft/PortConfig.java

@@ -4,9 +4,12 @@ import net.neoforged.neoforge.common.ModConfigSpec;
 
 /** Server-owned gameplay policies adapted from 1.21.1. */
 public final class PortConfig {
+    public enum LibraryLootMode { LEGACY, AGE_ONLY }
+    public static final ModConfigSpec.EnumValue<LibraryLootMode> LIBRARY_LOOT_MODE;
     public enum ReturnLinkMode { ON_CREATION, ALWAYS, DISABLED }
     public static final ModConfigSpec SPEC;
     public static final ModConfigSpec.IntValue SYMBOL_INK_COST;
+    public static final ModConfigSpec.IntValue LINK_PANEL_INK_COST;
     public static final ModConfigSpec.EnumValue<ReturnLinkMode> RETURN_LINK_MODE;
     public static final ModConfigSpec.IntValue ACCELERATED_MAX_CHUNKS;
     public static final ModConfigSpec.IntValue ACCELERATED_MAX_ATTEMPTS;
@@ -18,9 +21,16 @@ public final class PortConfig {
                 "ON_CREATION issues one on the first arrival per Age/world; ALWAYS issues one each arrival; DISABLED issues none.")
                 .defineEnum("return_link_mode", ReturnLinkMode.DISABLED);
         builder.pop();
+        builder.push("libraries");
+        LIBRARY_LOOT_MODE = builder.comment("LEGACY uses writing supplies/Sealed Notebooks and random lectern pages; AGE_ONLY uses only pages written into this Age.")
+                .defineEnum("loot_mode", LibraryLootMode.LEGACY);
+        builder.pop();
         builder.push("writing");
         SYMBOL_INK_COST = builder.comment("Ink units consumed for one Writing Desk symbol copy.")
                 .defineInRange("symbol_ink_cost", 1, 1, 16);
+        LINK_PANEL_INK_COST = builder.comment("Ink units consumed when preparing one baseline Link Panel by hand with paper.",
+                "The Ink Mixer uses one ink unit per panel independently of this setting.")
+                .defineInRange("link_panel_ink_cost", 2, 1, 16);
         builder.pop();
         builder.push("accelerated_age");
         ACCELERATED_MAX_CHUNKS = builder.comment("Maximum already-loaded player-nearby chunks given extra random ticks per Age tick.")
@@ -28,6 +38,7 @@ public final class PortConfig {
         ACCELERATED_MAX_ATTEMPTS = builder.comment("Maximum extra random-tick positions sampled per Age tick, shared fairly across loaded sections; zero disables Accelerated.")
                 .defineInRange("max_random_tick_attempts_per_tick", 16384, 0, 65536);
         builder.pop();
+        net.dnorberg.rivencraft.age.PortInstabilityConfig.define(builder);
         SPEC = builder.build();
     }
 

ports/mc263/src/main/java/net/dnorberg/rivencraft/Rivencraft.java

@@ -95,6 +95,8 @@ public final class Rivencraft {
             COMPONENTS.registerComponentType("notebook_contents", builder -> builder
                     .persistent(net.dnorberg.rivencraft.writing.NotebookContents.CODEC)
                     .networkSynchronized(net.dnorberg.rivencraft.writing.NotebookContents.STREAM_CODEC));
+    public static final Supplier<DataComponentType<String>> LINK_DESTINATION_NAME = COMPONENTS.registerComponentType(
+            "link_destination_name", builder -> builder.persistent(Codec.STRING).networkSynchronized(ByteBufCodecs.STRING_UTF8));
     public static final Supplier<DataComponentType<LinkBookTarget>> LINK_BOOK_TARGET = COMPONENTS.registerComponentType(
             "link_book_target", builder -> builder.persistent(LinkBookTarget.CODEC)
                     .networkSynchronized(LinkBookTarget.STREAM_CODEC));
@@ -106,6 +108,8 @@ public final class Rivencraft {
             "symbol_page_id", builder -> builder.persistent(Identifier.CODEC)
                     .networkSynchronized(Identifier.STREAM_CODEC));
     /** Ordered authored page IDs remain on the finished book for later port slices. */
+    public static final Supplier<DataComponentType<String>> BOOK_AUTHOR = COMPONENTS.registerComponentType(
+            "book_author", builder -> builder.persistent(Codec.STRING).networkSynchronized(ByteBufCodecs.STRING_UTF8));
     public static final Supplier<DataComponentType<java.util.List<Identifier>>> BOOK_SYMBOLS = COMPONENTS.registerComponentType(
             "book_symbols", builder -> builder.persistent(Identifier.CODEC.listOf())
                     .networkSynchronized(ByteBufCodecs.<io.netty.buffer.ByteBuf, Identifier>list(252)
@@ -127,16 +131,48 @@ public final class Rivencraft {
             BLOCKS.registerBlock("cloud_platform", net.dnorberg.rivencraft.block.CloudPlatformBlock::new,
                     () -> BlockBehaviour.Properties.ofFullCopy(Blocks.AMETHYST_BLOCK)
                             .mapColor(MapColor.COLOR_BLUE).strength(0.3F).noLootTable());
+    public static final DeferredBlock<net.dnorberg.rivencraft.block.BookReceptacleBlock> BOOK_RECEPTACLE =
+            BLOCKS.registerBlock("book_receptacle", net.dnorberg.rivencraft.block.BookReceptacleBlock::new,
+                    () -> BlockBehaviour.Properties.ofFullCopy(Blocks.AMETHYST_BLOCK).noOcclusion().mapColor(MapColor.COLOR_BLUE));
+    public static final DeferredItem<BlockItem> BOOK_RECEPTACLE_ITEM = ITEMS.registerSimpleBlockItem(BOOK_RECEPTACLE);
+    public static final DeferredBlock<net.dnorberg.rivencraft.block.CrystalPortalBlock> CRYSTAL_PORTAL =
+            BLOCKS.registerBlock("crystal_portal", net.dnorberg.rivencraft.block.CrystalPortalBlock::new,
+                    () -> BlockBehaviour.Properties.ofFullCopy(Blocks.NETHER_PORTAL)
+                            .noCollision().noOcclusion().lightLevel(state -> 11).noLootTable());
+    public static final Supplier<BlockEntityType<net.dnorberg.rivencraft.block.entity.BookReceptacleBlockEntity>> BOOK_RECEPTACLE_BLOCK_ENTITY =
+            BLOCK_ENTITY_TYPES.register("book_receptacle", () -> new BlockEntityType<>(
+                    net.dnorberg.rivencraft.block.entity.BookReceptacleBlockEntity::new, BOOK_RECEPTACLE.get()));
+    public static final Supplier<BlockEntityType<net.dnorberg.rivencraft.block.entity.CrystalPortalBlockEntity>> CRYSTAL_PORTAL_BLOCK_ENTITY =
+            BLOCK_ENTITY_TYPES.register("crystal_portal", () -> new BlockEntityType<>(
+                    net.dnorberg.rivencraft.block.entity.CrystalPortalBlockEntity::new, CRYSTAL_PORTAL.get()));
+    public static final DeferredBlock<net.dnorberg.rivencraft.block.DecayBlock> DECAY =
+            BLOCKS.registerBlock("decay", net.dnorberg.rivencraft.block.DecayBlock::new,
+                    () -> BlockBehaviour.Properties.ofFullCopy(Blocks.STONE).strength(5.0F, 10.0F).noLootTable());
     public static final DeferredBlock<StarFissureBlock> STAR_FISSURE =
             BLOCKS.registerBlock("star_fissure", StarFissureBlock::new,
                     () -> BlockBehaviour.Properties.ofFullCopy(Blocks.END_PORTAL).lightLevel(state -> 6));
     public static final Supplier<BlockEntityType<StarFissureBlockEntity>>
             STAR_FISSURE_BLOCK_ENTITY = BLOCK_ENTITY_TYPES.register("star_fissure", () -> new BlockEntityType<>(
                     StarFissureBlockEntity::new, STAR_FISSURE.get()));
+    public static final DeferredBlock<net.dnorberg.rivencraft.block.BookStandBlock> BOOK_STAND =
+            BLOCKS.registerBlock("book_stand", net.dnorberg.rivencraft.block.BookStandBlock::new,
+                    () -> BlockBehaviour.Properties.ofFullCopy(Blocks.LECTERN));
+    public static final Supplier<BlockEntityType<net.dnorberg.rivencraft.block.entity.BookStandBlockEntity>> BOOK_STAND_BLOCK_ENTITY =
+            BLOCK_ENTITY_TYPES.register("book_stand", () -> new BlockEntityType<>(
+                    net.dnorberg.rivencraft.block.entity.BookStandBlockEntity::new, BOOK_STAND.get()));
     public static final DeferredBlock<PortBookBinderBlock> BOOK_BINDER = BLOCKS.registerBlock(
             "book_binder", PortBookBinderBlock::new,
             () -> BlockBehaviour.Properties.ofFullCopy(Blocks.CRAFTING_TABLE).noOcclusion());
     public static final DeferredItem<BlockItem> BOOK_BINDER_ITEM = ITEMS.registerSimpleBlockItem(BOOK_BINDER);
+    public static final DeferredBlock<net.dnorberg.rivencraft.block.LinkModifierBlock> LINK_MODIFIER = BLOCKS.registerBlock(
+            "link_modifier", net.dnorberg.rivencraft.block.LinkModifierBlock::new,
+            () -> BlockBehaviour.Properties.ofFullCopy(Blocks.STONE).noOcclusion());
+    public static final DeferredItem<BlockItem> LINK_MODIFIER_ITEM = ITEMS.registerSimpleBlockItem(LINK_MODIFIER);
+    public static final Supplier<BlockEntityType<net.dnorberg.rivencraft.block.entity.LinkModifierBlockEntity>> LINK_MODIFIER_BLOCK_ENTITY =
+            BLOCK_ENTITY_TYPES.register("link_modifier", () -> new BlockEntityType<>(
+                    net.dnorberg.rivencraft.block.entity.LinkModifierBlockEntity::new, LINK_MODIFIER.get()));
+    public static final Supplier<MenuType<net.dnorberg.rivencraft.menu.LinkModifierMenu>> LINK_MODIFIER_MENU =
+            MENUS.register("link_modifier", () -> IMenuTypeExtension.create(net.dnorberg.rivencraft.menu.LinkModifierMenu::new));
     public static final DeferredBlock<InkMixerBlock> INK_MIXER = BLOCKS.registerBlock(
             "ink_mixer", InkMixerBlock::new,
             () -> BlockBehaviour.Properties.ofFullCopy(Blocks.CRAFTING_TABLE).noOcclusion());
@@ -219,11 +255,17 @@ public final class Rivencraft {
         NeoForge.EVENT_BUS.addListener(net.dnorberg.rivencraft.age.PortAgeWeather::onLevelTickPre);
         NeoForge.EVENT_BUS.addListener(net.dnorberg.rivencraft.age.PortAcceleratedTicks::onLevelTickPost);
         NeoForge.EVENT_BUS.addListener(PortAgeCommands::register);
+        NeoForge.EVENT_BUS.addListener(net.dnorberg.rivencraft.event.BookStandConversionHandler::onRightClickBlock);
         NeoForge.EVENT_BUS.addListener(AgeCatalogSync::onLogin);
         NeoForge.EVENT_BUS.addListener(AgeCatalogSync::onLogout);
         NeoForge.EVENT_BUS.addListener(AgeCatalogSync::onServerStopped);
         modEventBus.addListener(AgeCatalogSync::registerPayloads);
         modEventBus.addListener(PortBookNetworking::registerPayloads);
+        net.dnorberg.rivencraft.age.PortStatusEffectProviders.register();
+        net.dnorberg.rivencraft.age.PortDecayProviders.register();
+        net.dnorberg.rivencraft.age.PortHazardProviders.register();
+        net.dnorberg.rivencraft.age.PortMeteorProvider.register();
+        net.dnorberg.rivencraft.age.PortEnvironmentalProviders.register();
         LOGGER.info("Initializing Rivencraft 26.3 port slice (not release-ready)");
     }
 }

ports/mc263/src/main/java/net/dnorberg/rivencraft/advancement/ProgressionAdvancements.java

@@ -0,0 +1,28 @@
+package net.dnorberg.rivencraft.advancement;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.age.RuntimeAgeBackend;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerPlayer;
+
+/** Awards action-only progression after the server has committed the action. */
+public final class ProgressionAdvancements {
+    public static final String OPEN_PORTAL = "open_portal";
+    public static final String LINK_PANEL = "link_panel";
+    public static final String COPY_PAGE = "copy_page";
+    public static final String BIND_AGE = "bind_age";
+    public static final String ENTER_AGE = "enter_age";
+
+    private ProgressionAdvancements() {}
+
+    public static void award(ServerPlayer player, String path) {
+        var advancement = player.level().getServer().getAdvancements().get(
+                Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "progression/" + path));
+        if (advancement != null) player.getAdvancements().award(advancement, "completed");
+    }
+
+    public static void awardAgeTravel(ServerPlayer player) {
+        if (RuntimeAgeBackend.savedAges(player.level().getServer()).containsKey(player.level().dimension().identifier()))
+            award(player, ENTER_AGE);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/AgeLevelIndex.java

@@ -42,7 +42,9 @@ final class AgeLevelIndex extends SavedData {
             Codec.unboundedMap(Identifier.CODEC, PortAgeColors.CODEC)
                     .optionalFieldOf("colors", Map.of()).forGetter(index -> index.colors),
             Codec.unboundedMap(Identifier.CODEC, PortDayCycle.CODEC)
-                    .optionalFieldOf("day_cycles", Map.of()).forGetter(index -> index.dayCycles)
+                    .optionalFieldOf("day_cycles", Map.of()).forGetter(index -> index.dayCycles),
+            Codec.unboundedMap(Identifier.CODEC, Codec.STRING)
+                    .optionalFieldOf("display_names", Map.of()).forGetter(index -> index.displayNames)
     ).apply(instance, AgeLevelIndex::new));
 
     static final SavedDataType<AgeLevelIndex> TYPE = new SavedDataType<>(
@@ -65,6 +67,7 @@ final class AgeLevelIndex extends SavedData {
     private final Map<Identifier, PortSkyStyle> sky;
     private final Map<Identifier, PortAgeColors> colors;
     private final Map<Identifier, PortDayCycle> dayCycles;
+    private final Map<Identifier, String> displayNames;
 
     private AgeLevelIndex() {
         this.ages = new LinkedHashMap<>();
@@ -81,6 +84,7 @@ final class AgeLevelIndex extends SavedData {
         this.sky = new LinkedHashMap<>();
         this.colors = new LinkedHashMap<>();
         this.dayCycles = new LinkedHashMap<>();
+        this.displayNames = new LinkedHashMap<>();
     }
 
     private AgeLevelIndex(Map<Identifier, Long> ages, List<Identifier> retired,
@@ -94,7 +98,7 @@ final class AgeLevelIndex extends SavedData {
                           Map<Identifier, PortTerrainFeaturePlan> terrainFeatures,
                           Map<Identifier, PortLighting> lighting,
                           Map<Identifier, PortSkyStyle> sky, Map<Identifier, PortAgeColors> colors,
-                          Map<Identifier, PortDayCycle> dayCycles) {
+                          Map<Identifier, PortDayCycle> dayCycles, Map<Identifier, String> displayNames) {
         this.ages = new LinkedHashMap<>(ages);
         this.retired = new LinkedHashSet<>(retired);
         this.biomeOverrides = new LinkedHashMap<>(biomeOverrides);
@@ -109,6 +113,16 @@ final class AgeLevelIndex extends SavedData {
         this.sky = new LinkedHashMap<>(sky);
         this.colors = new LinkedHashMap<>(colors);
         this.dayCycles = new LinkedHashMap<>(dayCycles);
+        this.displayNames = new LinkedHashMap<>(displayNames);
+    }
+
+    String displayName(Identifier id) { return ages.containsKey(id) ? displayNames.get(id) : null; }
+
+    void setDisplayName(Identifier id, String name) {
+        if (!ages.containsKey(id)) throw new IllegalArgumentException("Age not indexed: " + id);
+        if (name == null || name.isBlank() || name.length() > 32) throw new IllegalArgumentException("Invalid Age display name");
+        displayNames.put(id, name.strip());
+        setDirty();
     }
 
     Map<Identifier, Long> entries() {

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/InstabilityProviderCatalog.java

@@ -0,0 +1,74 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.ArrayList;
+import java.util.List;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.resources.Identifier;
+
+/** Frozen Legacy 0.13.7.06 deck cards and default activation costs, not effect implementations. */
+public final class InstabilityProviderCatalog {
+    public enum Deck {
+        BASIC(0), HARSH(2_500), DESTRUCTIVE(10_000), EATING(15_000), DEATH(20_000);
+
+        private final int entryCost;
+
+        Deck(int entryCost) { this.entryCost = entryCost; }
+        public int entryCost() { return entryCost; }
+    }
+
+    public record Card(Identifier id, int cost) {
+        public Card {
+            if (cost <= 0) throw new IllegalArgumentException("Provider cost must be positive");
+        }
+    }
+
+    private static final List<List<Card>> DECKS = createDecks();
+
+    private InstabilityProviderCatalog() {}
+
+    public static List<Card> cards(Deck deck) { return DECKS.get(deck.ordinal()); }
+
+    public static boolean contains(Identifier id) {
+        return DECKS.stream().flatMap(List::stream).anyMatch(card -> card.id().equals(id));
+    }
+
+    private static List<List<Card>> createDecks() {
+        List<List<Card>> decks = new ArrayList<>();
+        for (Deck ignored : Deck.values()) decks.add(new ArrayList<>());
+        add(decks, "blindness", 1000, 0, 0, 0, 1, 0);
+        add(decks, "blindness_global", 1500, 0, 0, 0, 0, 1);
+        add(decks, "enemyregen_global", 1000, 5, 2, 0, 0, 0);
+        add(decks, "enemyresist_global", 1000, 2, 1, 0, 0, 0);
+        add(decks, "fatigue", 500, 5, 0, 0, 0, 0);
+        add(decks, "fatigue_global", 1000, 0, 5, 0, 0, 0);
+        add(decks, "hunger", 500, 8, 2, 0, 0, 0);
+        add(decks, "hunger_global", 1000, 0, 5, 0, 0, 0);
+        add(decks, "nausea", 1000, 0, 0, 0, 1, 0);
+        add(decks, "nausea_global", 1500, 0, 0, 0, 0, 1);
+        add(decks, "poison", 500, 9, 3, 0, 0, 0);
+        add(decks, "poison_global", 1000, 0, 5, 0, 0, 0);
+        add(decks, "slow", 500, 6, 1, 0, 0, 0);
+        add(decks, "slow_global", 1000, 0, 5, 0, 0, 0);
+        add(decks, "weakness", 500, 8, 2, 0, 0, 0);
+        add(decks, "weakness_global", 1000, 0, 5, 0, 0, 0);
+        add(decks, "wither", 1000, 0, 1, 1, 2, 0);
+        add(decks, "wither_global", 2000, 0, 0, 1, 1, 1);
+        add(decks, "burning", 500, 0, 1, 0, 0, 0);
+        add(decks, "crumble", 2000, 0, 0, 6, 0, 0);
+        add(decks, "decayblue", 2000, 0, 0, 0, 2, 1);
+        add(decks, "decaypurple", 2000, 0, 0, 0, 2, 1);
+        add(decks, "decayred", 2000, 0, 0, 0, 2, 1);
+        add(decks, "decaywhite", 5000, 0, 0, 0, 1, 3);
+        add(decks, "explosions", 1000, 0, 0, 8, 0, 0);
+        add(decks, "lightning", 1000, 0, 4, 4, 0, 0);
+        add(decks, "meteors", 1000, 0, 0, 4, 0, 0);
+        return decks.stream().map(List::copyOf).toList();
+    }
+
+    private static void add(List<List<Card>> decks, String path, int cost, int... copies) {
+        Card card = new Card(Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, path), cost);
+        for (Deck deck : Deck.values()) {
+            for (int copy = 0; copy < copies[deck.ordinal()]; copy++) decks.get(deck.ordinal()).add(card);
+        }
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortAgeColors.java

@@ -69,7 +69,8 @@ public record PortAgeColors(int sky, int ambient, int celestial) {
     }
 
     public static PortAgeColors compile(List<Identifier> pages, long seed) {
-        if (!validNumbers(pages)) throw new IllegalArgumentException("Number pages must precede a supported Color, Length, Phase, Angle, or Size modifier");
+        // Numbers only attach to the immediately following target. Misplaced
+        // numbers are diagnosed by PortWritingRecovery, never moved to a later color.
         int red = 0, green = 0, blue = 0, sky = -1, ambient = -1, celestial = -1;
         boolean written = false;
         for (int i = 0; i < pages.size(); i++) {

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortAgeCommands.java

@@ -35,6 +35,12 @@ public final class PortAgeCommands {
     public static void register(RegisterCommandsEvent event) {
         event.getDispatcher().register(Commands.literal("rivencraft_port")
                 .requires(Commands.hasPermission(Commands.LEVEL_ADMINS))
+                .then(Commands.literal("recipe_discovery_probe")
+                        .executes(context -> {
+                            PortProgressionProbe.recipeDiscovery(context.getSource().getServer().overworld());
+                            context.getSource().sendSuccess(() -> Component.literal("Recipe discovery checks passed for all six crafting unlocks"), false);
+                            return 1;
+                        }))
                 .then(Commands.literal("compat")
                         .executes(context -> {
                             StringBuilder mods = new StringBuilder("Optional mods: ");
@@ -69,6 +75,44 @@ public final class PortAgeCommands {
                                     return 1;
                                 })))
                 .then(Commands.literal("age")
+                        .then(Commands.literal("create_drop_conversion_fixture")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .then(Commands.argument("seed", LongArgumentType.longArg())
+                                                .executes(context -> {
+                                                    var level = RuntimeAgeBackend.create(context.getSource().getServer(), ageId(context),
+                                                            LongArgumentType.getLong(context, "seed"), null, PortAgeTerrain.VOID);
+                                                    PortBookDropConversionProbe.create(level);
+                                                    context.getSource().sendSuccess(() -> Component.literal("Drop sources queued; run drop_conversion_probe after server tasks complete"), false);
+                                                    return 1;
+                                                }))))
+                        .then(Commands.literal("drop_conversion_probe")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .executes(context -> {
+                                            var level = context.getSource().getServer().getLevel(ResourceKey.create(Registries.DIMENSION, ageId(context)));
+                                            if (level == null) throw new IllegalArgumentException("Age not loaded");
+                                            PortBookDropConversionProbe.verify(level);
+                                            context.getSource().sendSuccess(() -> Component.literal("Universal book drop conversion/ownership checks passed"), false);
+                                            return 1;
+                                        })))
+                        .then(Commands.literal("create_book_stand_fixture")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .then(Commands.argument("seed", LongArgumentType.longArg())
+                                                .executes(context -> {
+                                                    var level = RuntimeAgeBackend.create(context.getSource().getServer(), ageId(context),
+                                                            LongArgumentType.getLong(context, "seed"), null, PortAgeTerrain.VOID);
+                                                    PortBookStandProbe.create(level);
+                                                    context.getSource().sendSuccess(() -> Component.literal("Book Stand conversion/ownership/source checks passed"), false);
+                                                    return 1;
+                                                }))))
+                        .then(Commands.literal("book_stand_probe")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .executes(context -> {
+                                            var level = context.getSource().getServer().getLevel(ResourceKey.create(Registries.DIMENSION, ageId(context)));
+                                            if (level == null) throw new IllegalArgumentException("Age not loaded");
+                                            PortBookStandProbe.verify(level);
+                                            context.getSource().sendSuccess(() -> Component.literal("Book Stand persistence passed"), false);
+                                            return 1;
+                                        })))
                         .then(Commands.literal("create_writing_desk_fixture")
                                 .then(Commands.argument("name", StringArgumentType.word())
                                         .then(Commands.argument("seed", LongArgumentType.longArg())
@@ -79,6 +123,15 @@ public final class PortAgeCommands {
                                                     context.getSource().sendSuccess(() -> Component.literal("Writing Desk transaction/removal checks passed"), false);
                                                     return 1;
                                                 }))))
+                        .then(Commands.literal("progression_probe")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .executes(context -> {
+                                            var level = context.getSource().getServer().getLevel(ResourceKey.create(Registries.DIMENSION, ageId(context)));
+                                            if (level == null) throw new IllegalArgumentException("Age not loaded");
+                                            PortProgressionProbe.run(level);
+                                            context.getSource().sendSuccess(() -> Component.literal("Progression data/action checks passed"), false);
+                                            return 1;
+                                        })))
                         .then(Commands.literal("writing_desk_probe")
                                 .then(Commands.argument("name", StringArgumentType.word())
                                         .executes(context -> {
@@ -766,8 +819,8 @@ public final class PortAgeCommands {
                     || new PortDayCycle(true, 2, 0).ticks(12000) != 6000
                     || new PortDayCycle(true, 0, 321).ticks(-123456) != 321
                     || new PortDayCycle(true, 0, 321).ticks(123456) != 321
-                    || PortDayCycle.validWriting(java.util.List.of(symbol.apply("period/half")))
-                    || PortDayCycle.validWriting(java.util.List.of(PortDayCycle.NORMAL_TIME, symbol.apply("period/half"))))
+                    || !PortDayCycle.validWriting(java.util.List.of(symbol.apply("period/half")))
+                    || !PortDayCycle.validWriting(java.util.List.of(PortDayCycle.NORMAL_TIME, symbol.apply("period/half"))))
                 throw new IllegalStateException("Day cycle fixture failed");
             var server = context.getSource().getServer();
             var biomes = net.dnorberg.rivencraft.writing.PortAuthoredWriting.biomePlan(pages, server.registryAccess());
@@ -1563,7 +1616,7 @@ public final class PortAgeCommands {
                         || Math.abs(moving.bodyAngle(origin + 100) + 3F) > 0.0001F
                         || !PortDayCycle.validWriting(java.util.List.of(target, PortDayCycle.NORMAL_TIME))
                         || !PortDayCycle.validWriting(java.util.List.of(target, target))
-                        || PortDayCycle.validWriting(java.util.List.of(target, symbol.apply("size/large"))))
+                        || !PortDayCycle.validWriting(java.util.List.of(target, symbol.apply("size/large"))))
                     throw new IllegalStateException("Single-body modifier/order invariant failed");
             }
             var older = PortDayCycle.CODEC.parse(com.mojang.serialization.JsonOps.INSTANCE,

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortAgeTravel.java

@@ -18,26 +18,45 @@ public final class PortAgeTravel {
     }
 
     public static String enter(ServerPlayer player, Identifier id) {
+        return enter(player, id, net.dnorberg.rivencraft.item.LinkProperties.NONE);
+    }
+    public static String enter(ServerPlayer player, Identifier id, net.dnorberg.rivencraft.item.LinkProperties properties) {
         ServerLevel target = player.level().getServer().getLevel(ResourceKey.create(Registries.DIMENSION, id));
         if (target == null) return "Age not loaded: " + id;
         if (!AgeCatalogSync.ready(player, id)) {
             return "Age catalog not acknowledged by client; remaining in source dimension";
         }
+        BlockPos landing = resolveLanding(target, player, properties);
+        if (landing == null) return "No safe landing available; remaining in source dimension";
+        boolean moved = player.teleportTo(target, landing.getX() + 0.5, landing.getY(), landing.getZ() + 0.5,
+                Set.of(), player.getYRot(), player.getXRot(), true);
+        return moved ? null : "Teleportation failed; remaining in source dimension";
+    }
+
+    public static BlockPos resolveLanding(ServerLevel target) { return resolveLanding(target, true); }
+    public static BlockPos resolveLanding(ServerLevel target, net.minecraft.world.entity.Entity entity,
+                                          net.dnorberg.rivencraft.item.LinkProperties properties) {
+        BlockPos landing = resolveLanding(target, !properties.has(net.dnorberg.rivencraft.item.LinkProperties.DISABLE_PLATFORM));
+        if (landing == null || !properties.has(net.dnorberg.rivencraft.item.LinkProperties.RELATIVE_LINK)) return landing;
+        return findFootedDestination(target, net.dnorberg.rivencraft.item.PortLinkDestinations.relativeOrigin(
+                (ServerLevel) entity.level(), target, entity.blockPosition())).orElse(null);
+    }
+    public static BlockPos resolveLanding(ServerLevel target, boolean generatePlatform) {
         boolean fissure = target.getChunkSource().getGenerator() instanceof PortFeatureChunkGenerator features
                 && features.terrainFeatures() != null && features.terrainFeatures().starFissures();
         BlockPos landing = fissure ? PortStarFissureFeature.savedSpawn(target) : null;
         if (landing != null) landing = isCaveTerrain(target)
                 ? findFootedDestination(target, landing).orElse(null)
                 : findSurfaceLanding(target, landing.getX(), landing.getZ());
-        if (landing == null) landing = findLanding(target);
-        if (landing == null) return "No safe test landing available; remaining in source dimension";
+        if (landing == null) landing = findLanding(target, generatePlatform);
+        if (landing == null) return null;
         if (fissure) PortStarFissureFeature.generateOnce(target, landing, isCaveTerrain(target));
-        boolean moved = player.teleportTo(target, landing.getX() + 0.5, landing.getY(), landing.getZ() + 0.5,
-                Set.of(), player.getYRot(), player.getXRot(), true);
-        return moved ? null : "Teleportation failed; remaining in source dimension";
+        if (target instanceof PortAgeLevel) PortInstabilityData.get(target.getServer()).recordSpawn(target, landing);
+        return landing;
     }
 
-    static BlockPos findLanding(ServerLevel target) {
+    static BlockPos findLanding(ServerLevel target) { return findLanding(target, true); }
+    static BlockPos findLanding(ServerLevel target, boolean generatePlatform) {
         if (isCaveTerrain(target)) {
             // The cave roof is not a valid arrival surface. Search down from
             // Legacy's Y=64 start, then construct the normal safety platform
@@ -53,7 +72,7 @@ public final class PortAgeTravel {
                     }
                 }
             }
-            return makePlatform(target, new BlockPos(0, 64, 0));
+            return generatePlatform ? makePlatform(target, new BlockPos(0, 64, 0)) : null;
         }
         BlockPos surface = findSurfaceLanding(target, 0, 0);
         if (surface != null) return surface;
@@ -61,7 +80,7 @@ public final class PortAgeTravel {
         // beneath it. Void Ages retain the usual platform floor at Y=63.
         BlockPos obstruction = highestObstruction(target, 0, 0);
         int y = obstruction == null ? 64 : Math.max(64, obstruction.getY() + 3);
-        return makePlatform(target, new BlockPos(0, y, 0));
+        return generatePlatform ? makePlatform(target, new BlockPos(0, y, 0)) : null;
     }
 
     static BlockPos findSurfaceLanding(ServerLevel target, int originX, int originZ) {

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortBinderCollectionProbe.java

@@ -52,7 +52,7 @@ final class PortBinderCollectionProbe {
         if (!binder.importCollection(folder, -1).isEmpty() || !binder.importCollection(folder, 1).isEmpty())
             throw new IllegalStateException("Invalid collection insertion point accepted");
         binder.insertPage(0, page("terrain/flat"));
-        var player = net.neoforged.neoforge.common.util.FakePlayerFactory.get(level,
+        var player = new PortProgressionPlayer(level,
                 new com.mojang.authlib.GameProfile(java.util.UUID.fromString("5225a1ed-5ead-44b5-a63c-c78e7dca86f5"), "RivenBinderProbe"));
         player.setPos(0.5, 64, 2.5);
         var menu = new PortBookBinderMenu(1, player.getInventory(), binder);
@@ -81,6 +81,52 @@ final class PortBinderCollectionProbe {
                     || !binder.getItem(PortBookBinderBlockEntity.COVER).isEmpty()
                     || !binder.getItem(PortBookBinderBlockEntity.PANEL).isEmpty())
                 throw new IllegalStateException("Collection-backed Binder assembly regression");
+            if (!PortProgressionProbe.isComplete(player, "bind_age"))
+                throw new IllegalStateException("Missing bind_age award");
+            if (!player.getGameProfile().name().equals(book.get(Rivencraft.BOOK_AUTHOR.get())))
+                throw new IllegalStateException("Binder author was not server assigned");
+            var pages = net.dnorberg.rivencraft.writing.DescriptiveBookPages.from(book);
+            if (pages.lastPage() != EXPECTED.size() || pages.symbolAt(0).isPresent()
+                    || !pages.symbolAt(1).orElseThrow().equals(EXPECTED.getFirst())
+                    || !pages.symbolAt(EXPECTED.size()).orElseThrow().equals(EXPECTED.getLast())
+                    || pages.symbolAt(EXPECTED.size() + 1).isPresent()
+                    || pages.turn(0, -1) != 0 || pages.turn(pages.lastPage(), 1) != pages.lastPage())
+                throw new IllegalStateException("Authored book page indexing failed");
+            var old = net.dnorberg.rivencraft.writing.DescriptiveBookPages.from(new ItemStack(Rivencraft.DESCRIPTIVE_BOOK.get()));
+            if (old.lastPage() != 1 || !old.author().isEmpty() || old.symbolAt(1).isPresent())
+                throw new IllegalStateException("Older panel-only book fallback failed");
+            var repeated = new net.dnorberg.rivencraft.writing.DescriptiveBookPages(
+                    List.of(EXPECTED.getFirst(), EXPECTED.getFirst()), "Test");
+            if (repeated.lastPage() != 2 || !repeated.symbolAt(1).equals(repeated.symbolAt(2)))
+                throw new IllegalStateException("Repeated symbol display was collapsed");
+            var ageId = book.get(Rivencraft.AGE_BOOK_ID.get());
+            var server = level.getServer();
+            if (!RuntimeAgeBackend.savedAgeName(server, ageId).orElseThrow().equals("Collection Fixture104"))
+                throw new IllegalStateException("Created Age lost its display name");
+            var namedLevel = server.getLevel(net.minecraft.resources.ResourceKey.create(
+                    net.minecraft.core.registries.Registries.DIMENSION, ageId));
+            if (!net.dnorberg.rivencraft.item.LinkingBookItem.destinationName(namedLevel).equals("Collection Fixture104"))
+                throw new IllegalStateException("Link binding name lookup did not use Age title");
+            RuntimeAgeBackend.setAgeDisplayName(server, ageId, "Crystal Garden's Dawn");
+            var target = new net.dnorberg.rivencraft.item.LinkBookTarget(ageId, -0.5, 64, -1.25, 90, 0);
+            var link = new ItemStack(Rivencraft.LINKING_BOOK.get());
+            link.set(Rivencraft.LINK_BOOK_TARGET.get(), target);
+            link.set(Rivencraft.LINK_DESTINATION_NAME.get(), net.dnorberg.rivencraft.item.LinkingBookItem.destinationName(namedLevel));
+            if (!net.dnorberg.rivencraft.item.LinkingBookItem.destinationName(link, target).getString().equals("Crystal Garden's Dawn"))
+                throw new IllegalStateException("Link destination label ignored saved name");
+            var mode = net.dnorberg.rivencraft.PortConfig.RETURN_LINK_MODE.get();
+            player.getInventory().clearContent();
+            try {
+                net.dnorberg.rivencraft.PortConfig.RETURN_LINK_MODE.set(net.dnorberg.rivencraft.PortConfig.ReturnLinkMode.ALWAYS);
+                PortReturnLinks.afterSuccessfulTravel(player, ageId, target);
+                var returned = java.util.stream.IntStream.range(0, player.getInventory().getContainerSize())
+                        .mapToObj(i -> player.getInventory().getItem(i)).filter(i -> i.is(Rivencraft.LINKING_BOOK.get()))
+                        .findFirst().orElseThrow();
+                if (!"Crystal Garden's Dawn".equals(returned.get(Rivencraft.LINK_DESTINATION_NAME.get())))
+                    throw new IllegalStateException("Automatic Return Link lost departure name");
+                chest.setItem(4, returned.copy());
+            } finally { net.dnorberg.rivencraft.PortConfig.RETURN_LINK_MODE.set(mode); }
+            chest.setItem(3, link);
             chest.setItem(2, book.copy());
             menu.setCarried(ItemStack.EMPTY);
         } finally { player.getInventory().clearContent(); }
@@ -93,6 +139,18 @@ final class PortBinderCollectionProbe {
             throw new IllegalStateException("Empty collection covers were not preserved");
         for (int i = 0; i < 2; i++) if (chest.getItem(i).get(Rivencraft.NOTEBOOK_CONTENTS.get()).pageCount() != 0)
             throw new IllegalStateException("Imported pages remained in a collection");
+        if (!"RivenBinderProbe".equals(chest.getItem(2).get(Rivencraft.BOOK_AUTHOR.get())))
+            throw new IllegalStateException("Authored book lost its author");
+        var ageId = chest.getItem(2).get(Rivencraft.AGE_BOOK_ID.get());
+        if (!RuntimeAgeBackend.savedAgeName(level.getServer(), ageId).orElseThrow().equals("Crystal Garden's Dawn")
+                || !"Crystal Garden's Dawn".equals(chest.getItem(3).get(Rivencraft.LINK_DESTINATION_NAME.get()))
+                || !"Crystal Garden's Dawn".equals(chest.getItem(4).get(Rivencraft.LINK_DESTINATION_NAME.get())))
+            throw new IllegalStateException("Age/Linking/Return destination names did not survive persistence");
+        var old = new ItemStack(Rivencraft.LINKING_BOOK.get());
+        var overworld = new net.dnorberg.rivencraft.item.LinkBookTarget(net.minecraft.world.level.Level.OVERWORLD.identifier(), 0, 64, 0, 0, 0);
+        if (!net.dnorberg.rivencraft.item.LinkingBookItem.destinationName(old, overworld).getString()
+                .equals(net.minecraft.network.chat.Component.translatable("dimension.minecraft.overworld").getString()))
+            throw new IllegalStateException("Older book vanilla name fallback changed");
         if (!EXPECTED.equals(chest.getItem(2).get(Rivencraft.BOOK_SYMBOLS.get())))
             throw new IllegalStateException("Authored book page order was not preserved");
     }

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortBlockInstability.java

@@ -0,0 +1,314 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import net.dnorberg.rivencraft.Rivencraft;
+
+import net.dnorberg.rivencraft.writing.PortRegistryPages;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.chunk.LevelChunk;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import net.neoforged.neoforge.common.Tags;
+import net.neoforged.neoforge.event.level.ChunkEvent;
+import net.neoforged.neoforge.event.server.ServerStoppingEvent;
+import net.neoforged.neoforge.event.tick.ServerTickEvent;
+
+/** Legacy-style excess-block profiling with gradual spawn-area generation. */
+@net.neoforged.fml.common.EventBusSubscriber(modid = Rivencraft.MOD_ID)
+public final class PortBlockInstability {
+    // Legacy's watched blocks and factor-1 values; modern ore variants share their parent weight.
+    // Storage blocks are deliberate extensions, including the requested diamond-block case.
+    private static final Map<Identifier, Double> VANILLA_WEIGHTS = weights();
+    private static final Map<String, Double> COMMON_MINERAL_WEIGHTS = Map.ofEntries(
+            Map.entry("coal", 5.0), Map.entry("sulfur", 5.0), Map.entry("sulphur", 5.0),
+            Map.entry("salt", 5.0), Map.entry("tin", 60.0), Map.entry("lead", 60.0),
+            Map.entry("aluminum", 60.0), Map.entry("aluminium", 60.0),
+            Map.entry("zinc", 60.0), Map.entry("copper", 60.0),
+            Map.entry("iron", 60.0), Map.entry("nickel", 200.0),
+            Map.entry("osmium", 200.0), Map.entry("silver", 200.0),
+            Map.entry("emerald", 200.0), Map.entry("ruby", 200.0),
+            Map.entry("sapphire", 200.0), Map.entry("redstone", 250.0),
+            Map.entry("gold", 750.0), Map.entry("uranium", 750.0),
+            Map.entry("platinum", 750.0), Map.entry("diamond", 4000.0),
+            Map.entry("iridium", 4000.0), Map.entry("netherite", 8000.0));
+    private static final int MAX_PENDING = 2048;
+    private static final int SAMPLES_PER_TICK = 4;
+    private static final int GENERATION_INTERVAL_TICKS = 20;
+    private static final List<ChunkPos> SPAWN_OFFSETS = spawnOffsets();
+    private static final Map<MinecraftServer, ArrayDeque<Pending>> PENDING = new java.util.WeakHashMap<>();
+    private static final Map<MinecraftServer, Map<Identifier, Integer>> NEXT_SPAWN_SAMPLE =
+            new java.util.WeakHashMap<>();
+    private static final Map<MinecraftServer, Integer> NEXT_TARGET = new java.util.WeakHashMap<>();
+    private static final Map<MinecraftServer, Boolean> GENERATION_IN_FLIGHT =
+            new java.util.WeakHashMap<>();
+
+    private PortBlockInstability() {}
+
+    /** Track recognized materials from installed mods without requiring any mod-specific API. */
+    static boolean tracked(Identifier id) {
+        if (VANILLA_WEIGHTS.containsKey(id)) return true;
+        if (id.getNamespace().equals("minecraft") || id.getNamespace().equals("rivencraft")) return false;
+        if (!BuiltInRegistries.BLOCK.containsKey(id)) return false;
+        var block = BuiltInRegistries.BLOCK.getValue(id);
+        return eligibleMaterial(block) && (configuredOverride(id) != null || inferredModdedWeight(id, block) > 0);
+    }
+
+    static double weight(Identifier id) {
+        Double vanilla = VANILLA_WEIGHTS.get(id);
+        if (vanilla != null) return vanilla;
+        if (id.getNamespace().equals("minecraft") || id.getNamespace().equals("rivencraft")
+                || !BuiltInRegistries.BLOCK.containsKey(id)) return 0;
+        var block = BuiltInRegistries.BLOCK.getValue(id);
+        if (!eligibleMaterial(block)) return 0;
+        return moddedWeight(id, inferredModdedWeight(id, block),
+                PortInstabilityConfig.moddedMaterialOverrides());
+    }
+
+    private static boolean eligibleMaterial(net.minecraft.world.level.block.Block block) {
+        return PortRegistryPages.materialCategory(block) != null;
+    }
+
+    private static Double configuredOverride(Identifier id) {
+        return configuredOverride(id, PortInstabilityConfig.moddedMaterialOverrides());
+    }
+
+    private static Double configuredOverride(Identifier id, List<? extends String> overrides) {
+        for (String entry : overrides) {
+            int separator = entry.lastIndexOf('=');
+            if (separator > 0 && entry.substring(0, separator).equals(id.toString()))
+                return (double) Integer.parseInt(entry.substring(separator + 1));
+        }
+        return null;
+    }
+
+    static double moddedWeight(Identifier id, double inferred, List<? extends String> overrides) {
+        Double override = configuredOverride(id, overrides);
+        return override == null ? inferred : override;
+    }
+
+    private static double inferredModdedWeight(Identifier id, net.minecraft.world.level.block.Block block) {
+        if ("rivencraft:fluid".equals(PortRegistryPages.materialCategory(block))) return 1.25;
+        var state = block.defaultBlockState();
+        String path = id.getPath();
+        boolean ore = state.is(Tags.BlockItems.ORES.block()) || path.endsWith("_ore") || path.contains("_ore_");
+        boolean storage = state.is(Tags.BlockItems.STORAGE_BLOCKS.block())
+                || (path.endsWith("_block") || path.startsWith("block_of_"))
+                && namedMineralWeight(path) != null;
+        return inferredModdedWeight(id, ore, storage, false);
+    }
+
+    static double inferredModdedWeight(Identifier id, boolean ore, boolean storage, boolean fluid) {
+        if (fluid) return 1.25;
+        Double named = namedMineralWeight(id.getPath());
+        if (ore) return named == null ? 60.0 : named;
+        if (storage) return named == null ? 120.0 : named;
+        return 0;
+    }
+
+    private static Double namedMineralWeight(String path) {
+        for (String part : path.split("[/_]")) {
+            Double value = COMMON_MINERAL_WEIGHTS.get(part);
+            if (value != null) return value;
+        }
+        return null;
+    }
+
+    @net.neoforged.bus.api.SubscribeEvent
+    public static void onChunkLoad(ChunkEvent.Load event) {
+        if (!(event.getLevel() instanceof ServerLevel level)
+                || !(event.getChunk() instanceof LevelChunk chunk)) return;
+        boolean overworld = level.dimension() == net.minecraft.world.level.Level.OVERWORLD;
+        if (!overworld && !PortInstabilityRuntime.isAge(level)) return;
+        // Chunk-load callbacks can occur while chunk storage is updating. Defer saved-data
+        // access to a bounded server-tick lane to avoid reentering that storage path.
+        synchronized (PENDING) {
+            var queue = PENDING.computeIfAbsent(level.getServer(), ignored -> new ArrayDeque<>());
+            if (queue.size() < MAX_PENDING) queue.addLast(new Pending(level, chunk));
+        }
+    }
+
+    @net.neoforged.bus.api.SubscribeEvent
+    public static void onServerTickPost(ServerTickEvent.Post event) {
+        for (int index = 0; index < SAMPLES_PER_TICK; index++) {
+            Pending pending;
+            synchronized (PENDING) {
+                var queue = PENDING.get(event.getServer());
+                pending = queue == null ? null : queue.pollFirst();
+            }
+            if (pending == null) break;
+            var pos = pending.chunk().getPos();
+            if (pending.level().getServer().getLevel(pending.level().dimension()) == pending.level()
+                    && pending.level().getChunkSource().getChunkNow(pos.x(), pos.z()) == pending.chunk())
+                PortBlockProfileSavedData.get(pending.level()).sample(pending.chunk());
+        }
+        if (event.getServer().getTickCount() % GENERATION_INTERVAL_TICKS == 0) {
+            generateNextSpawnSample(event.getServer());
+        }
+    }
+
+    @net.neoforged.bus.api.SubscribeEvent
+    public static void onServerStopping(ServerStoppingEvent event) {
+        synchronized (PENDING) { PENDING.remove(event.getServer()); }
+        NEXT_SPAWN_SAMPLE.remove(event.getServer());
+        NEXT_TARGET.remove(event.getServer());
+        GENERATION_IN_FLIGHT.remove(event.getServer());
+    }
+
+    /** Generate at most one chunk per second across the active Age and its Overworld baseline. */
+    private static void generateNextSpawnSample(MinecraftServer server) {
+        if (GENERATION_IN_FLIGHT.containsKey(server)) return;
+        List<SampleTarget> targets = new ArrayList<>();
+        for (ServerLevel level : server.getAllLevels()) {
+            if (!PortInstabilityRuntime.isAge(level)
+                    || level.players().isEmpty()) continue;
+            var data = PortInstabilityData.get(server);
+            if (!data.supportsProfiling(level)) continue;
+            var age = data.age(level);
+            targets.add(new SampleTarget(level, age.spawn().orElseGet(() -> level.getRespawnData().pos()),
+                    PortBlockProfileSavedData.MIN_AGE_SAMPLES));
+        }
+        if (targets.isEmpty()) return;
+        ServerLevel overworld = server.overworld();
+        targets.add(0, new SampleTarget(overworld, overworld.getRespawnData().pos(),
+                PortBlockProfileSavedData.MIN_BASELINE_SAMPLES));
+        int first = Math.floorMod(NEXT_TARGET.getOrDefault(server, 0), targets.size());
+        for (int offset = 0; offset < targets.size(); offset++) {
+            int index = (first + offset) % targets.size();
+            SampleTarget target = targets.get(index);
+            if (generateNextSpawnSample(target.level(), target.origin(), target.minimum(), server)) {
+                NEXT_TARGET.put(server, index + 1);
+                return;
+            }
+        }
+    }
+
+    private static boolean generateNextSpawnSample(ServerLevel level, net.minecraft.core.BlockPos origin,
+                                                   int minimum, MinecraftServer server) {
+        PortBlockProfileSavedData profile = PortBlockProfileSavedData.get(level);
+        if (profile.count() >= minimum) return false;
+        Map<Identifier, Integer> cursors = NEXT_SPAWN_SAMPLE.computeIfAbsent(server,
+                ignored -> new HashMap<>());
+        Identifier dimension = level.dimension().identifier();
+        int index = cursors.getOrDefault(dimension, 0);
+        ChunkPos center = ChunkPos.containing(origin);
+        while (index < SPAWN_OFFSETS.size()) {
+            ChunkPos offset = SPAWN_OFFSETS.get(index++);
+            ChunkPos target = new ChunkPos(center.x() + offset.x(), center.z() + offset.z());
+            if (profile.contains(target)) continue;
+            cursors.put(dimension, index);
+            GENERATION_IN_FLIGHT.put(server, true);
+            // getChunkFuture blocks when called on the server thread. Its off-thread
+            // path schedules generation on Minecraft's chunk executor instead.
+            CompletableFuture.supplyAsync(() -> level.getChunkSource()
+                            .getChunkFuture(target.x(), target.z(), ChunkStatus.FULL, true))
+                    .thenCompose(future -> future)
+                    .whenComplete((result, error) -> {
+                        if (server.isStopped()) return;
+                        server.execute(() -> {
+                            if (GENERATION_IN_FLIGHT.remove(server) == null) return;
+                            if (error != null) {
+                                Rivencraft.LOGGER.warn("Could not profile chunk {} in {}", target, dimension, error);
+                            } else if (server.getLevel(level.dimension()) == level
+                                    && result.orElse(null) instanceof LevelChunk chunk) {
+                                profile.sample(chunk);
+                            }
+                        });
+                    });
+            return true;
+        }
+        return false;
+    }
+
+    private static List<ChunkPos> spawnOffsets() {
+        List<ChunkPos> offsets = new ArrayList<>(PortBlockProfileSavedData.MAX_SAMPLES);
+        offsets.add(new ChunkPos(0, 0));
+        for (int radius = 1; offsets.size() < PortBlockProfileSavedData.MAX_SAMPLES; radius++) {
+            for (int x = -radius; x <= radius; x++) {
+                offsets.add(new ChunkPos(x, -radius));
+                offsets.add(new ChunkPos(x, radius));
+            }
+            for (int z = -radius + 1; z < radius; z++) {
+                offsets.add(new ChunkPos(-radius, z));
+                offsets.add(new ChunkPos(radius, z));
+            }
+        }
+        return List.copyOf(offsets.subList(0, PortBlockProfileSavedData.MAX_SAMPLES));
+    }
+
+    /** Zero until the Age exceeds 400 samples and the baseline reaches 500. */
+    static int score(PortBlockProfileSavedData age, PortBlockProfileSavedData baseline) {
+        return score(age.totals(), age.count(), baseline.totals(), baseline.count());
+    }
+
+    static int score(Map<Identifier, Long> age, int ageChunks,
+                     Map<Identifier, Long> baseline, int baselineChunks) {
+        if (ageChunks < PortBlockProfileSavedData.MIN_AGE_SAMPLES
+                || baselineChunks < PortBlockProfileSavedData.MIN_BASELINE_SAMPLES) return 0;
+        double result = 0;
+        Set<Identifier> watched = new HashSet<>(age.keySet());
+        watched.addAll(baseline.keySet());
+        for (Identifier id : watched) {
+            double weight = weight(id);
+            if (weight <= 0) continue;
+            double excess = age.getOrDefault(id, 0L) / (double) ageChunks
+                    - 1.05 * baseline.getOrDefault(id, 0L) / (double) baselineChunks;
+            if (excess > 0) result += excess * weight;
+        }
+        return (int) Math.min(100_000, Math.round(result));
+    }
+
+    public static int score(ServerLevel level) {
+        if (!PortInstabilityRuntime.isAge(level) || !PortInstabilityData.get(level.getServer()).supportsProfiling(level)) return 0;
+        return score(PortBlockProfileSavedData.get(level), PortBlockProfileSavedData.get(level.getServer().overworld()));
+    }
+    public static int sampledChunks(ServerLevel level) { return PortBlockProfileSavedData.get(level).count(); }
+
+    public static int difficultyScore(long rawScore, int difficulty) {
+        double multiplier = switch (difficulty) {
+            case 0 -> 0.25;
+            case 1 -> 0.5;
+            case 2 -> 1.0;
+            case 3 -> 1.75;
+            default -> throw new IllegalArgumentException("Unknown instability difficulty " + difficulty);
+        };
+        return (int) Math.min(Integer.MAX_VALUE, Math.max(0, rawScore * multiplier));
+    }
+
+    private static Map<Identifier, Double> weights() {
+        Map<Identifier, Double> values = new HashMap<>();
+        add(values, 5, "coal_ore", "deepslate_coal_ore", "lapis_ore", "deepslate_lapis_ore");
+        add(values, 60, "iron_ore", "deepslate_iron_ore");
+        add(values, 200, "emerald_ore", "deepslate_emerald_ore");
+        add(values, 250, "redstone_ore", "deepslate_redstone_ore");
+        add(values, 750, "gold_ore", "deepslate_gold_ore");
+        add(values, 4000, "diamond_ore", "deepslate_diamond_ore", "diamond_block");
+        add(values, 20, "nether_quartz_ore");
+        add(values, 50, "glowstone");
+        values.put(Identifier.parse("rivencraft:crystal_block"), 20.0);
+        // Valuable blocks introduced after Legacy, and storage forms authorable in Rivencraft.
+        add(values, 200, "emerald_block");
+        add(values, 750, "gold_block", "raw_gold_block");
+        add(values, 4000, "ancient_debris");
+        add(values, 60, "iron_block", "raw_iron_block");
+        add(values, 8000, "netherite_block");
+        return Map.copyOf(values);
+    }
+
+    private static void add(Map<Identifier, Double> values, int weight, String... paths) {
+        for (String path : paths) values.put(Identifier.withDefaultNamespace(path), (double) weight);
+    }
+
+    private record Pending(ServerLevel level, LevelChunk chunk) {}
+
+    private record SampleTarget(ServerLevel level, net.minecraft.core.BlockPos origin, int minimum) {}
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortBlockProfileSavedData.java

@@ -0,0 +1,63 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.chunk.LevelChunk;
+import net.minecraft.world.level.saveddata.SavedData;
+import net.minecraft.world.level.saveddata.SavedDataType;
+
+/** Persistent generated-chunk snapshots. Each chunk is counted once, up to the 1.21.1 cap. */
+final class PortBlockProfileSavedData extends SavedData {
+    static final int MIN_AGE_SAMPLES = 401, MIN_BASELINE_SAMPLES = 500, MAX_SAMPLES = 1024;
+    private static final int VERSION = 2;
+    private record Sample(long chunk, Map<Identifier, Integer> counts) {
+        private static final Codec<Sample> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+                Codec.LONG.fieldOf("chunk").forGetter(Sample::chunk),
+                Codec.unboundedMap(Identifier.CODEC, Codec.intRange(1, Integer.MAX_VALUE))
+                        .fieldOf("blocks").forGetter(Sample::counts)
+        ).apply(instance, Sample::new));
+    }
+    private static final Codec<PortBlockProfileSavedData> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+            Codec.INT.fieldOf("version").forGetter(data -> VERSION),
+            Sample.CODEC.listOf(0, MAX_SAMPLES).fieldOf("samples").forGetter(data -> data.samples.entrySet().stream()
+                    .map(entry -> new Sample(entry.getKey(), entry.getValue())).toList())
+    ).apply(instance, PortBlockProfileSavedData::new));
+    private static final SavedDataType<PortBlockProfileSavedData> TYPE = new SavedDataType<>(
+            Identifier.fromNamespaceAndPath("rivencraft", "block_profile"),
+            () -> new PortBlockProfileSavedData(VERSION, List.of()), CODEC);
+    private final Map<Long, Map<Identifier, Integer>> samples = new HashMap<>();
+    private final Map<Identifier, Long> totals = new HashMap<>();
+    private PortBlockProfileSavedData(int version, List<Sample> values) {
+        if (version == VERSION) for (var value : values) put(value.chunk(), value.counts());
+    }
+    static PortBlockProfileSavedData get(ServerLevel level) { return level.getDataStorage().computeIfAbsent(TYPE); }
+    int count() { return samples.size(); }
+    boolean contains(ChunkPos pos) { return samples.containsKey(pos.pack()); }
+    Map<Identifier, Long> totals() { return Map.copyOf(totals); }
+    boolean sample(LevelChunk chunk) {
+        if (count() >= MAX_SAMPLES || contains(chunk.getPos())) return false;
+        Map<Identifier, Integer> counts = new HashMap<>();
+        for (var section : chunk.getSections()) {
+            if (section.hasOnlyAir()) continue;
+            section.getStates().count((state, amount) -> {
+                Identifier id = BuiltInRegistries.BLOCK.getKey(state.getBlock());
+                if (PortBlockInstability.tracked(id)) counts.merge(id, amount, Integer::sum);
+            });
+        }
+        put(chunk.getPos().pack(), counts);
+        setDirty();
+        return true;
+    }
+    private void put(long pos, Map<Identifier, Integer> counts) {
+        if (count() >= MAX_SAMPLES || samples.containsKey(pos)) return;
+        samples.put(pos, Map.copyOf(counts));
+        counts.forEach((id, amount) -> totals.merge(id, amount.longValue(), Long::sum));
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortBookDropConversionProbe.java

@@ -0,0 +1,110 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.List;
+import java.util.UUID;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.entity.DroppedBookEntity;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.TickTask;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.util.ProblemReporter;
+import net.minecraft.world.entity.item.ItemEntity;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.storage.TagValueOutput;
+import net.minecraft.world.phys.AABB;
+import net.minecraft.world.phys.Vec3;
+
+/** Join conversion runs on queued server tasks: create and inspect on separate commands. */
+final class PortBookDropConversionProbe {
+    private static final UUID OWNER = UUID.fromString("cc5909e5-aafa-43d6-b841-a917ec9c0115");
+    private static final AABB AREA = new AABB(-16, -64, -16, 32, 320, 32);
+    private static ItemStack book(boolean descriptive, String label) {
+        var stack = new ItemStack(descriptive ? Rivencraft.DESCRIPTIVE_BOOK.get() : Rivencraft.LINKING_BOOK.get());
+        stack.set(DataComponents.CUSTOM_NAME, Component.literal(label));
+        return stack;
+    }
+    static void create(ServerLevel level) {
+        for (int x = 0; x < 16; x++) for (int z = 0; z < 16; z++) level.setBlock(new BlockPos(x, 63, z), Blocks.STONE.defaultBlockState(), 2);
+        var player = net.neoforged.neoforge.common.util.FakePlayerFactory.get(level,
+                new com.mojang.authlib.GameProfile(UUID.fromString("84f38604-48fe-48d3-a4fb-f858a7200115"), "RivenDropProbe"));
+        player.setPos(8.5, 64, 8.5);
+        // Test exact factory state before physics can advance position or pickup timers.
+        var sample = new ItemEntity(level, 8.5, 66, 8.5, book(false, "state_copy"));
+        sample.getItem().set(Rivencraft.LINK_BOOK_TARGET.get(), new net.dnorberg.rivencraft.item.LinkBookTarget(
+                level.dimension().identifier(), -0.5, 64, -1.25, 135, -20));
+        sample.getItem().set(Rivencraft.LINK_DESTINATION_NAME.get(), "Named destination");
+        sample.getItem().set(Rivencraft.LINK_PROPERTIES.get(), new net.dnorberg.rivencraft.item.LinkProperties(net.dnorberg.rivencraft.item.LinkProperties.DISARM
+                | net.dnorberg.rivencraft.item.LinkProperties.MAINTAIN_MOMENTUM));
+        sample.setTarget(OWNER);
+        sample.setThrower(player);
+        sample.setPickUpDelay(80);
+        sample.setDeltaMovement(new Vec3(0.2, 0.1, -0.3));
+        sample.setYRot(37);
+        sample.setXRot(12);
+        sample.setNoGravity(true);
+        var copy = DroppedBookEntity.fromDrop(sample);
+        if (!copy.position().equals(sample.position()) || !copy.getDeltaMovement().equals(sample.getDeltaMovement())
+                || copy.getYRot() != 37 || copy.getXRot() != 12 || !copy.isNoGravity()
+                || !ItemStack.matches(copy.getItem(), sample.getItem()) || !OWNER.equals(copy.getTarget())
+                || copy.getUUID().equals(sample.getUUID()) || copy.getAge() != -32768)
+            throw new IllegalStateException("Drop conversion lost placement, ownership or item components");
+        var originalTag = TagValueOutput.createWithContext(ProblemReporter.DISCARDING, level.registryAccess());
+        var copiedTag = TagValueOutput.createWithContext(ProblemReporter.DISCARDING, level.registryAccess());
+        sample.saveWithoutId(originalTag); copy.saveWithoutId(copiedTag);
+        for (String key : List.of("PickupDelay", "Owner", "Thrower", "Item"))
+            if (!java.util.Objects.equals(originalTag.buildResult().get(key), copiedTag.buildResult().get(key)))
+                throw new IllegalStateException("Drop conversion lost metadata: " + key);
+        // Four ordinary book variants must all convert through the actual event route.
+        for (String name : List.of("manual_link", "manual_description", "unwritten_link", "unwritten_description")) {
+            var stack = book(name.endsWith("description"), name);
+            if (name.equals("manual_link")) {
+                stack.set(Rivencraft.LINK_BOOK_TARGET.get(), sample.getItem().get(Rivencraft.LINK_BOOK_TARGET.get()));
+                stack.set(Rivencraft.LINK_DESTINATION_NAME.get(), "Named destination");
+            }
+            if (name.equals("manual_description")) stack.set(Rivencraft.AGE_BOOK_ID.get(), level.dimension().identifier());
+            var item = new ItemEntity(level, 8.5, 66, 8.5, stack);
+            item.setNoGravity(true); item.setDeltaMovement(Vec3.ZERO); item.setTarget(OWNER);
+            level.addFreshEntity(item);
+        }
+        player.drop(book(false, "player_toss"), false, net.minecraft.util.Prediction.SERVER_ONLY);
+        net.minecraft.world.Containers.dropItemStack(level, 8.5, 65, 8.5, book(true, "container"));
+        var standPos = new BlockPos(10, 64, 8);
+        level.setBlock(standPos, Rivencraft.BOOK_STAND.get().defaultBlockState(), 3);
+        ((net.dnorberg.rivencraft.block.entity.BookStandBlockEntity) level.getBlockEntity(standPos)).setBook(book(false, "stand"));
+        level.destroyBlock(standPos, true);
+        var custom = new DroppedBookEntity(level, new Vec3(8.5, 66, 8.5), book(false, "already_custom"));
+        custom.setNoGravity(true);
+        level.addFreshEntity(custom);
+        level.addFreshEntity(new ItemEntity(level, 8.5, 66, 8.5, net.dnorberg.rivencraft.item.PageItem.createLinkPanelPage()));
+        java.util.function.Consumer<net.neoforged.neoforge.event.entity.EntityJoinLevelEvent> cancel = event -> {
+            if (event.getLevel() == level && event.getEntity() instanceof DroppedBookEntity dropped
+                    && dropped.getItem().getHoverName().getString().equals("cancel_preserve")) event.setCanceled(true);
+        };
+        net.neoforged.neoforge.common.NeoForge.EVENT_BUS.addListener(cancel);
+        try {
+            var item = new ItemEntity(level, 8.5, 66, 8.5, book(false, "cancel_preserve"));
+            item.setNoGravity(true); item.setDeltaMovement(Vec3.ZERO);
+            level.addFreshEntity(item);
+        } finally {
+            // Queued after that source's conversion task; no fixture listener remains installed.
+            level.getServer().schedule(new TickTask(0, () -> net.neoforged.neoforge.common.NeoForge.EVENT_BUS.unregister(cancel)));
+        }
+    }
+    static void verify(ServerLevel level) {
+        var drops = level.getEntitiesOfClass(ItemEntity.class, AREA);
+        for (String name : List.of("manual_link", "manual_description", "unwritten_link", "unwritten_description",
+                "player_toss", "container", "stand", "already_custom", "cancel_preserve")) {
+            var found = drops.stream().filter(e -> e.getItem().getHoverName().getString().equals(name)).toList();
+            if (found.size() != 1 || !name.equals("cancel_preserve") && !(found.getFirst() instanceof DroppedBookEntity))
+                throw new IllegalStateException("Expected one open book for " + name + ", found " + found.size());
+        }
+        var named = drops.stream().filter(e -> e.getItem().getHoverName().getString().equals("manual_link")).findFirst().orElseThrow();
+        if (!OWNER.equals(named.getTarget()) || !"Named destination".equals(named.getItem().get(Rivencraft.LINK_DESTINATION_NAME.get())))
+            throw new IllegalStateException("Converted book lost owner or destination");
+        if (drops.stream().filter(e -> e.getItem().is(Rivencraft.PAGE.get())).anyMatch(e -> e instanceof DroppedBookEntity))
+            throw new IllegalStateException("Non-book item was converted");
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortBookStandProbe.java

@@ -0,0 +1,93 @@
+package net.dnorberg.rivencraft.age;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.block.BookStandBlock;
+import net.dnorberg.rivencraft.block.entity.BookStandBlockEntity;
+import net.dnorberg.rivencraft.event.BookStandConversionHandler;
+import net.dnorberg.rivencraft.item.PageItem;
+import net.dnorberg.rivencraft.network.PortBookNetworking;
+import net.dnorberg.rivencraft.network.UseBookStandPayload;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.LecternBlock;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+
+/** Isolated conversion, ownership, stale-screen and persistence checks. */
+final class PortBookStandProbe {
+    private static final BlockPos POS = new BlockPos(0, 64, 0);
+    static void create(ServerLevel level) {
+        var player = net.neoforged.neoforge.common.util.FakePlayerFactory.get(level,
+                new com.mojang.authlib.GameProfile(java.util.UUID.fromString("a5c323a1-3b58-4dd6-927f-e08000800110"), "RivenStandProbe"));
+        player.setPos(0.5, 64, 2.5);
+        try {
+            for (Direction facing : Direction.Plane.HORIZONTAL) for (InteractionHand hand : InteractionHand.values())
+                for (var sample : java.util.List.of(new ItemStack(Rivencraft.LINKING_BOOK.get()),
+                        new ItemStack(Rivencraft.DESCRIPTIVE_BOOK.get()), PageItem.createLinkPanelPage().copyWithCount(3))) {
+                    level.setBlock(POS, Blocks.LECTERN.defaultBlockState().setValue(LecternBlock.FACING, facing), 3);
+                    player.setItemInHand(hand, sample.copy());
+                    if (!BookStandConversionHandler.convert(player, hand, POS)) throw new IllegalStateException("Conversion failed");
+                    var stand = (BookStandBlockEntity) level.getBlockEntity(POS);
+                    var stored = sample.copyWithCount(1);
+                    if (!ItemStack.matches(stand.getBook(), stored) || player.getItemInHand(hand).getCount() != sample.getCount() - 1
+                            || stand.getBlockState().getValue(BookStandBlock.FACING) != facing)
+                        throw new IllegalStateException("Conversion lost ownership or facing");
+                    var packet = new UseBookStandPayload(level.dimension().identifier(), POS, stored.copy());
+                    if (PortBookNetworking.validatedStandBook(player, packet).isEmpty()) throw new IllegalStateException("Valid source rejected");
+                    player.setPos(100, 64, 100);
+                    if (!PortBookNetworking.validatedStandBook(player, packet).isEmpty()) throw new IllegalStateException("Distant source accepted");
+                    player.setPos(0.5, 64, 2.5);
+                    if (!PortBookNetworking.validatedStandBook(player, new UseBookStandPayload(
+                            net.minecraft.resources.Identifier.fromNamespaceAndPath("minecraft", "overworld"), POS, stored)).isEmpty())
+                        throw new IllegalStateException("Wrong dimension accepted");
+                    if (!PortBookNetworking.validatedStandBook(player, new UseBookStandPayload(packet.dimension(), POS, new ItemStack(Items.DIRT))).isEmpty())
+                        throw new IllegalStateException("Replaced book accepted");
+                    var loaded = net.minecraft.world.level.block.entity.BlockEntity.loadStatic(POS, stand.getBlockState(),
+                            stand.saveWithFullMetadata(level.registryAccess()), level.registryAccess());
+                    if (!(loaded instanceof BookStandBlockEntity copy) || !ItemStack.matches(copy.getBook(), stored))
+                        throw new IllegalStateException("Stand serialization lost content");
+                    player.getInventory().clearContent();
+                    player.setShiftKeyDown(true);
+                    stand.getBlockState().useWithoutItem(level, player, new BlockHitResult(Vec3.atCenterOf(POS), Direction.UP, POS, false));
+                    player.setShiftKeyDown(false);
+                    if (!level.getBlockState(POS).is(Blocks.LECTERN)
+                            || level.getBlockState(POS).getValue(LecternBlock.FACING) != facing
+                            || player.getInventory().countItem(stored.getItem()) != 1
+                            || !PortBookNetworking.validatedStandBook(player, packet).isEmpty())
+                        throw new IllegalStateException("Retrieval did not restore lectern or recover item exactly once");
+                    player.getInventory().clearContent();
+                    player.setItemInHand(hand, stored.copy());
+                    BookStandConversionHandler.convert(player, hand, POS);
+                    level.destroyBlock(POS, true);
+                    var drops = level.getEntitiesOfClass(net.minecraft.world.entity.item.ItemEntity.class,
+                            new net.minecraft.world.phys.AABB(-2, 62, -2, 3, 68, 3));
+                    int items = drops.stream().filter(e -> e.getItem().is(stored.getItem())).mapToInt(e -> e.getItem().getCount()).sum();
+                    int lecterns = drops.stream().filter(e -> e.getItem().is(Items.LECTERN)).mapToInt(e -> e.getItem().getCount()).sum();
+                    if (items != 1 || lecterns != 1) throw new IllegalStateException("Break drops duplicated/lost: " + items + "/" + lecterns);
+                    drops.forEach(net.minecraft.world.entity.Entity::discard);
+                }
+            level.setBlock(POS, Blocks.LECTERN.defaultBlockState().setValue(LecternBlock.HAS_BOOK, true), 3);
+            player.setItemInHand(InteractionHand.MAIN_HAND, PageItem.createLinkPanelPage());
+            if (BookStandConversionHandler.convert(player, InteractionHand.MAIN_HAND, POS)) throw new IllegalStateException("Occupied lectern converted");
+            level.setBlock(POS, Blocks.LECTERN.defaultBlockState(), 3);
+            player.setItemInHand(InteractionHand.MAIN_HAND, new ItemStack(Items.DIRT));
+            if (BookStandConversionHandler.convert(player, InteractionHand.MAIN_HAND, POS)) throw new IllegalStateException("Unrelated item accepted");
+            var named = new ItemStack(Rivencraft.LINKING_BOOK.get());
+            named.set(net.minecraft.core.component.DataComponents.CUSTOM_NAME, net.minecraft.network.chat.Component.literal("Stand persistence"));
+            player.setItemInHand(InteractionHand.MAIN_HAND, named);
+            if (!BookStandConversionHandler.convert(player, InteractionHand.MAIN_HAND, POS)) throw new IllegalStateException("Final stand missing");
+        } finally { player.setShiftKeyDown(false); player.getInventory().clearContent(); }
+        verify(level);
+    }
+    static void verify(ServerLevel level) {
+        if (!(level.getBlockEntity(POS) instanceof BookStandBlockEntity stand)
+                || !stand.getBook().is(Rivencraft.LINKING_BOOK.get())
+                || !stand.getBook().getHoverName().getString().equals("Stand persistence"))
+            throw new IllegalStateException("Stand restart persistence failed");
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortDayCycle.java

@@ -127,19 +127,15 @@ public record PortDayCycle(boolean authored, double period, int stoppedTime,
     }
 
     public static boolean validWriting(List<Identifier> pages) {
-        int periods = 0, phases = 0, directions = 0, angles = 0, sizes = 0, suns = 0, moons = 0;
-        for (Identifier page : pages) {
-            if (isPeriod(page) && ++periods > 1 || isPhase(page) && ++phases > 1
-                    || isDirection(page) && ++directions > 1 || isAngle(page) && ++angles > 1
-                    || isSize(page) && ++sizes > 1) return false;
-            if (isController(page)) {
-                if (!page.getPath().equals("celestial/moon")) suns++;
-                if (!page.getPath().equals("celestial/sun")) moons++;
-                if (suns > 10 || moons > 10) return false;
-                periods = phases = directions = angles = sizes = 0;
-            }
+        int suns = 0, moons = 0;
+        for (Identifier page : pages) if (isController(page)) {
+            if (!page.getPath().equals("celestial/moon")) suns++;
+            if (!page.getPath().equals("celestial/sun")) moons++;
+            if (suns > 10 || moons > 10) return false;
         }
-        return periods + phases + directions + angles + sizes == 0;
+        // Repeated modifiers overwrite the pending value. Unconsumed modifiers
+        // earn grammar instability, but never affect an earlier body.
+        return true;
     }
 
     public static PortDayCycle compile(List<Identifier> pages, long seed) {
@@ -148,8 +144,8 @@ public record PortDayCycle(boolean authored, double period, int stoppedTime,
 
     /** Creation-only completion. Exact diagnostic fixtures can still use compile. */
     public static PortDayCycle resolve(List<Identifier> pages, long seed, long nativeTicks) {
-        if (!validWriting(pages) || !PortAgeColors.validNumbers(pages))
-            throw new IllegalArgumentException("Invalid celestial modifier order");
+        if (!validWriting(pages))
+            throw new IllegalArgumentException("An Age may have at most ten suns and ten moons");
         if (pages.stream().anyMatch(PortDayCycle::isController)) return compile(pages, seed, nativeTicks);
         // Match root AgeSkyProfile.random's count draw positions: sky style,
         // mixed sky color, then independent 0..3 sun and moon counts.
@@ -167,7 +163,7 @@ public record PortDayCycle(boolean authored, double period, int stoppedTime,
     }
 
     public static PortDayCycle compile(List<Identifier> pages, long seed, long nativeTicks) {
-        if (!validWriting(pages)) throw new IllegalArgumentException("Place at most one of each celestial modifier before its controller; limit ten suns and ten moons");
+        if (!validWriting(pages)) throw new IllegalArgumentException("An Age may have at most ten suns and ten moons");
         if (pages.stream().filter(PortDayCycle::isController).count() <= 1)
             return compileOne(pages, seed, nativeTicks, 0);
         var bodies = new java.util.ArrayList<PortCelestialBody>();
@@ -190,8 +186,13 @@ public record PortDayCycle(boolean authored, double period, int stoppedTime,
     }
 
     private static PortDayCycle compileOne(List<Identifier> pages, long seed, long nativeTicks, int ordinal) {
-        var controller = pages.stream().filter(PortDayCycle::isController).findFirst().orElse(null);
-        if (controller == null) return NATIVE;
+        int controllerIndex = -1;
+        for (int i = 0; i < pages.size(); i++) if (isController(pages.get(i))) { controllerIndex = i; break; }
+        // Only preceding modifiers belong to this controller. In particular, a
+        // trailing dangling modifier must not rewrite the single-body fast path.
+        if (controllerIndex < 0) return NATIVE;
+        pages = pages.subList(0, controllerIndex + 1);
+        var controller = pages.getLast();
         int mode = controller.getPath().equals("celestial/sun") ? SUN
                 : controller.getPath().equals("celestial/moon") ? MOON : PAIRED;
         if (mode != PAIRED && !hasBodyModifiers(pages)) return randomUnmodified(seed, ordinal, nativeTicks, mode);

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortDecayProviders.java

@@ -0,0 +1,202 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.block.DecayBlock;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.tags.BlockTags;
+import net.minecraft.tags.TagKey;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.neoforged.neoforge.common.NeoForge;
+import net.neoforged.neoforge.common.util.BlockSnapshot;
+import net.neoforged.neoforge.common.util.FakePlayerFactory;
+import net.neoforged.neoforge.event.level.BlockEvent;
+
+/** Bounded, per-Age decay seeding and six-direction Legacy-style spreading. */
+public final class PortDecayProviders {
+    public static final TagKey<Block> PROTECTED = TagKey.create(Registries.BLOCK,
+            Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "decay_protected"));
+    private static final Map<Identifier, DecayBlock.Color> COLORS = Map.of(
+            id("decayblue"), DecayBlock.Color.BLUE,
+            id("decaypurple"), DecayBlock.Color.PURPLE,
+            id("decayred"), DecayBlock.Color.RED,
+            id("decaywhite"), DecayBlock.Color.WHITE);
+    private static final Direction[] DIRECTIONS = Direction.values();
+
+    private PortDecayProviders() {}
+
+    public static void register() {
+        COLORS.keySet().forEach(id -> PortInstabilityRuntime.register(id, true, PortDecayProviders::apply));
+    }
+
+    /** Operator test hook; never changes the Age's saved instability score or provider plan. */
+    public static int pulseForTesting(ServerPlayer player, DecayBlock.Color color, int count) {
+        ServerLevel level = player.level();
+        if (!PortInstabilityConfig.decayEnabled() || !PortInstabilityConfig.instabilityWorldMutation()
+                || !PortInstabilityRuntime.isAge(level)
+                || level.getChunkSource().getChunkNow(player.chunkPosition().x(), player.chunkPosition().z()) == null) return -1;
+        var age = PortInstabilityData.get(level.getServer()).age(level);
+        Identifier id = id("decay" + color.getSerializedName());
+        if (!PortInstabilityConfig.instabilityEnabled() || !age.enabled()
+                || !PortInstabilityConfig.instabilityProviderEnabled(id)) return -1;
+        int changed = 0;
+        for (int i = 0; i < Math.min(count, 32); i++) {
+            PortInstabilityRuntime.Budget budget = new PortInstabilityRuntime.Budget(1);
+            apply(new PortInstabilityRuntime.Context(level, age, List.of(player.chunkPosition()),
+                    level.getServer().getTickCount(), budget), id, 1);
+            changed += budget.applied();
+        }
+        return changed;
+    }
+
+    static void apply(PortInstabilityRuntime.Context context, Identifier id, int level) {
+        if (!PortInstabilityConfig.decayEnabled() || !PortInstabilityConfig.instabilityWorldMutation()
+                || !PortInstabilityRuntime.isAge(context.level())
+                || context.loadedChunks().isEmpty()) return;
+        DecayBlock.Color color = COLORS.get(id);
+        if (color == null) return;
+        PortDecaySavedData data = PortDecaySavedData.get(context.level());
+        Random random = new Random(context.age().seed() ^ data.nextAttempt() * 0x9E3779B97F4A7C15L
+                ^ id.hashCode());
+        List<BlockPos> frontier = data.frontier(color);
+        BlockPos source = selectLoadedSource(context.level(), context.loadedChunks(), frontier, random);
+        if (source == null) {
+            seed(context, color, data, random);
+            return;
+        }
+        BlockState sourceState = context.level().getBlockState(source);
+        if (!sourceState.is(Rivencraft.DECAY.get()) || sourceState.getValue(DecayBlock.COLOR) != color) {
+            data.remove(color, source);
+            return;
+        }
+        for (int attempt = 0; attempt < PortInstabilityConfig.decayMaxAttempts(); attempt++) {
+            BlockPos target = source.relative(DIRECTIONS[random.nextInt(DIRECTIONS.length)]);
+            if (!isLoadedTarget(context.level(), context.loadedChunks(), target)
+                    || isSpawnProtected(context.age(), target)) continue;
+            BlockState prior = context.level().getBlockState(target);
+            if (!canReplace(context.level(), target, prior, color)) continue;
+            int difficulty = conversionDifficulty(context.level(), target, prior, color);
+            if (random.nextInt(difficulty) != 0) continue;
+            if (replace(context, target, prior, color)) data.add(color, target);
+            return;
+        }
+    }
+
+    private static void seed(PortInstabilityRuntime.Context context, DecayBlock.Color color,
+                             PortDecaySavedData data, Random random) {
+        ChunkPos chunk = context.loadedChunks().get(random.nextInt(context.loadedChunks().size()));
+        int x = chunk.getMinBlockX() + random.nextInt(16);
+        int z = chunk.getMinBlockZ() + random.nextInt(16);
+        BlockPos pos = new BlockPos(x,
+                context.level().getHeight(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES, x, z) - 1, z);
+        if (!isLoadedTarget(context.level(), context.loadedChunks(), pos)
+                || isSpawnProtected(context.age(), pos)) return;
+        BlockState prior = context.level().getBlockState(pos);
+        if (canReplace(context.level(), pos, prior, color) && replace(context, pos, prior, color)) {
+            data.add(color, pos);
+        }
+    }
+
+    private static BlockPos selectLoadedSource(ServerLevel level, List<ChunkPos> chunks,
+                                                List<BlockPos> frontier, Random random) {
+        if (frontier.isEmpty()) return null;
+        int start = random.nextInt(frontier.size());
+        for (int i = 0; i < Math.min(frontier.size(), 16); i++) {
+            BlockPos pos = frontier.get((start + i) % frontier.size());
+            if (isLoadedTarget(level, chunks, pos)) return pos;
+        }
+        return null;
+    }
+
+    static boolean isLoadedTarget(ServerLevel level, List<ChunkPos> chunks, BlockPos pos) {
+        return level.isInWorldBounds(pos) && level.getChunkSource().getChunkNow(pos.getX() >> 4, pos.getZ() >> 4) != null
+                && chunks.contains(ChunkPos.containing(pos));
+    }
+
+    static boolean isSpawnProtected(PortInstabilityData.Age age, BlockPos pos) {
+        BlockPos spawn = age.spawn().orElse(null);
+        return spawn != null && Math.abs(pos.getX() - spawn.getX()) <= 4
+                && Math.abs(pos.getZ() - spawn.getZ()) <= 4
+                && pos.getY() >= spawn.getY() - 2 && pos.getY() <= spawn.getY() + 4;
+    }
+
+    static boolean canReplace(ServerLevel level, BlockPos pos, BlockState prior, DecayBlock.Color color) {
+        if (!PortInstabilityRuntime.isAge(level)
+                || !level.isInWorldBounds(pos) || level.getChunkSource().getChunkNow(pos.getX() >> 4, pos.getZ() >> 4) == null
+                || prior.is(PROTECTED) || prior.is(BlockTags.PORTALS)
+                || prior.hasBlockEntity() || level.getBlockEntity(pos) != null
+                || prior.getDestroySpeed(level, pos) < 0 || !prior.getFluidState().isEmpty()
+                || isCritical(prior)) return false;
+        return !prior.is(Rivencraft.DECAY.get()) || prior.getValue(DecayBlock.COLOR) != color;
+    }
+
+    private static boolean isCritical(BlockState prior) {
+        return prior.is(Blocks.BEDROCK) || prior.is(Blocks.BARRIER)
+                || prior.is(Blocks.END_PORTAL) || prior.is(Blocks.END_PORTAL_FRAME)
+                || prior.is(Blocks.END_GATEWAY) || prior.is(Blocks.NETHER_PORTAL)
+                || prior.is(Blocks.COMMAND_BLOCK) || prior.is(Blocks.CHAIN_COMMAND_BLOCK)
+                || prior.is(Blocks.REPEATING_COMMAND_BLOCK) || prior.is(Blocks.STRUCTURE_BLOCK)
+                || prior.is(Blocks.JIGSAW) || prior.is(Blocks.LIGHT)
+                || prior.is(Blocks.REINFORCED_DEEPSLATE)
+                || prior.getBlock() != Rivencraft.DECAY.get()
+                && net.minecraft.core.registries.BuiltInRegistries.BLOCK.getKey(prior.getBlock())
+                        .getNamespace().equals(Rivencraft.MOD_ID);
+    }
+
+    static int conversionDifficulty(ServerLevel level, BlockPos pos, BlockState state, DecayBlock.Color color) {
+        if (state.isAir()) return switch (color) {
+            case BLUE, RED -> 20;
+            case PURPLE -> 8;
+            case WHITE -> 50;
+        };
+        if (state.is(Rivencraft.DECAY.get())) return color == DecayBlock.Color.WHITE ? 1 : 5;
+        float hardness = Math.min(1000.0F, Math.max(0.0F, state.getDestroySpeed(level, pos)));
+        return switch (color) {
+            case BLUE -> Math.max(1, (int) hardness * 2);
+            case RED -> Math.max(1, (int) hardness);
+            case PURPLE -> Math.max(1, ((int) hardness + 1) * 10);
+            case WHITE -> 1;
+        };
+    }
+
+    private static boolean replace(PortInstabilityRuntime.Context context, BlockPos pos, BlockState prior,
+                                   DecayBlock.Color color) {
+        ServerLevel level = context.level();
+        // A fake player gives claim/protection listeners the Age and exact block position.
+        var actor = FakePlayerFactory.getMinecraft(level);
+        actor.setPos(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        if (!prior.isAir()) {
+            var breakEvent = new net.neoforged.neoforge.event.level.block.BreakBlockEvent(level, pos, prior, actor);
+            NeoForge.EVENT_BUS.post(breakEvent);
+            if (breakEvent.isCanceled()) return false;
+        }
+        if (level.getBlockState(pos) != prior || !context.budget().claim()) return false;
+        var snapshot = BlockSnapshot.create(level.dimension(), level, pos);
+        BlockState decay = Rivencraft.DECAY.get().defaultBlockState().setValue(DecayBlock.COLOR, color);
+        if (!level.setBlock(pos, decay, 3)) return false;
+        var placeEvent = new BlockEvent.EntityPlaceEvent(snapshot, prior, actor);
+        NeoForge.EVENT_BUS.post(placeEvent);
+        if (placeEvent.isCanceled()) {
+            snapshot.restore();
+            return false;
+        }
+        context.budget().recordApplied();
+        return true;
+    }
+
+    private static Identifier id(String path) {
+        return Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, path);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortDecaySavedData.java

@@ -0,0 +1,44 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import java.util.ArrayList;
+import java.util.EnumMap;
+import java.util.List;
+import java.util.Map;
+import net.dnorberg.rivencraft.block.DecayBlock;
+import net.minecraft.core.BlockPos;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.util.StringRepresentable;
+import net.minecraft.world.level.saveddata.SavedData;
+import net.minecraft.world.level.saveddata.SavedDataType;
+
+/** Persisted per-Age frontier and attempt sequence, bounded to 1,024 positions per color. */
+public final class PortDecaySavedData extends SavedData {
+    private static final int MAX_FRONTIER_PER_COLOR = 1024;
+    private static final Codec<PortDecaySavedData> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+            net.minecraft.util.ExtraCodecs.NON_NEGATIVE_LONG.optionalFieldOf("attempts", 0L).forGetter(data -> data.attempts),
+            Codec.unboundedMap(StringRepresentable.fromEnum(DecayBlock.Color::values),
+                    BlockPos.CODEC.listOf(0, MAX_FRONTIER_PER_COLOR)).fieldOf("frontiers").forGetter(data -> data.frontiers)
+    ).apply(instance, PortDecaySavedData::new));
+    private static final SavedDataType<PortDecaySavedData> TYPE = new SavedDataType<>(
+            Identifier.fromNamespaceAndPath("rivencraft", "decay"), () -> new PortDecaySavedData(0, Map.of()), CODEC);
+    private final EnumMap<DecayBlock.Color, List<BlockPos>> frontiers = new EnumMap<>(DecayBlock.Color.class);
+    private long attempts;
+    private PortDecaySavedData(long attempts, Map<DecayBlock.Color, List<BlockPos>> positions) {
+        this.attempts = attempts;
+        for (var color : DecayBlock.Color.values()) frontiers.put(color,
+                new ArrayList<>(positions.getOrDefault(color, List.of()).stream().distinct().map(BlockPos::immutable).toList()));
+    }
+    public static PortDecaySavedData get(ServerLevel level) { return level.getDataStorage().computeIfAbsent(TYPE); }
+    public long nextAttempt() { setDirty(); return attempts++; }
+    public List<BlockPos> frontier(DecayBlock.Color color) { return frontiers.get(color); }
+    public void add(DecayBlock.Color color, BlockPos pos) {
+        var frontier = frontiers.get(color);
+        if (frontier.contains(pos)) return;
+        if (frontier.size() >= MAX_FRONTIER_PER_COLOR) frontier.removeFirst();
+        frontier.add(pos.immutable()); setDirty();
+    }
+    public void remove(DecayBlock.Color color, BlockPos pos) { if (frontiers.get(color).remove(pos)) setDirty(); }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortEnvironmentalProviders.java

@@ -0,0 +1,178 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Random;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.block.DecayBlock;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.entity.EntityTypeTest;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.AABB;
+import net.neoforged.neoforge.common.NeoForge;
+import net.neoforged.neoforge.common.util.BlockSnapshot;
+import net.neoforged.neoforge.common.util.FakePlayerFactory;
+import net.neoforged.neoforge.event.level.BlockEvent;
+
+/** Active Legacy burning and the 1.21.1 test-enabled erosion policy. */
+public final class PortEnvironmentalProviders {
+    public static final Identifier BURNING = Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "burning");
+    public static final Identifier EROSION = Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "erosion");
+    private static final Direction[] FLUID_SIDES = {
+            Direction.UP, Direction.NORTH, Direction.SOUTH, Direction.EAST, Direction.WEST
+    };
+    private PortEnvironmentalProviders() {}
+    public static void register() {
+        PortInstabilityRuntime.register(BURNING, false, (context, id, level) -> {
+            if (PortInstabilityRuntime.isAge(context.level()) && !context.loadedChunks().isEmpty()) scorch(context, level);
+        });
+        PortInstabilityRuntime.register(EROSION, true, (context, id, level) -> {
+            if (PortInstabilityRuntime.isAge(context.level()) && !context.loadedChunks().isEmpty()) erode(context);
+        });
+    }
+    public static boolean isEnvironmental(Identifier id) { return id.equals(BURNING) || id.equals(EROSION); }
+    static void tickPlanned(ServerLevel level, PortInstabilityData.Age age, long tick,
+                            List<PortInstabilityPlan.ProviderLevel> providers) {
+        var cards = providers.stream().filter(card -> isEnvironmental(card.id())).toList();
+        boolean erosion = PortInstabilityConfig.erosionEnabled() && PortInstabilityRuntime.effectiveScore(level)
+                >= InstabilityProviderCatalog.Deck.DESTRUCTIVE.entryCost();
+        if (cards.isEmpty() && !erosion) return;
+        var chunks = PortHazardProviders.loadedChunksNearPlayers(level, PortInstabilityConfig.hazardsMaxChunks());
+        if (chunks.isEmpty()) return;
+        for (var card : cards) {
+            int budget = card.id().equals(BURNING) ? PortInstabilityConfig.scorchMaxTargets() : 1;
+            PortInstabilityRuntime.invoke(new PortInstabilityRuntime.Context(level, age, chunks, tick,
+                    new PortInstabilityRuntime.Budget(budget)), card.id(), card.level());
+        }
+        if (erosion && cards.stream().noneMatch(card -> card.id().equals(EROSION)))
+            PortInstabilityRuntime.invoke(new PortInstabilityRuntime.Context(level, age, chunks, tick,
+                    new PortInstabilityRuntime.Budget(1)), EROSION, 1);
+    }
+    /** Skips random burning selection or looks at one erosion target, preserving policy. */
+    public static int pulseForTesting(ServerPlayer player, String effect) {
+        ServerLevel level = player.level();
+        if (!PortInstabilityRuntime.isAge(level)) return -1;
+        var age = PortInstabilityData.get(level.getServer()).age(level);
+        Identifier id = effect.equals("burning") ? BURNING : EROSION;
+        if (!PortInstabilityConfig.instabilityEnabled() || !age.enabled()
+                || !PortInstabilityConfig.instabilityProviderEnabled(id)) return 0;
+        var chunks = PortHazardProviders.loadedChunksNearPlayers(level, 16);
+        if (chunks.isEmpty()) return 0;
+        var context = new PortInstabilityRuntime.Context(level, age, chunks,
+                level.getServer().getTickCount(), new PortInstabilityRuntime.Budget(1));
+        if (effect.equals("burning")) {
+            if (!PortInstabilityConfig.scorchEnabled() || !PortInstabilityConfig.scorchPlayers()
+                    || !eligibleScorch(context, player)) return 0;
+            if (player.isInWaterOrRain()) return -2;
+            player.igniteForSeconds(4);
+            return 1;
+        }
+        if (!effect.equals("erosion") || !PortInstabilityConfig.erosionEnabled() || !PortHazardProviders.canMutate(level)
+                || PortInstabilityRuntime.effectiveScore(level) < InstabilityProviderCatalog.Deck.DESTRUCTIVE.entryCost()
+                || !(player.pick(6.0, 0.0F, false) instanceof BlockHitResult hit)
+                || hit.getType() != net.minecraft.world.phys.HitResult.Type.BLOCK) return 0;
+        return erodeAt(context, hit.getBlockPos()) ? 1 : 0;
+    }
+
+    private static void scorch(PortInstabilityRuntime.Context context, int effectiveLevel) {
+        if (!PortInstabilityConfig.scorchEnabled() || PortInstabilityConfig.scorchMaxTargets() == 0) return;
+        ServerLevel level = context.level();
+        Random random = new Random(context.age().seed() ^ PortHazardSavedData.get(level).nextAttempt()
+                * 0x9E3779B97F4A7C15L ^ BURNING.hashCode());
+        int start = random.nextInt(context.loadedChunks().size());
+        int affected = 0;
+        for (int offset = 0; offset < Math.min(8, context.loadedChunks().size()); offset++) {
+            ChunkPos chunk = context.loadedChunks().get((start + offset) % context.loadedChunks().size());
+            AABB bounds = new AABB(chunk.getMinBlockX(), level.getMinY(), chunk.getMinBlockZ(),
+                    chunk.getMaxBlockX() + 1, level.getMaxY(), chunk.getMaxBlockZ() + 1);
+            List<LivingEntity> candidates = new ArrayList<>();
+            level.getEntities(EntityTypeTest.forClass(LivingEntity.class), bounds,
+                    entity -> eligibleScorch(context, entity), candidates, 8);
+            candidates.sort(Comparator.comparing(Entity::getUUID));
+            for (LivingEntity entity : candidates) {
+                if (affected >= PortInstabilityConfig.scorchMaxTargets() || context.budget().remaining() == 0) return;
+                // Legacy sampled each chunk each tick with a 1/10 gate. With 20 ticks/pass this
+                // gives at least one opportunity for nearly every inspected loaded chunk.
+                if (random.nextDouble() >= PortHazardProviders.legacyChance(1,
+                        PortInstabilityConfig.instabilityCooldown(), 1, 10)) continue;
+                if (!context.budget().claim()) return;
+                entity.igniteForSeconds(Math.min(12, 4 * effectiveLevel));
+                context.budget().recordApplied();
+                affected++;
+                break;
+            }
+        }
+    }
+
+    private static boolean eligibleScorch(PortInstabilityRuntime.Context context, LivingEntity entity) {
+        if (!entity.isAlive() || entity.isRemoved() || entity.level() != context.level()
+                || !context.level().canSeeSky(entity.blockPosition())
+                || PortDecayProviders.isSpawnProtected(context.age(), entity.blockPosition())) return false;
+        if (entity instanceof Player player) return PortInstabilityConfig.scorchPlayers()
+                && !player.isCreative() && !player.isSpectator();
+        return true;
+    }
+
+    private static void erode(PortInstabilityRuntime.Context context) {
+        if (!PortInstabilityConfig.erosionEnabled() || !PortHazardProviders.canMutate(context.level())) return;
+        ServerLevel level = context.level();
+        Random random = new Random(context.age().seed() ^ PortHazardSavedData.get(level).nextAttempt()
+                * 0xC2B2AE3D27D4EB4FL ^ EROSION.hashCode());
+        for (int attempt = 0; attempt < 8; attempt++) {
+            ChunkPos chunk = context.loadedChunks().get(random.nextInt(context.loadedChunks().size()));
+            int x = chunk.getMinBlockX() + random.nextInt(16);
+            int z = chunk.getMinBlockZ() + random.nextInt(16);
+            int y = level.getMinY() + 1 + random.nextInt(level.getHeight() - 2);
+            if (erodeAt(context, new BlockPos(x, y, z))) return;
+        }
+    }
+
+    static boolean erodeAt(PortInstabilityRuntime.Context context, BlockPos pos) {
+        ServerLevel level = context.level();
+        if (!PortDecayProviders.isLoadedTarget(level, context.loadedChunks(), pos)
+                || PortDecayProviders.isSpawnProtected(context.age(), pos)) return false;
+        BlockState prior = level.getBlockState(pos);
+        if (!PortDecayProviders.canReplace(level, pos, prior, DecayBlock.Color.BLUE)) return false;
+        for (Direction direction : FLUID_SIDES) {
+            BlockPos neighbor = pos.relative(direction);
+            if (!PortDecayProviders.isLoadedTarget(level, context.loadedChunks(), neighbor)) continue;
+            var fluid = level.getFluidState(neighbor);
+            if (fluid.isSource() && replaceFluid(context, pos, prior, fluid.createLegacyBlock())) return true;
+        }
+        return false;
+    }
+
+    private static boolean replaceFluid(PortInstabilityRuntime.Context context, BlockPos pos,
+            BlockState prior, BlockState fluidBlock) {
+        ServerLevel level = context.level();
+        var actor = FakePlayerFactory.getMinecraft(level);
+        actor.setPos(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+        if (!prior.isAir()) {
+            var breaking = new net.neoforged.neoforge.event.level.block.BreakBlockEvent(level, pos, prior, actor);
+            NeoForge.EVENT_BUS.post(breaking);
+            if (breaking.isCanceled()) return false;
+        }
+        if (level.getBlockState(pos) != prior || !context.budget().claim()) return false;
+        var snapshot = BlockSnapshot.create(level.dimension(), level, pos);
+        if (!level.setBlock(pos, fluidBlock, 3)) return false;
+        var placing = new BlockEvent.EntityPlaceEvent(snapshot, prior, actor);
+        NeoForge.EVENT_BUS.post(placing);
+        if (placing.isCanceled()) {
+            snapshot.restore();
+            return false;
+        }
+        context.budget().recordApplied();
+        return true;
+    }
+
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortFeatureChunkGenerator.java

@@ -70,10 +70,12 @@ public final class PortFeatureChunkGenerator extends ChunkGenerator {
                     .forGetter(generator -> Optional.ofNullable(generator.lakes)),
             PortTerrainFeaturePlan.CODEC.optionalFieldOf("terrain_features")
                     .forGetter(generator -> Optional.ofNullable(generator.terrainFeatures)),
-            com.mojang.serialization.Codec.LONG.fieldOf("age_seed").forGetter(generator -> generator.ageSeed)
-    ).apply(instance, (base, rocks, vegetation, dungeons, lakes, terrainFeatures, seed) ->
+            com.mojang.serialization.Codec.LONG.fieldOf("age_seed").forGetter(generator -> generator.ageSeed),
+            com.mojang.serialization.Codec.BOOL.optionalFieldOf("libraries", false).forGetter(generator -> generator.libraries),
+            Identifier.CODEC.listOf().optionalFieldOf("library_symbols", List.of()).forGetter(generator -> generator.librarySymbols)
+    ).apply(instance, (base, rocks, vegetation, dungeons, lakes, terrainFeatures, seed, libraries, symbols) ->
             new PortFeatureChunkGenerator(base, rocks.orElse(null), vegetation.orElse(null),
-                    dungeons, lakes.orElse(null), terrainFeatures.orElse(null), seed)));
+                    dungeons, lakes.orElse(null), terrainFeatures.orElse(null), seed, libraries, symbols)));
 
     private final ChunkGenerator base;
     private final PortRockPlan rocks;
@@ -82,10 +84,19 @@ public final class PortFeatureChunkGenerator extends ChunkGenerator {
     private final PortLakePlan lakes;
     private final PortTerrainFeaturePlan terrainFeatures;
     private final long ageSeed;
+    private final boolean libraries;
+    private final List<Identifier> librarySymbols;
 
     public PortFeatureChunkGenerator(ChunkGenerator base, PortRockPlan rocks,
                                      PortVegetationPlan vegetation, int dungeons, PortLakePlan lakes,
                                      PortTerrainFeaturePlan terrainFeatures, long ageSeed) {
+        this(base, rocks, vegetation, dungeons, lakes, terrainFeatures, ageSeed, false, List.of());
+    }
+
+    public PortFeatureChunkGenerator(ChunkGenerator base, PortRockPlan rocks,
+                                     PortVegetationPlan vegetation, int dungeons, PortLakePlan lakes,
+                                     PortTerrainFeaturePlan terrainFeatures, long ageSeed,
+                                     boolean libraries, List<Identifier> librarySymbols) {
         super(base.getBiomeSource(), base::getBiomeGenerationSettings);
         this.base = base;
         this.rocks = rocks;
@@ -94,6 +105,8 @@ public final class PortFeatureChunkGenerator extends ChunkGenerator {
         this.lakes = lakes;
         this.terrainFeatures = terrainFeatures;
         this.ageSeed = ageSeed;
+        this.libraries = libraries;
+        this.librarySymbols = List.copyOf(librarySymbols);
     }
 
     public ChunkGenerator base() { return base; }
@@ -286,5 +299,6 @@ public final class PortFeatureChunkGenerator extends ChunkGenerator {
                 if (PortVegetationPlan.addsLogs(page)) mushroomHosts = null;
             }
         }
+        if (libraries) PortLibraryFeature.generate(level, chunk, ageSeed, librarySymbols);
     }
 }

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortHazardProviders.java

@@ -0,0 +1,356 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.Comparator;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Optional;
+import java.util.Random;
+import java.util.Set;
+import java.util.UUID;
+import java.util.function.Predicate;
+import net.dnorberg.rivencraft.Rivencraft;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.tags.BlockTags;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.EntityTypes;
+import net.minecraft.world.entity.LightningBolt;
+import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.level.BlockGetter;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.Explosion;
+import net.minecraft.world.level.ExplosionDamageCalculator;
+import net.minecraft.world.level.gamerules.GameRules;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.phys.AABB;
+import net.neoforged.neoforge.common.NeoForge;
+import net.neoforged.neoforge.common.util.FakePlayerFactory;
+import net.neoforged.neoforge.event.level.BlockEvent;
+
+/** Legacy hazard cards, with one loaded-chunk event and explicit damage budgets. */
+public final class PortHazardProviders {
+    private static final Identifier LIGHTNING = id("lightning");
+    private static final Identifier EXPLOSIONS = id("explosions");
+
+    private PortHazardProviders() {}
+
+    public static void register() {
+        // Visuals and entity damage remain available when block mutation is disabled.
+        PortInstabilityRuntime.register(LIGHTNING, false, PortHazardProviders::apply);
+        PortInstabilityRuntime.register(EXPLOSIONS, false, PortHazardProviders::apply);
+    }
+
+    static boolean isHazard(Identifier id) {
+        return LIGHTNING.equals(id) || EXPLOSIONS.equals(id);
+    }
+
+    /** Roll every selected hazard card each scheduler pass, independently of other providers. */
+    static void tickPlanned(ServerLevel level, PortInstabilityData.Age age, long tick,
+                            List<PortInstabilityPlan.ProviderLevel> providers) {
+        if (!PortInstabilityConfig.hazardsEnabled()) return;
+        List<PortInstabilityPlan.ProviderLevel> hazards = providers.stream()
+                .filter(provider -> isHazard(provider.id())).toList();
+        if (hazards.isEmpty()) return;
+        List<ChunkPos> chunks = loadedChunksNearPlayers(level, PortInstabilityConfig.hazardsMaxChunks());
+        if (chunks.isEmpty()) return;
+        for (PortInstabilityPlan.ProviderLevel hazard : hazards) {
+            var context = new PortInstabilityRuntime.Context(level, age, chunks, tick,
+                    new PortInstabilityRuntime.Budget(1));
+            PortInstabilityRuntime.invoke(context, hazard.id(), hazard.level());
+        }
+    }
+
+    static List<ChunkPos> loadedChunksNearPlayers(ServerLevel level, int maximum) {
+        List<ChunkPos> players = level.players().stream()
+                .sorted(Comparator.comparing(Entity::getUUID))
+                .map(ServerPlayer::chunkPosition).toList();
+        return candidateChunks(players, maximum,
+                chunk -> level.getChunkSource().getChunkNow(chunk.x(), chunk.z()) != null);
+    }
+
+    /** Pure candidate selection; the caller's predicate must only report already-loaded chunks. */
+    static List<ChunkPos> candidateChunks(List<ChunkPos> players, int maximum,
+                                           Predicate<ChunkPos> loaded) {
+        if (maximum <= 0) return List.of();
+        Set<ChunkPos> chunks = new LinkedHashSet<>();
+        for (int radius = 0; radius <= 4; radius++) {
+            for (int dx = -radius; dx <= radius; dx++) {
+                for (int dz = -radius; dz <= radius; dz++) {
+                    if (Math.max(Math.abs(dx), Math.abs(dz)) != radius) continue;
+                    for (ChunkPos center : players) {
+                        int x = center.x() + dx;
+                        int z = center.z() + dz;
+                        ChunkPos candidate = new ChunkPos(x, z);
+                        if (loaded.test(candidate)) chunks.add(candidate);
+                        if (chunks.size() >= maximum) return List.copyOf(chunks);
+                    }
+                }
+            }
+        }
+        return List.copyOf(chunks);
+    }
+
+    /** Operator-only test pulse; skips the random roll, not Age, cooldown, or safety checks. */
+    public static int pulseForTesting(ServerPlayer player, boolean lightning) {
+        return pulseForTesting(player.level(), player.blockPosition(), lightning);
+    }
+
+    public static int pulseForTesting(ServerLevel level, BlockPos origin, boolean lightning) {
+        if (!PortInstabilityConfig.hazardsEnabled()
+                || !PortInstabilityRuntime.isAge(level)) return -1;
+        var age = PortInstabilityData.get(level.getServer()).age(level);
+        if (!PortInstabilityConfig.instabilityEnabled() || !age.enabled()
+                || !PortInstabilityConfig.instabilityProviderEnabled(lightning ? LIGHTNING : EXPLOSIONS)) return -1;
+        PortHazardSavedData data = PortHazardSavedData.get(level);
+        if (!data.ready(lightning, level.getGameTime(), PortInstabilityConfig.hazardsMinInterval())) return 0;
+        ChunkPos center = ChunkPos.containing(origin);
+        for (int dx = -1; dx <= 1; dx++) {
+            for (int dz = -1; dz <= 1; dz++) {
+                ChunkPos chunk = new ChunkPos(center.x() + dx, center.z() + dz);
+                if (level.getChunkSource().getChunkNow(chunk.x(), chunk.z()) == null) continue;
+                int x = chunk.getMinBlockX() + 8;
+                int z = chunk.getMinBlockZ() + 8;
+                int y = lightning ? level.getHeight(Heightmap.Types.MOTION_BLOCKING, x, z)
+                        : origin.getY();
+                BlockPos pos = new BlockPos(x, y, z);
+                var context = new PortInstabilityRuntime.Context(level, age, List.of(chunk),
+                        level.getServer().getTickCount(), new PortInstabilityRuntime.Budget(1));
+                if (!safeTarget(context, pos, 8)) continue;
+                data.nextAttempt();
+                data.record(lightning, level.getGameTime());
+                return (lightning ? strike(level, age, chunk, pos) : explode(level, age, chunk, pos)) ? 1 : 0;
+            }
+        }
+        return 0;
+    }
+
+    static void apply(PortInstabilityRuntime.Context context, Identifier id, int effectiveLevel) {
+        ServerLevel level = context.level();
+        if (!PortInstabilityConfig.hazardsEnabled() || context.loadedChunks().isEmpty()
+                || !PortInstabilityRuntime.isAge(level)) return;
+        boolean lightning = id.equals(LIGHTNING);
+        if (!lightning && !id.equals(EXPLOSIONS)) return;
+        PortHazardSavedData data = PortHazardSavedData.get(level);
+        long gameTime = level.getGameTime();
+        if (!data.ready(lightning, gameTime, PortInstabilityConfig.hazardsMinInterval())) return;
+        Random random = new Random(context.age().seed() ^ data.nextAttempt() * 0x9E3779B97F4A7C15L
+                ^ id.hashCode());
+        int legacyDenominator = lightning ? level.isRaining() && level.isThundering() ? 5000 : 100000 : 1000;
+        // Legacy rolled once per chunk per tick; the shared scheduler visits this Age every >=20 ticks.
+        double chance = legacyChance(context.loadedChunks().size(), PortInstabilityConfig.instabilityCooldown(),
+                effectiveLevel, legacyDenominator);
+        if (random.nextDouble() >= chance) return;
+        ChunkPos chunk = context.loadedChunks().get(random.nextInt(context.loadedChunks().size()));
+        int margin = lightning ? 2 : 6;
+        int x = chunk.getMinBlockX() + margin + random.nextInt(16 - margin * 2);
+        int z = chunk.getMinBlockZ() + margin + random.nextInt(16 - margin * 2);
+        int y = lightning ? level.getHeight(Heightmap.Types.MOTION_BLOCKING, x, z)
+                : level.getMinY() + 1 + random.nextInt(level.getHeight() - 2);
+        BlockPos pos = new BlockPos(x, y, z);
+        if (!safeTarget(context, pos, 8) || !context.budget().claim()) return;
+        data.record(lightning, gameTime); // persist before dispatch so a restart cannot replay the event
+        if (lightning ? strike(level, context.age(), chunk, pos) : explode(level, context.age(), chunk, pos))
+            context.budget().recordApplied();
+    }
+
+    static double legacyChance(int loadedChunks, int intervalTicks, int copies, int denominator) {
+        if (loadedChunks <= 0 || intervalTicks <= 0 || copies <= 0 || denominator <= 0) return 0;
+        return 1.0 - Math.pow(1.0 - 1.0 / denominator, (double) loadedChunks * intervalTicks * copies);
+    }
+
+    static boolean safeTarget(PortInstabilityRuntime.Context context, BlockPos pos, int spawnMargin) {
+        if (!PortDecayProviders.isLoadedTarget(context.level(), context.loadedChunks(), pos)) return false;
+        BlockPos spawn = context.age().spawn().orElse(null);
+        return spawn == null || Math.abs(pos.getX() - spawn.getX()) > spawnMargin
+                || Math.abs(pos.getZ() - spawn.getZ()) > spawnMargin;
+    }
+
+    private static boolean strike(ServerLevel level, PortInstabilityData.Age age, ChunkPos chunk, BlockPos pos) {
+        AABB bounds = new AABB(pos).inflate(2);
+        if (!level.getEntitiesOfClass(LightningBolt.class, bounds).isEmpty()) return false;
+        LightningBolt bolt = EntityTypes.LIGHTNING_BOLT.create(level, net.minecraft.world.entity.EntitySpawnReason.TRIGGERED);
+        if (bolt == null) return false;
+        bolt.setPos(pos.getX() + 0.5, pos.getY(), pos.getZ() + 0.5);
+        bolt.setVisualOnly(true); // vanilla bolt damage/fire bypasses our explicit budgets
+        if (!level.addFreshEntity(bolt)) return false;
+        List<LivingEntity> targets = level.getEntitiesOfClass(LivingEntity.class, bounds,
+                entity -> entity.isAlive() && entity.level() == level && eligibleEntity(entity));
+        targets.sort(Comparator.comparing(Entity::getUUID));
+        int count = 0;
+        for (LivingEntity target : targets) {
+            if (count++ >= PortInstabilityConfig.hazardsMaxEntities()) break;
+            if (PortInstabilityConfig.hazardsMaxDamage() > 0)
+                target.hurtServer(level, level.damageSources().lightningBolt(), Math.min(5, PortInstabilityConfig.hazardsMaxDamage()));
+        }
+        // Legacy lightning started fires. Keep it separately gated by block policy and game rule.
+        if (canMutate(level) && PortInstabilityConfig.hazardsFire()
+                && level.canSpreadFireAround(pos)
+                && !PortDecayProviders.isSpawnProtected(age, pos)
+                && PortDecayProviders.isLoadedTarget(level, List.of(chunk), pos)) ignite(level, pos);
+        return true;
+    }
+
+    private static boolean explode(ServerLevel level, PortInstabilityData.Age age, ChunkPos chunk, BlockPos pos) {
+        return explodeBounded(level, age, chunk, pos, PortInstabilityConfig.hazardsBlockDamage(),
+                PortInstabilityConfig.hazardsPlayerDamage(), PortInstabilityConfig.hazardsFire(),
+                PortInstabilityConfig.hazardsMaxBlocks(), PortInstabilityConfig.hazardsMaxEntities(),
+                PortInstabilityConfig.hazardsMaxDamage(), PortInstabilityConfig.hazardsExplosionRadius());
+    }
+
+    /** Shared blast guard for meteor impacts; each effect supplies its own damage policy. */
+    static boolean explodeBounded(ServerLevel level, PortInstabilityData.Age age, ChunkPos chunk, BlockPos pos,
+            boolean blockDamage, boolean playerDamage, boolean ignite, int maxBlocks, int maxEntities,
+            int maxDamage, int radius) {
+        boolean grief = destructiveBlocksAllowed(PortInstabilityConfig.instabilityWorldMutation(),
+                level.getGameRules().get(GameRules.MOB_GRIEFING), blockDamage, maxBlocks);
+        boolean fire = grief && ignite
+                && level.canSpreadFireAround(pos);
+        BoundedExplosion calculator = new BoundedExplosion(level, age, chunk, grief,
+                playerDamage, maxBlocks, maxEntities, maxDamage);
+        level.explode(null, null, calculator,
+                pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5,
+                radius, false,
+                grief ? Level.ExplosionInteraction.BLOCK : Level.ExplosionInteraction.NONE);
+        if (fire) {
+            int ignited = 0;
+            for (BlockPos affected : calculator.approved) {
+                if (ignited >= 4) break;
+                if (level.canSpreadFireAround(affected) && !PortDecayProviders.isSpawnProtected(age, affected)
+                        && ignite(level, affected)) ignited++;
+            }
+        }
+        return calculator.started;
+    }
+
+    private static boolean ignite(ServerLevel level, BlockPos pos) {
+        if (!level.getBlockState(pos).isAir() || !Blocks.FIRE.defaultBlockState().canSurvive(level, pos))
+            return false;
+        var actor = FakePlayerFactory.getMinecraft(level);
+        actor.setPos(pos.getX() + 0.5, pos.getY(), pos.getZ() + 0.5);
+        var snapshot = net.neoforged.neoforge.common.util.BlockSnapshot.create(level.dimension(), level, pos);
+        BlockState prior = level.getBlockState(pos);
+        if (!level.setBlock(pos, Blocks.FIRE.defaultBlockState(), 3)) return false;
+        var place = new BlockEvent.EntityPlaceEvent(snapshot, prior, actor);
+        NeoForge.EVENT_BUS.post(place);
+        if (place.isCanceled()) {
+            snapshot.restore();
+            return false;
+        }
+        return true;
+    }
+
+    static boolean canMutate(ServerLevel level) {
+        return PortInstabilityConfig.instabilityWorldMutation()
+                && level.getGameRules().get(GameRules.MOB_GRIEFING);
+    }
+
+    static boolean destructiveBlocksAllowed(boolean worldMutation, boolean mobGriefing,
+                                            boolean blockDamage, int maxBlocks) {
+        return worldMutation && mobGriefing && blockDamage && maxBlocks > 0;
+    }
+
+    static boolean protectedBlock(ServerLevel level, PortInstabilityData.Age age, BlockPos pos, BlockState state) {
+        return state.isAir() || state.hasBlockEntity() || state.is(Blocks.TNT)
+                || state.is(PortDecayProviders.PROTECTED) || state.is(BlockTags.PORTALS)
+                || PortDecayProviders.isSpawnProtected(age, pos)
+                || state.getDestroySpeed(level, pos) < 0
+                || BuiltInRegistries.BLOCK.getKey(state.getBlock()).getNamespace().equals(Rivencraft.MOD_ID);
+    }
+
+    private static boolean eligibleEntity(Entity entity) {
+        return eligibleEntity(entity, PortInstabilityConfig.hazardsPlayerDamage());
+    }
+
+    private static boolean eligibleEntity(Entity entity, boolean playerDamage) {
+        return !(entity instanceof Player player) || playerDamage
+                && !player.isCreative() && !player.isSpectator();
+    }
+
+    private static Identifier id(String path) {
+        return Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, path);
+    }
+
+    private static final class BoundedExplosion extends ExplosionDamageCalculator {
+        private final ServerLevel level;
+        private final PortInstabilityData.Age age;
+        private final ChunkPos chunk;
+        private final boolean grief;
+        private final boolean playerDamage;
+        private final int maxBlocks;
+        private final int maxEntities;
+        private final int maxDamage;
+        private final Set<BlockPos> approved = new LinkedHashSet<>();
+        private final Set<UUID> damagedEntities = new HashSet<>();
+        private int damaged;
+        private boolean started;
+
+        private BoundedExplosion(ServerLevel level, PortInstabilityData.Age age, ChunkPos chunk, boolean grief,
+                boolean playerDamage, int maxBlocks, int maxEntities, int maxDamage) {
+            this.level = level;
+            this.age = age;
+            this.chunk = chunk;
+            this.grief = grief;
+            this.playerDamage = playerDamage;
+            this.maxBlocks = maxBlocks;
+            this.maxEntities = maxEntities;
+            this.maxDamage = maxDamage;
+        }
+
+        @Override
+        public Optional<Float> getBlockExplosionResistance(Explosion explosion, BlockGetter reader,
+                BlockPos pos, BlockState state, FluidState fluid) {
+            started = true;
+            if (!inLoadedChunk(pos)) return Optional.of(Float.MAX_VALUE);
+            return super.getBlockExplosionResistance(explosion, reader, pos, state, fluid);
+        }
+
+        @Override
+        public boolean shouldBlockExplode(Explosion explosion, BlockGetter reader, BlockPos pos,
+                BlockState state, float power) {
+            if (!grief || !inLoadedChunk(pos) || protectedBlock(level, age, pos, state)) return false;
+            if (approved.contains(pos)) return true;
+            if (approved.size() >= maxBlocks) return false;
+            var actor = FakePlayerFactory.getMinecraft(level);
+            actor.setPos(pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5);
+            var event = new net.neoforged.neoforge.event.level.block.BreakBlockEvent(level, pos, state, actor);
+            NeoForge.EVENT_BUS.post(event);
+            if (event.isCanceled()) return false;
+            approved.add(pos.immutable());
+            return true;
+        }
+
+        @Override
+        public boolean shouldDamageEntity(Explosion explosion, Entity entity) {
+            if (damaged >= maxEntities || !eligibleEntity(entity, playerDamage)
+                    || maxDamage == 0) return false;
+            damaged++;
+            damagedEntities.add(entity.getUUID());
+            return true;
+        }
+
+        @Override
+        public float getEntityDamageAmount(Explosion explosion, Entity entity, float exposure) {
+            return Math.min(super.getEntityDamageAmount(explosion, entity, exposure), maxDamage);
+        }
+
+        @Override
+        public float getKnockbackMultiplier(Entity entity) {
+            return damagedEntities.contains(entity.getUUID()) ? 1.0F : 0.0F;
+        }
+
+        private boolean inLoadedChunk(BlockPos pos) {
+            return level.isInWorldBounds(pos) && ChunkPos.containing(pos).equals(chunk)
+                    && level.getChunkSource().getChunkNow(chunk.x(), chunk.z()) != null;
+        }
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortHazardSavedData.java

@@ -0,0 +1,34 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.saveddata.SavedData;
+import net.minecraft.world.level.saveddata.SavedDataType;
+
+/** Per-Age random sequence and event cooldowns survive unload and restart. */
+public final class PortHazardSavedData extends SavedData {
+    private static final Codec<PortHazardSavedData> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+            net.minecraft.util.ExtraCodecs.NON_NEGATIVE_LONG.optionalFieldOf("attempts", 0L).forGetter(data -> data.attempts),
+            Codec.LONG.optionalFieldOf("last_lightning", Long.MIN_VALUE).forGetter(data -> data.lastLightning),
+            Codec.LONG.optionalFieldOf("last_explosion", Long.MIN_VALUE).forGetter(data -> data.lastExplosion),
+            Codec.LONG.optionalFieldOf("last_meteor", Long.MIN_VALUE).forGetter(data -> data.lastMeteor)
+    ).apply(instance, PortHazardSavedData::new));
+    private static final SavedDataType<PortHazardSavedData> TYPE = new SavedDataType<>(
+            Identifier.fromNamespaceAndPath("rivencraft", "hazards"),
+            () -> new PortHazardSavedData(0, Long.MIN_VALUE, Long.MIN_VALUE, Long.MIN_VALUE), CODEC);
+    private long attempts, lastLightning, lastExplosion, lastMeteor;
+    private PortHazardSavedData(long attempts, long lightning, long explosion, long meteor) {
+        this.attempts = attempts; lastLightning = lightning; lastExplosion = explosion; lastMeteor = meteor;
+    }
+    public static PortHazardSavedData get(ServerLevel level) { return level.getDataStorage().computeIfAbsent(TYPE); }
+    public long nextAttempt() { setDirty(); return attempts++; }
+    public boolean ready(boolean lightning, long time, int interval) {
+        long last = lightning ? lastLightning : lastExplosion;
+        return last == Long.MIN_VALUE || time < last || time - last >= interval;
+    }
+    public void record(boolean lightning, long time) { if (lightning) lastLightning = time; else lastExplosion = time; setDirty(); }
+    public boolean meteorReady(long time, int interval) { return lastMeteor == Long.MIN_VALUE || time < lastMeteor || time - lastMeteor >= interval; }
+    public void recordMeteor(long time) { lastMeteor = time; setDirty(); }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortInstabilityCommands.java

@@ -0,0 +1,172 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.brigadier.arguments.BoolArgumentType;
+import com.mojang.brigadier.arguments.IntegerArgumentType;
+import com.mojang.brigadier.arguments.StringArgumentType;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.commands.Commands;
+import net.minecraft.commands.CommandSourceStack;
+import net.minecraft.core.BlockPos;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.Identifier;
+import net.neoforged.bus.api.SubscribeEvent;
+import net.neoforged.fml.common.EventBusSubscriber;
+import net.neoforged.neoforge.event.RegisterCommandsEvent;
+
+/** Scores and test overrides are deliberately operator-only, never book tooltip data. */
+@EventBusSubscriber(modid = Rivencraft.MOD_ID)
+public final class PortInstabilityCommands {
+    private PortInstabilityCommands() {}
+    @SubscribeEvent public static void register(RegisterCommandsEvent event) {
+        event.getDispatcher().register(Commands.literal("rivencraft_port")
+                .requires(Commands.hasPermission(Commands.LEVEL_ADMINS))
+                .then(Commands.literal("instability")
+                        .then(Commands.literal("status").executes(context -> {
+                            var source = context.getSource(); var level = requireAge(source);
+                            var age = PortInstabilityData.get(source.getServer()).age(level);
+                            source.sendSuccess(() -> Component.literal("Age " + level.dimension().identifier()
+                                    + ": frozen score=" + age.score() + ", enabled=" + age.enabled()
+                                    + ", session test score=" + PortInstabilityRuntime.testScore(level)
+                                    + ", protected spawn=" + age.spawn().map(BlockPos::toShortString).orElse("not recorded; re-enter this Age")), false);
+                            source.sendSuccess(() -> Component.literal("  live block score=" + PortBlockInstability.score(level)
+                                    + "; effective score=" + PortInstabilityRuntime.effectiveScore(level)
+                                    + "; difficulty=" + PortInstabilityConfig.instabilityDifficulty()
+                                    + "; samples Age=" + PortBlockInstability.sampledChunks(level) + "/" + PortBlockProfileSavedData.MIN_AGE_SAMPLES
+                                    + ", Overworld=" + PortBlockInstability.sampledChunks(source.getServer().overworld()) + "/" + PortBlockProfileSavedData.MIN_BASELINE_SAMPLES
+                                    + "; profiling=" + PortInstabilityData.get(source.getServer()).supportsProfiling(level)), false);
+                            for (var cost : age.contributions()) source.sendSuccess(() -> Component.literal(
+                                    "  " + cost.reason() + " page=" + cost.page() + " +" + cost.points()), false);
+                            source.sendSuccess(() -> Component.literal("  erosion testing policy (not a saved card): "
+                                    + PortInstabilityRuntime.providerStatus(level, PortEnvironmentalProviders.EROSION)
+                                    + "; current score=" + PortInstabilityRuntime.effectiveScore(level)), false);
+                            for (var provider : PortInstabilityRuntime.plan(level).providers())
+                                source.sendSuccess(() -> Component.literal("  " + provider.id() + " level=" + provider.level()
+                                        + " [" + PortInstabilityRuntime.providerStatus(level, provider.id()) + "]"), false);
+                            return 1;
+                        }))
+                        .then(Commands.literal("enabled").then(Commands.argument("enabled", BoolArgumentType.bool())
+                                .executes(context -> {
+                                    var level = requireAge(context.getSource());
+                                    boolean enabled = BoolArgumentType.getBool(context, "enabled");
+                                    PortInstabilityData.get(level.getServer()).enabled(level, enabled);
+                                    if (!enabled) PortStatusEffectProviders.clearAge(level);
+                                    context.getSource().sendSuccess(() -> Component.literal("Age instability enabled=" + enabled
+                                            + "; saved score and provider selection unchanged"), false);
+                                    return 1;
+                                })))
+                        .then(Commands.literal("test_score").then(Commands.argument("score", IntegerArgumentType.integer(0, 1_000_000))
+                                .executes(context -> {
+                                    var level = requireAge(context.getSource());
+                                    PortInstabilityRuntime.testScore(level, IntegerArgumentType.getInteger(context, "score"));
+                                    PortStatusEffectProviders.clearAge(level);
+                                    context.getSource().sendSuccess(() -> Component.literal("Session-only score override set; frozen score unchanged. Restart or clear_test_score removes it."), false);
+                                    return 1;
+                                })))
+                        .then(Commands.literal("clear_test_score").executes(context -> {
+                            var level = requireAge(context.getSource()); PortInstabilityRuntime.testScore(level, null);
+                            PortStatusEffectProviders.clearAge(level);
+                            context.getSource().sendSuccess(() -> Component.literal("Cleared test override; restored live effective provider selection"), false); return 1;
+                        }))
+                        .then(Commands.literal("decay").then(Commands.argument("color", StringArgumentType.word())
+                                .suggests((context, builder) -> {
+                                    for (var color : net.dnorberg.rivencraft.block.DecayBlock.Color.values())
+                                        if (color.getSerializedName().startsWith(builder.getRemaining())) builder.suggest(color.getSerializedName());
+                                    return builder.buildFuture();
+                                }).executes(context -> decay(context, 1))
+                                .then(Commands.argument("attempts", IntegerArgumentType.integer(1, 32))
+                                        .executes(context -> decay(context, IntegerArgumentType.getInteger(context, "attempts"))))))
+                        .then(Commands.literal("environment").then(Commands.argument("effect", StringArgumentType.word())
+                                .suggests((context, builder) -> {
+                                    for (String effect : java.util.List.of("burning", "erosion"))
+                                        if (effect.startsWith(builder.getRemaining())) builder.suggest(effect);
+                                    return builder.buildFuture();
+                                }).executes(context -> {
+                                    var source = context.getSource(); requireAge(source);
+                                    String effect = StringArgumentType.getString(context, "effect");
+                                    if (!effect.equals("burning") && !effect.equals("erosion")) {
+                                        source.sendFailure(Component.literal("Choose burning or erosion")); return 0;
+                                    }
+                                    int result = PortEnvironmentalProviders.pulseForTesting(source.getPlayerOrException(), effect);
+                                    if (result > 0) source.sendSuccess(() -> Component.literal("Applied " + effect + "; saved score/plan unchanged"), false);
+                                    else source.sendFailure(Component.literal(result == -2 ? "Burning would be extinguished by water or rain"
+                                            : "No effect applied. Check Age/config/provider policy, spawn protection and sky exposure; burning requires Survival/Adventure, erosion requires score >=10000 and a source fluid beside/above the targeted block."));
+                                    return Math.max(0, result);
+                                })))
+                        .then(Commands.literal("meteor").executes(context -> {
+                            var source = context.getSource(); requireAge(source);
+                            int result = PortMeteorProvider.pulseForTesting(source.getPlayerOrException());
+                            if (result > 0) source.sendSuccess(() -> Component.literal("Meteor descent scheduled; impact in 30 ticks. Saved score/plan unchanged."), false);
+                            else source.sendFailure(Component.literal("No meteor scheduled: check cooldown (200 ticks), active flight, safe loaded terrain and Age/config/provider policy."));
+                            return Math.max(0, result);
+                        }))
+                        .then(Commands.literal("hazard").then(Commands.argument("type", StringArgumentType.word())
+                                .suggests((context, builder) -> {
+                                    for (String type : java.util.List.of("lightning", "explosions"))
+                                        if (type.startsWith(builder.getRemaining())) builder.suggest(type);
+                                    return builder.buildFuture();
+                                }).executes(context -> {
+                                    var source = context.getSource(); var level = requireAge(source);
+                                    String type = StringArgumentType.getString(context, "type");
+                                    if (!type.equals("lightning") && !type.equals("explosions")) {
+                                        source.sendFailure(Component.literal("Choose lightning or explosions")); return 0;
+                                    }
+                                    int result = PortHazardProviders.pulseForTesting(level, BlockPos.containing(source.getPosition()), type.equals("lightning"));
+                                    if (result > 0) source.sendSuccess(() -> Component.literal("Triggered " + type
+                                            + " in a nearby loaded chunk; saved score/plan unchanged"), false);
+                                    else source.sendFailure(Component.literal(result < 0 ? "Hazard disabled by config, Age or provider policy"
+                                            : "No hazard triggered: cooldown, protected spawn, unloaded terrain or event cancellation"));
+                                    return Math.max(0, result);
+                                })))
+                        .then(Commands.literal("pulse").then(Commands.argument("provider", StringArgumentType.word())
+                                .suggests((context, builder) -> {
+                                    for (var deck : InstabilityProviderCatalog.Deck.values()) for (var card : InstabilityProviderCatalog.cards(deck))
+                                        if (card.id().getPath().startsWith(builder.getRemaining())) builder.suggest(card.id().getPath());
+                                    return builder.buildFuture();
+                                }).executes(context -> {
+                                    var source = context.getSource(); var level = requireAge(source);
+                                    String name = StringArgumentType.getString(context, "provider");
+                                    Identifier id = Identifier.tryParse(name.contains(":") ? name : "rivencraft:" + name);
+                                    if (id == null || !InstabilityProviderCatalog.contains(id)) throw new com.mojang.brigadier.exceptions.SimpleCommandExceptionType(Component.literal("Unknown instability provider")).create();
+                                    var chunk = net.minecraft.world.level.ChunkPos.containing(BlockPos.containing(source.getPosition()));
+                                    if (level.getChunkSource().getChunkNow(chunk.x(), chunk.z()) == null)
+                                        throw new com.mojang.brigadier.exceptions.SimpleCommandExceptionType(Component.literal("Current chunk must already be loaded")).create();
+                                    var budget = new PortInstabilityRuntime.Budget(1);
+                                    var effect = new PortInstabilityRuntime.Context(level, PortInstabilityData.get(level.getServer()).age(level),
+                                            java.util.List.of(chunk), source.getServer().getTickCount(), budget);
+                                    boolean attempted = PortInstabilityRuntime.invoke(effect, id, 1);
+                                    boolean applied = attempted && budget.applied() > 0;
+                                    if (applied) source.sendSuccess(() -> Component.literal("Applied " + id + " (" + budget.applied() + " successful action in this chunk)"), false);
+                                    else source.sendFailure(Component.literal("No effect applied. Check eligible targets/terrain, sky exposure, existing effects and protection. Provider status: "
+                                            + PortInstabilityRuntime.providerStatus(level, id)));
+                                    return applied ? 1 : 0;
+                                })))));
+    }
+    private static int decay(com.mojang.brigadier.context.CommandContext<CommandSourceStack> context, int attempts)
+            throws com.mojang.brigadier.exceptions.CommandSyntaxException {
+        requireAge(context.getSource());
+        var color = java.util.Arrays.stream(net.dnorberg.rivencraft.block.DecayBlock.Color.values())
+                .filter(value -> value.getSerializedName().equalsIgnoreCase(StringArgumentType.getString(context, "color")))
+                .findFirst().orElse(null);
+        if (color == null) {
+            context.getSource().sendFailure(Component.literal("Choose blue, purple, red or white")); return 0;
+        }
+        int changed = PortDecayProviders.pulseForTesting(context.getSource().getPlayerOrException(), color, attempts);
+        if (changed < 0) {
+            context.getSource().sendFailure(Component.literal("Decay is disabled by config, Age or provider policy")); return 0;
+        }
+        context.getSource().sendSuccess(() -> Component.literal("Decay " + color.getSerializedName() + ": " + changed
+                + " block changes from " + attempts + " bounded attempts; saved score/plan unchanged"), false);
+        var player = context.getSource().getPlayerOrException();
+        var nearby = PortDecaySavedData.get(player.level()).frontier(color).reversed().stream()
+                .filter(pos -> net.minecraft.world.level.ChunkPos.containing(pos).equals(player.chunkPosition()))
+                .limit(4).map(BlockPos::toShortString).toList();
+        if (!nearby.isEmpty()) context.getSource().sendSuccess(() -> Component.literal("Nearby tracked decay: " + nearby), false);
+        return changed;
+    }
+    private static net.minecraft.server.level.ServerLevel requireAge(CommandSourceStack source)
+            throws com.mojang.brigadier.exceptions.CommandSyntaxException {
+        if (!PortInstabilityRuntime.isAge(source.getLevel())) throw new com.mojang.brigadier.exceptions.SimpleCommandExceptionType(
+                Component.literal("Use this command inside a Rivencraft Age")).create();
+        return source.getLevel();
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortInstabilityConfig.java

@@ -0,0 +1,147 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.List;
+import net.minecraft.resources.Identifier;
+import net.neoforged.neoforge.common.ModConfigSpec;
+
+/** The 1.21.1 scheduler and status-provider defaults, in the port's server-owned config. */
+public final class PortInstabilityConfig {
+    private static ModConfigSpec.BooleanValue enabled, status, players, nonplayers, hostiles, worldMutation, decay;
+    private static ModConfigSpec.IntValue cooldown, ages, providers, actions, level, chunks, active, candidates, duration, decayAttempts;
+    private static ModConfigSpec.ConfigValue<List<? extends String>> disabledProviders;
+    private static ModConfigSpec.BooleanValue hazards, hazardBlocks, hazardPlayers, hazardFire;
+    private static ModConfigSpec.IntValue hazardInterval, hazardChunks, hazardMaxBlocks, hazardEntities, hazardDamage, hazardRadius;
+    private static ModConfigSpec.BooleanValue meteor, meteorBlocks, meteorPlayers, meteorFire;
+    private static ModConfigSpec.IntValue meteorMaxBlocks, meteorEntities, meteorDamage;
+    private static ModConfigSpec.BooleanValue scorch, scorchPlayers, erosion;
+    private static ModConfigSpec.IntValue scorchTargets;
+    private static ModConfigSpec.IntValue difficulty;
+    private static ModConfigSpec.ConfigValue<List<? extends String>> materialOverrides;
+    private PortInstabilityConfig() {}
+    public static void define(ModConfigSpec.Builder builder) {
+        builder.push("instability");
+        enabled = builder.comment("Run implemented instability providers. Saved scores and plans remain unchanged when disabled.")
+                .define("enabled", true);
+        difficulty = builder.comment("Legacy instability difficulty: 0=quarter, 1=half, 2=normal, 3=1.75x; saved scores stay unchanged.")
+                .defineInRange("difficulty", 2, 0, 3);
+        worldMutation = builder.comment("Allow implemented instability providers to change blocks, as in 1.21.1.")
+                .define("world_mutation", true);
+        cooldown = builder.defineInRange("cooldown_ticks", 20, 20, 1200);
+        ages = builder.defineInRange("max_ages_per_tick", 4, 1, 16);
+        providers = builder.defineInRange("max_providers_per_age", 2, 1, 16);
+        actions = builder.defineInRange("max_actions_per_age", 1, 1, 16);
+        level = builder.defineInRange("max_effect_level", 3, 1, 16);
+        chunks = builder.defineInRange("max_loaded_chunks", 16, 1, 64);
+        disabledProviders = builder.comment("Disable particular providers without changing saved selections. Accepts poison or rivencraft:poison.")
+                .defineListAllowEmpty("disabled_providers", List.of(), () -> "poison", value -> value instanceof String text
+                        && Identifier.tryParse(text) != null);
+        builder.pop();
+        builder.push("instability_status_effects");
+        status = builder.define("enabled", true);
+        players = builder.comment("Affect Survival/Adventure players; Creative and Spectator remain exempt.")
+                .define("affect_players", true);
+        nonplayers = builder.define("affect_nonplayers", true);
+        hostiles = builder.define("buff_hostiles", true);
+        active = builder.defineInRange("max_active_per_age", 32, 1, 128);
+        candidates = builder.defineInRange("max_candidates_per_attempt", 8, 1, 16);
+        duration = builder.defineInRange("max_duration_ticks", 200, 20, 200);
+        builder.pop();
+        builder.push("instability_decay");
+        decay = builder.comment("Allow colored decay in loaded Ages. Also requires instability.world_mutation.")
+                .define("enabled", true);
+        decayAttempts = builder.comment("Maximum six-neighbor conversion attempts per provider call; at most one block changes.")
+                .defineInRange("max_attempts_per_call", 4, 1, 6);
+        builder.pop();
+        builder.push("instability_hazards");
+        hazards = builder.comment("Run Legacy lightning and explosion cards in loaded Ages.").define("enabled", true);
+        hazardBlocks = builder.comment("Allow block destruction; also requires world_mutation and mobGriefing.").define("block_damage", true);
+        hazardPlayers = builder.comment("Allow damage to Survival/Adventure players.").define("player_damage", true);
+        hazardFire = builder.comment("Allow ignition where the vanilla fire-spread rule permits it.").define("fire", true);
+        hazardInterval = builder.defineInRange("minimum_gap_ticks", 20, 20, 12000);
+        hazardChunks = builder.defineInRange("max_loaded_chunks", 81, 1, 169);
+        hazardMaxBlocks = builder.defineInRange("max_explosion_blocks", 16, 0, 64);
+        hazardEntities = builder.defineInRange("max_damaged_entities", 8, 0, 32);
+        hazardDamage = builder.defineInRange("max_entity_damage", 12, 0, 40);
+        hazardRadius = builder.comment("Legacy strength 3, bounded to one already-loaded chunk.").defineInRange("explosion_radius", 3, 1, 3);
+        builder.pop();
+        builder.push("instability_meteor");
+        meteor = builder.comment("Run the active Legacy meteor card in loaded Ages.").define("enabled", true);
+        meteorBlocks = builder.comment("Allow impact block destruction; also requires world_mutation and mobGriefing.")
+                .define("block_damage", true);
+        meteorPlayers = builder.comment("Allow impacts to hurt Survival/Adventure players.").define("player_damage", true);
+        meteorFire = builder.comment("Allow impact fire where the vanilla fire-spread rule permits it.").define("fire", true);
+        meteorMaxBlocks = builder.defineInRange("max_impact_blocks", 24, 0, 64);
+        meteorEntities = builder.defineInRange("max_damaged_entities", 8, 0, 32);
+        meteorDamage = builder.defineInRange("max_entity_damage", 12, 0, 40);
+        builder.pop();
+        builder.push("instability_scorching");
+        scorch = builder.comment("Run Legacy's active burning card on sky-exposed entities.").define("enabled", true);
+        scorchPlayers = builder.comment("Allow burning on Survival/Adventure players.").define("affect_players", true);
+        scorchTargets = builder.defineInRange("max_targets_per_pass", 4, 0, 16);
+        builder.pop();
+        builder.push("instability_erosion");
+        erosion = builder.comment("Enable Legacy's dormant erosion effect for testing; no saved card is added.",
+                "Ages with a score of at least 10000 can spread adjacent source fluid into one eligible block per pass.")
+                .define("enabled", true);
+        builder.pop();
+        builder.push("instability_modded_materials");
+        materialOverrides = builder.comment("Recognized ores, mineral blocks and source fluids from installed mods are scored automatically.",
+                "Optional exact modid:block_id=points overrides; zero excludes a block. No content mod is required.")
+                .defineListAllowEmpty("block_weight_overrides", List.of(), () -> "examplemod:rare_ore=4000", PortInstabilityConfig::validMaterialOverride);
+        builder.pop();
+    }
+    private static boolean validMaterialOverride(Object value) {
+        if (!(value instanceof String entry)) return false;
+        int separator = entry.lastIndexOf('=');
+        if (separator < 1) return false;
+        Identifier id = Identifier.tryParse(entry.substring(0, separator));
+        if (id == null || !entry.substring(0, separator).contains(":")
+                || id.getNamespace().equals("minecraft") || id.getNamespace().equals("rivencraft")) return false;
+        try { int weight = Integer.parseInt(entry.substring(separator + 1)); return weight >= 0 && weight <= 100000; }
+        catch (NumberFormatException ignored) { return false; }
+    }
+    public static int instabilityDifficulty() { return difficulty.get(); }
+    public static List<? extends String> moddedMaterialOverrides() { return materialOverrides.get(); }
+    public static boolean scorchEnabled() { return scorch.get(); }
+    public static boolean scorchPlayers() { return scorchPlayers.get(); }
+    public static int scorchMaxTargets() { return scorchTargets.get(); }
+    public static boolean erosionEnabled() { return erosion.get(); }
+    public static boolean meteorEnabled() { return meteor.get(); }
+    public static boolean meteorBlockDamage() { return meteorBlocks.get(); }
+    public static boolean meteorPlayerDamage() { return meteorPlayers.get(); }
+    public static boolean meteorFire() { return meteorFire.get(); }
+    public static int meteorMaxBlocks() { return meteorMaxBlocks.get(); }
+    public static int meteorMaxEntities() { return meteorEntities.get(); }
+    public static int meteorMaxDamage() { return meteorDamage.get(); }
+    public static boolean hazardsEnabled() { return hazards.get(); }
+    public static boolean hazardsBlockDamage() { return hazardBlocks.get(); }
+    public static boolean hazardsPlayerDamage() { return hazardPlayers.get(); }
+    public static boolean hazardsFire() { return hazardFire.get(); }
+    public static int hazardsMinInterval() { return hazardInterval.get(); }
+    public static int hazardsMaxChunks() { return hazardChunks.get(); }
+    public static int hazardsMaxBlocks() { return hazardMaxBlocks.get(); }
+    public static int hazardsMaxEntities() { return hazardEntities.get(); }
+    public static int hazardsMaxDamage() { return hazardDamage.get(); }
+    public static int hazardsExplosionRadius() { return hazardRadius.get(); }
+    public static boolean instabilityWorldMutation() { return worldMutation.get(); }
+    public static boolean decayEnabled() { return decay.get(); }
+    public static int decayMaxAttempts() { return decayAttempts.get(); }
+    public static boolean instabilityEnabled() { return enabled.get(); }
+    public static boolean instabilityProviderEnabled(Identifier id) {
+        return disabledProviders.get().stream().noneMatch(value -> value.equals(id.toString())
+                || id.getNamespace().equals("rivencraft") && value.equals(id.getPath()));
+    }
+    public static int instabilityCooldown() { return cooldown.get(); }
+    public static int instabilityMaxAges() { return ages.get(); }
+    public static int instabilityMaxProviders() { return providers.get(); }
+    public static int instabilityMaxActions() { return actions.get(); }
+    public static int instabilityMaxLevel() { return level.get(); }
+    public static int instabilityMaxChunks() { return chunks.get(); }
+    public static boolean statusEffectsEnabled() { return status.get(); }
+    public static boolean statusEffectsPlayers() { return players.get(); }
+    public static boolean statusEffectsNonplayers() { return nonplayers.get(); }
+    public static boolean statusEffectsHostiles() { return hostiles.get(); }
+    public static int statusEffectsMaxActive() { return active.get(); }
+    public static int statusEffectsMaxCandidates() { return candidates.get(); }
+    public static int statusEffectsMaxDuration() { return duration.get(); }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortInstabilityData.java

@@ -0,0 +1,115 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.saveddata.SavedData;
+import net.minecraft.world.level.saveddata.SavedDataType;
+
+/** Frozen creation-time contributions and Legacy deck selections. Never silently rescores older Ages. */
+public final class PortInstabilityData extends SavedData {
+    public record Contribution(String reason, int page, int points) {
+        public static final Codec<Contribution> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+                Codec.STRING.fieldOf("reason").forGetter(Contribution::reason),
+                Codec.INT.fieldOf("page").forGetter(Contribution::page),
+                Codec.intRange(0, Integer.MAX_VALUE).fieldOf("points").forGetter(Contribution::points)
+        ).apply(instance, Contribution::new));
+    }
+    public record Age(long seed, List<Contribution> contributions, PortInstabilityPlan plan, boolean enabled, java.util.Optional<net.minecraft.core.BlockPos> spawn) {
+        public static final Codec<Age> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+                Codec.LONG.fieldOf("seed").forGetter(Age::seed),
+                Contribution.CODEC.listOf().fieldOf("contributions").forGetter(Age::contributions),
+                PortInstabilityPlan.CODEC.fieldOf("plan").forGetter(Age::plan),
+                Codec.BOOL.optionalFieldOf("enabled", true).forGetter(Age::enabled),
+                net.minecraft.core.BlockPos.CODEC.optionalFieldOf("spawn").forGetter(Age::spawn)
+        ).apply(instance, Age::new));
+        public Age { contributions = List.copyOf(contributions); spawn = spawn.map(net.minecraft.core.BlockPos::immutable); }
+        public Age(long seed, List<Contribution> contributions, PortInstabilityPlan plan, boolean enabled) {
+            this(seed, contributions, plan, enabled, java.util.Optional.empty());
+        }
+        public int score() { return contributions.stream().mapToInt(Contribution::points).reduce(0, Math::addExact); }
+    }
+    private static final SavedDataType<PortInstabilityData> TYPE = new SavedDataType<>(
+            Identifier.fromNamespaceAndPath("rivencraft", "instability"), () -> new PortInstabilityData(Map.of()),
+            Codec.unboundedMap(Identifier.CODEC, Age.CODEC).fieldOf("ages").codec()
+                    .xmap(PortInstabilityData::new, data -> Map.copyOf(data.ages)));
+    private final Map<Identifier, Age> ages = new HashMap<>();
+    private PortInstabilityData(Map<Identifier, Age> values) { ages.putAll(values); }
+    public static PortInstabilityData get(MinecraftServer server) { return server.overworld().getDataStorage().computeIfAbsent(TYPE); }
+    public Age age(ServerLevel level) {
+        Age age = ages.get(level.dimension().identifier());
+        return age != null ? age : new Age(level.getSeed(),
+                List.of(new Contribution("predates_instability", -1, 0)), PortInstabilityPlan.empty(), true);
+    }
+    /** Older neutral Ages stay neutral even if an arrival or enabled flag was later saved. */
+    public boolean supportsProfiling(ServerLevel level) {
+        Age state = ages.get(level.dimension().identifier());
+        return state != null && state.contributions().stream().noneMatch(cost -> cost.reason().equals("predates_instability"));
+    }
+    public void enabled(ServerLevel level, boolean enabled) {
+        Age previous = age(level);
+        ages.put(level.dimension().identifier(), new Age(previous.seed(), previous.contributions(), previous.plan(), enabled, previous.spawn()));
+        setDirty();
+    }
+    /** First resolved arrival remains protected without rescoring or rerolling the Age. */
+    public void recordSpawn(ServerLevel level, net.minecraft.core.BlockPos spawn) {
+        Age previous = age(level);
+        if (previous.spawn().isPresent()) return;
+        ages.put(level.dimension().identifier(), new Age(previous.seed(), previous.contributions(), previous.plan(),
+                previous.enabled(), java.util.Optional.of(spawn.immutable())));
+        setDirty();
+    }
+    public void create(ServerLevel level, List<Identifier> pages, PortAgeTerrain terrain,
+                       PortLighting lighting, PortDayCycle cycle) {
+        Identifier id = level.dimension().identifier();
+        if (ages.containsKey(id)) throw new IllegalArgumentException("Instability already recorded for " + id);
+        List<Contribution> costs = new ArrayList<>();
+        costs.add(new Contribution(pages.isEmpty() ? "random_baseline" : "authored_baseline", -1, 0));
+        for (var diagnostic : net.dnorberg.rivencraft.writing.PortWritingRecovery.recover(pages).diagnostics())
+            costs.add(new Contribution("writing_" + diagnostic.code(), diagnostic.index(), diagnostic.points()));
+        boolean authoredBright = false;
+        Map<Identifier, Integer> structures = new HashMap<>();
+        var biomes = level.getChunkSource().getGenerator().getBiomeSource().possibleBiomes().stream()
+                .flatMap(holder -> holder.unwrapKey().stream()).map(key -> key.identifier()).toList();
+        for (int i = 0; i < pages.size(); i++) {
+            Identifier page = pages.get(i);
+            if (!page.getNamespace().equals("rivencraft")) continue;
+            String path = page.getPath();
+            if (path.equals("lighting/bright")) { costs.add(new Contribution("bright_lighting", i, 500)); authoredBright = true; }
+            if (page.equals(PortAcceleratedTicks.PAGE)) costs.add(new Contribution("accelerated", i, 1000));
+            if (isCorrupted(page)) costs.add(new Contribution("corrupted_" + path.substring(10), i,
+                    path.endsWith("small") ? 2000 : path.endsWith("medium") ? 1000 : 0));
+            // Legacy charges for sky/weather controllers that Cave terrain cannot apply.
+            if (terrain == PortAgeTerrain.CAVE && (PortWeatherMode.forPage(page) != null
+                    || PortDayCycle.isController(page) || PortDayCycle.isPeriod(page)
+                    || PortDayCycle.isPhase(page) || PortDayCycle.isAngle(page) || PortDayCycle.isDirection(page)))
+                costs.add(new Contribution("cave_ignored_" + path.replace('/', '_'), i, 100));
+            if (PortStructurePages.supports(page)) {
+                int count = structures.merge(page, 1, Integer::sum);
+                if (count > 3) costs.add(new Contribution("excess_" + path, i, 100));
+                var allowed = PortStructurePages.compatibleBiomes(page, level.registryAccess());
+                if (!allowed.isEmpty() && biomes.stream().anyMatch(biome -> !allowed.contains(biome)))
+                    costs.add(new Contribution("forced_biome_" + path, i, 100));
+            }
+        }
+        if (lighting == PortLighting.BRIGHT && !authoredBright) costs.add(new Contribution("seeded_bright_lighting", -1, 500));
+        int suns = 0;
+        for (var body : cycle.bodies()) if (body.kind() == PortDayCycle.SUN && ++suns > 2)
+            costs.add(new Contribution("extra_sun_" + suns, -1, 1000 * (suns - 2)));
+        int score = costs.stream().mapToInt(Contribution::points).reduce(0, Math::addExact);
+        ages.put(id, new Age(level.getSeed(), costs, PortInstabilityPlan.select(score, level.getSeed()), true));
+        setDirty();
+    }
+    public static boolean isCorrupted(Identifier page) {
+        return page.getNamespace().equals("rivencraft") && switch (page.getPath()) {
+            case "corrupted/large", "corrupted/medium", "corrupted/small" -> true;
+            default -> false;
+        };
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortInstabilityPlan.java

@@ -0,0 +1,60 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Random;
+import net.minecraft.resources.Identifier;
+
+/** Frozen provider selection; handler availability and server settings never reroll this plan. */
+public record PortInstabilityPlan(int version, List<ProviderLevel> providers) {
+    public static final com.mojang.serialization.Codec<PortInstabilityPlan> CODEC =
+            com.mojang.serialization.codecs.RecordCodecBuilder.create(instance -> instance.group(
+                    com.mojang.serialization.Codec.INT.fieldOf("version").forGetter(PortInstabilityPlan::version),
+                    ProviderLevel.CODEC.listOf().fieldOf("providers").forGetter(PortInstabilityPlan::providers)
+            ).apply(instance, PortInstabilityPlan::new));
+    public static final int CURRENT_VERSION = 1;
+
+    public PortInstabilityPlan {
+        if (version != CURRENT_VERSION) throw new IllegalArgumentException("Unsupported provider-plan version " + version);
+        providers = List.copyOf(providers);
+        if (providers.stream().map(ProviderLevel::id).distinct().count() != providers.size()) {
+            throw new IllegalArgumentException("Duplicate provider ID in saved Age plan");
+        }
+    }
+
+    public static PortInstabilityPlan empty() { return new PortInstabilityPlan(CURRENT_VERSION, List.of()); }
+
+    public static PortInstabilityPlan select(int score, long ageSeed) {
+        int roundedScore = score / 500 * 500;
+        Map<Identifier, Integer> levels = new LinkedHashMap<>();
+        for (InstabilityProviderCatalog.Deck deck : InstabilityProviderCatalog.Deck.values()) {
+            int remaining = roundedScore - deck.entryCost();
+            if (remaining <= 0) continue;
+            List<InstabilityProviderCatalog.Card> cards = new ArrayList<>(InstabilityProviderCatalog.cards(deck));
+            Collections.shuffle(cards, new Random(ageSeed ^ (0x9E3779B97F4A7C15L * (deck.ordinal() + 1))));
+            for (InstabilityProviderCatalog.Card card : cards) {
+                if (remaining < card.cost()) break;
+                remaining -= card.cost();
+                levels.merge(card.id(), 1, Integer::sum);
+            }
+        }
+        return new PortInstabilityPlan(CURRENT_VERSION, levels.entrySet().stream()
+                .map(entry -> new ProviderLevel(entry.getKey(), entry.getValue())).toList());
+    }
+
+    public record ProviderLevel(Identifier id, int level) {
+        public static final com.mojang.serialization.Codec<ProviderLevel> CODEC =
+                com.mojang.serialization.codecs.RecordCodecBuilder.create(instance -> instance.group(
+                        Identifier.CODEC.fieldOf("id").forGetter(ProviderLevel::id),
+                        com.mojang.serialization.Codec.intRange(1, 255).fieldOf("level").forGetter(ProviderLevel::level)
+                ).apply(instance, ProviderLevel::new));
+        public ProviderLevel {
+            Objects.requireNonNull(id, "id");
+            if (level < 1 || level > 255) throw new IllegalArgumentException("Invalid provider level " + level);
+        }
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortInstabilityRuntime.java

@@ -0,0 +1,178 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.WeakHashMap;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.ChunkPos;
+import net.neoforged.bus.api.SubscribeEvent;
+import net.neoforged.fml.common.EventBusSubscriber;
+import net.neoforged.neoforge.event.server.ServerStoppingEvent;
+import net.neoforged.neoforge.event.tick.LevelTickEvent;
+
+/** The 1.21.1 bounded Age scheduler. Unported cards remain saved and visibly unavailable to operators. */
+@EventBusSubscriber(modid = Rivencraft.MOD_ID)
+public final class PortInstabilityRuntime {
+    private static final Map<ServerLevel, CachedPlan> PLANS = new WeakHashMap<>();
+    private record CachedPlan(int score, long seed, PortInstabilityPlan plan) {}
+    private static final Map<Identifier, Handler> HANDLERS = new HashMap<>();
+    private static final Map<ServerLevel, Map<Identifier, Long>> FAILURES = new WeakHashMap<>();
+    private static final Map<MinecraftServer, Map<Identifier, Integer>> TEST_SCORES = new WeakHashMap<>();
+    private static final Map<MinecraftServer, TickState> TICKS = new WeakHashMap<>();
+    private PortInstabilityRuntime() {}
+    public static void register(Identifier id, ProviderEffect handler) {
+        register(id, false, handler);
+    }
+    public static void register(Identifier id, boolean worldMutating, ProviderEffect handler) {
+        if (HANDLERS.putIfAbsent(id, new Handler(worldMutating, handler)) != null)
+            throw new IllegalArgumentException("Duplicate instability provider " + id);
+    }
+    public static boolean isAge(ServerLevel level) { return level instanceof PortAgeLevel; }
+    public static PortInstabilityPlan plan(ServerLevel level) {
+        var age = PortInstabilityData.get(level.getServer()).age(level);
+        Integer test = testScore(level);
+        int profile = test == null ? PortBlockInstability.score(level) : 0;
+        int difficulty = PortInstabilityConfig.instabilityDifficulty();
+        if (test == null && difficulty == 2 && profile == 0) return age.plan();
+        int score = test != null ? test : PortBlockInstability.difficultyScore((long) age.score() + profile, difficulty);
+        var cached = PLANS.get(level);
+        if (cached == null || cached.score() != score || cached.seed() != age.seed()) {
+            cached = new CachedPlan(score, age.seed(), PortInstabilityPlan.select(score, age.seed()));
+            PLANS.put(level, cached);
+        }
+        return cached.plan();
+    }
+    public static Integer testScore(ServerLevel level) {
+        return TEST_SCORES.getOrDefault(level.getServer(), Map.of()).get(level.dimension().identifier());
+    }
+    public static int effectiveScore(ServerLevel level) {
+        Integer test = testScore(level);
+        if (test != null) return test;
+        return PortBlockInstability.difficultyScore((long) PortInstabilityData.get(level.getServer()).age(level).score()
+                + PortBlockInstability.score(level), PortInstabilityConfig.instabilityDifficulty());
+    }
+    public static void testScore(ServerLevel level, Integer score) {
+        var values = TEST_SCORES.computeIfAbsent(level.getServer(), ignored -> new HashMap<>());
+        if (score == null) values.remove(level.dimension().identifier()); else values.put(level.dimension().identifier(), score);
+    }
+    @SubscribeEvent public static void tick(LevelTickEvent.Post event) {
+        if (!(event.getLevel() instanceof ServerLevel level) || !isAge(level) || level.players().isEmpty()
+                || !PortInstabilityConfig.instabilityEnabled()) return;
+        var server = level.getServer();
+        long tick = server.getTickCount();
+        int cooldown = PortInstabilityConfig.instabilityCooldown();
+        if (tick % cooldown != 0) return;
+        TickState state = TICKS.computeIfAbsent(server, ignored -> new TickState());
+        if (state.tick != tick) {
+            state.tick = tick;
+            var eligible = new ArrayList<Identifier>();
+            for (var loaded : server.getAllLevels()) if (isAge(loaded) && !loaded.players().isEmpty()
+                    && PortInstabilityData.get(server).age(loaded).enabled() && !plan(loaded).providers().isEmpty())
+                eligible.add(loaded.dimension().identifier());
+            eligible.sort(Comparator.comparing(Identifier::toString));
+            state.eligible = List.copyOf(eligible);
+        }
+        int index = state.eligible.indexOf(level.dimension().identifier());
+        if (index < 0 || state.eligible.size() > PortInstabilityConfig.instabilityMaxAges()
+                && Math.floorMod(index - (int) Math.floorMod(tick / cooldown, state.eligible.size()), state.eligible.size())
+                    >= PortInstabilityConfig.instabilityMaxAges()) return;
+        var age = PortInstabilityData.get(server).age(level);
+        if (!age.enabled()) return;
+        var providers = plan(level).providers();
+        PortHazardProviders.tickPlanned(level, age, tick, providers);
+        PortMeteorProvider.tickPlanned(level, age, tick, providers);
+        PortEnvironmentalProviders.tickPlanned(level, age, tick, providers);
+        var chunks = loadedChunks(level);
+        if (providers.isEmpty() || chunks.isEmpty()) return;
+        Context context = new Context(level, age, chunks, tick, new Budget(PortInstabilityConfig.instabilityMaxActions()));
+        int first = (int) Math.floorMod(tick / cooldown + age.seed(), providers.size());
+        int ran = 0;
+        for (int offset = 0; offset < providers.size() && ran < PortInstabilityConfig.instabilityMaxProviders()
+                && context.budget().remaining() > 0; offset++) {
+            var provider = providers.get((first + offset) % providers.size());
+            if (!PortHazardProviders.isHazard(provider.id()) && !provider.id().equals(PortMeteorProvider.METEORS)
+                    && !PortEnvironmentalProviders.isEnvironmental(provider.id()) && invoke(context, provider.id(), provider.level())) ran++;
+        }
+    }
+    public static boolean invoke(Context context, Identifier id, int level) {
+        if (!PortInstabilityConfig.instabilityEnabled() || !PortInstabilityConfig.instabilityProviderEnabled(id)
+                || !PortInstabilityData.get(context.level().getServer()).age(context.level()).enabled()) return false;
+        Handler handler = HANDLERS.get(id);
+        if (handler == null || handler.worldMutating() && !PortInstabilityConfig.instabilityWorldMutation()) return false;
+        var failures = FAILURES.computeIfAbsent(context.level(), ignored -> new HashMap<>());
+        if (context.serverTick() < failures.getOrDefault(id, 0L)) return false;
+        try {
+            handler.effect().apply(context, id, Math.min(level, PortInstabilityConfig.instabilityMaxLevel()));
+        } catch (RuntimeException exception) {
+            failures.put(id, context.serverTick() + Math.max(200L, PortInstabilityConfig.instabilityCooldown() * 10L));
+            Rivencraft.LOGGER.error("Instability provider {} failed in {}; temporarily quarantined", id,
+                    context.level().dimension().identifier(), exception);
+        }
+        return true;
+    }
+    public static String providerStatus(ServerLevel level, Identifier id) {
+        if (!HANDLERS.containsKey(id)) return "not ported yet";
+        if (!PortInstabilityConfig.instabilityEnabled()) return "global config off";
+        if (!PortInstabilityData.get(level.getServer()).age(level).enabled()) return "Age disabled";
+        if (!PortInstabilityConfig.instabilityProviderEnabled(id)) return "provider config off";
+        if (PortHazardProviders.isHazard(id)) {
+            if (!PortInstabilityConfig.hazardsEnabled()) return "hazards config off";
+        } else if (id.equals(PortMeteorProvider.METEORS)) {
+            if (!PortInstabilityConfig.meteorEnabled()) return "meteor config off";
+        } else if (id.equals(PortEnvironmentalProviders.BURNING)) {
+            if (!PortInstabilityConfig.scorchEnabled()) return "burning config off";
+            if (PortInstabilityConfig.scorchMaxTargets() == 0) return "burning target budget zero";
+        } else if (HANDLERS.get(id).worldMutating()) {
+            if (!PortInstabilityConfig.instabilityWorldMutation()) return "world mutation off";
+            if (id.getPath().startsWith("decay") && !PortInstabilityConfig.decayEnabled()) return "decay config off";
+            if (id.equals(PortEnvironmentalProviders.EROSION)) {
+                if (!PortInstabilityConfig.erosionEnabled()) return "erosion config off";
+                if (!PortHazardProviders.canMutate(level)) return "mobGriefing off";
+                if (effectiveScore(level) < InstabilityProviderCatalog.Deck.DESTRUCTIVE.entryCost()) return "erosion threshold not met";
+            }
+        } else {
+            if (!PortInstabilityConfig.statusEffectsEnabled()) return "status effects config off";
+            if (id.getPath().startsWith("enemy") && !PortInstabilityConfig.statusEffectsHostiles()) return "hostile buffs disabled";
+            if (!id.getPath().startsWith("enemy") && !PortInstabilityConfig.statusEffectsPlayers()
+                    && !PortInstabilityConfig.statusEffectsNonplayers()) return "all general targets disabled";
+        }
+        if (level.getServer().getTickCount() < FAILURES.getOrDefault(level, Map.of()).getOrDefault(id, 0L)) return "quarantined";
+        return level.players().isEmpty() ? "no players in Age" : "eligible; sky, targets and budgets still apply";
+    }
+    static List<ChunkPos> loadedChunks(ServerLevel level) {
+        var chunks = new LinkedHashSet<ChunkPos>();
+        for (var player : level.players()) {
+            ChunkPos center = player.chunkPosition();
+            for (int x = -1; x <= 1; x++) for (int z = -1; z <= 1; z++) {
+                if (level.getChunkSource().getChunkNow(center.x() + x, center.z() + z) != null)
+                    chunks.add(new ChunkPos(center.x() + x, center.z() + z));
+                if (chunks.size() >= PortInstabilityConfig.instabilityMaxChunks()) return List.copyOf(chunks);
+            }
+        }
+        return List.copyOf(chunks);
+    }
+    @SubscribeEvent public static void stopping(ServerStoppingEvent event) {
+        TEST_SCORES.remove(event.getServer()); TICKS.remove(event.getServer()); FAILURES.clear(); PLANS.clear();
+    }
+    public interface ProviderEffect { void apply(Context context, Identifier id, int level); }
+    public record Context(ServerLevel level, PortInstabilityData.Age age, List<ChunkPos> loadedChunks,
+                          long serverTick, Budget budget) { public Context { loadedChunks = List.copyOf(loadedChunks); } }
+    public static final class Budget {
+        private int remaining;
+        private int applied;
+        public Budget(int maximum) { remaining = maximum; }
+        public boolean claim() { if (remaining <= 0) return false; remaining--; return true; }
+        public int remaining() { return remaining; }
+        public void recordApplied() { applied++; }
+        public int applied() { return applied; }
+    }
+    private record Handler(boolean worldMutating, ProviderEffect effect) {}
+    private static final class TickState { long tick = Long.MIN_VALUE; List<Identifier> eligible = List.of(); }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortLibraryCommands.java

@@ -0,0 +1,121 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.brigadier.arguments.IntegerArgumentType;
+import net.minecraft.commands.Commands;
+import net.minecraft.core.BlockPos;
+import net.minecraft.network.chat.Component;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.block.ChestBlock;
+import net.minecraft.world.phys.Vec3;
+import net.neoforged.bus.api.SubscribeEvent;
+import net.neoforged.fml.common.EventBusSubscriber;
+import net.neoforged.neoforge.event.RegisterCommandsEvent;
+
+/** Explicit operator tools; normal generation does not search or force-load remote chunks. */
+@EventBusSubscriber(modid = "rivencraft")
+public final class PortLibraryCommands {
+    @SubscribeEvent public static void register(RegisterCommandsEvent event) {
+        var root = Commands.literal("rivencraft_port").requires(Commands.hasPermission(Commands.LEVEL_ADMINS));
+        root.then(Commands.literal("library")
+                .then(Commands.literal("test_place").executes(context -> {
+                    var level = context.getSource().getLevel();
+                    var direction = context.getSource().getEntity() instanceof net.minecraft.world.entity.player.Player player
+                            ? player.getDirection() : net.minecraft.core.Direction.NORTH;
+                    var result = PortLibraryFeature.testPlace(level, BlockPos.containing(context.getSource().getPosition()), direction,
+                            level.getSeed(), PortLibraryWriting.get(level.getServer()).symbols(level.dimension().identifier()));
+                    if (result.isEmpty()) { context.getSource().sendFailure(Component.literal("No clear placement nearby; use open ground with headroom.")); return 0; }
+                    context.getSource().sendSuccess(() -> Component.literal("Library placed. Chest: " + result.get().toShortString()), false);
+                    return 1;
+                }))
+                .then(Commands.literal("test_spacing").then(Commands.argument("chunks", IntegerArgumentType.integer(1, 32))
+                        .executes(context -> {
+                            var level = context.getSource().getLevel();
+                            if (!RuntimeAgeBackend.savedAges(level.getServer()).containsKey(level.dimension().identifier()))
+                                throw new IllegalArgumentException("Use this test override inside a Rivencraft Age");
+                            int spacing = IntegerArgumentType.getInteger(context, "chunks");
+                            PortLibraryFeature.setTestSpacing(level.getSeed(), spacing);
+                            context.getSource().sendSuccess(() -> Component.literal("Session-only library spacing: " + spacing
+                                    + " chunks. Applies to newly generated chunks; 32 restores normal spacing."), false);
+                            return 1;
+                        })))
+                .then(Commands.literal("candidate").executes(context -> {
+                    var level = context.getSource().getLevel();
+                    var origin = ChunkPos.containing(BlockPos.containing(context.getSource().getPosition()));
+                    ChunkPos best = null;
+                    long distance = Long.MAX_VALUE;
+                    for (int spacing : new int[]{32, PortLibraryFeature.spacing(level.getSeed())}) {
+                        int rx = Math.floorDiv(origin.x(), spacing), rz = Math.floorDiv(origin.z(), spacing);
+                        for (int dx = -2; dx <= 2; dx++) for (int dz = -2; dz <= 2; dz++) {
+                            var candidate = PortLibraryFeature.candidateChunk(level.getSeed(), rx + dx, rz + dz, spacing);
+                            long x = candidate.x() - origin.x(), z = candidate.z() - origin.z();
+                            long d = x * x + z * z;
+                            if (d < distance) { best = candidate; distance = d; }
+                        }
+                    }
+                    var candidate = best;
+                    context.getSource().sendSuccess(() -> Component.literal("Nearest candidate chunk " + candidate
+                            + ", center X=" + (candidate.getMinBlockX() + 8) + " Z=" + (candidate.getMinBlockZ() + 8)
+                            + ". A candidate is not a guaranteed library: footing, slope and clear space must pass."), false);
+                    return 1;
+                }))
+                .then(Commands.literal("probe").executes(context -> {
+                    var level = context.getSource().getLevel();
+                    var chunk = level.getChunkAt(BlockPos.containing(context.getSource().getPosition()));
+                    var chest = PortLibraryFeature.libraryChest(chunk);
+                    if (chest.isPresent()) context.getSource().sendSuccess(() -> Component.literal("Generated library chest: " + chest.get().toShortString()), false);
+                    else {
+                        var check = PortLibraryFeature.check(level, chunk.getPos(), level.getSeed());
+                        context.getSource().sendSuccess(() -> Component.literal(check.eligible() ? "Eligible library candidate, floor Y=" + check.floorY()
+                                : "No library in this chunk: " + check.reason()), false);
+                    }
+                    return 1;
+                }))
+                .then(Commands.literal("inspect_loot").executes(context -> {
+                    var level = context.getSource().getLevel();
+                    var chunk = level.getChunkAt(BlockPos.containing(context.getSource().getPosition()));
+                    var pos = PortLibraryFeature.libraryChest(chunk);
+                    if (pos.isEmpty()) { context.getSource().sendFailure(Component.literal("No marked library chest in this chunk.")); return 0; }
+                    var chest = (net.minecraft.world.level.block.entity.ChestBlockEntity) level.getBlockEntity(pos.get());
+                    var items = new java.util.ArrayList<String>();
+                    for (int i = 0; i < chest.getContainerSize(); i++) {
+                        var item = chest.getItem(i); // Materializes loot exactly as opening the chest does.
+                        if (!item.isEmpty()) items.add(item.getCount() + "x " + item.getHoverName().getString());
+                    }
+                    long stands = chunk.getBlockEntities().values().stream()
+                            .filter(be -> be instanceof net.dnorberg.rivencraft.block.entity.BookStandBlockEntity).count();
+                    context.getSource().sendSuccess(() -> Component.literal("Library at " + pos.get().toShortString()
+                            + "; stands in this chunk=" + stands + "; chest=" + items), false);
+                    return 1;
+                }))
+                .then(Commands.literal("nearest_loaded").executes(context -> {
+                    var player = context.getSource().getPlayerOrException();
+                    var level = player.level();
+                    var origin = player.chunkPosition();
+                    BlockPos best = null; double distance = Double.MAX_VALUE;
+                    for (int x = origin.x() - 16; x <= origin.x() + 16; x++) for (int z = origin.z() - 16; z <= origin.z() + 16; z++) {
+                        var chunk = level.getChunkSource().getChunkNow(x, z);
+                        if (chunk == null) continue;
+                        var found = PortLibraryFeature.libraryChest(chunk);
+                        if (found.isPresent()) {
+                            double d = player.distanceToSqr(Vec3.atCenterOf(found.get()));
+                            if (d < distance) { best = found.get(); distance = d; }
+                        }
+                    }
+                    if (best == null) { context.getSource().sendFailure(Component.literal("No library in loaded chunks within 16 chunks. Use candidate or test_spacing to explore new terrain.")); return 0; }
+                    var facing = level.getBlockState(best).getValue(ChestBlock.FACING);
+                    var feet = best.relative(facing, 2).relative(facing.getCounterClockWise());
+                    var target = Vec3.atBottomCenterOf(feet);
+                    if (!level.getBlockState(feet.below()).isFaceSturdy(level, feet.below(), net.minecraft.core.Direction.UP)
+                            || !level.getFluidState(feet).isEmpty() || !level.getFluidState(feet.above()).isEmpty()
+                            || !level.noCollision(player, player.getBoundingBox().move(target.subtract(player.position())))) {
+                        context.getSource().sendFailure(Component.literal("Library found at " + best.toShortString() + " but its aisle is obstructed.")); return 0;
+                    }
+                    player.teleportTo(level, target.x, target.y, target.z, java.util.Set.of(), facing.getOpposite().toYRot(), 0, true);
+                    return 1;
+                })));
+        event.getDispatcher().register(root);
+    }
+    @SubscribeEvent public static void stopped(net.neoforged.neoforge.event.server.ServerStoppedEvent event) {
+        PortLibraryFeature.clearTestSpacing();
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortLibraryFeature.java

@@ -0,0 +1,358 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+import net.dnorberg.rivencraft.PortConfig;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.writing.PortSymbolPages;
+import net.dnorberg.rivencraft.block.BookStandBlock;
+import net.dnorberg.rivencraft.block.entity.BookStandBlockEntity;
+import net.dnorberg.rivencraft.item.PageItem;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.tags.BlockTags;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.Identifier;
+import net.minecraft.util.RandomSource;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.phys.AABB;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.ChestBlock;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.block.entity.ChestBlockEntity;
+import net.minecraft.world.level.chunk.ChunkAccess;
+import net.minecraft.world.level.chunk.LevelChunk;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.LegacyRandomSource;
+import net.minecraft.world.level.levelgen.WorldgenRandom;
+import net.minecraft.world.level.storage.loot.LootTable;
+import net.minecraft.world.level.block.Rotation;
+import net.minecraft.world.level.levelgen.structure.templatesystem.StructurePlaceSettings;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+
+/** Sparse, page-free Age library. Its entire footprint lives in its candidate chunk. */
+public final class PortLibraryFeature {
+    public static final int REGION = 32;
+    static final int FOOTPRINT = 11;
+    private static final int OFFSET_BOUND = 24;
+    private static final int MAX_SUPPORT_DEPTH = 24;
+    private static final int SALT = 14357617;
+    private static final int TEST_SALT = 0x4C494252;
+    private static final String CHEST_MARKER = "RivencraftLibrary";
+    private static final ConcurrentHashMap<Long, Integer> TEST_SPACING = new ConcurrentHashMap<>();
+    // x, y, z, clockwise turns relative to the left stand. The middle row
+    // faces across the room; the far stand faces back toward the entrance.
+    private static final int[][] STANDS = {{6, 1, 2, 0}, {8, 1, 4, 1}, {8, 1, 5, 1},
+            {8, 1, 6, 1}, {6, 1, 8, 2}};
+    private static final Identifier TEMPLATE = Identifier.fromNamespaceAndPath(
+            "rivencraft", "mystcraft_library");
+    private static final ResourceKey<LootTable> CHEST_LOOT = ResourceKey.create(Registries.LOOT_TABLE,
+            Identifier.fromNamespaceAndPath("rivencraft", "chests/mystcraft_library"));
+
+    private PortLibraryFeature() {}
+
+    record Site(int x, int z, int rotation) {}
+
+    public static int spacing(long seed) {
+        return TEST_SPACING.getOrDefault(seed, REGION);
+    }
+
+    /** Session-only testing override; normal 32-chunk sites always remain eligible. */
+    public static void setTestSpacing(long seed, int chunks) {
+        if (chunks < 1 || chunks > REGION) throw new IllegalArgumentException("Invalid library spacing " + chunks);
+        if (chunks == REGION) TEST_SPACING.remove(seed);
+        else TEST_SPACING.put(seed, chunks);
+    }
+
+    public static void clearTestSpacing() {
+        TEST_SPACING.clear();
+    }
+
+    /** The single deterministic candidate in one Legacy-sized region. */
+    public static ChunkPos candidateChunk(long seed, int regionX, int regionZ) {
+        return candidateChunk(seed, regionX, regionZ, REGION);
+    }
+
+    public static ChunkPos candidateChunk(long seed, int regionX, int regionZ, int spacing) {
+        if (spacing < 1 || spacing > REGION) throw new IllegalArgumentException("Invalid library spacing " + spacing);
+        WorldgenRandom random = new WorldgenRandom(new LegacyRandomSource(0L));
+        random.setLargeFeatureWithSalt(seed, regionX, regionZ,
+                spacing == REGION ? SALT : TEST_SALT ^ spacing);
+        int bound = spacing == REGION ? OFFSET_BOUND : spacing;
+        return new ChunkPos(regionX * spacing + random.nextInt(bound),
+                regionZ * spacing + random.nextInt(bound));
+    }
+
+    static Site site(long seed, ChunkPos chunk) {
+        Site normal = site(seed, chunk, REGION);
+        return normal != null ? normal : spacing(seed) == REGION ? null : site(seed, chunk, spacing(seed));
+    }
+
+    private static Site site(long seed, ChunkPos chunk, int spacing) {
+        int rx = Math.floorDiv(chunk.x(), spacing);
+        int rz = Math.floorDiv(chunk.z(), spacing);
+        WorldgenRandom random = new WorldgenRandom(new LegacyRandomSource(0L));
+        random.setLargeFeatureWithSalt(seed, rx, rz,
+                spacing == REGION ? SALT : TEST_SALT ^ spacing);
+        int bound = spacing == REGION ? OFFSET_BOUND : spacing;
+        int candidateX = rx * spacing + random.nextInt(bound);
+        int candidateZ = rz * spacing + random.nextInt(bound);
+        if (chunk.x() != candidateX || chunk.z() != candidateZ) return null;
+        return new Site(chunk.getMinBlockX() + 2, chunk.getMinBlockZ() + 2, random.nextInt(4));
+    }
+
+    /** A saved marker distinguishes a generated library from player-built chests. */
+    public static Optional<BlockPos> libraryChest(LevelChunk chunk) {
+        return chunk.getBlockEntities().entrySet().stream()
+                .filter(entry -> entry.getValue() instanceof ChestBlockEntity chest
+                        && chest.getPersistentData().getBooleanOr(CHEST_MARKER, false))
+                .map(java.util.Map.Entry::getKey).findFirst();
+    }
+
+    /** Recognize libraries generated before the chest marker was introduced. */
+    public static Optional<BlockPos> libraryChest(LevelChunk chunk, long seed) {
+        Optional<BlockPos> marked = libraryChest(chunk);
+        if (marked.isPresent()) return marked;
+        Site site = site(seed, chunk.getPos());
+        if (site == null) return Optional.empty();
+        for (var entry : chunk.getBlockEntities().entrySet()) {
+            if (!(entry.getValue() instanceof ChestBlockEntity chest)) continue;
+            int y = entry.getKey().getY();
+            BlockPos.MutableBlockPos cursor = new BlockPos.MutableBlockPos();
+            if (!entry.getKey().equals(mapped(site, cursor, 4, y, 2))
+                    || !chunk.getBlockState(mapped(site, cursor, 2, y, 2)).is(Blocks.BOOKSHELF)
+                    || !chunk.getBlockState(mapped(site, cursor, 2, y + 1, 2)).is(Blocks.BOOKSHELF)
+                    || !chunk.getBlockState(mapped(site, cursor, 4, y + 6, 2)).is(Blocks.OAK_PLANKS))
+                continue;
+            chest.getPersistentData().putBoolean(CHEST_MARKER, true);
+            chest.setChanged();
+            return Optional.of(entry.getKey());
+        }
+        return Optional.empty();
+    }
+
+    /** Open interior aisle, directly above the cobblestone floor. */
+    public static BlockPos arrival(long seed, ChunkPos chunk, int chestY) {
+        Site site = site(seed, chunk);
+        if (site == null) throw new IllegalArgumentException("Not a library candidate chunk: " + chunk);
+        return mapped(site, new BlockPos.MutableBlockPos(), 5, chestY, 4).immutable();
+    }
+
+    public record PlacementCheck(String reason, int floorY, int[][] heights) {
+        public boolean eligible() { return reason == null; }
+    }
+
+    /** Inspect one candidate without placing blocks. The same test gates natural placement. */
+    public static PlacementCheck check(WorldGenLevel level, ChunkPos chunk, long seed) {
+        Site site = site(seed, chunk);
+        if (site == null) return rejected("not a candidate chunk");
+        BlockPos.MutableBlockPos cursor = new BlockPos.MutableBlockPos();
+        int low = Integer.MAX_VALUE;
+        int high = Integer.MIN_VALUE;
+        int[][] heights = new int[FOOTPRINT][FOOTPRINT];
+        for (int x = 0; x < FOOTPRINT; x++) for (int z = 0; z < FOOTPRINT; z++) {
+            int wx = site.x() + x;
+            int wz = site.z() + z;
+            int y = level.getHeight(Heightmap.Types.WORLD_SURFACE_WG, wx, wz);
+            // The heightmap includes tree canopies. Libraries sit on terrain, not leaves.
+            while (y > level.getMinY() + 2) {
+                BlockState below = level.getBlockState(cursor.set(wx, y - 1, wz));
+                if (!below.isAir() && !isVegetation(below)) break;
+                y--;
+            }
+            if (y < level.getMinY() + 2) return rejected("no surface footing");
+            BlockState ground = level.getBlockState(cursor.set(wx, y - 1, wz));
+            if (!ground.getFluidState().isEmpty()) return rejected("fluid at ground level");
+            if (ground.hasBlockEntity() || !ground.isFaceSturdy(level, cursor, Direction.UP))
+                return rejected("ground is not sturdy terrain");
+            heights[x][z] = y;
+            low = Math.min(low, y);
+            high = Math.max(high, y);
+        }
+        if (high + 10 >= level.getMaxY()) return rejected("insufficient build height");
+        if (high - low > MAX_SUPPORT_DEPTH) return rejected("slope exceeds support depth ("
+                + (high - low) + " > " + MAX_SUPPORT_DEPTH + ")");
+        // Check the entire raised foundation and house. Foliage can be cleared, but not
+        // structures, fluids, or block entities already occupying this volume.
+        for (int x = 0; x < FOOTPRINT; x++) for (int z = 0; z < FOOTPRINT; z++)
+            for (int y = heights[x][z]; y <= high + 10; y++) {
+                BlockState state = level.getBlockState(cursor.set(site.x() + x, y, site.z() + z));
+                if (!state.getFluidState().isEmpty()) return rejected("fluid inside footprint");
+                if (state.hasBlockEntity()) return rejected("block entity inside footprint");
+                if (!(state.isAir() || state.canBeReplaced() || isVegetation(state)))
+                    return rejected("solid obstruction inside footprint: "
+                            + state.getBlock().getDescriptionId());
+            }
+        return new PlacementCheck(null, high, heights);
+    }
+
+    private static PlacementCheck rejected(String reason) {
+        return new PlacementCheck(reason, 0, null);
+    }
+
+    private static boolean isVegetation(BlockState state) {
+        return state.is(BlockTags.LEAVES) || state.is(BlockTags.LOGS)
+                || state.is(BlockTags.FLOWERS) || state.is(BlockTags.SAPLINGS)
+                || !state.isAir() && state.canBeReplaced() && state.getFluidState().isEmpty();
+    }
+
+    static boolean generate(WorldGenLevel level, ChunkAccess chunk, long seed,
+                            List<Identifier> ageSymbols) {
+        Site site = site(seed, chunk.getPos());
+        if (site == null) return false;
+        PlacementCheck check = check(level, chunk.getPos(), seed);
+        if (!check.eligible()) return false;
+        BlockPos.MutableBlockPos cursor = new BlockPos.MutableBlockPos();
+        for (int x = 0; x < FOOTPRINT; x++) for (int z = 0; z < FOOTPRINT; z++)
+            for (int y = check.heights()[x][z]; y <= check.floorY() + 10; y++) {
+                BlockPos pos = cursor.set(site.x() + x, y, site.z() + z);
+                if (isVegetation(level.getBlockState(pos))) level.setBlock(pos, Blocks.AIR.defaultBlockState(), 2);
+            }
+        return build(level, site, check.floorY(), check.heights(), seed, ageSymbols);
+    }
+
+    /** Explicit OP testing placement. Never overwrites existing blocks or entities. */
+    public static Optional<BlockPos> testPlace(ServerLevel level, BlockPos playerPos, Direction facing,
+                                               long seed, List<Identifier> ageSymbols) {
+        Direction horizontal = facing.getAxis().isHorizontal() ? facing : Direction.NORTH;
+        BlockPos center = playerPos.relative(horizontal, 13);
+        int rotation = switch (horizontal) {
+            case NORTH -> 2;
+            case EAST -> 3;
+            case WEST -> 1;
+            default -> 0;
+        };
+        Site site = new Site(center.getX() - FOOTPRINT / 2, center.getZ() - FOOTPRINT / 2, rotation);
+        int floorY = playerPos.getY() + 2;
+        for (int x = 0; x < FOOTPRINT; x++) for (int z = 0; z < FOOTPRINT; z++)
+            floorY = Math.max(floorY, level.getHeight(Heightmap.Types.WORLD_SURFACE,
+                    site.x() + x, site.z() + z) + 1);
+        if (floorY + 10 >= level.getMaxY() || floorY - playerPos.getY() > 20)
+            return Optional.empty();
+        BlockPos.MutableBlockPos cursor = new BlockPos.MutableBlockPos();
+        for (int x = 0; x < FOOTPRINT; x++) for (int z = 0; z < FOOTPRINT; z++)
+            for (int y = floorY; y <= floorY + 10; y++) {
+                BlockPos pos = cursor.set(site.x() + x, y, site.z() + z);
+                if (!level.getWorldBorder().isWithinBounds(pos) || !level.getBlockState(pos).isAir())
+                    return Optional.empty();
+            }
+        if (!level.getEntities(null, new AABB(site.x(), floorY, site.z(),
+                site.x() + FOOTPRINT, floorY + 11, site.z() + FOOTPRINT)).isEmpty())
+            return Optional.empty();
+        if (!build(level, site, floorY, null, seed, ageSymbols)) return Optional.empty();
+        return Optional.of(mapped(site, cursor, 4, floorY + 1, 2).immutable());
+    }
+
+    private static boolean build(WorldGenLevel level, Site site, int floorY, int[][] heights,
+                                 long seed, List<Identifier> ageSymbols) {
+        BlockPos.MutableBlockPos cursor = new BlockPos.MutableBlockPos();
+        var template = level.getLevel().getStructureTemplateManager().get(TEMPLATE).orElse(null);
+        if (template == null || template.getSize().getX() != FOOTPRINT
+                || template.getSize().getY() != FOOTPRINT || template.getSize().getZ() != FOOTPRINT)
+            return false;
+        for (int x = 0; x < FOOTPRINT; x++) for (int z = 0; z < FOOTPRINT; z++) {
+            for (int y = heights == null ? floorY : heights[x][z] - 1; y <= floorY; y++)
+                place(level, site, cursor, x, y, z, Blocks.COBBLESTONE.defaultBlockState());
+        }
+        Rotation rotation = switch (site.rotation()) {
+            case 1 -> Rotation.CLOCKWISE_90;
+            case 2 -> Rotation.CLOCKWISE_180;
+            case 3 -> Rotation.COUNTERCLOCKWISE_90;
+            default -> Rotation.NONE;
+        };
+        BlockPos origin = new BlockPos(site.x(), floorY, site.z());
+        var settings = new StructurePlaceSettings().setRotation(rotation)
+                .setRotationPivot(new BlockPos(5, 0, 5)).setIgnoreEntities(true);
+        long positionSalt = new ChunkPos(site.x() >> 4, site.z() >> 4).pack();
+        if (!template.placeInWorld(level, origin, origin, settings,
+                RandomSource.create(seed ^ positionSalt), 2)) return false;
+
+        BlockPos chestPos = mapped(site, cursor, 4, floorY + 1, 2).immutable();
+        level.setBlock(chestPos, Blocks.CHEST.defaultBlockState().setValue(ChestBlock.FACING,
+                Direction.from2DDataValue(site.rotation())), 2);
+        PortConfig.LibraryLootMode mode = PortConfig.LIBRARY_LOOT_MODE.get();
+        boolean ageOnly = mode == PortConfig.LibraryLootMode.AGE_ONLY;
+        List<Identifier> symbols = symbolsForLoot(ageSymbols, mode);
+        RandomSource random = RandomSource.create(seed ^ positionSalt ^ SALT);
+        if (level.getBlockEntity(chestPos) instanceof ChestBlockEntity chest) {
+            chest.getPersistentData().putBoolean(CHEST_MARKER, true);
+            chest.setChanged();
+            if (ageOnly) {
+                // Pages are frozen in the Age generator, then saved as real chest items.
+                boolean[] occupied = new boolean[chest.getContainerSize()];
+                for (int i = 0, count = symbols.isEmpty() ? 0 : 4 + random.nextInt(5); i < count; i++) {
+                    int slot;
+                    do slot = random.nextInt(occupied.length); while (occupied[slot]);
+                    occupied[slot] = true;
+                    chest.setItem(slot, page(symbols, random));
+                }
+            } else {
+                chest.setLootTable(CHEST_LOOT, seed ^ chestPos.asLong());
+            }
+        }
+        for (int[] standCoords : STANDS) {
+            BlockPos pos = mapped(site, cursor, standCoords[0], floorY + standCoords[1], standCoords[2]).immutable();
+            if (!level.getBlockState(pos).isAir()) continue;
+            level.setBlock(pos, Rivencraft.BOOK_STAND.get().defaultBlockState()
+                    .setValue(BookStandBlock.FACING, standFacing(site, standCoords[3]))
+                    .setValue(BookStandBlock.HAS_BOOK, true), 2);
+            if (level.getBlockEntity(pos) instanceof BookStandBlockEntity stand) {
+                stand.setBook(symbols.isEmpty() ? new ItemStack(Items.BOOK) : page(symbols, random));
+            }
+        }
+        return true;
+    }
+
+    static Direction standFacing(Site site, int clockwiseTurns) {
+        return Direction.from2DDataValue((site.rotation() + clockwiseTurns) & 3);
+    }
+
+    /** Correct older generated stands in place, retaining their block entities and pages. */
+    public static int repairStandFacings(ServerLevel level, LevelChunk chunk, long seed) {
+        Site site = site(seed, chunk.getPos());
+        if (site == null || libraryChest(chunk, seed).isEmpty()) return -1;
+        int changed = 0;
+        BlockPos.MutableBlockPos cursor = new BlockPos.MutableBlockPos();
+        int chestY = libraryChest(chunk, seed).orElseThrow().getY();
+        for (int[] standCoords : STANDS) {
+            BlockPos pos = mapped(site, cursor, standCoords[0], chestY, standCoords[2]);
+            BlockState state = level.getBlockState(pos);
+            if (!state.is(Rivencraft.BOOK_STAND.get())) continue;
+            Direction facing = standFacing(site, standCoords[3]);
+            if (state.getValue(BookStandBlock.FACING) != facing) {
+                level.setBlock(pos, state.setValue(BookStandBlock.FACING, facing), 3);
+                changed++;
+            }
+        }
+        return changed;
+    }
+
+    static List<Identifier> symbolsForLoot(List<Identifier> ageSymbols, PortConfig.LibraryLootMode mode) {
+        return mode == PortConfig.LibraryLootMode.AGE_ONLY
+                ? ageSymbols.stream().filter(id -> PortSymbolPages.find(id) != null).distinct().toList()
+                : PortSymbolPages.sealedCandidateIds();
+    }
+
+    private static ItemStack page(List<Identifier> symbols, RandomSource random) {
+        return PageItem.createSymbolPage(symbols.get(random.nextInt(symbols.size())));
+    }
+
+    private static BlockPos.MutableBlockPos mapped(Site site, BlockPos.MutableBlockPos cursor, int x, int y, int z) {
+        return switch (site.rotation()) {
+            case 1 -> cursor.set(site.x() + FOOTPRINT - 1 - z, y, site.z() + x);
+            case 2 -> cursor.set(site.x() + FOOTPRINT - 1 - x, y, site.z() + FOOTPRINT - 1 - z);
+            case 3 -> cursor.set(site.x() + z, y, site.z() + FOOTPRINT - 1 - x);
+            default -> cursor.set(site.x() + x, y, site.z() + z);
+        };
+    }
+
+    private static void place(WorldGenLevel level, Site site, BlockPos.MutableBlockPos cursor,
+                              int x, int y, int z, BlockState state) {
+        level.setBlock(mapped(site, cursor, x, y, z), state, 2);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortLibraryWriting.java

@@ -0,0 +1,26 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.serialization.Codec;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.world.level.saveddata.SavedData;
+import net.minecraft.world.level.saveddata.SavedDataType;
+
+/** Written pages for library Age-only loot, kept outside the legacy backend index codec. */
+final class PortLibraryWriting extends SavedData {
+    static final Codec<PortLibraryWriting> CODEC = Codec.unboundedMap(Identifier.CODEC, Identifier.CODEC.listOf())
+            .fieldOf("ages").codec().xmap(PortLibraryWriting::new, data -> Map.copyOf(data.pages));
+    static final SavedDataType<PortLibraryWriting> TYPE = new SavedDataType<>(
+            Identifier.fromNamespaceAndPath("rivencraft", "library_writing"), () -> new PortLibraryWriting(Map.of()), CODEC);
+    private final Map<Identifier, List<Identifier>> pages = new HashMap<>();
+    private PortLibraryWriting(Map<Identifier, List<Identifier>> pages) { pages.forEach((id, list) -> this.pages.put(id, List.copyOf(list))); }
+    static PortLibraryWriting get(MinecraftServer server) { return server.overworld().getDataStorage().computeIfAbsent(TYPE); }
+    List<Identifier> symbols(Identifier id) { return pages.getOrDefault(id, List.of()); }
+    void put(Identifier id, List<Identifier> symbols) {
+        if (symbols.isEmpty()) pages.remove(id); else pages.put(id, List.copyOf(symbols));
+        setDirty();
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortMeteorProvider.java

@@ -0,0 +1,133 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.WeakHashMap;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.particles.ParticleTypes;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.sounds.SoundSource;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.neoforged.bus.api.SubscribeEvent;
+import net.neoforged.fml.common.EventBusSubscriber;
+import net.neoforged.neoforge.event.level.LevelEvent;
+import net.neoforged.neoforge.event.server.ServerStoppingEvent;
+import net.neoforged.neoforge.event.tick.LevelTickEvent;
+
+/** The 1.21.1 meteor's short particle descent and bounded impact, without a new entity. */
+@EventBusSubscriber(modid = Rivencraft.MOD_ID)
+public final class PortMeteorProvider {
+    public static final Identifier METEORS = Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "meteors");
+    private static final int METEOR_FLIGHT_TICKS = 30;
+    private static final int MAX_ACTIVE_AGES = 16;
+    private static final Map<ServerLevel, Meteor> ACTIVE = new WeakHashMap<>();
+    private PortMeteorProvider() {}
+    public static void register() {
+        PortInstabilityRuntime.register(METEORS, false, (context, id, level) -> {
+            if (PortInstabilityRuntime.isAge(context.level())) scheduleMeteor(context, level, false);
+        });
+    }
+    static void tickPlanned(ServerLevel level, PortInstabilityData.Age age, long tick,
+                            List<PortInstabilityPlan.ProviderLevel> providers) {
+        var card = providers.stream().filter(provider -> provider.id().equals(METEORS)).findFirst();
+        if (card.isEmpty() || !PortInstabilityConfig.meteorEnabled()) return;
+        var chunks = PortHazardProviders.loadedChunksNearPlayers(level, PortInstabilityConfig.hazardsMaxChunks());
+        if (!chunks.isEmpty()) PortInstabilityRuntime.invoke(new PortInstabilityRuntime.Context(level, age, chunks,
+                tick, new PortInstabilityRuntime.Budget(1)), METEORS, card.get().level());
+    }
+    /** Skip the chance roll only; retain per-Age policy, loading, active-flight and cooldown checks. */
+    public static int pulseForTesting(ServerPlayer player) {
+        ServerLevel level = player.level();
+        if (!PortInstabilityRuntime.isAge(level)) return -1;
+        var age = PortInstabilityData.get(level.getServer()).age(level);
+        if (!PortInstabilityConfig.instabilityEnabled() || !PortInstabilityConfig.meteorEnabled()
+                || !age.enabled() || !PortInstabilityConfig.instabilityProviderEnabled(METEORS)) return 0;
+        var chunks = PortHazardProviders.loadedChunksNearPlayers(level, 16);
+        if (chunks.isEmpty()) return 0;
+        return scheduleMeteor(new PortInstabilityRuntime.Context(level, age, chunks,
+                level.getServer().getTickCount(), new PortInstabilityRuntime.Budget(1)), 1, true) ? 1 : 0;
+    }
+
+    private static boolean scheduleMeteor(PortInstabilityRuntime.Context context, int effectiveLevel, boolean force) {
+        if (!PortInstabilityConfig.meteorEnabled() || ACTIVE.containsKey(context.level())
+                || ACTIVE.size() >= MAX_ACTIVE_AGES) return false;
+        PortHazardSavedData data = PortHazardSavedData.get(context.level());
+        long gameTime = context.level().getGameTime();
+        if (!data.meteorReady(gameTime, 200)) return false;
+        Random random = new Random(context.age().seed() ^ data.nextAttempt() * 0xD1B54A32D192ED03L
+                ^ METEORS.hashCode());
+        if (!force && random.nextDouble() >= PortHazardProviders.legacyChance(context.loadedChunks().size(),
+                PortInstabilityConfig.instabilityCooldown(), effectiveLevel, 50000)) return false;
+        int start = random.nextInt(context.loadedChunks().size());
+        for (int offset = 0; offset < Math.min(16, context.loadedChunks().size()); offset++) {
+            ChunkPos chunk = context.loadedChunks().get((start + offset) % context.loadedChunks().size());
+            int x = chunk.getMinBlockX() + 6 + random.nextInt(4);
+            int z = chunk.getMinBlockZ() + 6 + random.nextInt(4);
+            int surfaceY = context.level().getHeight(Heightmap.Types.MOTION_BLOCKING_NO_LEAVES, x, z);
+            BlockPos impact = new BlockPos(x, surfaceY, z);
+            if (surfaceY >= context.level().getMaxY() - 8
+                    || !PortHazardProviders.safeTarget(context, impact, 8)) continue;
+            if (!context.budget().claim()) return false;
+            int startY = Math.min(context.level().getMaxY() - 2, surfaceY + 48);
+            data.recordMeteor(gameTime);
+            ACTIVE.put(context.level(), new Meteor(chunk, impact, startY, METEOR_FLIGHT_TICKS));
+            context.level().playSound(null, impact, Rivencraft.METEOR_ROAR.get(), SoundSource.WEATHER, 2.0F, 1.0F);
+            context.budget().recordApplied();
+            return true;
+        }
+        return false;
+    }
+
+    @SubscribeEvent
+    public static void onLevelTickPost(LevelTickEvent.Post event) {
+        if (!(event.getLevel() instanceof ServerLevel level)) return;
+        Meteor meteor = ACTIVE.get(level);
+        if (meteor == null) return;
+        if (!PortInstabilityConfig.instabilityEnabled() || !PortInstabilityConfig.meteorEnabled()
+                || !PortInstabilityRuntime.isAge(level)
+                || level.players().isEmpty()
+                || level.getChunkSource().getChunkNow(meteor.chunk().x(), meteor.chunk().z()) == null) {
+            ACTIVE.remove(level);
+            return;
+        }
+        var age = PortInstabilityData.get(level.getServer()).age(level);
+        if (!age.enabled()
+                || !PortInstabilityConfig.instabilityProviderEnabled(METEORS)) {
+            ACTIVE.remove(level);
+            return;
+        }
+        int remaining = meteor.remaining() - 1;
+        if (remaining <= 0) {
+            ACTIVE.remove(level); // clear before impact so an exception cannot replay it
+            PortHazardProviders.explodeBounded(level, age, meteor.chunk(), meteor.impact(),
+                    PortInstabilityConfig.meteorBlockDamage(), PortInstabilityConfig.meteorPlayerDamage(),
+                    PortInstabilityConfig.meteorFire(), PortInstabilityConfig.meteorMaxBlocks(),
+                    PortInstabilityConfig.meteorMaxEntities(), PortInstabilityConfig.meteorMaxDamage(), 3);
+            return;
+        }
+        double progress = 1.0 - remaining / (double) METEOR_FLIGHT_TICKS;
+        double y = meteor.startY() + (meteor.impact().getY() - meteor.startY()) * progress;
+        double x = meteor.impact().getX() + 0.5 + (1.0 - progress) * 2.0;
+        double z = meteor.impact().getZ() + 0.5 + (1.0 - progress) * 2.0;
+        level.sendParticles(ParticleTypes.FLAME, x, y, z, 5, 0.25, 0.25, 0.25, 0.01);
+        level.sendParticles(ParticleTypes.LARGE_SMOKE, x, y, z, 2, 0.3, 0.3, 0.3, 0.02);
+        ACTIVE.put(level, new Meteor(meteor.chunk(), meteor.impact(), meteor.startY(), remaining));
+    }
+
+    @SubscribeEvent
+    public static void onServerStopping(ServerStoppingEvent event) {
+        ACTIVE.clear(); // an interrupted descent is cancelled, never replayed after restart
+    }
+
+    @SubscribeEvent
+    public static void onLevelUnload(LevelEvent.Unload event) {
+        if (event.getLevel() instanceof ServerLevel level) ACTIVE.remove(level);
+    }
+
+    private record Meteor(ChunkPos chunk, BlockPos impact, int startY, int remaining) {}
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortProgressionPlayer.java

@@ -0,0 +1,25 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.authlib.GameProfile;
+import net.minecraft.server.PlayerAdvancements;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.util.datafix.DataFixers;
+import net.minecraft.world.level.storage.LevelResource;
+import net.neoforged.neoforge.common.util.FakePlayer;
+
+/** FakePlayer normally discards all advancement progress; fixtures need vanilla tracking. */
+final class PortProgressionPlayer extends FakePlayer {
+    private PlayerAdvancements progress;
+
+    PortProgressionPlayer(ServerLevel level, GameProfile profile) { super(level, profile); }
+
+    @Override public PlayerAdvancements getAdvancements() {
+        if (progress == null) {
+            var server = level().getServer();
+            progress = new PlayerAdvancements(DataFixers.getDataFixer(), server.getPlayerList(),
+                    server.getAdvancements(), server.getWorldPath(LevelResource.PLAYER_ADVANCEMENTS_DIR)
+                            .resolve(getUUID() + ".json"), this);
+        }
+        return progress;
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortProgressionProbe.java

@@ -0,0 +1,101 @@
+package net.dnorberg.rivencraft.age;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.advancement.ProgressionAdvancements;
+import net.dnorberg.rivencraft.block.entity.InkMixerBlockEntity;
+import net.dnorberg.rivencraft.menu.InkMixerMenu;
+import net.minecraft.core.BlockPos;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.inventory.ContainerInput;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+
+/** Disposable operator fixture for loaded advancement data and committed action awards. */
+final class PortProgressionProbe {
+    /** Operator-fixture assertion; deliberately requires the real loaded advancement. */
+    static boolean isComplete(net.minecraft.server.level.ServerPlayer player, String path) {
+        var advancement = player.level().getServer().getAdvancements().get(
+                net.minecraft.resources.Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "progression/" + path));
+        if (advancement == null) throw new IllegalStateException("Missing progression advancement: " + path);
+        return player.getAdvancements().getOrStartProgress(advancement).isDone();
+    }
+
+
+    static void recipeDiscovery(ServerLevel level) {
+        var materials = java.util.Map.of(
+                "ink_vial", Items.DYE.black(),
+                "ink_mixer", Items.GLASS_BOTTLE,
+                "book_binder", Items.IRON_INGOT,
+                "crystal_block", Rivencraft.CRYSTAL_SHARD.get(),
+                "notebook", Items.LEATHER,
+                "writing_desk", Items.FEATHER);
+        for (var entry : materials.entrySet()) {
+            var id = net.minecraft.resources.Identifier.fromNamespaceAndPath("rivencraft", entry.getKey());
+            var key = net.minecraft.resources.ResourceKey.create(net.minecraft.core.registries.Registries.RECIPE, id);
+            var player = new PortProgressionPlayer(level, new com.mojang.authlib.GameProfile(
+                    java.util.UUID.nameUUIDFromBytes(id.toString().getBytes(java.nio.charset.StandardCharsets.UTF_8)),
+                    "RivenRecipe"));
+            var advancement = level.getServer().getAdvancements().get(
+                    net.minecraft.resources.Identifier.fromNamespaceAndPath("rivencraft", "recipes/misc/" + entry.getKey()));
+            if (advancement == null || level.getServer().getRecipeManager().byKey(key).isEmpty())
+                throw new IllegalStateException("Missing recipe/discovery data: " + id);
+            var progress = player.getAdvancements();
+            net.minecraft.advancements.triggers.CriteriaTriggers.INVENTORY_CHANGED.trigger(player,
+                    player.getInventory(), new ItemStack(Items.COBBLESTONE));
+            if (player.getRecipeBook().contains(key))
+                throw new IllegalStateException("Wrong material unlocked " + id);
+            var material = new ItemStack(entry.getValue());
+            player.getInventory().setItem(0, material);
+            net.minecraft.advancements.triggers.CriteriaTriggers.INVENTORY_CHANGED.trigger(player, player.getInventory(), material);
+            if (!player.getRecipeBook().contains(key) || !progress.getOrStartProgress(advancement).isDone())
+                throw new IllegalStateException("Material did not unlock " + id);
+            // The second criterion supports /recipe give without first obtaining its material.
+            var other = new PortProgressionPlayer(level, new com.mojang.authlib.GameProfile(
+                    java.util.UUID.randomUUID(), "RivenRecipeGive"));
+            if (other.getRecipeBook().contains(key)) throw new IllegalStateException("Recipe leaked between players");
+            other.awardRecipes(java.util.List.of(level.getServer().getRecipeManager().byKey(key).orElseThrow()));
+            if (!other.getAdvancements().getOrStartProgress(advancement).isDone())
+                throw new IllegalStateException("Recipe unlock criterion did not complete " + id);
+        }
+    }
+
+    static void run(ServerLevel level) {
+        var player = new PortProgressionPlayer(level,
+                new com.mojang.authlib.GameProfile(java.util.UUID.fromString("b428c3ef-57a6-43dc-95e8-441b6a171107"), "RivenProgression"));
+        var pos = new BlockPos(4, 64, 0);
+        player.setPos(4.5, 64, 2.5);
+        level.setBlock(pos, Rivencraft.INK_MIXER.get().defaultBlockState(), 3);
+        var mixer = (InkMixerBlockEntity) level.getBlockEntity(pos);
+        try {
+            // Every tree node must decode; portal advancement waits for its missing item/feature port.
+            for (String path : new String[]{"root", "page", "linking_book", "link_panel", "copy_page", "bind_age", "enter_age"})
+                if (isComplete(player, path))
+                    throw new IllegalStateException("Fixture requires fresh player advancement data");
+            var menu = new InkMixerMenu(1, player.getInventory(), mixer);
+            menu.clicked(InkMixerMenu.RESULT, 0, ContainerInput.PICKUP, player);
+            if (isComplete(player, "link_panel"))
+                throw new IllegalStateException("Empty Mixer awarded progression");
+            mixer.setItem(InkMixerBlockEntity.PAPER, new ItemStack(Items.PAPER, 2));
+            mixer.setItem(InkMixerBlockEntity.INK, new ItemStack(Rivencraft.INK_VIAL.get()));
+            menu.broadcastChanges();
+            if (isComplete(player, "link_panel"))
+                throw new IllegalStateException("Mixer preview awarded progression");
+            menu.clicked(InkMixerMenu.RESULT, 0, ContainerInput.PICKUP, player);
+            if (!isComplete(player, "link_panel"))
+                throw new IllegalStateException("Mixer pickup did not award progression");
+            menu.setCarried(ItemStack.EMPTY);
+            var advancement = level.getServer().getAdvancements().get(
+                    net.minecraft.resources.Identifier.fromNamespaceAndPath("rivencraft", "progression/link_panel"));
+            player.getAdvancements().revoke(advancement, "completed");
+            menu.quickMoveStack(player, InkMixerMenu.RESULT);
+            if (!isComplete(player, "link_panel"))
+                throw new IllegalStateException("Mixer shift pickup did not award progression");
+            ProgressionAdvancements.awardAgeTravel(player);
+            if (!isComplete(player, "enter_age"))
+                throw new IllegalStateException("Registered Age did not award entry");
+        } finally {
+            player.getInventory().clearContent();
+            level.removeBlock(pos, false);
+        }
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortReturnLinks.java

@@ -21,6 +21,10 @@ public final class PortReturnLinks {
         boolean issue = shouldIssue(mode, storage.computeIfAbsent(PortAgeVisits.TYPE), age);
         if (!issue) return;
         ItemStack book = createBook(departure);
+        var source = player.level().getServer().getLevel(net.minecraft.resources.ResourceKey.create(
+                net.minecraft.core.registries.Registries.DIMENSION, departure.dimension()));
+        if (source != null) book.set(Rivencraft.LINK_DESTINATION_NAME.get(),
+                net.dnorberg.rivencraft.item.LinkingBookItem.destinationName(source));
         if (!player.getInventory().add(book)) player.drop(book, false, Prediction.SERVER_ONLY);
         // Persist the once-per-Age marker before the next arrival can issue another.
         if (mode == PortConfig.ReturnLinkMode.ON_CREATION)

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortStatusEffectProviders.java

@@ -0,0 +1,233 @@
+package net.dnorberg.rivencraft.age;
+
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.WeakHashMap;
+import net.dnorberg.rivencraft.Rivencraft;
+
+import net.minecraft.core.Holder;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.effect.MobEffect;
+import net.minecraft.world.effect.MobEffectInstance;
+import net.minecraft.world.effect.MobEffects;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.entity.monster.Monster;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.entity.EntityTypeTest;
+import net.minecraft.world.phys.AABB;
+import net.neoforged.neoforge.event.entity.EntityTravelToDimensionEvent;
+import net.neoforged.neoforge.event.entity.player.PlayerEvent;
+import net.neoforged.neoforge.event.server.ServerStoppingEvent;
+import net.neoforged.neoforge.event.tick.ServerTickEvent;
+
+/** Legacy potion cards adapted to bounded, Age-local server effects. */
+@net.neoforged.fml.common.EventBusSubscriber(modid = Rivencraft.MOD_ID)
+public final class PortStatusEffectProviders {
+    private static final int MAX_TRACKED_AGES = 64;
+    private static final Map<Identifier, Spec> SPECS = createSpecs();
+    private static final Map<ServerLevel, List<Lease>> LEASES = new WeakHashMap<>();
+
+    private PortStatusEffectProviders() {}
+
+    public static void register() {
+        SPECS.keySet().forEach(id -> PortInstabilityRuntime.register(id, PortStatusEffectProviders::apply));
+    }
+
+    static void apply(PortInstabilityRuntime.Context context, Identifier id, int level) {
+        if (!PortInstabilityConfig.statusEffectsEnabled()
+                || !PortInstabilityRuntime.isAge(context.level())) return;
+        Spec spec = SPECS.get(id);
+        if (spec == null || spec.target() == Target.HOSTILE && !PortInstabilityConfig.statusEffectsHostiles()
+                || spec.target() == Target.GENERAL && !PortInstabilityConfig.statusEffectsPlayers()
+                && !PortInstabilityConfig.statusEffectsNonplayers()) return;
+        List<Lease> leases = LEASES.get(context.level());
+        if (leases == null) {
+            if (LEASES.size() >= MAX_TRACKED_AGES) return;
+            leases = new ArrayList<>();
+            LEASES.put(context.level(), leases);
+        }
+        prune(context.level(), leases, context.serverTick(), false);
+        if (leases.size() >= PortInstabilityConfig.statusEffectsMaxActive()) return;
+
+        Random random = new Random(context.age().seed() ^ (context.serverTick() * 0x9E3779B97F4A7C15L)
+                ^ id.hashCode());
+        ChunkPos chunk = context.loadedChunks().get(random.nextInt(context.loadedChunks().size()));
+        AABB bounds = new AABB(chunk.getMinBlockX(), context.level().getMinY(), chunk.getMinBlockZ(),
+                chunk.getMaxBlockX() + 1, context.level().getMaxY(), chunk.getMaxBlockZ() + 1);
+        int duration = Math.min(spec.legacyDuration(), PortInstabilityConfig.statusEffectsMaxDuration());
+        int amplifier = Math.max(0, level - 1);
+        MobEffectInstance instance = new MobEffectInstance(spec.effect(), duration, amplifier);
+        List<LivingEntity> candidates = new ArrayList<>();
+        context.level().getEntities(EntityTypeTest.forClass(LivingEntity.class), bounds,
+                entity -> eligible(context.level(), entity, spec, instance), candidates,
+                PortInstabilityConfig.statusEffectsMaxCandidates());
+        if (candidates.isEmpty()) return;
+        candidates.sort(Comparator.comparing(Entity::getUUID));
+        LivingEntity target = candidates.get(random.nextInt(candidates.size()));
+        if (!context.budget().claim() || !target.addEffect(instance)) return;
+        context.budget().recordApplied();
+        leases.add(new Lease(id, new WeakReference<>(target), instance,
+                context.serverTick() + duration, spec.target()));
+    }
+
+    private static boolean eligible(ServerLevel level, LivingEntity entity, Spec spec,
+                                    MobEffectInstance instance) {
+        if (!entity.isAlive() || entity.isRemoved() || entity.level() != level
+                || entity.getEffect(spec.effect()) != null || !entity.canBeAffected(instance)
+                || !spec.global() && !level.canSeeSky(entity.blockPosition())) return false;
+        return allowedByPolicy(spec.target(), entity);
+    }
+
+    private static boolean allowedByPolicy(Target target, LivingEntity entity) {
+        if (entity instanceof Player player) {
+            return target == Target.GENERAL && PortInstabilityConfig.statusEffectsPlayers()
+                    && !player.isCreative() && !player.isSpectator();
+        }
+        return target == Target.GENERAL ? PortInstabilityConfig.statusEffectsNonplayers()
+                : entity instanceof Monster && PortInstabilityConfig.statusEffectsHostiles();
+    }
+
+    @net.neoforged.bus.api.SubscribeEvent
+    public static void onServerTickPost(ServerTickEvent.Post event) {
+        if (event.getServer().getTickCount() % 20 != 0) return;
+        boolean disabled = !PortInstabilityConfig.instabilityEnabled() || !PortInstabilityConfig.statusEffectsEnabled();
+        long tick = event.getServer().getTickCount();
+        for (var entry : LEASES.entrySet()) {
+            prune(entry.getKey(), entry.getValue(), tick, disabled
+                    || !PortInstabilityData.get(entry.getKey().getServer()).age(entry.getKey()).enabled());
+        }
+        LEASES.values().removeIf(List::isEmpty);
+    }
+
+    @net.neoforged.bus.api.SubscribeEvent
+    public static void onEntityTravel(EntityTravelToDimensionEvent event) {
+        Entity entity = event.getEntity();
+        if (entity instanceof LivingEntity living && !entity.level().dimension().equals(event.getDimension())) {
+            clearEntity(living);
+        }
+    }
+
+    @net.neoforged.bus.api.SubscribeEvent
+    public static void onPlayerChangedDimension(PlayerEvent.PlayerChangedDimensionEvent event) {
+        if (event.getEntity() instanceof ServerPlayer player) clearEntity(player);
+    }
+
+    @net.neoforged.bus.api.SubscribeEvent
+    public static void onPlayerLoggedOut(PlayerEvent.PlayerLoggedOutEvent event) {
+        if (event.getEntity() instanceof ServerPlayer player) clearEntity(player);
+    }
+
+    @net.neoforged.bus.api.SubscribeEvent
+    public static void onServerStopping(ServerStoppingEvent event) {
+        long tick = event.getServer().getTickCount();
+        for (var entry : LEASES.entrySet()) prune(entry.getKey(), entry.getValue(), tick, true);
+        LEASES.clear();
+    }
+
+    public static void clearAge(ServerLevel level) {
+        var leases = LEASES.remove(level);
+        if (leases != null) prune(level, leases, level.getServer().getTickCount(), true);
+    }
+
+    private static void clearEntity(LivingEntity entity) {
+        for (List<Lease> leases : LEASES.values()) {
+            Iterator<Lease> iterator = leases.iterator();
+            while (iterator.hasNext()) {
+                Lease lease = iterator.next();
+                if (lease.entity().get() != entity) continue;
+                removeOwnedEffect(entity, lease);
+                iterator.remove();
+            }
+        }
+    }
+
+    private static void prune(ServerLevel level, List<Lease> leases, long tick, boolean removeAll) {
+        Iterator<Lease> iterator = leases.iterator();
+        while (iterator.hasNext()) {
+            Lease lease = iterator.next();
+            LivingEntity entity = lease.entity().get();
+            if (entity == null || entity.isRemoved() || entity.getEffect(lease.instance().getEffect()) == null) {
+                iterator.remove();
+                continue;
+            }
+            boolean revoke = removeAll || !PortInstabilityConfig.instabilityProviderEnabled(lease.provider())
+                    || entity.level() != level
+                    || !allowedByPolicy(lease.target(), entity);
+            if (revoke || tick >= lease.expiresAt()) {
+                removeOwnedEffect(entity, lease);
+                iterator.remove();
+            }
+        }
+    }
+
+    private static void removeOwnedEffect(LivingEntity entity, Lease lease) {
+        // addEffect stores the supplied instance when no effect exists. Do not remove
+        // a replacement from another mod (or a stronger/extended effect).
+        if (entity.getEffect(lease.instance().getEffect()) == lease.instance()
+                && lease.instance().getAmplifier() == lease.amplifier()
+                && lease.instance().getDuration() <= lease.originalDuration()) {
+            entity.removeEffect(lease.instance().getEffect());
+        }
+    }
+
+    static int legacyDuration(Identifier id) {
+        Spec spec = SPECS.get(id);
+        return spec == null ? -1 : spec.legacyDuration();
+    }
+
+    static boolean localRequiresSky(Identifier id) {
+        Spec spec = SPECS.get(id);
+        return spec != null && !spec.global();
+    }
+
+    static boolean eligibleTarget(ServerLevel level, LivingEntity entity, Identifier id) {
+        Spec spec = SPECS.get(id);
+        return spec != null && eligible(level, entity, spec,
+                new MobEffectInstance(spec.effect(), spec.legacyDuration(), 0));
+    }
+
+    private static Map<Identifier, Spec> createSpecs() {
+        Map<Identifier, Spec> specs = new HashMap<>();
+        addPair(specs, "blindness", MobEffects.BLINDNESS, 60);
+        addPair(specs, "fatigue", MobEffects.MINING_FATIGUE, 80);
+        addPair(specs, "hunger", MobEffects.HUNGER, 80);
+        addPair(specs, "nausea", MobEffects.NAUSEA, 60);
+        addPair(specs, "poison", MobEffects.POISON, 80);
+        addPair(specs, "slow", MobEffects.SLOWNESS, 80);
+        addPair(specs, "weakness", MobEffects.WEAKNESS, 80);
+        addPair(specs, "wither", MobEffects.WITHER, 30);
+        specs.put(id("enemyregen_global"), new Spec(MobEffects.REGENERATION, 200, true, Target.HOSTILE));
+        specs.put(id("enemyresist_global"), new Spec(MobEffects.RESISTANCE, 200, true, Target.HOSTILE));
+        return Map.copyOf(specs);
+    }
+
+    private static void addPair(Map<Identifier, Spec> specs, String name,
+                                Holder<MobEffect> effect, int duration) {
+        specs.put(id(name), new Spec(effect, duration, false, Target.GENERAL));
+        specs.put(id(name + "_global"), new Spec(effect, duration, true, Target.GENERAL));
+    }
+
+    private static Identifier id(String path) {
+        return Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, path);
+    }
+
+    private enum Target { GENERAL, HOSTILE }
+    private record Spec(Holder<MobEffect> effect, int legacyDuration, boolean global, Target target) {}
+    private record Lease(Identifier provider, WeakReference<LivingEntity> entity, MobEffectInstance instance, long expiresAt,
+                         Target target, int amplifier, int originalDuration) {
+        private Lease(Identifier provider, WeakReference<LivingEntity> entity, MobEffectInstance instance, long expiresAt,
+                      Target target) {
+            this(provider, entity, instance, expiresAt, target, instance.getAmplifier(), instance.getDuration());
+        }
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/PortWritingDeskProbe.java

@@ -23,7 +23,7 @@ final class PortWritingDeskProbe {
 
     static void create(ServerLevel level) {
         PortAgeTravel.findLanding(level);
-        var player = net.neoforged.neoforge.common.util.FakePlayerFactory.get(level,
+        var player = new PortProgressionPlayer(level,
                 new com.mojang.authlib.GameProfile(java.util.UUID.fromString("f92ad9ee-1ff0-4fe2-bcd3-994d4c035933"), "RivenDeskProbe"));
         player.setPos(0.5, 64, 2.5);
         // New Minecraft drops Container block-entity contents during removal.
@@ -69,6 +69,8 @@ final class PortWritingDeskProbe {
             if (menu.getCarried().isEmpty() || desk.inkRemaining() != 15
                     || desk.getItem(WritingDeskBlockEntity.PAPER).getCount() != 1 || desk.getItem(0).isEmpty())
                 throw new IllegalStateException("Desk copy did not consume exactly one paper/ink");
+            if (!PortProgressionProbe.isComplete(player, "copy_page"))
+                throw new IllegalStateException("Missing copy_page award");
             menu.setCarried(ItemStack.EMPTY);
             for (int slot = 0; slot < player.getInventory().getContainerSize(); slot++)
                 player.getInventory().setItem(slot, new ItemStack(Items.COBBLESTONE, 64));

ports/mc263/src/main/java/net/dnorberg/rivencraft/age/RuntimeAgeBackend.java

@@ -149,14 +149,26 @@ public final class RuntimeAgeBackend {
                                      PortVegetationPlan vegetation, int dungeons, PortLakePlan lakes,
                                      PortTerrainFeaturePlan terrainFeatures, PortWeatherMode weather,
                                      PortLighting lighting, PortSkyStyle sky, PortAgeColors colors, PortDayCycle dayCycle) {
+        return create(server, id, seed, biomePlan, terrain, rocks, vegetation, dungeons, lakes,
+                terrainFeatures, weather, lighting, sky, colors, dayCycle, List.of());
+    }
+
+    public static ServerLevel create(MinecraftServer server, Identifier id, long seed,
+                                     PortBiomePlan biomePlan, PortAgeTerrain terrain, PortRockPlan rocks,
+                                     PortVegetationPlan vegetation, int dungeons, PortLakePlan lakes,
+                                     PortTerrainFeaturePlan terrainFeatures, PortWeatherMode weather,
+                                     PortLighting lighting, PortSkyStyle sky, PortAgeColors colors, PortDayCycle dayCycle,
+                                     List<Identifier> librarySymbols) {
         checkServerThread(server);
         ageName(id);
         AgeLevelIndex index = index(server);
         if (index.contains(id)) throw new IllegalArgumentException("Age already exists: " + id);
+        PortLibraryWriting.get(server).put(id, librarySymbols);
         ServerLevel level = load(server, id, seed, biomePlan, terrain, rocks, vegetation, dungeons, lakes,
                 terrainFeatures, lighting, sky, colors, dayCycle);
         ((PortAgeLevel) level).configureWeather(weather);
         index.add(id, seed, biomePlan, terrain, rocks, vegetation, dungeons, lakes, terrainFeatures, lighting, sky, colors, dayCycle);
+        PortInstabilityData.get(server).create(level, librarySymbols, terrain, lighting, dayCycle);
         // A newly bound book may be used immediately. Persist its Age identity
         // before publishing the catalog so a later crash cannot leave that
         // book pointing at a world omitted from the on-disk index.
@@ -270,6 +282,18 @@ public final class RuntimeAgeBackend {
         Rivencraft.LOGGER.info("Retired 26.3 prototype Age {} (archived at {})", id, paths.archive());
     }
 
+    /** Display metadata never changes the dimension identity, seed or filesystem path. */
+    public static java.util.Optional<String> savedAgeName(MinecraftServer server, Identifier id) {
+        checkServerThread(server);
+        return java.util.Optional.ofNullable(index(server).displayName(id));
+    }
+
+    public static void setAgeDisplayName(MinecraftServer server, Identifier id, String name) {
+        checkServerThread(server);
+        index(server).setDisplayName(id, name);
+        server.overworld().getDataStorage().saveAndJoin();
+    }
+
     public static Map<Identifier, Long> savedAges(MinecraftServer server) {
         checkServerThread(server);
         return index(server).entries();
@@ -470,8 +494,8 @@ public final class RuntimeAgeBackend {
             };
             generator = new NoiseBasedChunkGenerator(source, PortBiomeMaterialRules.apply(server.registryAccess(), settings.value()));
         }
-        if (rocks != null || vegetation != null || dungeons > 0 || lakes != null || terrainFeatures != null)
-            generator = new PortFeatureChunkGenerator(generator, rocks, vegetation, dungeons, lakes, terrainFeatures, seed);
+        generator = new PortFeatureChunkGenerator(generator, rocks, vegetation, dungeons, lakes, terrainFeatures, seed,
+                terrain != PortAgeTerrain.CAVE, PortLibraryWriting.get(server).symbols(id));
         LevelStem stem = new LevelStem(lighting.dimensionType(server, terrain, overworldStem.type(), sky),
                 generator, OptionalLong.of(seed));
         long biomeZoomSeed = BiomeManager.obfuscateSeed(server.getWorldGenSettings().options().seed());

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/BookReceptacleBlock.java

@@ -0,0 +1,136 @@
+package net.dnorberg.rivencraft.block;
+
+import net.dnorberg.rivencraft.advancement.ProgressionAdvancements;
+import net.dnorberg.rivencraft.block.entity.BookReceptacleBlockEntity;
+import net.dnorberg.rivencraft.portal.CrystalPortalNetwork;
+import net.dnorberg.rivencraft.portal.PortalBookTravel;
+
+
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.sounds.SoundEvents;
+import net.minecraft.sounds.SoundSource;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.InteractionResult;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.context.BlockPlaceContext;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.BlockGetter;
+import net.minecraft.world.level.block.BaseEntityBlock;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.RenderShape;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.entity.BlockEntityTicker;
+import net.minecraft.world.level.block.entity.BlockEntityType;
+
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.block.state.StateDefinition;
+import net.minecraft.world.level.block.state.properties.BlockStateProperties;
+import net.minecraft.world.level.block.state.properties.EnumProperty;
+import net.minecraft.world.level.block.state.properties.BooleanProperty;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.shapes.CollisionContext;
+import net.minecraft.world.phys.shapes.VoxelShape;
+
+/** A book-holding crystal attachment, with server-authoritative frame activation. */
+public final class BookReceptacleBlock extends BaseEntityBlock {
+    public static final EnumProperty<Direction> FACING = BlockStateProperties.FACING;
+    public static final BooleanProperty HAS_BOOK = BlockStateProperties.HAS_BOOK;
+
+    public BookReceptacleBlock(Properties properties) {
+        super(properties);
+        registerDefaultState(stateDefinition.any().setValue(FACING, Direction.NORTH).setValue(HAS_BOOK, false));
+    }
+
+    @Override protected RenderShape getRenderShape(BlockState state) { return RenderShape.MODEL; }
+    @Override protected VoxelShape getShape(BlockState state, BlockGetter level, BlockPos pos,
+                                             CollisionContext context) {
+        return switch (state.getValue(FACING)) {
+            case NORTH -> Block.box(0, 0, 10, 16, 16, 16);
+            case SOUTH -> Block.box(0, 0, 0, 16, 16, 6);
+            case EAST -> Block.box(0, 0, 0, 6, 16, 16);
+            case WEST -> Block.box(10, 0, 0, 16, 16, 16);
+            case UP -> Block.box(0, 0, 0, 16, 6, 16);
+            case DOWN -> Block.box(0, 10, 0, 16, 16, 16);
+        };
+    }
+    @Override protected void createBlockStateDefinition(StateDefinition.Builder<Block, BlockState> builder) {
+        builder.add(FACING, HAS_BOOK);
+    }
+    @Override public BlockEntity newBlockEntity(BlockPos pos, BlockState state) {
+        return new BookReceptacleBlockEntity(pos, state);
+    }
+    @Override public <T extends BlockEntity> BlockEntityTicker<T> getTicker(Level level, BlockState state,
+            BlockEntityType<T> type) {
+        return level instanceof ServerLevel
+                ? createTickerHelper(type, Rivencraft.BOOK_RECEPTACLE_BLOCK_ENTITY.get(), (world, pos, current, holder) -> BookReceptacleBlockEntity.serverTick((ServerLevel) world, pos, holder))
+                : null;
+    }
+    @Override public BlockState getStateForPlacement(BlockPlaceContext context) {
+        Direction face = context.getClickedFace();
+        if (!context.getLevel().getBlockState(
+                context.getClickedPos().relative(face.getOpposite())).is(Rivencraft.CRYSTAL_BLOCK.get())) return null;
+        return defaultBlockState().setValue(FACING, face);
+    }
+
+    @Override protected InteractionResult useItemOn(ItemStack stack, BlockState state, Level level, BlockPos pos,
+            Player player, InteractionHand hand, BlockHitResult hit) {
+        if (!isBoundBook(stack)) return InteractionResult.TRY_WITH_EMPTY_HAND;
+        if (level.isClientSide()) return InteractionResult.SUCCESS;
+        if (!(level instanceof ServerLevel server) ||
+                !(level.getBlockEntity(pos) instanceof BookReceptacleBlockEntity holder)) return InteractionResult.FAIL;
+        if (!holder.getBook().isEmpty()) return InteractionResult.FAIL;
+        CrystalPortalNetwork.Plan plan = CrystalPortalNetwork.plan(server, pos);
+        if (!plan.valid()) {
+            if (player instanceof ServerPlayer serverPlayer) serverPlayer.sendOverlayMessage(Component.translatable("message.rivencraft.portal.invalid_frame"));
+            return InteractionResult.FAIL;
+        }
+        if (!PortalBookTravel.available(server, stack)) {
+            if (player instanceof ServerPlayer serverPlayer) serverPlayer.sendOverlayMessage(Component.translatable("message.rivencraft.descriptive_book.unavailable"));
+            return InteractionResult.FAIL;
+        }
+        holder.setBook(stack.copyWithCount(1));
+        if (!CrystalPortalNetwork.activate(server, pos, plan, player)) {
+            holder.takeBook();
+            return InteractionResult.FAIL;
+        }
+        if (!player.getAbilities().instabuild) stack.shrink(1);
+        level.playSound(null, pos, SoundEvents.ENCHANTMENT_TABLE_USE, SoundSource.BLOCKS, 1, 1);
+        if (player instanceof ServerPlayer serverPlayer)
+            ProgressionAdvancements.award(serverPlayer, ProgressionAdvancements.OPEN_PORTAL);
+        return InteractionResult.SUCCESS;
+    }
+
+    @Override protected InteractionResult useWithoutItem(BlockState state, Level level, BlockPos pos,
+            Player player, BlockHitResult hit) {
+        if (level.isClientSide()) return InteractionResult.SUCCESS;
+        if (level instanceof ServerLevel server && level.getBlockEntity(pos) instanceof BookReceptacleBlockEntity holder
+                && !holder.getBook().isEmpty()) {
+            CrystalPortalNetwork.shutdown(server, pos);
+            ItemStack book = holder.takeBook();
+            if (!player.getInventory().add(book)) player.drop(book, false, net.minecraft.util.Prediction.SERVER_ONLY);
+            level.playSound(null, pos, SoundEvents.BOOK_PAGE_TURN, SoundSource.BLOCKS, 1, 1);
+            return InteractionResult.SUCCESS;
+        }
+        return InteractionResult.PASS;
+    }
+
+    @Override protected void neighborChanged(BlockState state, Level level, BlockPos pos, Block neighbor,
+            net.minecraft.world.level.redstone.Orientation orientation, boolean moved) {
+        super.neighborChanged(state, level, pos, neighbor, orientation, moved);
+        BlockPos support = pos.relative(state.getValue(FACING).getOpposite());
+        if (!level.isClientSide() && level.hasChunkAt(support) && !level.getBlockState(support)
+                .is(Rivencraft.CRYSTAL_BLOCK.get())) level.destroyBlock(pos, true);
+    }
+
+    private static boolean isBoundBook(ItemStack stack) {
+        return stack.is(Rivencraft.LINKING_BOOK.get()) && stack.has(Rivencraft.LINK_BOOK_TARGET.get())
+                || stack.is(Rivencraft.DESCRIPTIVE_BOOK.get()) && stack.has(Rivencraft.AGE_BOOK_ID.get());
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/BookStandBlock.java

@@ -0,0 +1,33 @@
+package net.dnorberg.rivencraft.block;
+
+import net.dnorberg.rivencraft.block.entity.BookStandBlockEntity;
+import net.minecraft.core.BlockPos;
+import net.minecraft.sounds.SoundEvents;
+import net.minecraft.sounds.SoundSource;
+import net.minecraft.util.Prediction;
+import net.minecraft.world.InteractionResult;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.LecternBlock;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.phys.BlockHitResult;
+
+/** Vanilla lectern geometry with Rivencraft storage instead of a vanilla book menu. */
+public final class BookStandBlock extends LecternBlock {
+    public BookStandBlock(Properties properties) { super(properties); }
+    @Override public BlockEntity newBlockEntity(BlockPos pos, BlockState state) { return new BookStandBlockEntity(pos, state); }
+    @Override protected InteractionResult useWithoutItem(BlockState state, Level level, BlockPos pos, Player player, BlockHitResult hit) {
+        if (!(level.getBlockEntity(pos) instanceof BookStandBlockEntity stand)) return InteractionResult.PASS;
+        if (player.isShiftKeyDown() && !level.isClientSide()) {
+            var book = stand.takeBook();
+            level.setBlock(pos, Blocks.LECTERN.defaultBlockState().setValue(FACING, state.getValue(FACING)), 3);
+            if (!player.getInventory().add(book)) player.drop(book, false, Prediction.SERVER_ONLY);
+            level.playSound(null, pos, SoundEvents.BOOK_PAGE_TURN, SoundSource.BLOCKS, 1, 1);
+        }
+        return InteractionResult.SUCCESS;
+    }
+    @Override protected net.minecraft.world.MenuProvider getMenuProvider(BlockState state, Level level, BlockPos pos) { return null; }
+    @Override protected int getAnalogOutputSignal(BlockState state, Level level, BlockPos pos, net.minecraft.core.Direction direction) { return 0; }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/CrystalPortalBlock.java

@@ -0,0 +1,79 @@
+package net.dnorberg.rivencraft.block;
+
+import net.dnorberg.rivencraft.block.entity.BookReceptacleBlockEntity;
+import net.dnorberg.rivencraft.block.entity.CrystalPortalBlockEntity;
+import net.dnorberg.rivencraft.portal.CrystalPortalNetwork;
+import net.dnorberg.rivencraft.portal.PortalTravelCooldown;
+import net.dnorberg.rivencraft.portal.PortalTravelQueue;
+import net.dnorberg.rivencraft.Rivencraft;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.util.RandomSource;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.BaseEntityBlock;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.RenderShape;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.block.state.StateDefinition;
+import net.minecraft.world.level.block.state.properties.BooleanProperty;
+import net.minecraft.world.level.block.state.properties.EnumProperty;
+import net.minecraft.world.level.material.Fluid;
+
+/** Non-solid linked surface; all travel is delegated to the held book's rules. */
+public final class CrystalPortalBlock extends BaseEntityBlock {
+    // Retained so portal blocks already saved with this state still deserialize.
+    public static final BooleanProperty LIVE_VIEW = BooleanProperty.create("live_view");
+    public static final EnumProperty<Direction.Axis> AXIS = EnumProperty.create("axis", Direction.Axis.class);
+
+    public CrystalPortalBlock(Properties properties) {
+        super(properties);
+        registerDefaultState(stateDefinition.any().setValue(LIVE_VIEW, false).setValue(AXIS, Direction.Axis.Z));
+    }
+    @Override protected void createBlockStateDefinition(StateDefinition.Builder<Block, BlockState> builder) {
+        builder.add(LIVE_VIEW, AXIS);
+    }
+    @Override protected RenderShape getRenderShape(BlockState state) {
+        // Keep the animated fallback until the optional destination view has
+        // actually been established, including after a world restart.
+        return RenderShape.MODEL;
+    }
+    @Override public BlockEntity newBlockEntity(BlockPos pos, BlockState state) {
+        return new CrystalPortalBlockEntity(pos, state);
+    }
+    @Override protected boolean canBeReplaced(BlockState state, Fluid fluid) { return false; }
+
+    @Override protected void entityInside(BlockState state, Level level, BlockPos pos, Entity entity, net.minecraft.world.entity.InsideBlockEffectApplier effects, boolean precise) {
+        if (!(level instanceof ServerLevel server) || !entity.canUsePortal(false)) return;
+        long now = server.getServer().getTickCount();
+        if (PortalTravelCooldown.blocked(entity, now)) return;
+        if (!(level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal)
+                || portal.receptacle() == null || !level.hasChunkAt(portal.receptacle())
+                || !(level.getBlockEntity(portal.receptacle()) instanceof BookReceptacleBlockEntity holder)) return;
+        ItemStack book = holder.getBook();
+        if (book.isEmpty()) return;
+        PortalTravelCooldown.mark(entity, now);
+        PortalTravelQueue.enqueue(entity, server, pos, portal.receptacle(), book, now);
+    }
+
+    @Override protected void neighborChanged(BlockState state, Level level, BlockPos pos, Block neighbor,
+            net.minecraft.world.level.redstone.Orientation orientation, boolean moved) {
+        super.neighborChanged(state, level, pos, neighbor, orientation, moved);
+        if (!(level instanceof ServerLevel server)
+                || !(level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal)
+                || portal.receptacle() == null) return;
+        // Like a vanilla portal, validate when the frame changes, not on a
+        // repeating timer that can race block entities loading after restart.
+        if (CrystalPortalNetwork.cellStatus(server, pos, portal.receptacle())
+                == CrystalPortalNetwork.CellStatus.INVALID) server.removeBlock(pos, false);
+    }
+
+    @Override protected void tick(BlockState state, ServerLevel level, BlockPos pos, RandomSource random) {
+        // Ignore validation ticks saved by older builds. Frame edits are
+        // handled by neighborChanged, and the receptacle maintains the view.
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/DecayBlock.java

@@ -0,0 +1,46 @@
+package net.dnorberg.rivencraft.block;
+
+import net.dnorberg.rivencraft.age.PortInstabilityRuntime;
+import net.dnorberg.rivencraft.age.PortInstabilityConfig;
+import net.minecraft.core.BlockPos;
+import net.minecraft.util.StringRepresentable;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.block.state.StateDefinition;
+import net.minecraft.world.level.block.state.properties.EnumProperty;
+
+/** The four colored decay variants selected by the current instability deck. */
+public final class DecayBlock extends Block {
+    public static final EnumProperty<Color> COLOR = EnumProperty.create("color", Color.class);
+
+    public DecayBlock(Properties properties) {
+        super(properties);
+        registerDefaultState(stateDefinition.any().setValue(COLOR, Color.BLUE));
+    }
+
+    @Override
+    protected void createBlockStateDefinition(StateDefinition.Builder<Block, BlockState> builder) {
+        builder.add(COLOR);
+    }
+
+    @Override
+    public void stepOn(Level level, BlockPos pos, BlockState state, Entity entity) {
+        if (level instanceof net.minecraft.server.level.ServerLevel server && state.getValue(COLOR) == Color.WHITE
+                && PortInstabilityConfig.decayEnabled() && PortInstabilityConfig.instabilityWorldMutation()
+                && PortInstabilityRuntime.isAge(server)) {
+            entity.hurtServer(server, level.damageSources().magic(), 1.0F);
+        }
+        super.stepOn(level, pos, state, entity);
+    }
+
+    public enum Color implements StringRepresentable {
+        BLUE, PURPLE, RED, WHITE;
+
+        @Override
+        public String getSerializedName() {
+            return name().toLowerCase(java.util.Locale.ROOT);
+        }
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/LinkModifierBlock.java

@@ -0,0 +1,51 @@
+package net.dnorberg.rivencraft.block;
+
+import net.dnorberg.rivencraft.block.entity.LinkModifierBlockEntity;
+import net.dnorberg.rivencraft.menu.LinkModifierMenu;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.InteractionResult;
+import net.minecraft.world.SimpleMenuProvider;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.context.BlockPlaceContext;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.BaseEntityBlock;
+import net.minecraft.world.level.block.RenderShape;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.block.state.StateDefinition;
+import net.minecraft.world.level.block.state.properties.BlockStateProperties;
+import net.minecraft.world.level.block.state.properties.EnumProperty;
+import net.minecraft.world.phys.BlockHitResult;
+
+public final class LinkModifierBlock extends BaseEntityBlock {
+    public static final EnumProperty<Direction> FACING = BlockStateProperties.HORIZONTAL_FACING;
+
+    public LinkModifierBlock(Properties properties) {
+        super(properties);
+        registerDefaultState(stateDefinition.any().setValue(FACING, Direction.NORTH));
+    }
+
+    @Override protected void createBlockStateDefinition(StateDefinition.Builder<net.minecraft.world.level.block.Block,
+            BlockState> builder) { builder.add(FACING); }
+    @Override public BlockState getStateForPlacement(BlockPlaceContext context) {
+        return defaultBlockState().setValue(FACING, context.getHorizontalDirection().getOpposite());
+    }
+    @Override protected RenderShape getRenderShape(BlockState state) { return RenderShape.MODEL; }
+    @Override public BlockEntity newBlockEntity(BlockPos pos, BlockState state) {
+        return new LinkModifierBlockEntity(pos, state);
+    }
+    @Override protected InteractionResult useWithoutItem(BlockState state, Level level, BlockPos pos,
+                                                          Player player, BlockHitResult hit) {
+        if (!level.isClientSide() && player instanceof ServerPlayer serverPlayer
+                && level.getBlockEntity(pos) instanceof LinkModifierBlockEntity modifier) {
+            serverPlayer.openMenu(new SimpleMenuProvider(
+                    (id, inventory, ignored) -> new LinkModifierMenu(id, inventory, modifier),
+                    Component.translatable("container.rivencraft.link_modifier")),
+                    buffer -> buffer.writeBlockPos(pos));
+        }
+        return InteractionResult.SUCCESS;
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/entity/BookReceptacleBlockEntity.java

@@ -0,0 +1,102 @@
+package net.dnorberg.rivencraft.block.entity;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.block.BookReceptacleBlock;
+import net.dnorberg.rivencraft.portal.CrystalPortalNetwork;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.HolderLookup;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.network.protocol.game.ClientboundBlockEntityDataPacket;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.storage.ValueInput;
+import net.minecraft.world.level.storage.ValueOutput;
+
+/** One persisted book owns the whole crystal network. Portal cells retain only its position. */
+public final class BookReceptacleBlockEntity extends BlockEntity {
+    private ItemStack book = ItemStack.EMPTY;
+    private boolean restore = true;
+    private int skyColor = 0xffffff;
+    public BookReceptacleBlockEntity(BlockPos pos, BlockState state) {
+        super(Rivencraft.BOOK_RECEPTACLE_BLOCK_ENTITY.get(), pos, state);
+    }
+    public ItemStack getBook() { return book; }
+    public int skyColor() { return skyColor; }
+    public void setBook(ItemStack value) {
+        book = value.copyWithCount(1);
+        skyColor = 0xffffff;
+        if (level instanceof ServerLevel source) {
+            var destination = book.get(Rivencraft.LINK_BOOK_TARGET.get());
+            var id = book.is(Rivencraft.DESCRIPTIVE_BOOK.get()) ? book.get(Rivencraft.AGE_BOOK_ID.get())
+                    : destination == null ? null : destination.dimension();
+            var target = id == null ? null : source.getServer().getLevel(net.minecraft.resources.ResourceKey.create(
+                    net.minecraft.core.registries.Registries.DIMENSION, id));
+            if (target != null) {
+                var pos = destination == null ? net.dnorberg.rivencraft.age.PortAgeTravel.resolveLanding(target, !book.getOrDefault(Rivencraft.LINK_PROPERTIES.get(),
+                        net.dnorberg.rivencraft.item.LinkProperties.NONE).has(net.dnorberg.rivencraft.item.LinkProperties.DISABLE_PLATFORM))
+                        : BlockPos.containing(destination.x(), destination.y(), destination.z());
+                if (pos != null) {
+                    int written = net.dnorberg.rivencraft.age.PortAgeColors.forLevel(target).sky();
+                    String type = target.dimensionTypeRegistration().unwrapKey()
+                            .map(key -> key.identifier().getPath()).orElse("");
+                    skyColor = written >= 0 ? written
+                            : target.dimension() == net.minecraft.world.level.Level.NETHER || type.endsWith("_sky_nether")
+                                ? 0x6b2725
+                            : target.dimension() == net.minecraft.world.level.Level.END || type.endsWith("_sky_end")
+                                ? 0x211835
+                            : net.minecraft.util.ARGB.colorFromVector3f(target.environmentAttributes().getValue(
+                                    net.minecraft.world.attribute.EnvironmentAttributes.SKY_COLOR, pos)) & 0xffffff;
+                }
+            }
+        }
+        sync();
+    }
+    public ItemStack takeBook() { ItemStack result = book; book = ItemStack.EMPTY; skyColor = 0xffffff; sync(); return result; }
+    private void sync() {
+        setChanged();
+        if (level != null && !level.isClientSide()) {
+            BlockState current = level.getBlockState(worldPosition);
+            if (current.is(Rivencraft.BOOK_RECEPTACLE.get())) {
+                level.setBlock(worldPosition, current.setValue(BookReceptacleBlock.HAS_BOOK, !book.isEmpty()), 2);
+                level.sendBlockUpdated(worldPosition, current, level.getBlockState(worldPosition), 2);
+            }
+        }
+    }
+    public static void serverTick(ServerLevel level, BlockPos pos, BookReceptacleBlockEntity holder) {
+        if (holder.book.isEmpty()) { holder.restore = false; return; }
+        int interval = holder.restore ? 20 : 200;
+        if (level.getGameTime() % interval != Math.floorMod(pos.asLong(), interval)) return;
+        var plan = CrystalPortalNetwork.plan(level, pos);
+        if (plan.waitingForChunks()) return;
+        boolean restoring = holder.restore;
+        if (restoring && !plan.valid() && CrystalPortalNetwork.recoverSavedOwners(level, pos))
+            plan = CrystalPortalNetwork.plan(level, pos);
+        CrystalPortalNetwork.reconcile(level, pos, plan);
+        holder.restore = false;
+        if (restoring) holder.sync();
+    }
+    @Override protected void loadAdditional(ValueInput input) {
+        super.loadAdditional(input);
+        book = input.read("Book", ItemStack.CODEC).orElse(ItemStack.EMPTY);
+        skyColor = input.getIntOr("SkyColor", 0xffffff);
+        restore = true;
+    }
+    @Override protected void saveAdditional(ValueOutput output) {
+        super.saveAdditional(output);
+        if (!book.isEmpty()) output.store("Book", ItemStack.CODEC, book);
+        output.putInt("SkyColor", skyColor);
+    }
+    @Override public CompoundTag getUpdateTag(HolderLookup.Provider registries) { return saveWithoutMetadata(registries); }
+    @Override public ClientboundBlockEntityDataPacket getUpdatePacket() { return ClientboundBlockEntityDataPacket.create(this); }
+    @Override public void preRemoveSideEffects(BlockPos pos, BlockState oldState) {
+        if (level instanceof ServerLevel server) {
+            CrystalPortalNetwork.shutdown(server, pos);
+            ItemStack removed = book;
+            book = ItemStack.EMPTY;
+            net.minecraft.world.Containers.dropItemStack(level, pos.getX() + 0.5, pos.getY() + 0.5, pos.getZ() + 0.5, removed);
+        }
+        super.preRemoveSideEffects(pos, oldState);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/entity/BookStandBlockEntity.java

@@ -0,0 +1,40 @@
+package net.dnorberg.rivencraft.block.entity;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.HolderLookup;
+import net.minecraft.network.protocol.game.ClientboundBlockEntityDataPacket;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.storage.ValueInput;
+import net.minecraft.world.level.storage.ValueOutput;
+
+/** One stored book or page, synchronized independently of the player's inventory. */
+public final class BookStandBlockEntity extends BlockEntity {
+    private ItemStack book = ItemStack.EMPTY;
+    public BookStandBlockEntity(BlockPos pos, BlockState state) { super(Rivencraft.BOOK_STAND_BLOCK_ENTITY.get(), pos, state); }
+    public ItemStack getBook() { return book; }
+    public void setBook(ItemStack stack) { book = stack; sync(); }
+    public ItemStack takeBook() { ItemStack result = book; book = ItemStack.EMPTY; sync(); return result; }
+    private void sync() {
+        setChanged();
+        if (level != null && !level.isClientSide()) level.sendBlockUpdated(worldPosition, getBlockState(), getBlockState(), 2);
+    }
+    @Override protected void loadAdditional(ValueInput input) {
+        super.loadAdditional(input);
+        book = input.read("Book", ItemStack.CODEC).orElse(ItemStack.EMPTY);
+    }
+    @Override protected void saveAdditional(ValueOutput output) {
+        super.saveAdditional(output);
+        if (!book.isEmpty()) output.store("Book", ItemStack.CODEC, book);
+    }
+    @Override public CompoundTag getUpdateTag(HolderLookup.Provider registries) { return saveWithoutMetadata(registries); }
+    @Override public ClientboundBlockEntityDataPacket getUpdatePacket() { return ClientboundBlockEntityDataPacket.create(this); }
+    @Override public void preRemoveSideEffects(BlockPos pos, BlockState oldState) {
+        if (level != null && !level.isClientSide())
+            net.minecraft.world.Containers.dropItemStack(level, pos.getX() + 0.5, pos.getY() + 1, pos.getZ() + 0.5, takeBook());
+        super.preRemoveSideEffects(pos, oldState);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/entity/CrystalPortalBlockEntity.java

@@ -0,0 +1,33 @@
+package net.dnorberg.rivencraft.block.entity;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.HolderLookup;
+import net.minecraft.network.protocol.game.ClientboundBlockEntityDataPacket;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.storage.ValueInput;
+import net.minecraft.world.level.storage.ValueOutput;
+
+/** One stored book or page, synchronized independently of the player's inventory. */
+public final class CrystalPortalBlockEntity extends BlockEntity {
+    private BlockPos receptacle;
+    public CrystalPortalBlockEntity(BlockPos pos, BlockState state) { super(Rivencraft.CRYSTAL_PORTAL_BLOCK_ENTITY.get(), pos, state); }
+    public BlockPos receptacle() { return receptacle; }
+    public void setReceptacle(BlockPos pos) {
+        receptacle = pos.immutable();
+        setChanged();
+        if (level != null && !level.isClientSide()) level.sendBlockUpdated(worldPosition, getBlockState(), getBlockState(), 2);
+    }
+    @Override protected void loadAdditional(ValueInput input) {
+        super.loadAdditional(input);
+        receptacle = input.read("Receptacle", BlockPos.CODEC).orElse(null);
+    }
+    @Override protected void saveAdditional(ValueOutput output) {
+        super.saveAdditional(output);
+        if (receptacle != null) output.store("Receptacle", BlockPos.CODEC, receptacle);
+    }
+    @Override public CompoundTag getUpdateTag(HolderLookup.Provider registries) { return saveWithoutMetadata(registries); }
+    @Override public ClientboundBlockEntityDataPacket getUpdatePacket() { return ClientboundBlockEntityDataPacket.create(this); }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/entity/LinkModifierBlockEntity.java

@@ -0,0 +1,69 @@
+package net.dnorberg.rivencraft.block.entity;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.storage.ValueInput;
+import net.minecraft.world.level.storage.ValueOutput;
+import net.minecraft.core.NonNullList;
+import net.minecraft.world.Container;
+import net.minecraft.world.ContainerHelper;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+
+/** One persisted book slot; edits are performed by the server menu. */
+public final class LinkModifierBlockEntity extends BlockEntity implements Container {
+    private NonNullList<ItemStack> items = NonNullList.withSize(1, ItemStack.EMPTY);
+
+    public LinkModifierBlockEntity(BlockPos pos, BlockState state) {
+        super(Rivencraft.LINK_MODIFIER_BLOCK_ENTITY.get(), pos, state);
+    }
+
+    @Override public int getContainerSize() { return 1; }
+    @Override public boolean isEmpty() { return items.getFirst().isEmpty(); }
+    @Override public ItemStack getItem(int slot) { return items.get(slot); }
+    @Override public ItemStack removeItem(int slot, int amount) {
+        ItemStack removed = ContainerHelper.removeItem(items, slot, amount);
+        if (!removed.isEmpty()) setChanged();
+        return removed;
+    }
+    @Override public ItemStack removeItemNoUpdate(int slot) {
+        ItemStack removed = ContainerHelper.takeItem(items, slot);
+        if (!removed.isEmpty()) setChanged();
+        return removed;
+    }
+    @Override public void setItem(int slot, ItemStack stack) {
+        items.set(slot, stack.copyWithCount(Math.min(1, stack.getCount())));
+        setChanged();
+    }
+    @Override public boolean canPlaceItem(int slot, ItemStack stack) {
+        return slot == 0 && (stack.is(Rivencraft.LINKING_BOOK.get())
+                || stack.is(Rivencraft.DESCRIPTIVE_BOOK.get()));
+    }
+    @Override public boolean stillValid(Player player) {
+        return level != null && level.isLoaded(worldPosition) && level.getBlockEntity(worldPosition) == this
+                && player.distanceToSqr(worldPosition.getX() + 0.5, worldPosition.getY() + 0.5,
+                        worldPosition.getZ() + 0.5) <= 64.0;
+    }
+    @Override public void preRemoveSideEffects(BlockPos pos, BlockState oldState) {
+        if (level != null && !level.isClientSide()) {
+            net.minecraft.world.Containers.dropContents(level, pos, this);
+            clearContent();
+        }
+        super.preRemoveSideEffects(pos, oldState);
+    }
+    @Override public void clearContent() {
+        items = NonNullList.withSize(1, ItemStack.EMPTY);
+        setChanged();
+    }
+    @Override protected void loadAdditional(ValueInput input) {
+        super.loadAdditional(input);
+        items = NonNullList.withSize(1, ItemStack.EMPTY);
+        ContainerHelper.loadAllItems(input, items);
+    }
+    @Override protected void saveAdditional(ValueOutput output) {
+        super.saveAdditional(output);
+        ContainerHelper.saveAllItems(output, items);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/block/entity/WritingDeskBlockEntity.java

@@ -116,13 +116,13 @@ public final class WritingDeskBlockEntity extends BlockEntity implements Contain
     public boolean canConsumeCopyMaterials() {
         ItemStack paper = items.get(PAPER);
         if (!canPlaceItem(PAPER, paper) || paper.isEmpty()) return false;
-        int cost = net.dnorberg.rivencraft.PortConfig.SYMBOL_INK_COST.get();
+        int cost = net.dnorberg.rivencraft.writing.WritingInkService.symbolCopyCost();
         return InkVialExchange.canPay(items, INK, RETURN, inkRemaining, cost);
     }
 
     public boolean consumeCopyMaterials() {
         if (!canConsumeCopyMaterials()) return false;
-        int cost = net.dnorberg.rivencraft.PortConfig.SYMBOL_INK_COST.get();
+        int cost = net.dnorberg.rivencraft.writing.WritingInkService.symbolCopyCost();
         if (inkRemaining < cost) {
             inkRemaining += InkVialExchange.exchange(items, INK, RETURN);
         }

ports/mc263/src/main/java/net/dnorberg/rivencraft/client/BookReceptacleRenderer.java

@@ -0,0 +1,67 @@
+package net.dnorberg.rivencraft.client;
+
+import com.mojang.blaze3d.vertex.PoseStack;
+import com.mojang.math.Axis;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.block.BookReceptacleBlock;
+import net.dnorberg.rivencraft.block.entity.BookReceptacleBlockEntity;
+import net.minecraft.client.model.geom.ModelLayers;
+import net.minecraft.client.model.object.book.BookModel;
+import net.minecraft.client.renderer.SubmitNodeCollector;
+import net.minecraft.client.renderer.blockentity.BlockEntityRenderer;
+import net.minecraft.client.renderer.blockentity.BlockEntityRendererProvider;
+import net.minecraft.client.renderer.blockentity.state.BlockEntityRenderState;
+import net.minecraft.client.renderer.feature.ModelFeatureRenderer;
+import net.minecraft.client.renderer.state.level.CameraRenderState;
+import net.minecraft.client.renderer.texture.OverlayTexture;
+import net.minecraft.core.Direction;
+import net.minecraft.resources.Identifier;
+import net.minecraft.world.phys.Vec3;
+
+/** The 1.21.1 receptacle book orientation in the 26.3 extracted renderer. */
+public final class BookReceptacleRenderer implements BlockEntityRenderer<BookReceptacleBlockEntity, BookReceptacleRenderer.State> {
+    private static final Identifier LINKING = Identifier.fromNamespaceAndPath("rivencraft", "textures/entity/linking_book.png");
+    private static final Identifier DESCRIPTIVE = Identifier.fromNamespaceAndPath("rivencraft", "textures/entity/descriptive_book.png");
+    private final BookModel model;
+    public BookReceptacleRenderer(BlockEntityRendererProvider.Context context) {
+        model = new BookModel(context.bakeLayer(ModelLayers.BOOK));
+    }
+    public static final class State extends BlockEntityRenderState {
+        boolean present, descriptive;
+        Direction facing = Direction.NORTH;
+    }
+    @Override public State createRenderState() { return new State(); }
+    @Override public void extractRenderState(BookReceptacleBlockEntity holder, State state, float partialTick,
+                                             Vec3 camera, ModelFeatureRenderer.CrumblingOverlay overlay) {
+        BlockEntityRenderer.super.extractRenderState(holder, state, partialTick, camera, overlay);
+        state.present = !holder.getBook().isEmpty() && holder.getBlockState().getValue(BookReceptacleBlock.HAS_BOOK);
+        state.descriptive = holder.getBook().is(Rivencraft.DESCRIPTIVE_BOOK.get());
+        state.facing = holder.getBlockState().getValue(BookReceptacleBlock.FACING);
+    }
+    @Override public void submit(State state, PoseStack pose, SubmitNodeCollector collector, CameraRenderState camera) {
+        if (!state.present) return;
+        pose.pushPose();
+        pose.translate(0.5F, 0.5F, 0.5F);
+        switch (state.facing) {
+            case UP -> {
+                pose.rotateDegrees(Axis.ZP, 180);
+                pose.rotateDegrees(Axis.XP, -90);
+                pose.rotateDegrees(Axis.YP, 90);
+                pose.rotateDegrees(Axis.ZP, 180);
+            }
+            case DOWN -> {
+                pose.rotateDegrees(Axis.XP, -90);
+                pose.rotateDegrees(Axis.YP, 90);
+                pose.rotateDegrees(Axis.ZP, 180);
+            }
+            case NORTH -> pose.rotateDegrees(Axis.YP, -90);
+            case SOUTH -> pose.rotateDegrees(Axis.YP, 90);
+            case EAST -> pose.rotateDegrees(Axis.YP, 180);
+            case WEST -> { }
+        }
+        pose.scale(0.8F, 0.8F, 0.8F);
+        collector.submitModel(model, BookModel.State.forAnimation(0, 0.1F, 0.1F, 0.005F), pose,
+                state.descriptive ? DESCRIPTIVE : LINKING, state.lightCoords, OverlayTexture.NO_OVERLAY, 0);
+        pose.popPose();
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/client/BookStandRenderer.java

@@ -0,0 +1,85 @@
+package net.dnorberg.rivencraft.client;
+
+import com.mojang.blaze3d.vertex.PoseStack;
+import com.mojang.math.Axis;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.block.BookStandBlock;
+import net.dnorberg.rivencraft.block.entity.BookStandBlockEntity;
+import net.minecraft.client.gui.Font;
+import net.minecraft.client.model.geom.ModelLayers;
+import net.minecraft.client.model.object.book.BookModel;
+import net.minecraft.client.renderer.SubmitNodeCollector;
+import net.minecraft.client.renderer.blockentity.BlockEntityRenderer;
+import net.minecraft.client.renderer.blockentity.BlockEntityRendererProvider;
+import net.minecraft.client.renderer.blockentity.state.BlockEntityRenderState;
+import net.minecraft.client.renderer.feature.ModelFeatureRenderer;
+import net.minecraft.client.renderer.item.ItemModelResolver;
+import net.minecraft.client.renderer.item.ItemStackRenderState;
+import net.minecraft.client.renderer.state.level.CameraRenderState;
+import net.minecraft.client.renderer.texture.OverlayTexture;
+import net.minecraft.core.Direction;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.Identifier;
+import net.minecraft.world.item.ItemDisplayContext;
+import net.minecraft.world.phys.Vec3;
+
+/** Extracted version of the 1.21.1 lectern display, retaining its final page orientation. */
+public final class BookStandRenderer implements BlockEntityRenderer<BookStandBlockEntity, BookStandRenderer.State> {
+    private static final Identifier LINKING = Identifier.fromNamespaceAndPath("rivencraft", "textures/entity/linking_book.png");
+    private static final Identifier DESCRIPTIVE = Identifier.fromNamespaceAndPath("rivencraft", "textures/entity/descriptive_book.png");
+    private final BookModel model;
+    private final ItemModelResolver resolver;
+    private final Font font;
+    public BookStandRenderer(BlockEntityRendererProvider.Context context) {
+        model = new BookModel(context.bakeLayer(ModelLayers.BOOK));
+        resolver = context.itemModelResolver();
+        font = context.font();
+    }
+    public static final class State extends BlockEntityRenderState {
+        final ItemStackRenderState page = new ItemStackRenderState();
+        boolean present, isPage, descriptive;
+        float rotation;
+        Component name;
+    }
+    @Override public State createRenderState() { return new State(); }
+    @Override public void extractRenderState(BookStandBlockEntity stand, State state, float partialTick,
+                                             Vec3 camera, ModelFeatureRenderer.CrumblingOverlay overlay) {
+        BlockEntityRenderer.super.extractRenderState(stand, state, partialTick, camera, overlay);
+        var book = stand.getBook();
+        state.present = !book.isEmpty();
+        state.isPage = book.is(Rivencraft.PAGE.get());
+        state.descriptive = book.is(Rivencraft.DESCRIPTIVE_BOOK.get());
+        state.name = state.present && !state.isPage ? book.getHoverName().copy() : null;
+        Direction facing = stand.getBlockState().getValue(BookStandBlock.FACING);
+        state.rotation = state.isPage ? facing.toYRot() - 180 + (facing.getAxis() == Direction.Axis.X ? 180 : 0)
+                : -facing.getClockWise().toYRot();
+        resolver.updateForTopItem(state.page, state.isPage ? book : net.minecraft.world.item.ItemStack.EMPTY,
+                ItemDisplayContext.FIXED, stand.getLevel(), null, 0);
+    }
+    @Override public void submit(State state, PoseStack pose, SubmitNodeCollector collector, CameraRenderState camera) {
+        if (!state.present) return;
+        pose.pushPose();
+        pose.translate(0.5F, 1.0625F, 0.5F);
+        pose.rotateDegrees(Axis.YP, state.rotation);
+        if (state.isPage) {
+            pose.rotateDegrees(Axis.XP, 67.5F);
+            pose.scale(0.7F, 0.7F, 0.7F);
+            state.page.submit(pose, collector, state.lightCoords, OverlayTexture.NO_OVERLAY, 0);
+        } else {
+            pose.rotateDegrees(Axis.ZP, 67.5F);
+            pose.translate(0, -0.125F, 0);
+            collector.submitModel(model, BookModel.State.forAnimation(0, 0.1F, 0.9F, 1.2F), pose,
+                    state.descriptive ? DESCRIPTIVE : LINKING, state.lightCoords, OverlayTexture.NO_OVERLAY, 0);
+        }
+        pose.popPose();
+        if (state.name != null) {
+            pose.pushPose();
+            pose.translate(0.5F, 1.6F, 0.5F);
+            pose.rotate(camera.orientation);
+            pose.scale(0.025F, -0.025F, 0.025F);
+            collector.submitText(pose, -font.width(state.name) / 2.0F, 0, state.name.getVisualOrderText(),
+                    false, Font.DisplayMode.NORMAL, state.lightCoords, 0xFFFFFFFF, 0, 0);
+            pose.popPose();
+        }
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/client/LinkModifierScreen.java

@@ -0,0 +1,120 @@
+package net.dnorberg.rivencraft.client;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.item.LinkProperties;
+import net.dnorberg.rivencraft.menu.LinkModifierMenu;
+import net.dnorberg.rivencraft.network.SetLinkModifierTitlePayload;
+import net.minecraft.client.gui.GuiGraphicsExtractor;
+import net.minecraft.client.gui.components.EditBox;
+import net.minecraft.client.gui.screens.inventory.AbstractContainerScreen;
+import net.minecraft.client.input.KeyEvent;
+import net.minecraft.client.gui.components.Button;
+import net.minecraft.client.gui.components.Tooltip;
+import net.minecraft.client.renderer.RenderPipelines;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.Identifier;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.item.ItemStack;
+import net.neoforged.neoforge.client.network.ClientPacketDistributor;
+
+/** Existing Legacy single-slot layout, using the 26.3 extraction/input APIs. */
+public final class LinkModifierScreen extends AbstractContainerScreen<LinkModifierMenu> {
+    private static final Identifier BACKGROUND = Identifier.fromNamespaceAndPath(
+            Rivencraft.MOD_ID, "textures/gui/link_modifier_legacy.png");
+    private static final int[] FLAGS = {LinkProperties.DISARM, LinkProperties.INTRA_LINKING,
+            LinkProperties.INTRA_LINKING_ONLY, LinkProperties.MAINTAIN_MOMENTUM, LinkProperties.RELATIVE_LINK, LinkProperties.DISABLE_PLATFORM};
+    private static final int[] IDS = {LinkModifierMenu.TOGGLE_DISARM, LinkModifierMenu.TOGGLE_INTRA,
+            LinkModifierMenu.TOGGLE_INTRA_ONLY, LinkModifierMenu.TOGGLE_MOMENTUM, LinkModifierMenu.TOGGLE_RELATIVE, LinkModifierMenu.TOGGLE_PLATFORM};
+    private static final String[] NAMES = {"disarm", "intra_linking", "intra_linking_only", "maintain_momentum", "relative_link", "generate_platform"};
+    private EditBox titleInput;
+    private ItemStack lastBook = ItemStack.EMPTY;
+    private boolean refreshing;
+    private final Button[] options = new Button[6];
+
+    public LinkModifierScreen(LinkModifierMenu menu, Inventory inventory, Component title) {
+        super(menu, inventory, title, 176, 166);
+        inventoryLabelY = 72;
+    }
+    @Override public boolean isPauseScreen() { return false; }
+    @Override protected void init() {
+        super.init();
+        titleInput = new EditBox(font, leftPos + 80, topPos + 56, 87, 14,
+                Component.translatable("screen.rivencraft.link_modifier.title"));
+        titleInput.setMaxLength(32);
+        titleInput.setResponder(value -> {
+            if (!refreshing) ClientPacketDistributor.sendToServer(new SetLinkModifierTitlePayload(menu.containerId, value));
+        });
+        addRenderableWidget(titleInput);
+        for (int index = 0; index < options.length; index++) {
+            final int option = index;
+            options[index] = addRenderableWidget(new Button(leftPos + 5 + (index / 3) * 20,
+                    topPos + 10 + (index % 3) * 20, 18, 18, label(index), button -> {
+                        if (minecraft != null && minecraft.gameMode != null)
+                            minecraft.gameMode.handleInventoryButtonClick(menu.containerId, IDS[option]);
+                    }, java.util.function.Supplier::get) {
+                @Override protected void extractContents(GuiGraphicsExtractor graphics, int mouseX, int mouseY, float partialTick) {
+                    int x = getX(), y = getY();
+                    graphics.fill(x, y, x + 18, y + 18, isHoveredOrFocused() ? 0xFFFFFFFF : 0xFFAAAAAA);
+                    graphics.fill(x + 2, y + 2, x + 17, y + 17, !active ? 0xFF555555
+                            : selected(option, menu.book().getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE))
+                                    ? 0xFFBBBBBB : 0xFF777777);
+                }
+            });
+            options[index].setTooltip(Tooltip.create(label(index)));
+        }
+        refreshControls();
+    }
+    @Override protected void containerTick() { refreshControls(); }
+    private void refreshControls() {
+        ItemStack book = menu.book();
+        // Changing book kinds refreshes immediately; otherwise avoid replacing
+        // focused text with an earlier server echo while the player is typing.
+        if (!ItemStack.isSameItem(book, lastBook) || !titleInput.isFocused()) {
+            if (!ItemStack.isSameItemSameComponents(book, lastBook)) {
+                Component name = book.get(DataComponents.CUSTOM_NAME);
+                refreshing = true;
+                titleInput.setValue(name == null ? "" : name.getString());
+                refreshing = false;
+                lastBook = book.copy();
+            }
+        }
+        titleInput.setEditable(!book.isEmpty());
+        for (int i = 0; i < options.length; i++) if (options[i] != null) {
+            options[i].active = available(i);
+            Component label = label(i);
+            if (!options[i].getMessage().equals(label)) {
+                options[i].setMessage(label);
+                options[i].setTooltip(Tooltip.create(label));
+            }
+        }
+    }
+    private boolean available(int index) {
+        return !menu.book().isEmpty() && ((index != 1 && index != 2) || menu.book().is(Rivencraft.LINKING_BOOK.get()));
+    }
+    private Component label(int index) {
+        Component name = Component.translatable("item.rivencraft.link_property." + NAMES[index]);
+        return name.copy().append(selected(index,
+                menu.book().getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE)) ? ": On" : ": Off");
+    }
+    @Override public boolean keyPressed(KeyEvent event) {
+        if (titleInput != null && titleInput.isFocused() && !event.isEscape()) {
+            titleInput.keyPressed(event);
+            return true; // Character input must never activate inventory/hotbar shortcuts.
+        }
+        return super.keyPressed(event);
+    }
+    @Override public void extractBackground(GuiGraphicsExtractor graphics, int mouseX, int mouseY, float partialTick) {
+        super.extractBackground(graphics, mouseX, mouseY, partialTick);
+        graphics.blit(RenderPipelines.GUI_TEXTURED, BACKGROUND, leftPos, topPos, 0, 0, imageWidth, imageHeight, 256, 256);
+    }
+
+    private boolean selected(int index, LinkProperties properties) {
+        if (index != 5) return properties.has(FLAGS[index]);
+        return menu.book().is(Rivencraft.LINKING_BOOK.get()) ? properties.has(LinkProperties.GENERATE_PLATFORM)
+                : !properties.has(LinkProperties.DISABLE_PLATFORM);
+    }
+    @Override protected void extractLabels(GuiGraphicsExtractor graphics, int mouseX, int mouseY) {
+        graphics.text(font, playerInventoryTitle, inventoryLabelX, inventoryLabelY, 0xFF404040, false);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/client/PortBookBinderClientEvents.java

@@ -20,12 +20,30 @@ public final class PortBookBinderClientEvents {
         event.registerBlockEntityRenderer(Rivencraft.STAR_FISSURE_BLOCK_ENTITY.get(), context -> new StarFissureRenderer());
         event.registerEntityRenderer(Rivencraft.DROPPED_BOOK.get(), DroppedBookRenderer::new);
         event.registerBlockEntityRenderer(Rivencraft.WRITING_DESK_BLOCK_ENTITY.get(), WritingDeskRenderer::new);
+        event.registerBlockEntityRenderer(Rivencraft.BOOK_STAND_BLOCK_ENTITY.get(), BookStandRenderer::new);
+        event.registerBlockEntityRenderer(Rivencraft.BOOK_RECEPTACLE_BLOCK_ENTITY.get(), BookReceptacleRenderer::new);
+    }
+
+    @SubscribeEvent
+    public static void portalTint(net.neoforged.neoforge.client.event.RegisterColorHandlersEvent.BlockTintSources event) {
+        event.register(java.util.List.of(new net.minecraft.client.color.block.BlockTintSource() {
+            @Override public int color(net.minecraft.world.level.block.state.BlockState state) { return 0xffffffff; }
+            @Override public int colorInWorld(net.minecraft.world.level.block.state.BlockState state,
+                    net.minecraft.client.renderer.block.BlockAndTintGetter level, net.minecraft.core.BlockPos pos) {
+                if (level.getBlockEntity(pos) instanceof net.dnorberg.rivencraft.block.entity.CrystalPortalBlockEntity portal
+                        && portal.receptacle() != null
+                        && level.getBlockEntity(portal.receptacle()) instanceof net.dnorberg.rivencraft.block.entity.BookReceptacleBlockEntity holder)
+                    return 0xff000000 | holder.skyColor();
+                return 0xffffffff;
+            }
+        }), Rivencraft.CRYSTAL_PORTAL.get());
     }
 
     @SubscribeEvent
     public static void registerScreens(RegisterMenuScreensEvent event) {
         event.register(Rivencraft.BOOK_BINDER_MENU.get(), PortBookBinderScreen::new);
         event.register(Rivencraft.INK_MIXER_MENU.get(), InkMixerScreen::new);
+        event.register(Rivencraft.LINK_MODIFIER_MENU.get(), LinkModifierScreen::new);
         event.register(Rivencraft.NOTEBOOK_MENU.get(), NotebookScreen::new);
         event.register(Rivencraft.WRITING_DESK_MENU.get(), WritingDeskScreen::new);
     }

ports/mc263/src/main/java/net/dnorberg/rivencraft/client/PortBookInteractionHandler.java

@@ -26,4 +26,19 @@ public final class PortBookInteractionHandler {
                 ? new PortLinkingBookScreen(event.getHand(), event.getItemStack().copy())
                 : new PortDescriptiveBookScreen(event.getHand(), event.getItemStack().copy()));
     }
+    @SubscribeEvent
+    public static void onRightClickBlock(PlayerInteractEvent.RightClickBlock event) {
+        if (!event.getLevel().isClientSide() || event.getEntity().isShiftKeyDown()
+                || !event.getItemStack().isEmpty()
+                || !(event.getLevel().getBlockEntity(event.getPos()) instanceof net.dnorberg.rivencraft.block.entity.BookStandBlockEntity stand)) return;
+        var book = stand.getBook();
+        if (!book.is(Rivencraft.LINKING_BOOK.get()) && !book.is(Rivencraft.DESCRIPTIVE_BOOK.get())) return;
+        event.setCanceled(true);
+        event.setCancellationResult(InteractionResult.SUCCESS);
+        var source = new net.dnorberg.rivencraft.network.UseBookStandPayload(
+                event.getLevel().dimension().identifier(), event.getPos(), book.copy());
+        Minecraft.getInstance().setScreenAndShow(book.is(Rivencraft.LINKING_BOOK.get())
+                ? new PortLinkingBookScreen(source) : new PortDescriptiveBookScreen(source));
+    }
+
 }

ports/mc263/src/main/java/net/dnorberg/rivencraft/client/PortDescriptiveBookScreen.java

@@ -10,81 +10,111 @@ import net.minecraft.client.gui.components.Button;
 import net.minecraft.client.gui.components.EditBox;
 import net.minecraft.client.gui.screens.Screen;
 import net.minecraft.client.input.MouseButtonEvent;
-import net.minecraft.client.renderer.RenderPipelines;
 import net.minecraft.network.chat.Component;
-import net.minecraft.resources.Identifier;
 import net.minecraft.world.InteractionHand;
 import net.minecraft.world.item.ItemStack;
 import net.neoforged.neoforge.client.network.ClientPacketDistributor;
 
-/** Temporary 26.3 descriptive-book interaction; authored pages and live previews remain unported. */
+/** Legacy book layout and authored glyph pages; destination rendering remains a port placeholder. */
 public final class PortDescriptiveBookScreen extends Screen {
     private static final int WIDTH = 327;
     private static final int HEIGHT = 199;
     private static final int TEXT_COLOR = 0xFF3B281B;
-    private static final Identifier COVER = texture("bookui_cover.png");
-    private static final Identifier LEFT_PAGE = texture("notebook_pages.png");
-    private static final Identifier RIGHT_PANEL = texture("bookui_pager.png");
+
 
     private final InteractionHand hand;
     private final boolean bound;
+    private final PortLegacyLinkPanel linkPanel = new PortLegacyLinkPanel();
+    private final net.dnorberg.rivencraft.writing.DescriptiveBookPages pages;
+    private int pageIndex;
+    private net.dnorberg.rivencraft.network.UseBookStandPayload standSource;
     private EditBox titleInput;
 
     public PortDescriptiveBookScreen(InteractionHand hand, ItemStack book) {
         super(book.getHoverName());
         this.hand = hand;
+        pages = net.dnorberg.rivencraft.writing.DescriptiveBookPages.from(book);
         bound = book.has(Rivencraft.AGE_BOOK_ID.get());
     }
 
+    public PortDescriptiveBookScreen(net.dnorberg.rivencraft.network.UseBookStandPayload source) {
+        this(InteractionHand.MAIN_HAND, source.book());
+        standSource = source;
+    }
+
     @Override
     protected void init() {
-        if (bound) return;
+        if (bound || standSource != null) return;
         int left = (width - WIDTH) / 2;
         int top = (height - HEIGHT) / 2;
         titleInput = new EditBox(font, left + 40, top + 69, 110, 20,
                 Component.literal("Age name"));
         titleInput.setMaxLength(PortBookNetworking.MAX_BOOK_TITLE_LENGTH);
-        titleInput.setHint(Component.literal("Name this Age"));
+        titleInput.setHint(Component.literal(standSource == null ? "Name this Age" : "Remove book to bind"));
         addRenderableWidget(titleInput);
         setInitialFocus(titleInput);
         addRenderableWidget(Button.builder(Component.literal("Bind"), button -> bind())
                 .bounds(left + 40, top + 100, 53, 20).build());
         addRenderableWidget(Button.builder(Component.literal("Cancel"), button -> onClose())
                 .bounds(left + 97, top + 100, 53, 20).build());
+        updatePageControls();
     }
 
     @Override
     public void extractRenderState(GuiGraphicsExtractor graphics, int mouseX, int mouseY, float partialTick) {
         int left = (width - WIDTH) / 2;
         int top = (height - HEIGHT) / 2;
-        blit(graphics, COVER, left, top + 7, 34, 192, 152, 0);
-        blit(graphics, COVER, left + 34, top + 7, 103, 192, 49, 0);
-        blit(graphics, COVER, left + 137, top + 7, 4, 192, 45, 0);
-        blit(graphics, COVER, left + 141, top + 7, 186, 192, 0, 0);
-        blit(graphics, LEFT_PAGE, left + 7, top, 156, 195, 0, 0);
-        blit(graphics, RIGHT_PANEL, left + 163, top, 156, 195, 0, 0);
-        graphics.text(font, title, left + 42, top + 29, TEXT_COLOR, false);
-        if (bound) {
-            graphics.fill(left + 173, top + 20, left + 305, top + 103, 0xFF15141D);
-            graphics.text(font, Component.literal("Age preview unavailable"), left + 181, top + 47,
-                    0xFFE9DFCB, false);
-            graphics.text(font, Component.literal("Click to enter"), left + 205, top + 65,
-                    0xFFE9DFCB, false);
-        } else {
-            graphics.text(font, Component.literal("Bind a prototype Age"), left + 183, top + 39,
-                    TEXT_COLOR, false);
+        PortLegacyBookArtwork.drawCover(graphics, left, top, true);
+        if (pageIndex > 0) PortLegacyBookArtwork.drawLeftPage(graphics, left, top);
+        if (pageIndex == 0) {
+            if (bound) {
+                graphics.nextStratum();
+                linkPanel.render(graphics, left, top, partialTick);
+                graphics.nextStratum();
+            }
+            PortLegacyBookArtwork.drawPanelPage(graphics, left, top);
+            if (bound) {
+                graphics.enableScissor(left + 38, top + 38, left + 154, top + 174);
+                int textY = PortLegacyBookArtwork.drawText(graphics, font, title, left + 40, top + 40, 110, TEXT_COLOR);
+                Component author = pages.author().isBlank()
+                        ? Component.translatable("screen.rivencraft.age.unknown_author") : Component.literal(pages.author());
+                PortLegacyBookArtwork.drawText(graphics, font, author, left + 50, textY + 2, 100, TEXT_COLOR);
+                graphics.disableScissor();
+            } else {
+                graphics.text(font, title, left + 42, top + 29, TEXT_COLOR, false);
+                graphics.text(font, Component.literal(standSource == null ? "Bind a prototype Age" : "Remove book to bind"),
+                        left + 183, top + 39, TEXT_COLOR, false);
+            }
+        } else if (pages.symbolAt(pageIndex).isPresent()) {
+            PortLegacyBookArtwork.drawFullPage(graphics, left, top);
+            graphics.nextStratum();
+            var symbol = pages.symbolAt(pageIndex).orElseThrow();
+            ItemStack glyph = new ItemStack(Rivencraft.PAGE.get());
+            glyph.set(Rivencraft.SYMBOL_PAGE_ID.get(), symbol);
+            glyph.set(Rivencraft.PAGE_GLYPH_ONLY.get(), true);
+            graphics.enableScissor(left + 174, top + 26, left + 306, top + 172);
+            graphics.pose().pushMatrix();
+            graphics.pose().translate(left + 177, top + 29);
+            graphics.pose().scale(8.0F, 8.0F);
+            graphics.fakeItem(glyph, 0, 0);
+            graphics.pose().popMatrix();
+            graphics.disableScissor();
         }
+        graphics.nextStratum();
+        PortLegacyBookArtwork.drawCounter(graphics, font, left, top, pageIndex, pages.lastPage());
         super.extractRenderState(graphics, mouseX, mouseY, partialTick);
     }
 
     @Override
     public boolean mouseClicked(MouseButtonEvent event, boolean doubleClick) {
-        if (bound && event.button() == InputConstants.MOUSE_BUTTON_LEFT) {
+        if (event.button() == InputConstants.MOUSE_BUTTON_LEFT) {
             int left = (width - WIDTH) / 2;
             int top = (height - HEIGHT) / 2;
-            if (event.x() >= left + 173 && event.x() < left + 305
-                    && event.y() >= top + 20 && event.y() < top + 103) {
-                ClientPacketDistributor.sendToServer(new UseDescriptiveBookPayload(hand == InteractionHand.OFF_HAND));
+            int direction = PortLegacyBookArtwork.turnDirection(event.x() - left, event.y() - top, pageIndex, pages.lastPage());
+            if (direction != 0) { turnPage(direction); return true; }
+            if (bound && pageIndex == 0 && PortLegacyLinkPanel.contains(event.x() - left, event.y() - top)) {
+                if (standSource != null) ClientPacketDistributor.sendToServer(standSource);
+                else ClientPacketDistributor.sendToServer(new UseDescriptiveBookPayload(hand == InteractionHand.OFF_HAND));
                 onClose();
                 return true;
             }
@@ -92,6 +122,36 @@ public final class PortDescriptiveBookScreen extends Screen {
         return super.mouseClicked(event, doubleClick);
     }
 
+    private void turnPage(int direction) {
+        int next = pages.turn(pageIndex, direction);
+        if (next == pageIndex) return;
+        pageIndex = next;
+        minecraft.getSoundManager().play(net.minecraft.client.resources.sounds.SimpleSoundInstance.forUI(
+                net.minecraft.sounds.SoundEvents.BOOK_PAGE_TURN, 1.0F, 0.65F));
+        updatePageControls();
+    }
+
+    private void updatePageControls() {
+        for (var widget : renderables) if (widget instanceof net.minecraft.client.gui.components.AbstractWidget control)
+            control.visible = pageIndex == 0;
+    }
+
+    @Override public boolean keyPressed(net.minecraft.client.input.KeyEvent event) {
+        if (event.isEscape()) return super.keyPressed(event);
+        if (titleInput == null || !titleInput.isFocused() || !titleInput.visible) {
+            if (event.isLeft()) { turnPage(-1); return true; }
+            if (event.isRight()) { turnPage(1); return true; }
+        } else {
+            // Keep inventory/hotbar actions out of a focused name field.
+            return titleInput.keyPressed(event);
+        }
+        return super.keyPressed(event);
+    }
+
+    @Override public void tick() {
+        if (bound) linkPanel.tick();
+    }
+
     @Override
     public boolean isPauseScreen() {
         return false;
@@ -105,12 +165,4 @@ public final class PortDescriptiveBookScreen extends Screen {
         onClose();
     }
 
-    private static Identifier texture(String filename) {
-        return Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "textures/gui/" + filename);
-    }
-
-    private static void blit(GuiGraphicsExtractor graphics, Identifier texture, int x, int y,
-                             int width, int height, int u, int v) {
-        graphics.blit(RenderPipelines.GUI_TEXTURED, texture, x, y, u, v, width, height, 256, 256);
-    }
 }

ports/mc263/src/main/java/net/dnorberg/rivencraft/client/PortLegacyBookArtwork.java

@@ -0,0 +1,70 @@
+package net.dnorberg.rivencraft.client;
+
+import net.minecraft.client.gui.GuiGraphicsExtractor;
+import net.minecraft.client.renderer.RenderPipelines;
+import net.minecraft.resources.Identifier;
+
+/** Original Mystcraft Legacy book atlases and page composition (LGPL-3.0,
+ * copyright XCompWiz, revision 9bc8ddc061845df0cd5ea47f4fdef773cff786ae). */
+final class PortLegacyBookArtwork {
+    private static final int ATLAS_SIZE = 256;
+    private static final Identifier COVER = texture("bookui_cover.png");
+    private static final Identifier LEFT_PAGE = texture("notebook_pages.png");
+    private static final Identifier RIGHT_PANEL = texture("bookui_pager.png");
+    private static final Identifier RIGHT_FULL = texture("bookui_rpage_full.png");
+
+    private PortLegacyBookArtwork() {}
+
+    static void drawCover(GuiGraphicsExtractor graphics, int left, int top, boolean gilded) {
+        blit(graphics, COVER, left, top + 7, 34, 192, 152, 0);
+        blit(graphics, COVER, left + 34, top + 7, 103, 192, 49, 0);
+        blit(graphics, COVER, left + 137, top + 7, 4, 192, 45, 0);
+        blit(graphics, COVER, left + 141, top + 7, 186, 192, 0, 0);
+        if (gilded) {
+            blit(graphics, COVER, left, top + 7, 34, 192, 186, 0);
+            blit(graphics, COVER, left + 293, top + 7, 34, 192, 186, 0);
+        }
+    }
+
+    static void drawLeftPage(GuiGraphicsExtractor graphics, int left, int top) {
+        blit(graphics, LEFT_PAGE, left + 7, top, 156, 195, 0, 0);
+    }
+
+    static void drawPanelPage(GuiGraphicsExtractor graphics, int left, int top) {
+        blit(graphics, RIGHT_PANEL, left + 163, top, 156, 195, 0, 0);
+    }
+
+    static void drawFullPage(GuiGraphicsExtractor graphics, int left, int top) {
+        blit(graphics, RIGHT_FULL, left + 163, top, 156, 195, 0, 0);
+    }
+
+    static int drawText(GuiGraphicsExtractor graphics, net.minecraft.client.gui.Font font,
+                        net.minecraft.network.chat.Component text, int x, int y, int width, int color) {
+        for (var line : font.split(text, width)) {
+            graphics.text(font, line, x, y, color, false);
+            y += font.lineHeight;
+        }
+        return y;
+    }
+
+    static void drawCounter(GuiGraphicsExtractor graphics, net.minecraft.client.gui.Font font,
+                            int left, int top, int page, int last) {
+        String counter = page + "/" + last;
+        graphics.text(font, counter, left + 165 - font.width(counter) / 2, top + 185, 0xFF000000, false);
+    }
+
+    static int turnDirection(double x, double y, int page, int last) {
+        if (y < 164 || y >= 195) return 0;
+        if (page > 0 && x >= 7 && x < 35) return -1;
+        return page < last && x >= 293 && x < 320 ? 1 : 0;
+    }
+
+    private static Identifier texture(String filename) {
+        return Identifier.fromNamespaceAndPath("rivencraft", "textures/gui/" + filename);
+    }
+
+    private static void blit(GuiGraphicsExtractor graphics, Identifier texture, int x, int y,
+                             int width, int height, int u, int v) {
+        graphics.blit(RenderPipelines.GUI_TEXTURED, texture, x, y, u, v, width, height, ATLAS_SIZE, ATLAS_SIZE);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/client/PortLegacyLinkPanel.java

@@ -0,0 +1,76 @@
+package net.dnorberg.rivencraft.client;
+
+import net.minecraft.client.gui.GuiGraphicsExtractor;
+
+/**
+ * Built-in linking-panel animation inspired by Mystcraft Legacy's portal bloom.
+ *
+ * <p>The original effect used a GLSL noise shader over an optional live world
+ * view. This port retains the 1.21.1 fallback's two noisy spirals and default teal
+ * tint, using the normal GUI API without a renderer mod.</p>
+ */
+final class PortLegacyLinkPanel {
+    static final int X = 173, Y = 20, WIDTH = 132, HEIGHT = 83;
+    private static final int CELL_SIZE = 3;
+    private static final int BORDER_COLOR = 0xFF7B6AA8;
+    private int ticks;
+    private static final int LINK_COLOR = 0xFF006666;
+
+    static boolean contains(double x, double y) {
+        return x >= X && x < X + WIDTH && y >= Y && y < Y + HEIGHT;
+    }
+
+    void render(GuiGraphicsExtractor graphics, int bookLeft, int bookTop, float partialTick) {
+        render(graphics, bookLeft + X, bookTop + Y, WIDTH, HEIGHT, partialTick);
+    }
+
+    void tick() {
+        ticks++;
+    }
+
+    private void render(GuiGraphicsExtractor graphics, int left, int top, int width, int height, float partialTick) {
+        graphics.fill(left, top, left + width, top + height, 0xFF000011);
+
+        float time = (ticks + partialTick) * 0.035F;
+        float reveal = Math.min(1.0F, time / 1.8F);
+        for (int y = 1; y < height - 1; y += CELL_SIZE) {
+            for (int x = 1; x < width - 1; x += CELL_SIZE) {
+                float normalizedX = (x - width * 0.5F) / height;
+                float normalizedY = (y - height * 0.5F) / height;
+                float first = spiral(normalizedX, normalizedY, time, 0.0F);
+                float second = spiral(normalizedX, normalizedY, time, 2.35F);
+                float intensity = Math.max(first, second) * reveal;
+                if (intensity <= 0.035F) {
+                    continue;
+                }
+
+                int color = scaledColor(LINK_COLOR, Math.min(1.0F, 0.12F + intensity));
+                graphics.fill(left + x, top + y,
+                        left + Math.min(width - 1, x + CELL_SIZE),
+                        top + Math.min(height - 1, y + CELL_SIZE), color);
+            }
+        }
+        graphics.outline(left, top, width, height, BORDER_COLOR);
+    }
+
+    private static float spiral(float x, float y, float time, float phase) {
+        float distance = (float)Math.sqrt(x * x + y * y);
+        float angle = (float)Math.atan2(y, x);
+        float arm = 0.5F + 0.5F * (float)Math.cos(angle * 3.0F - distance * 25.0F + time * 4.0F + phase);
+        float pulse = 0.72F + 0.28F * noise(x * 31.0F, y * 31.0F, time + phase);
+        float core = Math.max(0.0F, 1.0F - distance * 2.15F);
+        return core * (0.28F + arm * 0.72F) * pulse;
+    }
+
+    private static float noise(float x, float y, float time) {
+        double value = Math.sin(x * 12.9898D + y * 78.233D + time * 19.19D) * 43758.5453D;
+        return (float)(value - Math.floor(value));
+    }
+
+    private static int scaledColor(int color, float scale) {
+        int red = Math.min(255, Math.round(((color >> 16) & 0xFF) * scale + 18.0F * scale));
+        int green = Math.min(255, Math.round(((color >> 8) & 0xFF) * scale + 24.0F * scale));
+        int blue = Math.min(255, Math.round((color & 0xFF) * scale + 42.0F * scale));
+        return 0xFF000000 | red << 16 | green << 8 | blue;
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/client/PortLinkingBookScreen.java

@@ -10,35 +10,48 @@ import net.minecraft.client.gui.components.Button;
 import net.minecraft.client.gui.components.EditBox;
 import net.minecraft.client.gui.screens.Screen;
 import net.minecraft.client.input.MouseButtonEvent;
-import net.minecraft.client.renderer.RenderPipelines;
 import net.minecraft.network.chat.Component;
-import net.minecraft.resources.Identifier;
 import net.minecraft.world.InteractionHand;
 import net.minecraft.world.item.ItemStack;
 import net.neoforged.neoforge.client.network.ClientPacketDistributor;
 
-/** Minimal 26.3 book interaction using the Legacy artwork; live preview is not ported yet. */
+/** Legacy Linking Book front and final spreads with the shared fallback panel. */
 public final class PortLinkingBookScreen extends Screen {
     private static final int WIDTH = 327;
     private static final int HEIGHT = 199;
     private static final int TEXT_COLOR = 0xFF3B281B;
-    private static final Identifier COVER = texture("bookui_cover.png");
-    private static final Identifier LEFT_PAGE = texture("notebook_pages.png");
-    private static final Identifier RIGHT_PANEL = texture("bookui_pager.png");
+
 
     private final InteractionHand hand;
     private final boolean bound;
+    private final net.dnorberg.rivencraft.item.LinkBookTarget target;
+    private final boolean returnLink;
+    private final Component destination;
+    private int pageIndex;
+    private final PortLegacyLinkPanel linkPanel = new PortLegacyLinkPanel();
+    private net.dnorberg.rivencraft.network.UseBookStandPayload standSource;
     private EditBox titleInput;
 
     public PortLinkingBookScreen(InteractionHand hand, ItemStack book) {
         super(book.getHoverName());
         this.hand = hand;
-        bound = book.has(Rivencraft.LINK_BOOK_TARGET.get());
+        target = book.get(Rivencraft.LINK_BOOK_TARGET.get());
+        bound = target != null;
+        destination = bound ? net.dnorberg.rivencraft.item.LinkingBookItem.destinationName(book, target) : Component.empty();
+        Component customName = book.get(net.minecraft.core.component.DataComponents.CUSTOM_NAME);
+        returnLink = customName != null
+                && customName.getContents() instanceof net.minecraft.network.chat.contents.TranslatableContents translated
+                && translated.getKey().equals("item.rivencraft.linking_book.return");
+    }
+
+    public PortLinkingBookScreen(net.dnorberg.rivencraft.network.UseBookStandPayload source) {
+        this(InteractionHand.MAIN_HAND, source.book());
+        standSource = source;
     }
 
     @Override
     protected void init() {
-        if (bound) return;
+        if (bound || standSource != null) return;
         int left = (width - WIDTH) / 2;
         int top = (height - HEIGHT) / 2;
         titleInput = new EditBox(font, left + 40, top + 69, 110, 20,
@@ -51,38 +64,55 @@ public final class PortLinkingBookScreen extends Screen {
                 .bounds(left + 40, top + 100, 53, 20).build());
         addRenderableWidget(Button.builder(Component.literal("Cancel"), button -> onClose())
                 .bounds(left + 97, top + 100, 53, 20).build());
+        updatePageControls();
     }
 
     @Override
     public void extractRenderState(GuiGraphicsExtractor graphics, int mouseX, int mouseY, float partialTick) {
         int left = (width - WIDTH) / 2;
         int top = (height - HEIGHT) / 2;
-        blit(graphics, COVER, left, top + 7, 34, 192, 152, 0);
-        blit(graphics, COVER, left + 34, top + 7, 103, 192, 49, 0);
-        blit(graphics, COVER, left + 137, top + 7, 4, 192, 45, 0);
-        blit(graphics, COVER, left + 141, top + 7, 186, 192, 0, 0);
-        if (bound) blit(graphics, LEFT_PAGE, left + 7, top, 156, 195, 0, 0);
-        blit(graphics, RIGHT_PANEL, left + 163, top, 156, 195, 0, 0);
-        graphics.text(font, title, left + 42, top + 29, TEXT_COLOR, false);
-        if (bound) {
-            graphics.fill(left + 173, top + 20, left + 305, top + 103, 0xFF15141D);
-            graphics.text(font, Component.literal("Destination preview"), left + 185, top + 47, 0xFFE9DFCB, false);
-            graphics.text(font, Component.literal("Click to link"), left + 205, top + 65, 0xFFE9DFCB, false);
+        PortLegacyBookArtwork.drawCover(graphics, left, top, false);
+        if (pageIndex > 0) {
+            PortLegacyBookArtwork.drawLeftPage(graphics, left, top);
         } else {
-            graphics.text(font, Component.literal("Name this Linking Book"), left + 183, top + 39,
-                    TEXT_COLOR, false);
+            if (bound) {
+                graphics.nextStratum();
+                linkPanel.render(graphics, left, top, partialTick);
+                graphics.nextStratum();
+            }
+            PortLegacyBookArtwork.drawPanelPage(graphics, left, top);
+            graphics.enableScissor(left + 38, top + 38, left + 154, top + 174);
+            if (bound) {
+                int y = top + 40;
+                if (!returnLink) y = PortLegacyBookArtwork.drawText(graphics, font, title,
+                        left + 40, y, 110, TEXT_COLOR) + 4;
+                y = PortLegacyBookArtwork.drawText(graphics, font, destination, left + 50, y, 100, TEXT_COLOR) + 10;
+                var pos = net.minecraft.core.BlockPos.containing(target.x(), target.y(), target.z());
+                PortLegacyBookArtwork.drawText(graphics, font,
+                        Component.literal(pos.getX() + ", " + pos.getY() + ", " + pos.getZ()),
+                        left + 40, y, 110, TEXT_COLOR);
+            } else {
+                PortLegacyBookArtwork.drawText(graphics, font, Component.literal(
+                        standSource == null ? "Name this Linking Book" : "Remove book to bind"),
+                        left + 40, top + 43, 110, TEXT_COLOR);
+            }
+            graphics.disableScissor();
         }
+        graphics.nextStratum();
+        PortLegacyBookArtwork.drawCounter(graphics, font, left, top, pageIndex, 1);
         super.extractRenderState(graphics, mouseX, mouseY, partialTick);
     }
 
     @Override
     public boolean mouseClicked(MouseButtonEvent event, boolean doubleClick) {
-        if (bound && event.button() == InputConstants.MOUSE_BUTTON_LEFT) {
+        if (event.button() == InputConstants.MOUSE_BUTTON_LEFT) {
             int left = (width - WIDTH) / 2;
             int top = (height - HEIGHT) / 2;
-            if (event.x() >= left + 173 && event.x() < left + 305
-                    && event.y() >= top + 20 && event.y() < top + 103) {
-                ClientPacketDistributor.sendToServer(new UseLinkingBookPayload(hand == InteractionHand.OFF_HAND));
+            int direction = PortLegacyBookArtwork.turnDirection(event.x() - left, event.y() - top, pageIndex, 1);
+            if (direction != 0) { turnPage(direction); return true; }
+            if (bound && pageIndex == 0 && PortLegacyLinkPanel.contains(event.x() - left, event.y() - top)) {
+                if (standSource != null) ClientPacketDistributor.sendToServer(standSource);
+                else ClientPacketDistributor.sendToServer(new UseLinkingBookPayload(hand == InteractionHand.OFF_HAND));
                 onClose();
                 return true;
             }
@@ -90,6 +120,33 @@ public final class PortLinkingBookScreen extends Screen {
         return super.mouseClicked(event, doubleClick);
     }
 
+    private void turnPage(int direction) {
+        int next = Math.clamp(pageIndex + direction, 0, 1);
+        if (next == pageIndex) return;
+        pageIndex = next;
+        minecraft.getSoundManager().play(net.minecraft.client.resources.sounds.SimpleSoundInstance.forUI(
+                net.minecraft.sounds.SoundEvents.BOOK_PAGE_TURN, 1.0F, 0.65F));
+        updatePageControls();
+    }
+
+    private void updatePageControls() {
+        for (var widget : renderables) if (widget instanceof net.minecraft.client.gui.components.AbstractWidget control)
+            control.visible = pageIndex == 0;
+    }
+
+    @Override public boolean keyPressed(net.minecraft.client.input.KeyEvent event) {
+        if (event.isEscape()) return super.keyPressed(event);
+        if (titleInput == null || !titleInput.isFocused() || !titleInput.visible) {
+            if (event.isLeft()) { turnPage(-1); return true; }
+            if (event.isRight()) { turnPage(1); return true; }
+        } else return titleInput.keyPressed(event);
+        return super.keyPressed(event);
+    }
+
+    @Override public void tick() {
+        if (bound) linkPanel.tick();
+    }
+
     @Override
     public boolean isPauseScreen() {
         return false;
@@ -103,12 +160,4 @@ public final class PortLinkingBookScreen extends Screen {
         onClose();
     }
 
-    private static Identifier texture(String filename) {
-        return Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "textures/gui/" + filename);
-    }
-
-    private static void blit(GuiGraphicsExtractor graphics, Identifier texture, int x, int y,
-                             int width, int height, int u, int v) {
-        graphics.blit(RenderPipelines.GUI_TEXTURED, texture, x, y, u, v, width, height, 256, 256);
-    }
 }

ports/mc263/src/main/java/net/dnorberg/rivencraft/entity/DroppedBookEntity.java

@@ -26,6 +26,17 @@ public final class DroppedBookEntity extends ItemEntity {
         setPickUpDelay(20);
     }
 
+    /** Conversion preserves ordinary toss/drop state; the travel constructor has different placement rules. */
+    public static DroppedBookEntity fromDrop(ItemEntity source) {
+        var book = new DroppedBookEntity(Rivencraft.DROPPED_BOOK.get(), source.level());
+        book.restoreFrom(source);
+        // The original remains registered until replacement succeeds, so this needs a new identity.
+        book.setUUID(java.util.UUID.randomUUID());
+        book.setItem(source.getItem().copy());
+        book.setUnlimitedLifetime();
+        return book;
+    }
+
     @Override
     public void tick() {
         super.tick();

ports/mc263/src/main/java/net/dnorberg/rivencraft/event/BookStandConversionHandler.java

@@ -0,0 +1,40 @@
+package net.dnorberg.rivencraft.event;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.block.BookStandBlock;
+import net.dnorberg.rivencraft.block.entity.BookStandBlockEntity;
+import net.minecraft.core.BlockPos;
+import net.minecraft.sounds.SoundEvents;
+import net.minecraft.sounds.SoundSource;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.InteractionResult;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.LecternBlock;
+import net.neoforged.neoforge.event.entity.player.PlayerInteractEvent;
+
+public final class BookStandConversionHandler {
+    private BookStandConversionHandler() {}
+    public static void onRightClickBlock(PlayerInteractEvent.RightClickBlock event) {
+        var book = event.getItemStack();
+        if (!book.is(Rivencraft.LINKING_BOOK.get()) && !book.is(Rivencraft.DESCRIPTIVE_BOOK.get()) && !book.is(Rivencraft.PAGE.get())) return;
+        var state = event.getLevel().getBlockState(event.getPos());
+        if (!state.is(Blocks.LECTERN) || state.getValue(LecternBlock.HAS_BOOK)) return;
+        event.setCanceled(true);
+        event.setCancellationResult(InteractionResult.SUCCESS);
+        if (!event.getLevel().isClientSide()) convert(event.getEntity(), event.getHand(), event.getPos());
+    }
+    public static boolean convert(Player player, InteractionHand hand, BlockPos pos) {
+        var level = player.level();
+        var state = level.getBlockState(pos);
+        var book = player.getItemInHand(hand);
+        if (level.isClientSide() || !state.is(Blocks.LECTERN) || state.getValue(LecternBlock.HAS_BOOK)
+                || (!book.is(Rivencraft.LINKING_BOOK.get()) && !book.is(Rivencraft.DESCRIPTIVE_BOOK.get()) && !book.is(Rivencraft.PAGE.get()))) return false;
+        if (!level.setBlock(pos, Rivencraft.BOOK_STAND.get().defaultBlockState()
+                .setValue(BookStandBlock.FACING, state.getValue(LecternBlock.FACING)).setValue(BookStandBlock.HAS_BOOK, true), 3)) return false;
+        if (!(level.getBlockEntity(pos) instanceof BookStandBlockEntity stand)) return false;
+        stand.setBook(book.consumeAndReturn(1, player));
+        level.playSound(null, pos, SoundEvents.BOOK_PUT, SoundSource.BLOCKS, 1, 1);
+        return true;
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/event/DroppedBookConversionHandler.java

@@ -0,0 +1,37 @@
+package net.dnorberg.rivencraft.event;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.entity.DroppedBookEntity;
+import net.minecraft.server.TickTask;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.entity.item.ItemEntity;
+import net.minecraft.world.item.ItemStack;
+import net.neoforged.bus.api.EventPriority;
+import net.neoforged.bus.api.SubscribeEvent;
+import net.neoforged.fml.common.EventBusSubscriber;
+import net.neoforged.neoforge.event.entity.EntityJoinLevelEvent;
+
+/** Converts ordinary book drops from every source, including entities restored from disk. */
+@EventBusSubscriber(modid = Rivencraft.MOD_ID)
+public final class DroppedBookConversionHandler {
+    private DroppedBookConversionHandler() {}
+
+    @SubscribeEvent(priority = EventPriority.LOWEST)
+    public static void onJoin(EntityJoinLevelEvent event) {
+        if (!(event.getLevel() instanceof ServerLevel level)
+                || !(event.getEntity() instanceof ItemEntity item) || item instanceof DroppedBookEntity
+                || !isBook(item.getItem())) return;
+        // Join events can run before chunk promotion. Do not add another entity inside that callback.
+        // Keep the original until the queued replacement has actually been accepted.
+        level.getServer().schedule(new TickTask(0, () -> {
+            if (level.getServer().getLevel(level.dimension()) != level || item.isRemoved()
+                    || !item.isAddedToLevel() || item.level() != level || !isBook(item.getItem())) return;
+            var replacement = DroppedBookEntity.fromDrop(item);
+            if (level.addFreshEntity(replacement)) item.discard();
+        }));
+    }
+
+    private static boolean isBook(ItemStack stack) {
+        return stack.is(Rivencraft.LINKING_BOOK.get()) || stack.is(Rivencraft.DESCRIPTIVE_BOOK.get());
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/item/DescriptiveBookItem.java

@@ -36,5 +36,6 @@ public final class DescriptiveBookItem extends Item {
                                 Consumer<Component> tooltip, TooltipFlag flag) {
         Identifier id = stack.get(Rivencraft.AGE_BOOK_ID.get());
         tooltip.accept(Component.literal(id == null ? "Unbound (26.3 port preview)" : "Age: " + id));
+        stack.getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE).forDescriptiveBook().appendTooltip(tooltip);
     }
 }

ports/mc263/src/main/java/net/dnorberg/rivencraft/item/InkVialItem.java

@@ -3,13 +3,13 @@ package net.dnorberg.rivencraft.item;
 import java.util.function.Consumer;
 import net.dnorberg.rivencraft.Rivencraft;
 import net.minecraft.network.chat.Component;
-import net.minecraft.util.Prediction;
 import net.minecraft.world.InteractionHand;
 import net.minecraft.world.InteractionResult;
 import net.minecraft.world.entity.player.Player;
 import net.minecraft.world.item.Item;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.Items;
+import net.dnorberg.rivencraft.writing.WritingInkService;
 import net.minecraft.world.item.TooltipFlag;
 import net.minecraft.world.item.component.TooltipDisplay;
 import net.minecraft.world.level.Level;
@@ -17,8 +17,6 @@ import net.minecraft.world.level.Level;
 /** A stackable 16-use vial; using it with paper in the other hand prepares a Link Panel. */
 public final class InkVialItem extends Item {
     public static final int CAPACITY = 16;
-    // Match the 1.21.1 default; port the configurable cost with the full configuration system.
-    public static final int LINK_PANEL_COST = 2;
 
     public InkVialItem(Properties properties) {
         super(properties);
@@ -30,37 +28,16 @@ public final class InkVialItem extends Item {
 
     @Override
     public InteractionResult use(Level level, Player player, InteractionHand hand) {
-        InteractionHand paperHand = hand == InteractionHand.MAIN_HAND
-                ? InteractionHand.OFF_HAND : InteractionHand.MAIN_HAND;
-        ItemStack vial = player.getItemInHand(hand);
-        ItemStack paper = player.getItemInHand(paperHand);
-        int ink = remaining(vial);
-        if (!vial.is(Rivencraft.INK_VIAL.get()) || !paper.is(Items.PAPER)
-                || ink < LINK_PANEL_COST || ink > CAPACITY) {
-            return InteractionResult.PASS;
+        if (level.isClientSide()) {
+            // LOCAL gameplay config is not synchronized. Predict only item eligibility;
+            // the server decides affordability using its own configured cost.
+            var paperHand = hand == InteractionHand.MAIN_HAND ? InteractionHand.OFF_HAND : InteractionHand.MAIN_HAND;
+            int ink = remaining(player.getItemInHand(hand));
+            return player.getItemInHand(hand).is(Rivencraft.INK_VIAL.get())
+                    && player.getItemInHand(paperHand).is(Items.PAPER) && ink > 0 && ink <= CAPACITY
+                    ? InteractionResult.SUCCESS : InteractionResult.PASS;
         }
-        if (level.isClientSide()) return InteractionResult.SUCCESS;
-
-        ItemStack panel = PageItem.createLinkPanelPage();
-        int newInk = ink - LINK_PANEL_COST;
-        ItemStack spentVial = newInk == 0
-                ? new ItemStack(Items.GLASS_BOTTLE)
-                : new ItemStack(Rivencraft.INK_VIAL.get());
-        if (newInk > 0) spentVial.set(Rivencraft.INK_REMAINING.get(), newInk);
-
-        if (paper.getCount() == 1) {
-            player.setItemInHand(paperHand, panel);
-        } else {
-            paper.shrink(1);
-            giveOrDrop(player, panel);
-        }
-        if (vial.getCount() == 1) {
-            player.setItemInHand(hand, spentVial);
-        } else {
-            vial.shrink(1);
-            giveOrDrop(player, spentVial);
-        }
-        return InteractionResult.SUCCESS;
+        return WritingInkService.prepareLinkPanel(player, hand) ? InteractionResult.SUCCESS : InteractionResult.PASS;
     }
 
     @Override
@@ -70,7 +47,4 @@ public final class InkVialItem extends Item {
         tooltip.accept(Component.translatable("item.rivencraft.ink_vial.usage"));
     }
 
-    private static void giveOrDrop(Player player, ItemStack stack) {
-        if (!player.getInventory().add(stack)) player.drop(stack, false, Prediction.SERVER_ONLY);
-    }
 }

ports/mc263/src/main/java/net/dnorberg/rivencraft/item/LinkDisarmService.java

@@ -0,0 +1,64 @@
+package net.dnorberg.rivencraft.item;
+
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.phys.Vec3;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.Mob;
+import net.minecraft.world.entity.animal.equine.AbstractHorse;
+import net.minecraft.world.entity.item.ItemEntity;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.item.ItemStack;
+
+/** Legacy-style Disarm: leave carried items and eligible equipment at the departure point. */
+public final class LinkDisarmService {
+    private LinkDisarmService() {}
+
+    public static boolean mayTravel(Entity entity) {
+        // Legacy refuses loose items and dropped Link Books on Disarm links.
+        return !(entity instanceof ItemEntity);
+    }
+
+    public static void disarmAt(Entity entity, ServerLevel source, Vec3 departure) {
+        if (entity instanceof ServerPlayer player) {
+            eject(player.getInventory(), source, departure);
+            player.containerMenu.broadcastChanges();
+        }
+        if (entity instanceof Container container) eject(container, source, departure);
+        if (entity instanceof AbstractHorse horse) eject(horse.getInventory(), source, departure);
+        if (entity instanceof Mob mob) dropEquipment(mob, source, departure);
+    }
+
+    private static void eject(Container inventory, ServerLevel source, Vec3 departure) {
+        for (int slot = 0; slot < inventory.getContainerSize(); slot++) {
+            ItemStack stack = inventory.getItem(slot);
+            if (stack.isEmpty()) continue;
+            inventory.setItem(slot, ItemStack.EMPTY);
+            drop(stack, source, departure);
+        }
+        inventory.setChanged();
+    }
+
+    private static void dropEquipment(Mob mob, ServerLevel source, Vec3 departure) {
+        for (EquipmentSlot slot : EquipmentSlot.values()) {
+            ItemStack stack = mob.getItemBySlot(slot);
+            if (stack.isEmpty()) continue;
+            float chance = mob.getDropChances().byEquipment(slot);
+            mob.setItemSlot(slot, ItemStack.EMPTY);
+            if (chance <= 0 || mob.getRandom().nextFloat() >= chance) continue;
+            if (chance <= 1 && stack.isDamageableItem()) {
+                int minimum = Math.max(stack.getMaxDamage() - 25, 1);
+                int damage = stack.getMaxDamage() - mob.getRandom().nextInt(
+                        1 + mob.getRandom().nextInt(minimum));
+                stack.setDamageValue(Math.clamp(damage, 1, minimum));
+            }
+            drop(stack, source, departure);
+        }
+    }
+    private static void drop(ItemStack stack, ServerLevel source, Vec3 position) {
+        var dropped = new ItemEntity(source, position.x, position.y, position.z, stack);
+        dropped.setDefaultPickUpDelay();
+        source.addFreshEntity(dropped);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/item/LinkProperties.java

@@ -5,12 +5,17 @@ import io.netty.buffer.ByteBuf;
 import net.minecraft.network.codec.ByteBufCodecs;
 import net.minecraft.network.codec.StreamCodec;
 
-/** The three Ink Mixer modifiers currently supported by the 26.3 port. */
+/** Link Panel flags shared by the mixer, books and Link Modifier station. */
 public record LinkProperties(int flags) {
     public static final int DISARM = 1;
+    public static final int GENERATE_PLATFORM = 2;
+    public static final int INTRA_LINKING_ONLY = 16;
+    public static final int RELATIVE_LINK = 32;
+    public static final int DISABLE_PLATFORM = 64;
     public static final int MAINTAIN_MOMENTUM = 4;
     public static final int INTRA_LINKING = 8;
-    public static final int SUPPORTED = DISARM | MAINTAIN_MOMENTUM | INTRA_LINKING;
+    public static final int SUPPORTED = DISARM | GENERATE_PLATFORM | MAINTAIN_MOMENTUM | INTRA_LINKING
+            | INTRA_LINKING_ONLY | RELATIVE_LINK | DISABLE_PLATFORM;
     public static final LinkProperties NONE = new LinkProperties(0);
     public static final Codec<LinkProperties> CODEC = Codec.INT.xmap(LinkProperties::new, LinkProperties::flags);
     public static final StreamCodec<ByteBuf, LinkProperties> STREAM_CODEC = StreamCodec.of(
@@ -23,6 +28,18 @@ public record LinkProperties(int flags) {
         }
     }
 
+    public boolean allowsTravel(boolean sameDimension) {
+        return sameDimension ? has(INTRA_LINKING) || has(INTRA_LINKING_ONLY) : !has(INTRA_LINKING_ONLY);
+    }
+    public LinkProperties forDescriptiveBook() {
+        return new LinkProperties(flags & ~(INTRA_LINKING | INTRA_LINKING_ONLY));
+    }
+    public void appendTooltip(java.util.function.Consumer<net.minecraft.network.chat.Component> tooltip) {
+        int[] flags = {DISARM, MAINTAIN_MOMENTUM, INTRA_LINKING, INTRA_LINKING_ONLY, RELATIVE_LINK, GENERATE_PLATFORM, DISABLE_PLATFORM};
+        String[] names = {"disarm", "maintain_momentum", "intra_linking", "intra_linking_only", "relative_link", "generate_platform", "disable_platform"};
+        for (int i = 0; i < flags.length; i++) if (has(flags[i]))
+            tooltip.accept(net.minecraft.network.chat.Component.translatable("item.rivencraft.link_property." + names[i]));
+    }
     public boolean has(int flag) {
         return (flags & flag) != 0;
     }

ports/mc263/src/main/java/net/dnorberg/rivencraft/item/LinkingBookItem.java

@@ -18,7 +18,6 @@ import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.TooltipFlag;
 import net.minecraft.world.item.component.TooltipDisplay;
 import net.minecraft.world.level.Level;
-import net.minecraft.world.entity.item.ItemEntity;
 import net.minecraft.world.phys.Vec3;
 
 /** Handheld Linking Book; destination binding and travel are server-authoritative packets. */
@@ -40,12 +39,16 @@ public final class LinkingBookItem extends Item {
     }
 
     public static String travel(ServerPlayer player, ItemStack book) {
+        return travel(player, book, false);
+    }
+
+    public static String travel(ServerPlayer player, ItemStack book, boolean portal) {
         LinkBookTarget destination = book.get(Rivencraft.LINK_BOOK_TARGET.get());
         LinkProperties properties = book.getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE);
         if (destination == null) return "Unbound Linking Book (26.3 port preview)";
         if (!destination.valid()) return "Invalid Linking Book destination";
         if (player.level().dimension().identifier().equals(destination.dimension())
-                && !properties.has(LinkProperties.INTRA_LINKING)) {
+                && !properties.allowsTravel(true)) {
             return "Same-dimension linking requires an Intra-Linking page";
         }
         ServerLevel target = player.level().getServer().getLevel(
@@ -54,11 +57,13 @@ public final class LinkingBookItem extends Item {
         if (!AgeCatalogSync.ready(player, destination.dimension())) {
             return "Destination catalog not acknowledged by client";
         }
+        if (!properties.allowsTravel(target == player.level())) return "Intra-Linking Only cannot travel between dimensions";
+        destination = PortLinkDestinations.resolve(player.level(), target, player.blockPosition(), destination, properties);
+        if (!destination.valid()) return "Invalid relative destination";
         BlockPos feet = BlockPos.containing(destination.x(), destination.y(), destination.z());
         if (feet.getY() < target.getMinY() || feet.getY() + 1 >= target.getMaxY()
-                || !target.getWorldBorder().isWithinBounds(feet)) {
-            return "Destination is outside the world bounds";
-        }
+                || !target.getWorldBorder().isWithinBounds(feet)) return "Destination is outside the world bounds";
+        target.getChunkAt(feet);
         // Test the player's actual arrival volume: checking whole block shapes
         // would incorrectly reject links bound while standing on a slab.
         if (!target.noCollision(player, player.getBoundingBox().move(
@@ -71,14 +76,23 @@ public final class LinkingBookItem extends Item {
         Vec3 incoming = player.getDeltaMovement();
         boolean moved = player.teleportTo(target, destination.x(), destination.y(), destination.z(),
                 Set.of(), destination.yaw(), destination.pitch(), true);
-        if (moved) applySuccessfulLink(player, properties, source, departure, incoming, destination.yaw());
+        if (moved) {
+            PortLinkDestinations.generatePlatform(target, player.position(), properties);
+            applySuccessfulLink(player, properties, source, departure, incoming, destination.yaw(), portal);
+        }
         return moved ? null : "Teleportation failed";
     }
 
     /** Link Panel effects are shared by Linking and Descriptive Books. */
     public static void applySuccessfulLink(ServerPlayer player, LinkProperties properties,
                                            ServerLevel source, Vec3 departure, Vec3 incoming, float destinationYaw) {
-        LinkVisualEffects.play(source, departure, player, properties, false);
+        applySuccessfulLink(player, properties, source, departure, incoming, destinationYaw, false);
+    }
+
+    public static void applySuccessfulLink(ServerPlayer player, LinkProperties properties,
+                                           ServerLevel source, Vec3 departure, Vec3 incoming, float destinationYaw,
+                                           boolean portal) {
+        LinkVisualEffects.play(source, departure, player, properties, portal);
         if (properties.has(LinkProperties.MAINTAIN_MOMENTUM)) {
             double speed = Math.hypot(incoming.x, incoming.z);
             double yaw = Math.toRadians(destinationYaw);
@@ -88,33 +102,42 @@ public final class LinkingBookItem extends Item {
             player.setDeltaMovement(Vec3.ZERO);
         }
         if (properties.has(LinkProperties.DISARM)) {
-            for (int slot = 0; slot < player.getInventory().getContainerSize(); slot++) {
-                ItemStack carried = player.getInventory().getItem(slot);
-                if (carried.isEmpty()) continue;
-                player.getInventory().setItem(slot, ItemStack.EMPTY);
-                ItemEntity dropped = new ItemEntity(source, departure.x, departure.y, departure.z,
-                        carried.copy());
-                dropped.setDefaultPickUpDelay();
-                source.addFreshEntity(dropped);
-            }
-            player.getInventory().setChanged();
-            player.containerMenu.broadcastChanges();
+            LinkDisarmService.disarmAt(player, source, departure);
         }
     }
 
+    public static String destinationName(ServerLevel level) {
+        var id = level.dimension().identifier();
+        return net.dnorberg.rivencraft.age.RuntimeAgeBackend.savedAgeName(level.getServer(), id)
+                .orElseGet(() -> {
+                    if (id.equals(Level.OVERWORLD.identifier())) return "Overworld";
+                    if (id.equals(Level.NETHER.identifier())) return "The Nether";
+                    if (id.equals(Level.END.identifier())) return "The End";
+                    return id.toString();
+                });
+    }
+
+    public static Component destinationName(ItemStack book, LinkBookTarget target) {
+        String name = book.get(Rivencraft.LINK_DESTINATION_NAME.get());
+        if (name != null && !name.isBlank()) return Component.literal(name);
+        var id = target.dimension();
+        if (id.equals(Level.OVERWORLD.identifier())) return Component.translatable("dimension.minecraft.overworld");
+        if (id.equals(Level.NETHER.identifier())) return Component.translatable("dimension.minecraft.the_nether");
+        if (id.equals(Level.END.identifier())) return Component.translatable("dimension.minecraft.the_end");
+        return Component.literal(id.toString());
+    }
+
     @Override
     public void appendHoverText(ItemStack stack, TooltipContext context, TooltipDisplay display,
                                 Consumer<Component> tooltip, TooltipFlag flag) {
         LinkBookTarget target = stack.get(Rivencraft.LINK_BOOK_TARGET.get());
-        tooltip.accept(Component.literal(target == null ? "Unbound (26.3 port preview)"
-                : "Destination: " + target.dimension() + " (" + (int) target.x() + ", "
-                + (int) target.y() + ", " + (int) target.z() + ")"));
+        if (target == null) tooltip.accept(Component.literal("Unbound (26.3 port preview)"));
+        else {
+            BlockPos pos = BlockPos.containing(target.x(), target.y(), target.z());
+            tooltip.accept(Component.translatable("item.rivencraft.linking_book.destination",
+                    destinationName(stack, target).getString(), pos.getX(), pos.getY(), pos.getZ()));
+        }
         LinkProperties properties = stack.getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE);
-        if (properties.has(LinkProperties.DISARM))
-            tooltip.accept(Component.translatable("item.rivencraft.link_property.disarm"));
-        if (properties.has(LinkProperties.MAINTAIN_MOMENTUM))
-            tooltip.accept(Component.translatable("item.rivencraft.link_property.maintain_momentum"));
-        if (properties.has(LinkProperties.INTRA_LINKING))
-            tooltip.accept(Component.translatable("item.rivencraft.link_property.intra_linking"));
+        properties.appendTooltip(tooltip);
     }
 }

ports/mc263/src/main/java/net/dnorberg/rivencraft/item/PageItem.java

@@ -96,15 +96,7 @@ public final class PageItem extends Item {
             return;
         }
         LinkProperties properties = stack.getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE);
-        if (properties.has(LinkProperties.DISARM))
-            tooltip.accept(Component.translatable("item.rivencraft.link_property.disarm"));
-        if (properties.has(LinkProperties.MAINTAIN_MOMENTUM))
-            tooltip.accept(Component.translatable("item.rivencraft.link_property.maintain_momentum"));
-        if (properties.has(LinkProperties.INTRA_LINKING))
-            tooltip.accept(Component.translatable("item.rivencraft.link_property.intra_linking"));
-        tooltip.accept(Component.translatable(isLinkPanel(stack)
-                ? "item.rivencraft.page.link_panel.port_status"
-                : "item.rivencraft.page.blank.port_status"));
+        properties.appendTooltip(tooltip);
     }
 
     private static boolean isCorrupted(Identifier id) {

ports/mc263/src/main/java/net/dnorberg/rivencraft/item/PortHandheldTravel.java

@@ -21,6 +21,7 @@ public final class PortHandheldTravel {
         try {
             String failure = travel.get();
             if (failure != null) return failure;
+            net.dnorberg.rivencraft.advancement.ProgressionAdvancements.awardAgeTravel(player);
             dropped = source.addFreshEntity(new DroppedBookEntity(source, departure, book));
             return null;
         } finally {

ports/mc263/src/main/java/net/dnorberg/rivencraft/item/PortLinkDestinations.java

@@ -0,0 +1,30 @@
+package net.dnorberg.rivencraft.item;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.phys.Vec3;
+
+/** 1.21.1 Relative Link and optional Linking Book arrival-floor rules. */
+public final class PortLinkDestinations {
+    private PortLinkDestinations() {}
+    public static BlockPos relativeOrigin(BlockPos sourceSpawn, BlockPos destinationSpawn, BlockPos departure) {
+        return destinationSpawn.offset(departure.getX() - sourceSpawn.getX(), departure.getY() - sourceSpawn.getY(),
+                departure.getZ() - sourceSpawn.getZ());
+    }
+    public static BlockPos relativeOrigin(ServerLevel source, ServerLevel target, BlockPos departure) {
+        return relativeOrigin(source.getRespawnData().pos(), target.getRespawnData().pos(), departure);
+    }
+    public static LinkBookTarget resolve(ServerLevel source, ServerLevel target, BlockPos departure,
+                                          LinkBookTarget written, LinkProperties properties) {
+        if (!properties.has(LinkProperties.RELATIVE_LINK)) return written;
+        BlockPos pos = relativeOrigin(source, target, departure);
+        return new LinkBookTarget(written.dimension(), pos.getX() + 0.5, pos.getY(), pos.getZ() + 0.5, written.yaw(), written.pitch());
+    }
+    public static void generatePlatform(ServerLevel level, Vec3 arrival, LinkProperties properties) {
+        if (!properties.has(LinkProperties.GENERATE_PLATFORM)) return;
+        BlockPos feet = BlockPos.containing(arrival), floor = feet.below();
+        if (level.isEmptyBlock(floor) && level.isEmptyBlock(feet.above(2)))
+            level.setBlock(floor, Rivencraft.CLOUD_PLATFORM.get().defaultBlockState(), 3);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/menu/InkMixerMenu.java

@@ -1,6 +1,8 @@
 package net.dnorberg.rivencraft.menu;
 
 import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.advancement.ProgressionAdvancements;
+import net.minecraft.server.level.ServerPlayer;
 import net.dnorberg.rivencraft.block.entity.InkMixerBlockEntity;
 import net.minecraft.network.RegistryFriendlyByteBuf;
 import net.minecraft.world.Container;
@@ -110,6 +112,8 @@ public final class InkMixerMenu extends AbstractContainerMenu {
             if (!moveItemStackTo(remainder, PLAYER_START, slots.size(), true) || !remainder.isEmpty())
                 return ItemStack.EMPTY;
             if (!mixer.consumeLinkPanelMaterials()) return ItemStack.EMPTY;
+            if (player instanceof ServerPlayer serverPlayer)
+                ProgressionAdvancements.award(serverPlayer, ProgressionAdvancements.LINK_PANEL);
             refreshResult();
             return output;
         }
@@ -150,6 +154,8 @@ public final class InkMixerMenu extends AbstractContainerMenu {
         }
         @Override public void onTake(Player player, ItemStack stack) {
             if (!clientSide && mixer.consumeLinkPanelMaterials()) {
+                if (player instanceof ServerPlayer serverPlayer)
+                    ProgressionAdvancements.award(serverPlayer, ProgressionAdvancements.LINK_PANEL);
                 refreshResult();
             }
             super.onTake(player, stack);

ports/mc263/src/main/java/net/dnorberg/rivencraft/menu/LinkModifierMenu.java

@@ -0,0 +1,94 @@
+package net.dnorberg.rivencraft.menu;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.block.entity.LinkModifierBlockEntity;
+import net.dnorberg.rivencraft.item.LinkProperties;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.chat.Component;
+import net.minecraft.world.Container;
+import net.minecraft.world.SimpleContainer;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+
+/** 1.21.1's persistent single-book editing station, adapted to 26.3. */
+public final class LinkModifierMenu extends AbstractContainerMenu {
+    public static final int TOGGLE_DISARM = 1, TOGGLE_MOMENTUM = 2, TOGGLE_INTRA = 3,
+            TOGGLE_INTRA_ONLY = 5, TOGGLE_RELATIVE = 6, TOGGLE_PLATFORM = 7;
+    private final LinkModifierBlockEntity modifier;
+    private final Container books;
+    private final Player owner;
+    public LinkModifierMenu(int id, Inventory inventory, RegistryFriendlyByteBuf data) {
+        this(id, inventory, inventory.player.level().getBlockEntity(data.readBlockPos())
+                instanceof LinkModifierBlockEntity found ? found : null);
+    }
+    public LinkModifierMenu(int id, Inventory inventory, LinkModifierBlockEntity modifier) {
+        super(Rivencraft.LINK_MODIFIER_MENU.get(), id);
+        this.modifier = modifier;
+        books = modifier == null ? new SimpleContainer(1) : modifier;
+        owner = inventory.player;
+        addSlot(new Slot(books, 0, 80, 35) {
+            @Override public boolean mayPlace(ItemStack stack) { return isBook(stack); }
+            @Override public int getMaxStackSize() { return 1; }
+        });
+        for (int row = 0; row < 3; row++) for (int col = 0; col < 9; col++)
+            addSlot(new Slot(inventory, col + row * 9 + 9, 8 + col * 18, 84 + row * 18));
+        for (int col = 0; col < 9; col++) addSlot(new Slot(inventory, col, 8 + col * 18, 142));
+    }
+    private static boolean isBook(ItemStack stack) {
+        return stack.is(Rivencraft.LINKING_BOOK.get()) || stack.is(Rivencraft.DESCRIPTIVE_BOOK.get());
+    }
+    public ItemStack book() { return books.getItem(0); }
+    public boolean setTitle(Player player, String title) {
+        if (player.level().isClientSide() || !stillValid(player) || !isBook(book())
+                || title == null || title.length() > 32) return false;
+        String clean = title.strip();
+        if (clean.isEmpty()) book().remove(DataComponents.CUSTOM_NAME);
+        else book().set(DataComponents.CUSTOM_NAME, Component.literal(clean));
+        books.setChanged();
+        broadcastChanges();
+        return true;
+    }
+    @Override public boolean clickMenuButton(Player player, int id) {
+        if (player.level().isClientSide() || !stillValid(player) || !isBook(book())) return false;
+        int flag = switch (id) {
+            case TOGGLE_DISARM -> LinkProperties.DISARM;
+            case TOGGLE_MOMENTUM -> LinkProperties.MAINTAIN_MOMENTUM;
+            case TOGGLE_INTRA -> LinkProperties.INTRA_LINKING;
+            case TOGGLE_INTRA_ONLY -> LinkProperties.INTRA_LINKING_ONLY;
+            case TOGGLE_RELATIVE -> LinkProperties.RELATIVE_LINK;
+            case TOGGLE_PLATFORM -> book().is(Rivencraft.LINKING_BOOK.get())
+                    ? LinkProperties.GENERATE_PLATFORM : LinkProperties.DISABLE_PLATFORM;
+            default -> 0;
+        };
+        // Descriptive Books travel to an Age; Intra Linking is a Linking Book property.
+        if (flag == 0 || (flag == LinkProperties.INTRA_LINKING || flag == LinkProperties.INTRA_LINKING_ONLY) && book().is(Rivencraft.DESCRIPTIVE_BOOK.get())) return false;
+        int flags = book().getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE).flags();
+        if (flag == LinkProperties.INTRA_LINKING_ONLY && (flags & LinkProperties.INTRA_LINKING_ONLY) == 0)
+            flags |= LinkProperties.INTRA_LINKING;
+        if (flag == LinkProperties.INTRA_LINKING && (flags & LinkProperties.INTRA_LINKING) != 0)
+            flags &= ~LinkProperties.INTRA_LINKING_ONLY;
+        book().set(Rivencraft.LINK_PROPERTIES.get(), new LinkProperties(flags ^ flag));
+        books.setChanged();
+        broadcastChanges();
+        return true;
+    }
+    @Override public boolean stillValid(Player player) {
+        return player == owner && modifier != null && modifier.stillValid(player);
+    }
+    @Override public ItemStack quickMoveStack(Player player, int index) {
+        if (!stillValid(player) || index < 0 || index >= slots.size()) return ItemStack.EMPTY;
+        Slot slot = slots.get(index);
+        if (!slot.hasItem()) return ItemStack.EMPTY;
+        ItemStack source = slot.getItem(), copy = source.copy();
+        if (index == 0) {
+            if (!moveItemStackTo(source, 1, slots.size(), true)) return ItemStack.EMPTY;
+        } else if (!moveItemStackTo(source, 0, 1, false)) return ItemStack.EMPTY;
+        if (source.isEmpty()) slot.set(ItemStack.EMPTY);
+        else slot.setChanged();
+        return copy;
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/menu/PortBookBinderMenu.java

@@ -118,6 +118,7 @@ public final class PortBookBinderMenu extends AbstractContainerMenu {
         var id = PortBookNetworking.createAge(player, title, blockEntity.symbolPages());
         if (id == null) return;
         book.set(Rivencraft.AGE_BOOK_ID.get(), id);
+        book.set(Rivencraft.BOOK_AUTHOR.get(), player.getGameProfile().name());
         book.set(DataComponents.CUSTOM_NAME, Component.literal(title));
         if (blockEntity.hasSymbolPages())
             book.set(Rivencraft.BOOK_SYMBOLS.get(), blockEntity.symbolPages());
@@ -129,6 +130,8 @@ public final class PortBookBinderMenu extends AbstractContainerMenu {
         binder.setItem(PortBookBinderBlockEntity.PANEL, panel);
         blockEntity.clearSymbolPages();
         setCarried(book);
+        net.dnorberg.rivencraft.advancement.ProgressionAdvancements.award(player,
+                net.dnorberg.rivencraft.advancement.ProgressionAdvancements.BIND_AGE);
         broadcastChanges();
     }
 

ports/mc263/src/main/java/net/dnorberg/rivencraft/menu/WritingDeskMenu.java

@@ -1,6 +1,8 @@
 package net.dnorberg.rivencraft.menu;
 
 import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.advancement.ProgressionAdvancements;
+import net.minecraft.server.level.ServerPlayer;
 import net.dnorberg.rivencraft.block.entity.WritingDeskBlockEntity;
 import net.dnorberg.rivencraft.item.PageItem;
 import net.dnorberg.rivencraft.writing.NotebookContents;
@@ -321,6 +323,8 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
                 return ItemStack.EMPTY;
             }
             if (!blockEntity.consumeCopyMaterials()) return ItemStack.EMPTY;
+            if (player instanceof ServerPlayer serverPlayer)
+                ProgressionAdvancements.award(serverPlayer, ProgressionAdvancements.COPY_PAGE);
             refreshOutput();
             return copy;
         }
@@ -439,6 +443,8 @@ public final class WritingDeskMenu extends AbstractContainerMenu {
         }
         @Override public void onTake(Player player, ItemStack stack) {
             if (!clientSide && blockEntity.consumeCopyMaterials()) {
+                if (player instanceof ServerPlayer serverPlayer)
+                    ProgressionAdvancements.award(serverPlayer, ProgressionAdvancements.COPY_PAGE);
                 refreshOutput();
             }
             super.onTake(player, stack);

ports/mc263/src/main/java/net/dnorberg/rivencraft/network/PortBookNetworking.java

@@ -33,11 +33,21 @@ public final class PortBookNetworking {
 
     public static void registerPayloads(RegisterPayloadHandlersEvent event) {
         var registrar = event.registrar("1");
+        registrar.playToServer(SetLinkModifierTitlePayload.TYPE, SetLinkModifierTitlePayload.STREAM_CODEC,
+                (payload, context) -> {
+                    if (context.player() instanceof ServerPlayer player
+                            && player.containerMenu instanceof net.dnorberg.rivencraft.menu.LinkModifierMenu menu
+                            && menu.containerId == payload.containerId()) menu.setTitle(player, payload.title());
+                });
         registrar.playToClient(WritingDeskCatalogPayload.TYPE, WritingDeskCatalogPayload.STREAM_CODEC);
         registrar.playToServer(BindLinkingBookPayload.TYPE, BindLinkingBookPayload.STREAM_CODEC,
                 (payload, context) -> {
                     if (context.player() instanceof ServerPlayer player) bind(player, payload);
                 });
+        registrar.playToServer(UseBookStandPayload.TYPE, UseBookStandPayload.STREAM_CODEC,
+                (payload, context) -> {
+                    if (context.player() instanceof ServerPlayer player) useStand(player, payload);
+                });
         registrar.playToServer(UseLinkingBookPayload.TYPE, UseLinkingBookPayload.STREAM_CODEC,
                 (payload, context) -> {
                     if (context.player() instanceof ServerPlayer player) use(player, payload);
@@ -73,6 +83,7 @@ public final class PortBookNetworking {
         String title = payload.title().strip();
         if (title.isEmpty() || title.length() > MAX_BOOK_TITLE_LENGTH) return;
         stack.set(Rivencraft.LINK_BOOK_TARGET.get(), LinkBookTarget.at(player));
+        stack.set(Rivencraft.LINK_DESTINATION_NAME.get(), LinkingBookItem.destinationName(player.level()));
         stack.set(DataComponents.CUSTOM_NAME, Component.literal(title));
         player.level().playSound(null, player.blockPosition(), SoundEvents.BOOK_PAGE_TURN,
                 SoundSource.PLAYERS, 1.0F, 1.0F);
@@ -96,6 +107,7 @@ public final class PortBookNetworking {
         Identifier id = createAge(player, title);
         if (id == null) return;
         stack.set(Rivencraft.AGE_BOOK_ID.get(), id);
+        stack.set(Rivencraft.BOOK_AUTHOR.get(), player.getGameProfile().name());
         stack.set(DataComponents.CUSTOM_NAME, Component.literal(title));
         player.level().playSound(null, player.blockPosition(), SoundEvents.BOOK_PAGE_TURN,
                 SoundSource.PLAYERS, 1.0F, 1.0F);
@@ -111,6 +123,8 @@ public final class PortBookNetworking {
     public static Identifier createAge(ServerPlayer player, String title, List<Identifier> pages) {
         if (title == null || title.isBlank() || title.length() > MAX_BOOK_TITLE_LENGTH) return null;
         long seed = player.getRandom().nextLong();
+        var recovery = net.dnorberg.rivencraft.writing.PortWritingRecovery.recover(pages);
+        List<Identifier> activePages = recovery.activePages();
         net.dnorberg.rivencraft.age.PortBiomePlan biomePlan;
         PortAgeTerrain terrain;
         List<Identifier> generationPages;
@@ -142,7 +156,7 @@ public final class PortBookNetworking {
             id = Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "age/" + name);
         }
         try {
-            var environment = net.dnorberg.rivencraft.age.PortEnvironmentSelection.resolve(pages, seed, terrain);
+            var environment = net.dnorberg.rivencraft.age.PortEnvironmentSelection.resolve(activePages, seed, terrain);
             var randomFeatures = pages.isEmpty()
                     ? net.dnorberg.rivencraft.age.PortRandomFeatureSelection.select(server, seed, terrain, biomePlan) : null;
             var level = RuntimeAgeBackend.create(server, id, seed, biomePlan, terrain,
@@ -154,9 +168,10 @@ public final class PortBookNetworking {
                     environment.weather(), environment.lighting(), environment.sky(),
                     net.dnorberg.rivencraft.age.PortAgeColors.resolve(pages, seed),
                     net.dnorberg.rivencraft.age.PortDayCycle.resolve(pages, seed,
-                            net.dnorberg.rivencraft.age.PortDayCycle.nativeTicks(server.overworld())));
+                            net.dnorberg.rivencraft.age.PortDayCycle.nativeTicks(server.overworld())), pages);
             net.dnorberg.rivencraft.age.PortAcceleratedTicks.configure(level,
                     net.dnorberg.rivencraft.age.PortAcceleratedTicks.pageCount(pages));
+            RuntimeAgeBackend.setAgeDisplayName(server, id, title);
         } catch (IllegalArgumentException | IllegalStateException exception) {
             player.sendOverlayMessage(Component.literal("Age creation failed: " + exception.getMessage()));
             return null;
@@ -167,22 +182,56 @@ public final class PortBookNetworking {
     private static void enterAge(ServerPlayer player, UseDescriptiveBookPayload payload) {
         ItemStack stack = player.getItemInHand(hand(payload.offhand()));
         if (!stack.is(Rivencraft.DESCRIPTIVE_BOOK.get())) return;
+        travelDescriptive(player, stack, hand(payload.offhand()));
+    }
+
+    /** Validation is shared with operator fixtures; no remote chunk is loaded to inspect a stand. */
+    public static ItemStack validatedStandBook(ServerPlayer player, UseBookStandPayload payload) {
+        var level = player.level();
+        if (!level.dimension().identifier().equals(payload.dimension())
+                || player.distanceToSqr(Vec3.atCenterOf(payload.pos())) > 64
+                || !level.hasChunkAt(payload.pos())
+                || !level.getBlockState(payload.pos()).is(Rivencraft.BOOK_STAND.get())
+                || !(level.getBlockEntity(payload.pos()) instanceof net.dnorberg.rivencraft.block.entity.BookStandBlockEntity stand)
+                || !ItemStack.matches(stand.getBook(), payload.book())) return ItemStack.EMPTY;
+        return stand.getBook();
+    }
+
+    private static void useStand(ServerPlayer player, UseBookStandPayload payload) {
+        var book = validatedStandBook(player, payload);
+        if (book.is(Rivencraft.LINKING_BOOK.get())) {
+            String failure = LinkingBookItem.travel(player, book);
+            if (failure != null) player.sendOverlayMessage(Component.literal(failure));
+            else net.dnorberg.rivencraft.advancement.ProgressionAdvancements.awardAgeTravel(player);
+        } else if (book.is(Rivencraft.DESCRIPTIVE_BOOK.get())) travelDescriptive(player, book, null);
+    }
+
+    private static void travelDescriptive(ServerPlayer player, ItemStack stack, InteractionHand heldHand) {
+        travelDescriptive(player, stack, heldHand, false);
+    }
+
+    public static void travelDescriptive(ServerPlayer player, ItemStack stack, InteractionHand heldHand, boolean portal) {
         Identifier id = stack.get(Rivencraft.AGE_BOOK_ID.get());
         if (id == null) return;
         ServerLevel source = player.level();
         LinkBookTarget returnTarget = LinkBookTarget.at(player);
         Vec3 departure = player.position();
         Vec3 incoming = player.getDeltaMovement();
-        String failure = net.dnorberg.rivencraft.item.PortHandheldTravel.travel(player,
-                hand(payload.offhand()), stack, () -> {
-                    String result = PortAgeTravel.enter(player, id);
-                    if (result == null) LinkingBookItem.applySuccessfulLink(player,
-                            stack.getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE),
-                            source, departure, incoming, player.getYRot());
-                    return result;
-                });
+        java.util.function.Supplier<String> travel = () -> {
+            String result = PortAgeTravel.enter(player, id,
+                    stack.getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE).forDescriptiveBook());
+            if (result == null) LinkingBookItem.applySuccessfulLink(player,
+                    stack.getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE),
+                    source, departure, incoming, player.getYRot(), portal);
+            return result;
+        };
+        String failure = heldHand == null ? travel.get()
+                : net.dnorberg.rivencraft.item.PortHandheldTravel.travel(player, heldHand, stack, travel);
         if (failure != null) player.sendOverlayMessage(Component.literal(failure));
-        else net.dnorberg.rivencraft.age.PortReturnLinks.afterSuccessfulTravel(player, id, returnTarget);
+        else {
+            if (heldHand == null) net.dnorberg.rivencraft.advancement.ProgressionAdvancements.awardAgeTravel(player);
+            net.dnorberg.rivencraft.age.PortReturnLinks.afterSuccessfulTravel(player, id, returnTarget);
+        }
     }
 
     private static InteractionHand hand(boolean offhand) {

ports/mc263/src/main/java/net/dnorberg/rivencraft/network/SetLinkModifierTitlePayload.java

@@ -0,0 +1,18 @@
+package net.dnorberg.rivencraft.network;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.ByteBufCodecs;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
+import net.minecraft.resources.Identifier;
+
+public record SetLinkModifierTitlePayload(int containerId, String title) implements CustomPacketPayload {
+    public static final Type<SetLinkModifierTitlePayload> TYPE = new Type<>(
+            Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "set_link_modifier_title"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, SetLinkModifierTitlePayload> STREAM_CODEC =
+            StreamCodec.composite(ByteBufCodecs.VAR_INT, SetLinkModifierTitlePayload::containerId,
+                    ByteBufCodecs.stringUtf8(32), SetLinkModifierTitlePayload::title,
+                    SetLinkModifierTitlePayload::new);
+    @Override public Type<SetLinkModifierTitlePayload> type() { return TYPE; }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/network/UseBookStandPayload.java

@@ -0,0 +1,18 @@
+package net.dnorberg.rivencraft.network;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
+import net.minecraft.resources.Identifier;
+import net.minecraft.world.item.ItemStack;
+
+/** Carries the displayed source so a removed/replaced book cannot activate a stale screen. */
+public record UseBookStandPayload(Identifier dimension, BlockPos pos, ItemStack book) implements CustomPacketPayload {
+    public static final Type<UseBookStandPayload> TYPE = new Type<>(Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "use_book_stand"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, UseBookStandPayload> STREAM_CODEC = StreamCodec.composite(
+            Identifier.STREAM_CODEC, UseBookStandPayload::dimension, BlockPos.STREAM_CODEC, UseBookStandPayload::pos,
+            ItemStack.STREAM_CODEC, UseBookStandPayload::book, UseBookStandPayload::new);
+    @Override public Type<UseBookStandPayload> type() { return TYPE; }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/portal/CrystalPortalNetwork.java

@@ -0,0 +1,352 @@
+package net.dnorberg.rivencraft.portal;
+
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+import net.dnorberg.rivencraft.block.BookReceptacleBlock;
+import net.dnorberg.rivencraft.block.CrystalPortalBlock;
+import net.dnorberg.rivencraft.block.entity.BookReceptacleBlockEntity;
+import net.dnorberg.rivencraft.block.entity.CrystalPortalBlockEntity;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
+import net.neoforged.neoforge.common.NeoForge;
+import net.neoforged.neoforge.common.util.BlockSnapshot;
+import net.neoforged.neoforge.event.level.BlockEvent;
+
+/** Bounded, loaded-chunk-only adaptation of Legacy's crystal network flood. */
+public final class CrystalPortalNetwork {
+    public static final int MAX_RADIUS = 16;
+    private static final int CLEANUP_RADIUS = MAX_RADIUS + 1;
+    private static final int MAX_CRYSTALS = 2048;
+    private static final int MAX_PORTALS = 1024;
+    private static final int[][] EXPANSION = {
+            {1, 0, 0}, {-1, 0, 0}, {0, 1, 0}, {0, -1, 0}, {0, 0, 1}, {0, 0, -1},
+            {1, 1, 0}, {-1, 1, 0}, {1, -1, 0}, {-1, -1, 0},
+            {1, 0, 1}, {-1, 0, 1}, {1, 0, -1}, {-1, 0, -1},
+            {0, 1, 1}, {0, -1, 1}, {0, 1, -1}, {0, -1, -1}
+    };
+
+    private CrystalPortalNetwork() {}
+
+    public record Plan(List<BlockPos> portalCells, boolean waitingForChunks) {
+        public Plan(List<BlockPos> portalCells) { this(portalCells, false); }
+        public boolean valid() { return !portalCells.isEmpty(); }
+    }
+
+    public enum CellStatus { VALID, INVALID, WAITING_FOR_CHUNKS }
+
+    public static Plan plan(ServerLevel level, BlockPos receptacle) {
+        return plan(level, receptacle, false);
+    }
+
+    private static Plan plan(ServerLevel level, BlockPos receptacle, boolean allowUnownedCells) {
+        BlockState holder = level.getBlockState(receptacle);
+        if (!holder.is(Rivencraft.BOOK_RECEPTACLE.get())) return new Plan(List.of());
+        BlockPos base = receptacle.relative(holder.getValue(BookReceptacleBlock.FACING).getOpposite());
+        if (!level.hasChunkAt(base)) return new Plan(List.of(), true);
+        if (!level.getBlockState(base).is(Rivencraft.CRYSTAL_BLOCK.get())) return new Plan(List.of());
+
+        Set<BlockPos> crystals = new HashSet<>();
+        ArrayDeque<BlockPos> pendingCrystals = new ArrayDeque<>();
+        pendingCrystals.add(base);
+        while (!pendingCrystals.isEmpty()) {
+            BlockPos pos = pendingCrystals.removeFirst();
+            if (!within(base, pos) || !level.isInWorldBounds(pos)) continue;
+            if (!level.hasChunkAt(pos)) return new Plan(List.of(), true);
+            if (!level.getBlockState(pos).is(Rivencraft.CRYSTAL_BLOCK.get()) || !crystals.add(pos)) continue;
+            if (atBoundary(base, pos)) return new Plan(List.of());
+            if (crystals.size() > MAX_CRYSTALS) return new Plan(List.of());
+            for (Direction direction : Direction.values()) pendingCrystals.add(pos.relative(direction));
+        }
+
+        LinkedHashSet<BlockPos> portals = new LinkedHashSet<>();
+        ArrayDeque<BlockPos> candidates = new ArrayDeque<>();
+        Set<BlockPos> queued = new HashSet<>();
+        for (BlockPos crystal : crystals) addCandidates(crystal, base, queued, candidates);
+        while (!candidates.isEmpty()) {
+            BlockPos pos = candidates.removeFirst();
+            queued.remove(pos);
+            if (!level.isInWorldBounds(pos)) return new Plan(List.of());
+            if (!level.hasChunkAt(pos)) return new Plan(List.of(), true);
+            if (portals.contains(pos) || !mayFill(level, pos, receptacle, allowUnownedCells)) continue;
+            if (adjacentCount(pos, crystals, portals) < 2) continue;
+            portals.add(pos);
+            if (portals.size() > MAX_PORTALS) return new Plan(List.of());
+            addCandidates(pos, base, queued, candidates);
+        }
+
+        // Legacy's second pass deletes every cell without opposing neighbors on
+        // at least two axes. Repeat because deleting one cell can unbrace another.
+        boolean changed;
+        do {
+            changed = portals.removeIf(pos -> !hasTension(pos, crystals, portals));
+        } while (changed);
+        if (portals.isEmpty()) return new Plan(List.of());
+
+        // Every surviving cell must still be reachable from the receptacle's
+        // crystal base through this one network, never through another portal.
+        Set<BlockPos> reachable = new HashSet<>();
+        ArrayDeque<BlockPos> frontier = new ArrayDeque<>();
+        frontier.add(base);
+        while (!frontier.isEmpty()) {
+            BlockPos pos = frontier.removeFirst();
+            if (!reachable.add(pos)) continue;
+            for (Direction direction : Direction.values()) {
+                BlockPos next = pos.relative(direction);
+                if (!reachable.contains(next) && (crystals.contains(next) || portals.contains(next)))
+                    frontier.add(next);
+            }
+        }
+        if (!reachable.containsAll(portals)) return new Plan(List.of());
+        return new Plan(List.copyOf(portals));
+    }
+
+    public static boolean activate(ServerLevel level, BlockPos receptacle, Plan plan) {
+        return activate(level, receptacle, plan, null);
+    }
+
+    /** Repairs only existing, framed cells whose owner pointer was lost by an older live-view update. */
+    public static boolean recoverSavedOwners(ServerLevel level, BlockPos receptacle) {
+        if (!(level.getBlockEntity(receptacle) instanceof BookReceptacleBlockEntity holder)
+                || holder.getBook().isEmpty()) return false;
+        Plan plan = plan(level, receptacle, true);
+        if (!plan.valid()) return false;
+        for (BlockPos pos : plan.portalCells()) {
+            if (!(level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal)
+                    || portal.receptacle() != null && !receptacle.equals(portal.receptacle())) return false;
+        }
+        for (BlockPos pos : plan.portalCells()) {
+            CrystalPortalBlockEntity portal = (CrystalPortalBlockEntity) level.getBlockEntity(pos);
+            if (portal.receptacle() == null) portal.setReceptacle(receptacle);
+        }
+        return true;
+    }
+
+    /** The player who inserted the book owns each newly placed portal cell for claim checks. */
+    public static boolean activate(ServerLevel level, BlockPos receptacle, Plan plan, Entity actor) {
+        if (!plan.valid() || !(level.getBlockEntity(receptacle) instanceof BookReceptacleBlockEntity holder)
+                || holder.getBook().isEmpty()) return false;
+        List<BlockPos> placed = new ArrayList<>();
+        for (BlockPos pos : plan.portalCells()) {
+            if (!mayFill(level, pos, receptacle)) {
+                rollback(level, placed);
+                return false;
+            }
+            if (level.getBlockState(pos).isAir()) {
+                BlockSnapshot snapshot = actor == null ? null : BlockSnapshot.create(level.dimension(), level, pos);
+                BlockState prior = level.getBlockState(pos);
+                // Defer neighbor notifications until the entire opening exists.
+                // Otherwise the first cells see an incomplete brace and the
+                // portal's neighbor validator removes them during activation.
+                if (!level.setBlock(pos, Rivencraft.CRYSTAL_PORTAL.get().defaultBlockState(), 2)) {
+                    rollback(level, placed);
+                    return false;
+                }
+                if (snapshot != null) {
+                    var event = new BlockEvent.EntityPlaceEvent(snapshot, prior, actor);
+                    NeoForge.EVENT_BUS.post(event);
+                    if (event.isCanceled()) {
+                        snapshot.restore();
+                        rollback(level, placed);
+                        return false;
+                    }
+                }
+                placed.add(pos);
+            }
+            if (level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal) {
+                portal.setReceptacle(receptacle);
+            } else {
+                rollback(level, placed);
+                return false;
+            }
+        }
+        orientSurfaces(level, plan);
+        for (BlockPos pos : plan.portalCells()) {
+            if (!(level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal)
+                    || !receptacle.equals(portal.receptacle())) {
+                rollback(level, placed);
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static void shutdown(ServerLevel level, BlockPos receptacle) {
+        // A broken support can disconnect the graph. Scan a bounded volume rather
+        // than trusting a path through blocks that no longer exist.
+        for (BlockPos pos : BlockPos.betweenClosed(receptacle.offset(-CLEANUP_RADIUS, -CLEANUP_RADIUS, -CLEANUP_RADIUS),
+                receptacle.offset(CLEANUP_RADIUS, CLEANUP_RADIUS, CLEANUP_RADIUS))) {
+            if (!level.hasChunkAt(pos)) continue;
+            if (level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal
+                    && receptacle.equals(portal.receptacle()))
+                level.setBlock(pos, Blocks.AIR.defaultBlockState(), 3);
+        }
+    }
+
+    /** One bounded repair pass per receptacle, rather than a full flood per portal cell. */
+    public static boolean reconcile(ServerLevel level, BlockPos receptacle) {
+        return reconcile(level, receptacle, plan(level, receptacle));
+    }
+
+    public static boolean reconcile(ServerLevel level, BlockPos receptacle, Plan plan) {
+        if (!plan.valid()) {
+            // Neighboring chunks can still be loading when the receptacle first
+            // ticks after a restart. An incomplete view is not a broken frame.
+            if (!plan.waitingForChunks()) shutdown(level, receptacle);
+            return false;
+        }
+        Set<BlockPos> wanted = new HashSet<>(plan.portalCells());
+        // A background pass must not create blocks without the owner present:
+        // that would bypass the placement/protection event used at activation.
+        for (BlockPos pos : wanted) {
+            if (!(level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal)
+                    || !receptacle.equals(portal.receptacle())) {
+                shutdown(level, receptacle);
+                return false;
+            }
+        }
+        for (BlockPos pos : BlockPos.betweenClosed(receptacle.offset(-CLEANUP_RADIUS, -CLEANUP_RADIUS, -CLEANUP_RADIUS),
+                receptacle.offset(CLEANUP_RADIUS, CLEANUP_RADIUS, CLEANUP_RADIUS))) {
+            if (!level.hasChunkAt(pos)) continue;
+            if (level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal
+                    && receptacle.equals(portal.receptacle()) && !wanted.contains(pos))
+                level.setBlock(pos, Blocks.AIR.defaultBlockState(), 3);
+        }
+        orientSurfaces(level, plan);
+        return true;
+    }
+
+    private static void orientSurfaces(ServerLevel level, Plan plan) {
+        for (CrystalPortalSurfaces.Surface surface : CrystalPortalSurfaces.group(level, plan)) {
+            for (BlockPos pos : surface.cells()) {
+                BlockState state = level.getBlockState(pos);
+                Direction.Axis axis = surface.normal().getAxis();
+                if (state.getValue(CrystalPortalBlock.AXIS) != axis)
+                    updatePortalState(level, pos, state.setValue(CrystalPortalBlock.AXIS, axis));
+            }
+        }
+    }
+
+    /** The vanilla-style surface remains visible until its optional live view is ready. */
+    public static void setLiveView(ServerLevel level, Plan plan, boolean live) {
+        for (BlockPos pos : plan.portalCells()) {
+            BlockState state = level.getBlockState(pos);
+            if (state.is(Rivencraft.CRYSTAL_PORTAL.get()) && state.getValue(CrystalPortalBlock.LIVE_VIEW) != live)
+                updatePortalState(level, pos, state.setValue(CrystalPortalBlock.LIVE_VIEW, live));
+        }
+    }
+
+    private static void updatePortalState(ServerLevel level, BlockPos pos, BlockState replacement) {
+        BlockPos owner = level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal
+                ? portal.receptacle() : null;
+        if (!level.setBlock(pos, replacement, 2) || owner == null) return;
+        if (level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal
+                && !owner.equals(portal.receptacle())) portal.setReceptacle(owner);
+    }
+
+    public static CellStatus cellStatus(ServerLevel level, BlockPos pos, BlockPos receptacle) {
+        if (Math.abs(receptacle.getX() - pos.getX()) > CLEANUP_RADIUS
+                || Math.abs(receptacle.getY() - pos.getY()) > CLEANUP_RADIUS
+                || Math.abs(receptacle.getZ() - pos.getZ()) > CLEANUP_RADIUS) return CellStatus.INVALID;
+        if (!level.hasChunkAt(receptacle)) return CellStatus.WAITING_FOR_CHUNKS;
+        BlockState state = level.getBlockState(receptacle);
+        if (!state.is(Rivencraft.BOOK_RECEPTACLE.get())) return CellStatus.INVALID;
+        BlockPos base = receptacle.relative(state.getValue(BookReceptacleBlock.FACING).getOpposite());
+        if (!level.hasChunkAt(base)) return CellStatus.WAITING_FOR_CHUNKS;
+        if (!level.getBlockState(base).is(Rivencraft.CRYSTAL_BLOCK.get())) return CellStatus.INVALID;
+        if (!(level.getBlockEntity(receptacle) instanceof BookReceptacleBlockEntity holder))
+            return CellStatus.WAITING_FOR_CHUNKS;
+        if (holder.getBook().isEmpty()) return CellStatus.INVALID;
+        // A neighboring chunk may hold one of the braces. Do not tear down a
+        // persisted portal until all six neighbors are available to inspect.
+        for (Direction direction : Direction.values())
+            if (!level.hasChunkAt(pos.relative(direction))) return CellStatus.WAITING_FOR_CHUNKS;
+        for (Direction.Axis axis : Direction.Axis.values()) {
+            // Quick tension check before the bounded network/path revalidation.
+            if (!axisBraced(level, pos, axis)) continue;
+            int other = 0;
+            for (Direction.Axis alternative : Direction.Axis.values())
+                if (alternative != axis && axisBraced(level, pos, alternative)) other++;
+            if (other > 0) return CellStatus.VALID;
+        }
+        return CellStatus.INVALID;
+    }
+
+    private static boolean axisBraced(ServerLevel level, BlockPos pos, Direction.Axis axis) {
+        Direction positive = Direction.get(Direction.AxisDirection.POSITIVE, axis);
+        Direction negative = positive.getOpposite();
+        BlockPos a = pos.relative(positive);
+        BlockPos b = pos.relative(negative);
+        return level.hasChunkAt(a) && level.hasChunkAt(b)
+                && isFrameOrPortal(level.getBlockState(a)) && isFrameOrPortal(level.getBlockState(b));
+    }
+
+    private static boolean isFrameOrPortal(BlockState state) {
+        return state.is(Rivencraft.CRYSTAL_BLOCK.get()) || state.is(Rivencraft.CRYSTAL_PORTAL.get());
+    }
+
+    private static void rollback(ServerLevel level, List<BlockPos> placed) {
+        for (BlockPos pos : placed) level.setBlock(pos, Blocks.AIR.defaultBlockState(), 3);
+    }
+
+    private static boolean mayFill(ServerLevel level, BlockPos pos, BlockPos receptacle) {
+        return mayFill(level, pos, receptacle, false);
+    }
+
+    private static boolean mayFill(ServerLevel level, BlockPos pos, BlockPos receptacle, boolean allowUnowned) {
+        if (!level.hasChunkAt(pos) || !level.isInWorldBounds(pos)) return false;
+        BlockState state = level.getBlockState(pos);
+        return state.isAir() || state.is(Rivencraft.CRYSTAL_PORTAL.get())
+                && level.getBlockEntity(pos) instanceof CrystalPortalBlockEntity portal
+                && (receptacle.equals(portal.receptacle()) || allowUnowned && portal.receptacle() == null);
+    }
+
+    private static int adjacentCount(BlockPos pos, Set<BlockPos> crystals, Set<BlockPos> portals) {
+        int count = 0;
+        for (Direction direction : Direction.values())
+            if (crystals.contains(pos.relative(direction)) || portals.contains(pos.relative(direction))) count++;
+        return count;
+    }
+
+    private static boolean hasTension(BlockPos pos, Set<BlockPos> crystals, Set<BlockPos> portals) {
+        int axes = 0;
+        for (Direction.Axis axis : Direction.Axis.values()) {
+            Direction positive = Direction.get(Direction.AxisDirection.POSITIVE, axis);
+            if (member(pos.relative(positive), crystals, portals)
+                    && member(pos.relative(positive.getOpposite()), crystals, portals)) axes++;
+        }
+        return axes >= 2;
+    }
+
+    private static boolean member(BlockPos pos, Set<BlockPos> crystals, Set<BlockPos> portals) {
+        return crystals.contains(pos) || portals.contains(pos);
+    }
+
+    private static void addCandidates(BlockPos around, BlockPos base, Set<BlockPos> queued,
+                                      ArrayDeque<BlockPos> pending) {
+        for (int[] offset : EXPANSION) {
+            BlockPos candidate = around.offset(offset[0], offset[1], offset[2]);
+            if (within(base, candidate) && queued.add(candidate)) pending.add(candidate);
+        }
+    }
+
+    private static boolean within(BlockPos center, BlockPos pos) {
+        return Math.abs(center.getX() - pos.getX()) <= MAX_RADIUS
+                && Math.abs(center.getY() - pos.getY()) <= MAX_RADIUS
+                && Math.abs(center.getZ() - pos.getZ()) <= MAX_RADIUS;
+    }
+
+    private static boolean atBoundary(BlockPos center, BlockPos pos) {
+        return Math.abs(center.getX() - pos.getX()) == MAX_RADIUS
+                || Math.abs(center.getY() - pos.getY()) == MAX_RADIUS
+                || Math.abs(center.getZ() - pos.getZ()) == MAX_RADIUS;
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/portal/CrystalPortalSurfaces.java

@@ -0,0 +1,59 @@
+package net.dnorberg.rivencraft.portal;
+
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.phys.AABB;
+
+/** Groups portal cells into coherent, coplanar views while retaining irregular outlines. */
+public final class CrystalPortalSurfaces {
+    private CrystalPortalSurfaces() {}
+
+    public record Surface(Direction normal, AABB bounds, List<BlockPos> cells) {}
+    private record Plane(Direction normal, int coordinate) {}
+
+    public static List<Surface> group(ServerLevel level, CrystalPortalNetwork.Plan plan) {
+        Map<Plane, List<BlockPos>> planes = new LinkedHashMap<>();
+        for (BlockPos cell : plan.portalCells()) {
+            Direction normal = planeNormal(level, cell);
+            if (normal == null) continue;
+            int coordinate = normal.getAxis().choose(cell.getX(), cell.getY(), cell.getZ());
+            planes.computeIfAbsent(new Plane(normal, coordinate), ignored -> new ArrayList<>()).add(cell);
+        }
+        List<Surface> result = new ArrayList<>();
+        for (Map.Entry<Plane, List<BlockPos>> entry : planes.entrySet()) {
+            List<BlockPos> cells = entry.getValue();
+            int minX = cells.stream().mapToInt(BlockPos::getX).min().orElseThrow();
+            int minY = cells.stream().mapToInt(BlockPos::getY).min().orElseThrow();
+            int minZ = cells.stream().mapToInt(BlockPos::getZ).min().orElseThrow();
+            int maxX = cells.stream().mapToInt(BlockPos::getX).max().orElseThrow() + 1;
+            int maxY = cells.stream().mapToInt(BlockPos::getY).max().orElseThrow() + 1;
+            int maxZ = cells.stream().mapToInt(BlockPos::getZ).max().orElseThrow() + 1;
+            result.add(new Surface(entry.getKey().normal(), new AABB(minX, minY, minZ, maxX, maxY, maxZ),
+                    List.copyOf(cells)));
+        }
+        return List.copyOf(result);
+    }
+
+    private static Direction planeNormal(ServerLevel level, BlockPos cell) {
+        if (braced(level, cell, Direction.UP) && braced(level, cell, Direction.EAST)) return Direction.NORTH;
+        if (braced(level, cell, Direction.UP) && braced(level, cell, Direction.SOUTH)) return Direction.EAST;
+        if (braced(level, cell, Direction.EAST) && braced(level, cell, Direction.SOUTH)) return Direction.UP;
+        return null;
+    }
+
+    private static boolean braced(ServerLevel level, BlockPos cell, Direction direction) {
+        return linked(level, cell.relative(direction)) && linked(level, cell.relative(direction.getOpposite()));
+    }
+
+    private static boolean linked(ServerLevel level, BlockPos pos) {
+        if (!level.hasChunkAt(pos)) return false;
+        var state = level.getBlockState(pos);
+        return state.is(Rivencraft.CRYSTAL_BLOCK.get()) || state.is(Rivencraft.CRYSTAL_PORTAL.get());
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/portal/PortalBookTravel.java

@@ -0,0 +1,84 @@
+package net.dnorberg.rivencraft.portal;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.age.PortAgeTravel;
+import net.dnorberg.rivencraft.item.LinkBookTarget;
+import net.dnorberg.rivencraft.item.LinkProperties;
+import net.dnorberg.rivencraft.item.LinkDisarmService;
+import net.dnorberg.rivencraft.item.LinkingBookItem;
+import net.dnorberg.rivencraft.item.LinkVisualEffects;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.portal.TeleportTransition;
+import net.minecraft.world.phys.Vec3;
+
+/** Portal transport uses the book's arrival rules; no independent portal exit offset. */
+public final class PortalBookTravel {
+    private PortalBookTravel() {}
+    public static boolean available(ServerLevel source, ItemStack book) {
+        var id = book.is(Rivencraft.DESCRIPTIVE_BOOK.get()) ? book.get(Rivencraft.AGE_BOOK_ID.get())
+                : book.has(Rivencraft.LINK_BOOK_TARGET.get()) ? book.get(Rivencraft.LINK_BOOK_TARGET.get()).dimension() : null;
+        return id != null && source.getServer().getLevel(ResourceKey.create(Registries.DIMENSION, id)) != null;
+    }
+    public static void travel(Entity entity, ServerLevel source, ItemStack book) {
+        if (entity instanceof ServerPlayer player) {
+            if (book.is(Rivencraft.DESCRIPTIVE_BOOK.get())) {
+                net.dnorberg.rivencraft.network.PortBookNetworking.travelDescriptive(player, book, null, true);
+            } else {
+                String failure = LinkingBookItem.travel(player, book, true);
+                if (failure != null) player.sendOverlayMessage(net.minecraft.network.chat.Component.literal(failure));
+                else net.dnorberg.rivencraft.advancement.ProgressionAdvancements.awardAgeTravel(player);
+            }
+            return;
+        }
+        LinkProperties properties = book.getOrDefault(Rivencraft.LINK_PROPERTIES.get(), LinkProperties.NONE);
+        if (properties.has(LinkProperties.DISARM) && !LinkDisarmService.mayTravel(entity)) return;
+        boolean descriptive = book.is(Rivencraft.DESCRIPTIVE_BOOK.get());
+        LinkBookTarget destination = book.get(Rivencraft.LINK_BOOK_TARGET.get());
+        if (descriptive) {
+            var id = book.get(Rivencraft.AGE_BOOK_ID.get());
+            ServerLevel level = id == null ? null : source.getServer().getLevel(ResourceKey.create(Registries.DIMENSION, id));
+            if (level == null) return;
+            var landing = PortAgeTravel.resolveLanding(level, entity, properties.forDescriptiveBook());
+            if (landing == null) return;
+            destination = new LinkBookTarget(id, landing.getX() + 0.5, landing.getY(), landing.getZ() + 0.5,
+                    entity.getYRot(), entity.getXRot());
+        }
+        if (destination == null || !destination.valid()) return;
+        ServerLevel target = source.getServer().getLevel(ResourceKey.create(Registries.DIMENSION, destination.dimension()));
+        if (target == null || !entity.canTeleport(source, target) || !descriptive && !properties.allowsTravel(target == source)) return;
+        if (!descriptive) destination = net.dnorberg.rivencraft.item.PortLinkDestinations.resolve(source, target,
+                entity.blockPosition(), destination, properties);
+        if (!destination.valid()) return;
+        var feet = net.minecraft.core.BlockPos.containing(destination.x(), destination.y(), destination.z());
+        if (feet.getY() < target.getMinY() || entity.getBbHeight() + feet.getY() >= target.getMaxY()
+                || !target.getWorldBorder().isWithinBounds(feet)) return;
+        Vec3 arrival = new Vec3(destination.x(), destination.y(), destination.z());
+        target.getChunkAt(feet);
+        if (!target.noCollision(entity, entity.getBoundingBox().move(arrival.subtract(entity.position())))) return;
+        Vec3 incoming = entity.getDeltaMovement();
+        Vec3 velocity = Vec3.ZERO;
+        if (properties.has(LinkProperties.MAINTAIN_MOMENTUM)) {
+            double speed = Math.hypot(incoming.x, incoming.z), yaw = Math.toRadians(destination.yaw());
+            velocity = new Vec3(speed * Math.cos(yaw), incoming.y + 0.2, speed * Math.sin(yaw));
+        }
+        Vec3 departure = entity.position();
+        // Disarm only after a successful transfer, leaving equipment in the source world.
+        Entity arrived = entity.teleport(new TeleportTransition(target, arrival, velocity, destination.yaw(),
+                destination.pitch(), TeleportTransition.PLACE_PORTAL_TICKET));
+        if (arrived == null) return;
+        if (!descriptive) net.dnorberg.rivencraft.item.PortLinkDestinations.generatePlatform(target, arrival, properties);
+        if (properties.has(LinkProperties.DISARM)) {
+            LinkDisarmService.disarmAt(arrived, source, departure);
+        }
+        arrived.resetFallDistance();
+        PortalTravelCooldown.mark(arrived, source.getServer().getTickCount());
+        var sound = LinkVisualEffects.sound(properties, true);
+        source.playSound(null, departure.x, departure.y, departure.z, sound, net.minecraft.sounds.SoundSource.BLOCKS, 0.8F, 1);
+        target.playSound(null, arrival.x, arrival.y, arrival.z, sound, net.minecraft.sounds.SoundSource.BLOCKS, 0.8F, 1);
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/portal/PortalTravelCooldown.java

@@ -0,0 +1,33 @@
+package net.dnorberg.rivencraft.portal;
+
+import java.util.Map;
+import java.util.WeakHashMap;
+import net.minecraft.world.entity.Entity;
+
+/** Session-only portal cooldowns: tick counters must never be saved with players. */
+public final class PortalTravelCooldown {
+    public static final long TICKS = 40;
+    private static final Map<Entity, Long> LAST_USE = new WeakHashMap<>();
+
+    private PortalTravelCooldown() {}
+
+    public static boolean blocked(long now, long previous) {
+        return previous >= 0 && now >= previous && now - previous < TICKS;
+    }
+
+    public static boolean blocked(Entity entity, long now) {
+        return blocked(now, LAST_USE.getOrDefault(entity, -1L));
+    }
+
+    public static void mark(Entity entity, long now) {
+        LAST_USE.put(entity, now);
+    }
+
+    public static void forget(Entity entity) {
+        LAST_USE.remove(entity);
+    }
+
+    public static void clear() {
+        LAST_USE.clear();
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/portal/PortalTravelQueue.java

@@ -0,0 +1,54 @@
+package net.dnorberg.rivencraft.portal;
+
+import java.util.ArrayList;
+import java.util.IdentityHashMap;
+import java.util.Map;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.block.entity.BookReceptacleBlockEntity;
+import net.dnorberg.rivencraft.block.entity.CrystalPortalBlockEntity;
+import net.minecraft.core.BlockPos;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.item.ItemStack;
+import net.neoforged.bus.api.SubscribeEvent;
+import net.neoforged.fml.common.EventBusSubscriber;
+import net.neoforged.neoforge.event.tick.ServerTickEvent;
+import net.neoforged.neoforge.event.server.ServerStoppedEvent;
+
+/** Collision callbacks enqueue once; transport occurs after the entering movement packet finishes. */
+@EventBusSubscriber(modid = Rivencraft.MOD_ID)
+public final class PortalTravelQueue {
+    private record Pending(ServerLevel source, BlockPos portal, BlockPos receptacle, ItemStack book, long tick) {}
+    private static final Map<Entity, Pending> PENDING = new IdentityHashMap<>();
+    private PortalTravelQueue() {}
+    public static void enqueue(Entity entity, ServerLevel source, BlockPos portal, BlockPos receptacle, ItemStack book, long now) {
+        PENDING.putIfAbsent(entity, new Pending(source, portal.immutable(), receptacle.immutable(), book.copyWithCount(1), now));
+    }
+    @SubscribeEvent public static void tick(ServerTickEvent.Post event) {
+        var server = event.getServer();
+        var ready = new ArrayList<Map.Entry<Entity, Pending>>();
+        var iterator = PENDING.entrySet().iterator();
+        while (iterator.hasNext()) {
+            var entry = iterator.next();
+            if (server.getTickCount() <= entry.getValue().tick()) continue;
+            ready.add(Map.entry(entry.getKey(), entry.getValue()));
+            iterator.remove();
+        }
+        for (var entry : ready) {
+            Entity entity = entry.getKey();
+            Pending pending = entry.getValue();
+            if (entity.isRemoved() || !entity.isAlive() || entity.level() != pending.source()
+                    || entity instanceof ServerPlayer player && server.getPlayerList().getPlayer(player.getUUID()) != player
+                    || !pending.source().hasChunkAt(pending.portal()) || !pending.source().hasChunkAt(pending.receptacle())
+                    || !(pending.source().getBlockEntity(pending.portal()) instanceof CrystalPortalBlockEntity portal)
+                    || !pending.receptacle().equals(portal.receptacle())
+                    || !(pending.source().getBlockEntity(pending.receptacle()) instanceof BookReceptacleBlockEntity holder)
+                    || !ItemStack.isSameItemSameComponents(holder.getBook(), pending.book())
+                    || CrystalPortalNetwork.cellStatus(pending.source(), pending.portal(), pending.receptacle())
+                        != CrystalPortalNetwork.CellStatus.VALID) continue;
+            PortalBookTravel.travel(entity, pending.source(), pending.book());
+        }
+    }
+    @SubscribeEvent public static void stopped(ServerStoppedEvent event) { PENDING.clear(); PortalTravelCooldown.clear(); }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/registry/ModCreativeTabs.java

@@ -23,6 +23,7 @@ public final class ModCreativeTabs {
                     output.accept(Rivencraft.DESCRIPTIVE_BOOK.get());
                     output.accept(Rivencraft.LINKING_BOOK.get());
                     output.accept(Rivencraft.CRYSTAL_BLOCK_ITEM.get());
+                    output.accept(Rivencraft.BOOK_RECEPTACLE_ITEM.get());
                     output.accept(Rivencraft.BUDDING_CRYSTAL_ITEM.get());
                     output.accept(Rivencraft.SMALL_CRYSTAL_BUD_ITEM.get());
                     output.accept(Rivencraft.MEDIUM_CRYSTAL_BUD_ITEM.get());
@@ -32,6 +33,7 @@ public final class ModCreativeTabs {
                     output.accept(Rivencraft.INK_VIAL.get());
                     output.accept(Rivencraft.BOOK_BINDER_ITEM.get());
                     output.accept(Rivencraft.INK_MIXER_ITEM.get());
+                    output.accept(Rivencraft.LINK_MODIFIER_ITEM.get());
                     output.accept(Rivencraft.WRITING_DESK_ITEM.get());
                     output.accept(Rivencraft.NOTEBOOK.get());
                     output.accept(Rivencraft.COLLATION_FOLDER.get());

ports/mc263/src/main/java/net/dnorberg/rivencraft/writing/DescriptiveBookPages.java

@@ -0,0 +1,21 @@
+package net.dnorberg.rivencraft.writing;
+
+import java.util.List;
+import java.util.Optional;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.resources.Identifier;
+import net.minecraft.world.item.ItemStack;
+
+/** Client-readable snapshot of authored pages; index zero is the front/link-panel spread. */
+public record DescriptiveBookPages(List<Identifier> symbols, String author) {
+    public DescriptiveBookPages { symbols = List.copyOf(symbols); }
+    public static DescriptiveBookPages from(ItemStack book) {
+        return new DescriptiveBookPages(book.getOrDefault(Rivencraft.BOOK_SYMBOLS.get(), List.of()),
+                book.getOrDefault(Rivencraft.BOOK_AUTHOR.get(), ""));
+    }
+    public int lastPage() { return Math.max(1, symbols.size()); }
+    public int turn(int page, int direction) { return Math.clamp(page + direction, 0, lastPage()); }
+    public Optional<Identifier> symbolAt(int page) {
+        return page >= 1 && page <= symbols.size() ? Optional.of(symbols.get(page - 1)) : Optional.empty();
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/writing/PortAuthoredTerrainSelection.java

@@ -17,6 +17,20 @@ public final class PortAuthoredTerrainSelection {
     }
 
     public static Selection select(MinecraftServer server, List<Identifier> pages, long seed) {
+        if (!net.dnorberg.rivencraft.age.PortDayCycle.validWriting(pages))
+            throw new IllegalArgumentException("An Age may have at most ten suns and ten moons");
+        for (var page : pages) {
+            var entry = PortSymbolPages.find(page);
+            if (entry != null && entry.role().equals("biome")) {
+                var biome = PortRegistryPages.biomeId(page);
+                if (biome == null || server.registryAccess().lookupOrThrow(net.minecraft.core.registries.Registries.BIOME)
+                        .get(net.minecraft.resources.ResourceKey.create(net.minecraft.core.registries.Registries.BIOME, biome)).isEmpty())
+                    throw new IllegalArgumentException("Unknown biome page: " + page);
+            }
+        }
+        var recovered = PortWritingRecovery.recover(pages);
+        if (!recovered.implemented()) throw new IllegalArgumentException("Unimplemented symbol page in this book");
+        pages = recovered.activePages();
         var explicit = PortAuthoredWriting.explicitTerrain(pages);
         if (explicit != null) return compile(server, pages, seed, explicit);
         var preferred = PortRandomAgeSelection.terrain(seed);

ports/mc263/src/main/java/net/dnorberg/rivencraft/writing/PortAuthoredWriting.java

@@ -57,7 +57,8 @@ public final class PortAuthoredWriting {
         if (entry == null) return false;
         if (net.dnorberg.rivencraft.age.PortAgeColors.isModifier(page)
                 || net.dnorberg.rivencraft.age.PortDayCycle.supports(page)) return true;
-        if (page.equals(net.dnorberg.rivencraft.age.PortAcceleratedTicks.PAGE)) return true;
+        if (page.equals(net.dnorberg.rivencraft.age.PortAcceleratedTicks.PAGE)
+                || net.dnorberg.rivencraft.age.PortInstabilityData.isCorrupted(page)) return true;
         if (isTerrain(page) || controller(page) != null || PortWeatherMode.forPage(page) != null
                 || PortLighting.forPage(page) != null || PortSkyStyle.forPage(page) != null) return true;
         if (entry.category().equals("rivencraft:biome") && PortRegistryPages.biomeId(page) != null) return true;
@@ -71,20 +72,25 @@ public final class PortAuthoredWriting {
                 || PortStructurePages.supports(page) || PortCarverPages.supports(page);
     }
 
-    /** A page never disappears into an Age unless this port can apply its effect. */
+    /** Recover known category defects; unimplemented pages and unsupported runtime combinations still block binding. */
     public static boolean supports(List<Identifier> pages) {
-        if (pages.stream().noneMatch(PortAuthoredWriting::isTerrain))
+        if (!net.dnorberg.rivencraft.age.PortDayCycle.validWriting(pages)) return false;
+        var recovered = PortWritingRecovery.recover(pages);
+        if (!recovered.implemented()) return false;
+        List<Identifier> active = recovered.activePages();
+        if (active.stream().noneMatch(PortAuthoredWriting::isTerrain))
             return net.dnorberg.rivencraft.age.PortRandomAgeSelection.terrains().stream()
-                    .anyMatch(terrain -> supportsOnTerrain(pages, terrain, 0));
-        try {
-            return supportsExplicit(PortMaterialCompletion.complete(pages, 0));
-        } catch (IllegalArgumentException exception) { return false; }
+                    .anyMatch(terrain -> supportsOnTerrain(active, terrain, 0));
+        try { return supportsExplicit(PortMaterialCompletion.complete(active, 0)); }
+        catch (IllegalArgumentException exception) { return false; }
     }
 
     static boolean supportsOnTerrain(List<Identifier> pages, PortAgeTerrain terrain, long seed) {
-        try {
-            return supportsExplicit(PortMaterialCompletion.complete(withTerrain(pages, terrain), seed));
-        } catch (IllegalArgumentException exception) { return false; }
+        if (!net.dnorberg.rivencraft.age.PortDayCycle.validWriting(pages)) return false;
+        var recovered = PortWritingRecovery.recover(pages);
+        if (!recovered.implemented()) return false;
+        try { return supportsExplicit(PortMaterialCompletion.complete(withTerrain(recovered.activePages(), terrain), seed)); }
+        catch (IllegalArgumentException exception) { return false; }
     }
 
     static List<Identifier> withTerrain(List<Identifier> pages, PortAgeTerrain terrain) {
@@ -103,7 +109,6 @@ public final class PortAuthoredWriting {
     }
 
     private static boolean supportsExplicit(List<Identifier> pages) {
-        if (!net.dnorberg.rivencraft.age.PortAgeColors.validNumbers(pages)) return false;
         if (!net.dnorberg.rivencraft.age.PortDayCycle.validWriting(pages)) return false;
         boolean terrain = false;
         int biomes = 0;
@@ -129,6 +134,8 @@ public final class PortAuthoredWriting {
             if (net.dnorberg.rivencraft.age.PortAgeColors.isModifier(page)
                     || net.dnorberg.rivencraft.age.PortDayCycle.supports(page)) {
                 // Shared colors target Sky, Ambient Light Color or Normal Time; trailing colors tint the sky.
+            } else if (net.dnorberg.rivencraft.age.PortInstabilityData.isCorrupted(page)) {
+                // Legacy corrupted pages contribute instability, not terrain features.
             } else if (page.equals(net.dnorberg.rivencraft.age.PortAcceleratedTicks.PAGE)) {
                 // Every Accelerated page adds random-tick attempts; it is not a controller.
             } else if (isTerrain(page) && !terrain) {

ports/mc263/src/main/java/net/dnorberg/rivencraft/writing/PortRegistryPages.java

@@ -101,7 +101,7 @@ public final class PortRegistryPages {
                 || path.equals("deep_dark") || path.endsWith("_caves");
     }
 
-    private static String materialCategory(Block block) {
+    public static String materialCategory(Block block) {
         if (block == null || block == Blocks.AIR || block == Blocks.CAVE_AIR || block == Blocks.VOID_AIR
                 || block == Rivencraft.CLOUD_PLATFORM.get()
                 || block instanceof EntityBlock || block.defaultBlockState().hasBlockEntity()) return null;

ports/mc263/src/main/java/net/dnorberg/rivencraft/writing/PortSymbolPages.java

@@ -17,7 +17,13 @@ import net.dnorberg.rivencraft.item.PageItem;
 
 /** Bundled 1.21.1 symbol identities, shared by the port's creative pages. */
 public final class PortSymbolPages {
-    public record Entry(Identifier id, String category, String nameKey, String descriptionKey, String poem) {}
+    public record Entry(Identifier id, String category, String nameKey, String descriptionKey, String poem, String role) {
+        public Entry(Identifier id, String category, String nameKey, String descriptionKey, String poem) {
+            this(id, category, nameKey, descriptionKey, poem,
+                    category.equals("rivencraft:biome") ? "biome"
+                    : category.equals("rivencraft:block") || category.equals("rivencraft:fluid") ? "block" : "unknown");
+        }
+    }
 
     private static final Map<Identifier, Entry> ENTRIES = load();
 
@@ -100,7 +106,9 @@ public final class PortSymbolPages {
                     category = "rivencraft:biome_generation";
                 entries.put(id, new Entry(id, category, definition.get("name").getAsString(),
                         definition.get("description").getAsString(),
-                        definition.has("poem") ? definition.get("poem").getAsString() : ""));
+                        definition.has("poem") ? definition.get("poem").getAsString() : "",
+                        definition.has("semantics") ? definition.getAsJsonObject("semantics").get("role").getAsString()
+                                : id.getPath().equals("lighting/ambient_color") ? "ambient_color" : "unknown"));
             });
             return Collections.unmodifiableMap(entries);
         } catch (java.io.IOException exception) {

ports/mc263/src/main/java/net/dnorberg/rivencraft/writing/PortWritingRecovery.java

@@ -0,0 +1,99 @@
+package net.dnorberg.rivencraft.writing;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import net.minecraft.resources.Identifier;
+
+/** 1.21.1 grammar diagnostics and singular-controller recovery; preserve ordered modifier chains. */
+public final class PortWritingRecovery {
+    private static final Set<String> SINGULAR = Set.of("terrain", "biome_controller", "weather", "season", "lighting", "sky");
+    private static final Set<String> MODIFIERS = Set.of("period_modifier", "angle_modifier", "phase_modifier", "size_modifier",
+            "celestial_color", "direction_modifier");
+    public record Diagnostic(String code, int index, int points) {}
+    public record Result(List<Identifier> activePages, List<Diagnostic> diagnostics, boolean implemented) {
+        public Result { activePages = List.copyOf(activePages); diagnostics = List.copyOf(diagnostics); }
+    }
+    private PortWritingRecovery() {}
+    public static Result recover(List<Identifier> pages) {
+        Map<String, Integer> last = new HashMap<>();
+        List<Diagnostic> diagnostics = new ArrayList<>();
+        boolean implemented = pages.size() <= NotebookContents.MAX_PAGES;
+        int previousStage = -1, biomes = 0;
+        Map<String, Integer> pendingModifiers = new java.util.LinkedHashMap<>();
+        Integer pendingNumber = null;
+        for (int index = 0; index < pages.size(); index++) {
+            Identifier page = pages.get(index);
+            var entry = PortSymbolPages.find(page);
+            if (entry == null || !PortAuthoredWriting.isPageImplemented(page)) { implemented = false; continue; }
+            String role = entry.role();
+            if (pendingNumber != null && !numberTarget(role)) {
+                diagnostics.add(new Diagnostic("misplaced_modifier", pendingNumber, 100));
+                pendingNumber = null;
+            }
+            if (role.equals("color_number")) pendingNumber = index;
+            else if (numberTarget(role)) pendingNumber = null;
+            if (MODIFIERS.contains(role)) pendingModifiers.put(role, index);
+            else if (role.equals("celestial")) pendingModifiers.clear();
+            if (SINGULAR.contains(role)) {
+                Integer prior = last.put(role, index);
+                if (prior != null) {
+                    diagnostics.add(new Diagnostic(pages.get(prior).equals(page) ? "duplicate" : "conflict", index, 500));
+                    // Match WritingGrammar: a repeated singular choice does not also earn an order penalty.
+                    continue;
+                }
+            }
+            if (role.equals("biome")) biomes++;
+            int stage = stage(role);
+            if (stage < previousStage && !MODIFIERS.contains(role) && !role.equals("color") && !role.equals("color_number"))
+                diagnostics.add(new Diagnostic("out_of_order", index, 100));
+            else if (!role.equals("color") && !role.equals("color_number")) previousStage = stage;
+        }
+        if (pendingNumber != null) diagnostics.add(new Diagnostic("dangling_modifier", pendingNumber, 100));
+        for (int index : pendingModifiers.values())
+            diagnostics.add(new Diagnostic("dangling_modifier", index, 100));
+        Integer controller = last.get("biome_controller");
+        boolean nativeBiomes = controller != null && pages.get(controller).getPath().equals("biome/native");
+        boolean single = controller != null && pages.get(controller).getPath().equals("biome/single");
+        if (nativeBiomes && biomes > 0 || single && biomes > 1)
+            diagnostics.add(new Diagnostic("conflict", controller, 500));
+        List<Identifier> active = new ArrayList<>();
+        boolean retainedBiome = false;
+        for (int index = 0; index < pages.size(); index++) {
+            var page = pages.get(index);
+            var entry = PortSymbolPages.find(page);
+            if (entry != null) {
+                String role = entry.role();
+                if (SINGULAR.contains(role) && last.getOrDefault(role, -1) != index) continue;
+                if (role.equals("biome")) {
+                    if (nativeBiomes || single && retainedBiome) continue;
+                    retainedBiome = true;
+                }
+            }
+            active.add(page);
+        }
+        // Keep source order for material pairing and per-celestial modifier chains.
+        // The port's category compilers select by role, so no physical resort is necessary.
+        return new Result(active, diagnostics, implemented);
+    }
+    private static boolean numberTarget(String role) {
+        return role.equals("color") || role.equals("period_modifier") || role.equals("angle_modifier")
+                || role.equals("phase_modifier") || role.equals("size_modifier");
+    }
+    private static int stage(String role) {
+        return switch (role) {
+            case "terrain" -> 0;
+            case "biome" -> 1;
+            case "biome_controller" -> 2;
+            case "weather" -> 3;
+            case "season" -> 4;
+            case "lighting" -> 5;
+            case "sky", "sky_color", "ambient_color", "color", "color_number" -> 6;
+            case "period_modifier", "angle_modifier", "phase_modifier", "size_modifier", "celestial_color", "direction_modifier" -> 7;
+            case "celestial" -> 8;
+            default -> 9;
+        };
+    }
+}

ports/mc263/src/main/java/net/dnorberg/rivencraft/writing/WritingInkService.java

@@ -0,0 +1,77 @@
+package net.dnorberg.rivencraft.writing;
+
+import net.dnorberg.rivencraft.PortConfig;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.util.Prediction;
+import net.dnorberg.rivencraft.item.InkVialItem;
+import net.dnorberg.rivencraft.item.PageItem;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+
+/** Server-owned costs and the baseline blank-page-to-link-panel transaction. */
+public final class WritingInkService {
+    private WritingInkService() {
+    }
+
+    public static int symbolCopyCost() {
+        return PortConfig.SYMBOL_INK_COST.get();
+    }
+
+    public static int linkPanelCost() {
+        return PortConfig.LINK_PANEL_INK_COST.get();
+    }
+
+    public static boolean canPrepareLinkPanel(Player player, InteractionHand vialHand) {
+        ItemStack vial = player.getItemInHand(vialHand);
+        ItemStack page = player.getItemInHand(other(vialHand));
+        int remaining = InkVialItem.remaining(vial);
+        return vial.is(Rivencraft.INK_VIAL.get()) && remaining >= linkPanelCost()
+                && remaining <= InkVialItem.CAPACITY
+                && page.is(Items.PAPER);
+    }
+
+    public static boolean prepareLinkPanel(Player player, InteractionHand vialHand) {
+        if (player.level().isClientSide() || !canPrepareLinkPanel(player, vialHand)) {
+            return false;
+        }
+
+        InteractionHand pageHand = other(vialHand);
+        ItemStack page = player.getItemInHand(pageHand);
+        ItemStack vial = player.getItemInHand(vialHand);
+        int newInk = InkVialItem.remaining(vial) - linkPanelCost();
+        ItemStack panel = PageItem.createLinkPanelPage();
+        ItemStack spentVial = newInk == 0
+                ? new ItemStack(Items.GLASS_BOTTLE)
+                : new ItemStack(Rivencraft.INK_VIAL.get());
+        if (newInk > 0) {
+            spentVial.set(Rivencraft.INK_REMAINING.get(), newInk);
+        }
+
+        // All validation and output construction is complete before changing either input.
+        if (page.getCount() == 1) {
+            player.setItemInHand(pageHand, panel);
+        } else {
+            page.shrink(1);
+            giveOrDrop(player, panel);
+        }
+        if (vial.getCount() == 1) {
+            player.setItemInHand(vialHand, spentVial);
+        } else {
+            vial.shrink(1);
+            giveOrDrop(player, spentVial);
+        }
+        return true;
+    }
+
+    private static InteractionHand other(InteractionHand hand) {
+        return hand == InteractionHand.MAIN_HAND ? InteractionHand.OFF_HAND : InteractionHand.MAIN_HAND;
+    }
+
+    private static void giveOrDrop(Player player, ItemStack stack) {
+        if (!player.getInventory().add(stack)) {
+            player.drop(stack, false, Prediction.SERVER_ONLY);
+        }
+    }
+}

ports/mc263/src/main/resources/assets/rivencraft/items/book_receptacle.json

@@ -0,0 +1,6 @@
+{
+  "model": {
+    "type": "minecraft:model",
+    "model": "rivencraft:item/book_receptacle"
+  }
+}

ports/mc263/src/main/resources/assets/rivencraft/items/link_modifier.json

@@ -0,0 +1 @@
+{"model":{"type":"minecraft:model","model":"rivencraft:item/link_modifier"}}

ports/mc263/src/main/resources/data/rivencraft/advancement/progression/root.json

@@ -0,0 +1,21 @@
+{
+  "display": {
+    "icon": {
+      "id": "rivencraft:descriptive_book"
+    },
+    "title": {
+      "translate": "advancement.rivencraft.root.title"
+    },
+    "description": {
+      "translate": "advancement.rivencraft.root.description"
+    },
+    "background": "rivencraft:block/crystal_block",
+    "show_toast": false,
+    "announce_to_chat": false
+  },
+  "criteria": {
+    "completed": {
+      "trigger": "minecraft:tick"
+    }
+  }
+}

ports/mc263/src/main/resources/data/rivencraft/advancement/recipes/misc/book_binder.json

@@ -0,0 +1,34 @@
+{
+  "parent": "minecraft:recipes/root",
+  "criteria": {
+    "has_material": {
+      "trigger": "minecraft:inventory_changed",
+      "conditions": {
+        "items": [
+          {
+            "items": "minecraft:iron_ingot"
+          }
+        ]
+      }
+    },
+    "has_the_recipe": {
+      "trigger": "minecraft:recipe_unlocked",
+      "conditions": {
+        "recipes": [
+          "rivencraft:book_binder"
+        ]
+      }
+    }
+  },
+  "requirements": [
+    [
+      "has_material",
+      "has_the_recipe"
+    ]
+  ],
+  "rewards": {
+    "recipes": [
+      "rivencraft:book_binder"
+    ]
+  }
+}

ports/mc263/src/main/resources/data/rivencraft/advancement/recipes/misc/book_receptacle.json

@@ -0,0 +1,34 @@
+{
+  "parent": "minecraft:recipes/root",
+  "criteria": {
+    "has_material": {
+      "trigger": "minecraft:inventory_changed",
+      "conditions": {
+        "items": [
+          {
+            "items": "rivencraft:crystal_block"
+          }
+        ]
+      }
+    },
+    "has_the_recipe": {
+      "trigger": "minecraft:recipe_unlocked",
+      "conditions": {
+        "recipes": [
+          "rivencraft:book_receptacle"
+        ]
+      }
+    }
+  },
+  "requirements": [
+    [
+      "has_material",
+      "has_the_recipe"
+    ]
+  ],
+  "rewards": {
+    "recipes": [
+      "rivencraft:book_receptacle"
+    ]
+  }
+}

ports/mc263/src/main/resources/data/rivencraft/advancement/recipes/misc/crystal_block.json

@@ -0,0 +1,34 @@
+{
+  "parent": "minecraft:recipes/root",
+  "criteria": {
+    "has_crystal_shard": {
+      "trigger": "minecraft:inventory_changed",
+      "conditions": {
+        "items": [
+          {
+            "items": "rivencraft:crystal_shard"
+          }
+        ]
+      }
+    },
+    "has_the_recipe": {
+      "trigger": "minecraft:recipe_unlocked",
+      "conditions": {
+        "recipes": [
+          "rivencraft:crystal_block"
+        ]
+      }
+    }
+  },
+  "requirements": [
+    [
+      "has_crystal_shard",
+      "has_the_recipe"
+    ]
+  ],
+  "rewards": {
+    "recipes": [
+      "rivencraft:crystal_block"
+    ]
+  }
+}

ports/mc263/src/main/resources/data/rivencraft/advancement/recipes/misc/ink_mixer.json

@@ -0,0 +1,34 @@
+{
+  "parent": "minecraft:recipes/root",
+  "criteria": {
+    "has_material": {
+      "trigger": "minecraft:inventory_changed",
+      "conditions": {
+        "items": [
+          {
+            "items": "minecraft:glass_bottle"
+          }
+        ]
+      }
+    },
+    "has_the_recipe": {
+      "trigger": "minecraft:recipe_unlocked",
+      "conditions": {
+        "recipes": [
+          "rivencraft:ink_mixer"
+        ]
+      }
+    }
+  },
+  "requirements": [
+    [
+      "has_material",
+      "has_the_recipe"
+    ]
+  ],
+  "rewards": {
+    "recipes": [
+      "rivencraft:ink_mixer"
+    ]
+  }
+}