Port crystal growth, pages, ink vials and link crafting to 26.3

README.md

@@ -1,283 +1,117 @@
 # Rivencraft
 
-Rivencraft is a clean, incremental port of the ideas and gameplay of
-[Mystcraft Legacy](https://github.com/Mystcraft/Mystcraft-Legacy) to Minecraft
-1.21.1 on NeoForge.
+Write a book. Name an Age. Step into a world that did not exist before.
 
-The bootstrap, books/linking, Ages, writing-system, and Age-grammar milestones are complete.
-The writing system uses a data-pack symbol catalog and persistent
-ordered-writing model. Linking Books and Descriptive Books create persistent
-Ages from either authored supported symbols or seeded random completion.
-Milestone 6 instability work is in progress: Ages persist frozen instability
-scores and provider plans, and the bounded runtime implements status effects,
-colored decay, lightning, explosions, meteors, burning, and erosion. The
-[Milestone 5 acceptance record](docs/MILESTONE_5_ACCEPTANCE.md) lists the
-supported grammar, optional integrations, and limits; the
-[instability runtime policy](docs/INSTABILITY_RUNTIME.md) records the current
-effects and modern safety boundaries.
+Rivencraft brings the books, writing stations, symbols, and unpredictable Ages
+of [Mystcraft Legacy](https://github.com/Mystcraft/Mystcraft-Legacy) to
+Minecraft 1.21.1 on NeoForge. Mystcraft veterans will recognize the writing
+flow, D'ni-inspired glyphs, libraries, crystals, and instability. Rivencraft
+also lets you author modern terrain, biomes, structures, seasons, and celestial
+bodies. It is an active pre-public-release project, not a byte-for-byte copy of
+the 1.12.2 mod.
 
-Milestone 4 now includes stackable blank Pages plus server-created symbol,
-unresolved-symbol, and baseline link-panel states. Page visuals follow the
-legacy runtime-composition rules. Craft an Ink Vial from two black dye, a glass
-bottle, and a water bucket; the bucket is returned. Hold vanilla paper in one
-hand and use the Ink Vial in the other to prepare a baseline Link Panel Page.
-Each vial holds 16 ink units, and the default link-panel cost is two units.
-The spent vial returns a glass bottle. Server owners can adjust the symbol-copy
-and link-panel costs in the `writing` section of `rivencraft-server.toml`.
-The Ink Mixer now offers a Legacy-style station for producing Link Panels:
-insert paper and Ink Vials, then take a Link Panel from the result slot. Each
-vial fills its 16-unit basin and returns a glass bottle; taking one Link Panel
-uses the full vial. No server tick is needed. The earlier paper-in-one-hand
-method still uses the configurable link-panel ink cost. Ink Mixer
-additives can roll Disarm, Maintain Momentum, and Intra Linking onto a Link
-Panel. Descriptive Books retain Disarm and Momentum; Intra Linking is only
-meaningful for same-dimension travel with a Linking Book.
-TerraBlender 1.21.1 integration is optional: registered modded biomes receive
-Biome pages, with cave and Nether biomes in a separate Cave Biome creative tab.
-TerraBlender Overworld/Nether regions extend compatible Age
-biome pools. See [the compatibility matrix](docs/TERRABLENDER_COMPATIBILITY.md)
-for supported versions and in-game verification.
-Serene Seasons 1.21.1 can maintain separate season progress in an Age dimension.
-Rivencraft automatically whitelists loaded Ages without a restart when Serene is installed;
-season pages can instead opt an Age out or hold it in one season.
-See [the optional compatibility guide](docs/SERENE_SEASONS_COMPATIBILITY.md)
-for the supported manual configuration and current limits; Rivencraft does not
-require Serene Seasons or GlitchCore.
-The Writing Desk can copy a selected written page from its collection tabs.
-The Writing Desk is now craftable from planks, a glass bottle, and a feather.
-It occupies two adjacent blocks, with one shared inventory; loaded paper and
-the selected page appear on its Legacy-inspired model.
-Desks placed before 0.3.6.1 keep their old one-block footprint until broken
-and placed again; leave an adjacent space when replacing one.
-Its 88 collection tabs, paper input, ink vial input, empty glass-bottle return,
-16-unit ink meter, and inventory persist
-through world saves; breaking it drops stored contents. The desk screen is a
-functional foundation using Legacy's original desk and scrollbar textures.
-Four tabs are visible at once; the controls above and below them move by four
-(1–4, 5–8, through 85–88). Each viewer can browse a different group. Existing
-four-tab desks retain their collections and supplies when upgraded.
-With a notebook selected, pick up a Page from your inventory and click an empty
-position on the left surface to store one page there. Clear search/filter/sort
-and turn off `ALL` to place pages at specific positions; occupied positions are
-never overwritten. A notebook tab exposes all 27 notebook positions (scroll to
-reach the rest); a loose-page tab exposes only its one occupied position.
-Empty tabs have no page storage until a notebook or page is put in the tab slot.
-Click a page on the desk surface to select it for copying. Drag a page from one
-notebook position to an empty position to move it, or onto another page to swap
-their positions. This also works between notebooks shown in the `ALL` view.
-Drag a page out of the panel to turn it back into an item. Drop it over a player
-inventory slot or desk tab to place it there; a tab with a notebook adds it to
-the first open position. Dropping elsewhere leaves the page on the cursor for
-normal inventory placement. The source notebook or tab loses the page only after
-a valid drop.
-Put vanilla paper in the
-upper-left slot and Ink Vials in the upper-right; a copy appears in the
-lower-left result slot when the selected page is valid. Taking it consumes one
-paper and, by default, one ink. An available vial refills an empty ink meter
-when inserted or when copying uses its last ink, and returns a vanilla glass
-bottle to the lower-right slot. Removing a bottle also retries a blocked refill.
-Refilling waits if that slot is full or contains another item. The `AZ` control sorts
-visible pages by name; `ALL` shows pages held across every desk tab. Search and
-category filtering narrow the view without granting new pages, and cross-tab
-copy selection is checked by the server.
-Selecting a stored page on the desk surface shows its Legacy-proportioned
-portrait preview and name above the player inventory.
+## Getting started
 
-## Book Binder
+1. Make an Ink Vial from two black dyes, a glass bottle, and a water bucket.
+   Craft an Ink Mixer, Writing Desk, and Book Binder.
+2. Put paper and an Ink Vial in the Ink Mixer and take a Link Panel Page. Add
+   ingredients to the basin first if you want a chance of link modifiers.
+3. Put leather or an empty Notebook and the Link Panel in the Book Binder.
+   Name the Age and take the Descriptive Book. A book with only a Link Panel
+   creates a seeded random Age; add Symbol Pages to author its features.
+4. Open the book to create its Age, then click the destination preview to
+   travel. Bring a bound Linking Book for the return trip: automatic Return
+   Links are off by default.
 
-For a new survival Age: craft an Ink Vial, an Ink Mixer, a Writing Desk, and a Book Binder.
-Put vanilla paper and an Ink Vial in the Ink Mixer to make a Link Panel
-Page. Place leather (or an empty Notebook) and the Link Panel in the Book Binder,
-enter an Age name, and take the finished Descriptive Book. Written symbol Pages
-are optional; without them, the book creates a random Age. To duplicate a Page
-you already own, store it in a Writing Desk tab, select it, supply paper and ink,
-and take the copied Page from the output. A Notebook can hold and transfer a
-larger ordered collection of Pages between desks and the binder.
+Find new Symbol Pages in Age libraries, or copy pages you already own with
+paper and ink at the Writing Desk. The Notebook stores ordered pages, including
+intentional gaps. Written pages can control terrain, biome distribution,
+weather, lighting, seasons, sky color, suns and moons, decorations, structures,
+and more. Incorrect or excessive writing can make an Age unstable; instability
+may bring decay, lightning, explosions, meteors, burning, erosion, and other
+hazards. Some combinations are still unsupported and the Binder reports them
+before consuming ingredients.
 
-With JEI installed, Rivencraft displays the Ink Mixer operation in its own
-category and the hand-use, copying, binding, and Linking Book crafting flows in a Writing category.
-The Link Panel and individual symbol Pages, including registered vanilla biome
-pages, appear as separately searchable JEI ingredients.
-Creative inventory separates Link Pages and each symbol category into their own
-tabs, including distinct Biome and Biome Generation tabs. Blank Pages are hidden
-from creative inventory and JEI.
-JEI is optional; vanilla crafting
-recipes and all writing interactions work without it. For a development client
-with JEI, run `./gradlew runClient -PwithJei=true`.
+Place a Rivencraft book or page on a vanilla Lectern to convert it to a Book
+Stand. Crystal formations yield shards for Crystal Blocks. A connected crystal
+frame with a Book Receptacle and a bound book forms a portal; frames can stand
+upright or lie flat. Libraries, Book Stands, and portals use Legacy-inspired
+assets and sounds. Handheld travel drops the used book at the departure point,
+so plan how you will retrieve it.
 
-Four Crystal Shards craft one Crystal Block; eight Crystal Blocks around an
-empty crafting-grid center make one Book Receptacle. Picking up a shard unlocks
-the block recipe, and picking up a block unlocks the Receptacle recipe. The
-existing Ink Vial recipe uses two black dyes, a glass bottle, and a water
-bucket; the empty bucket stays in the crafting grid. These JSON recipes appear
-in JEI when it is installed and can be replaced by a data pack at
-`data/rivencraft/recipe/<recipe_name>.json`. To test a replacement, use a fresh
-world or `/reload`, then check the result in a crafting table and vanilla
-Crafter. A vanilla Lectern converts to a Rivencraft Book Stand when a Rivencraft
-book or page is placed on it; this in-world interaction has no JEI guide.
-With Create installed, Crystal Blocks and Book Receptacles have an optional Ponder scene
-showing crystal-frame construction, book activation, and a parrot crossing the portal. Use the Ponder shortcut
-while hovering either item; Rivencraft does not require Create to run.
-Crystal frames may stand vertically or lie flat: a 3×3 Crystal Block ring with
-an empty center forms a horizontal portal when a Book Receptacle is attached to
-the top or underside of one of its blocks. Insert a bound Linking or Descriptive
-Book to activate it; the book remains visible on the receptacle. A Linking Book aimed at its
-own dimension still opens a visual portal, but travel requires Intra Linking.
+## Requirements and optional integrations
 
-Sky writing includes eight color pages and a Static Sky page. Multiple sky-color
-pages blend their colors, tinting the Age sky, book preview, and the fallback
-surface of portals linked there. Multiple celestial-color pages blend for the
-next written sun or moon. An Age may have no suns or moons at all;
-Static Sky animates the sky with television-like noise. Sun and Moon pages add
-independent bodies; preceding color, size, angle, period, phase, and direction
-pages configure the next body. The third and each subsequent sun add increasing
-instability. Newly generated page-free Ages also choose a deterministic sky,
-color, and celestial arrangement from their Age seed; older saved Ages retain
-their previous sky.
+Install the same gameplay mods on the client and server:
 
-Craft a Book Binder from three iron ingots and five planks. Put leather or an
-empty Notebook in the left cover slot. Enter a title, then place a Link Panel
-Page first in the horizontal page strip. Click a page in the strip with a
-written Page on the cursor to insert it before that position; click it with an
-empty cursor to take it out. The arrows or mouse wheel scroll through up to
-27 written Pages. Clicking the strip with a filled Notebook imports its Pages
-at that position and leaves the emptied Notebook on the cursor. The right slot
-outputs a Descriptive Book once the title, cover, and Link Panel are present.
-Inputs are consumed only when the result is taken.
+- Minecraft **1.21.1**, NeoForge **21.1.264 or newer in the 21.1 line**, and
+  Java 21.
+- **Dynamic Dimensions AR Edition 0.9.1** and its **Bad Packets 0.8.2**
+  dependency. These are required for Age dimensions.
 
-The completed book receives its Age identity when assembled. With only a Link
-Panel, it describes a randomly generated Age. Authored writing is compiled once
-into a versioned, server-owned Age plan. The plan freezes the Age seed, resolved
-symbol meanings, page order, and runtime profile, so later data-pack changes do
-not reinterpret an existing Age. An authored terrain page selects its runtime
-profile. Built-in pages cover Standard, Amplified, Cave, Island, Flat, and Void;
-authored biome, environment, and supported feature pages also affect new Ages.
-The
-writing is also stored on the book; the Descriptive Book screen's turned pages
-show ordered symbols and unresolved IDs. The Descriptive Book screen follows
-Legacy's book spread: the title and Age details are on the left, the destination
-preview is on the right, and clicks in the bottom corners turn pages. Ordered
-symbol pages appear before the final blank spread with their runtime-rendered
-pictograms. Link-panel-only books use Rivencraft glyphs for their generated
-Age description.
+Rivencraft works without any of these optional integrations:
 
-## Linking Book
+| Mod | What it adds |
+| --- | --- |
+| JEI | Searchable Pages and guides for the Ink Mixer, Writing Desk, Book Binder, and Linking Book crafting. |
+| Create (bundles Ponder) | Ponder book snapshots and a crystal-portal construction guide. |
+| Immersive Portals | Live destination views in book previews and crystal portals. In `AUTO` preview mode it takes priority over Ponder. |
+| TerraBlender | Eligible biomes from mods using its Overworld/Nether regions become Age biome candidates and Pages. Biomes O' Plenty is one example; it is not hard-coded or required. |
+| Serene Seasons (with GlitchCore) | Independent per-Age seasons, including normal seasons, no seasons, and four eternal-season modes. |
+| Ruins | Authorable Ruins-template Pages and Ruins structures in Ages. |
 
-Craft an unwritten Linking Book from one Link Panel Page and one leather in any
-two crafting-grid positions. An unbound book opens a screen where it can be named and bound to the
-current location. A bound book opens its destination screen and travels when
-its preview panel is clicked. The destination is stored on the item and
-survives inventory and world saves. Travel only succeeds if the target
-dimension is loaded and a non-fluid, passable landing position can be found
-nearby.
-The Linking Book uses the same Legacy page layout and bottom-corner page turns
-as the Descriptive Book, but without the Descriptive Book's gold cover edges.
-Both screens play Minecraft's book-page-turn sound when a page is turned.
+The optional builds used in the latest development checks are JEI
+19.69.0.457, Create 6.0.10, Immersive Portals 6.0.7, TerraBlender 4.1.0.8,
+Serene Seasons 10.1.0.9, and Ruins 1.21.1.2NF. See the
+[compatibility review](docs/MILESTONE_7_COMPATIBILITY_REVIEW.md) for the
+evidence and limits of those combinations.
 
-Successful book travel plays Mystcraft Legacy's original linking sound at both
-the departure and arrival locations.
+Without Create or Immersive Portals, book previews use Rivencraft's built-in
+Legacy-style animation. Ecliptic Seasons is **not supported**: its 1.21.1 API
+does not offer the live dimension/season control Rivencraft needs.
 
-Right-click an empty vanilla lectern with a Rivencraft book to convert it into
-a Book Stand and place the book on it. Use a Linking Book on the stand by
-right-clicking with an empty hand. Sneak-right-click with an empty hand to take
-the book back and restore the vanilla lectern. Breaking a Book Stand drops both
-the stored book and a vanilla lectern.
+## Saves, settings, and current limits
 
-Bound Linking Books show a rotating Ponder snapshot when Create is installed.
-Without Create, they use a built-in animated linking panel tinted by the
-destination sky. The server independently validates every link.
+Ages and bound books use persistent UUIDs. Back up the **entire world folder**
+before changing mod versions, data packs, or optional biome mods: the Age
+registry and dimension data must be restored together. Rivencraft preserves
+known older save formats where possible, but pre-public-release worlds are not
+promised universal compatibility. Missing custom symbols retain their IDs in
+books; missing registry entries or dimension providers can still prevent an
+Age from loading. See [current implementation](docs/CURRENT_IMPLEMENTATION.md)
+for supported behavior and deliberate limits.
 
-## Descriptive Book
+Server settings include `descriptive_books.return_link_mode` (default
+`DISABLED`), `libraries.loot_mode` (`LEGACY` or `AGE_ONLY`), writing ink costs,
+season enrollment, and instability controls. The client setting
+`book_preview.mode` chooses `AUTO`, `IMMERSIVE_PORTALS`, `PONDER`, or `LEGACY`.
+An operator can inspect Ages and instability with `/rivencraft age` and find
+libraries with `/rivencraft library nearest`. The creative-only Link Modifier
+can edit link properties and retire an Age; use it carefully and keep backups.
+Binder status messages are off by default. An OP can run
+`/rivencraft binder messages enable` or `/rivencraft binder messages disable`
+to control them; only OPs see the diagnostics even when enabled.
 
-Open a page-free Descriptive Book, name its Age, and press Create. Rivencraft
-assigns the book a permanent Age UUID, selects a deterministic base terrain,
-creates a dedicated runtime dimension, and prepares a five-by-five cobblestone
-arrival platform at the
-highest suitable nearby terrain. Solid blocks and tree leaves are valid
-footing. Candidate columns are scanned from the top down so cave floors are not
-selected, and fluid-covered columns are excluded. If no suitable surface is
-available, the platform is generated at Y=63. Reopen the book and click its preview to travel.
-The book cannot reopen while its Age is being generated, whether held or on a
-Book Stand. Once creation finishes, reopening shows the written book.
-Copies of the written book continue to resolve to the same persistent Age
-across server restarts.
+## Project and development
 
-New Age dimension folders use a Minecraft-safe lowercase form of the assigned
-name. Conflicts receive incrementing suffixes such as `_2` and `_3`; existing
-Age folders are never renamed.
+This repository is the development source. See the [current implementation](docs/CURRENT_IMPLEMENTATION.md),
+[milestone summaries](docs/MILESTONES.md), [technical document index](docs/README.md),
+and [issues](https://git.paddedcell.org/dnorberg/rivencraft/issues).
+Help build the [Rivencraft wiki](https://git.paddedcell.org/dnorberg/rivencraft/wiki)
+with guides for Ages, pages, and crafting, or open an issue with documentation
+suggestions and corrections.
+Milestone 7 is complete in 1.0.0.2. Its [acceptance record](docs/MILESTONE_7_ACCEPTANCE.md)
+and [regression matrix](docs/MILESTONE_7_REGRESSION.md) distinguish automated
+checks from manual evidence and known limitations.
 
-Page-free Ages deterministically select one of six base terrains inspired by
-Mystcraft Legacy: Standard, Amplified, Island, Cave, Flat, or Void. The chosen
-profile is saved with the Age and does not change when the server restarts.
-
-Linking creates a bound Return Link to the exact source position and orientation
-according to the configured Return Link policy.
-
-Server owners can set `descriptive_books.return_link_mode` in Rivencraft's
-server config to `DISABLED` (default), `ON_CREATION`, or `ALWAYS`.
-Age creation, persistence, lifecycle commands, configuration, backups, and
-administrator recovery are documented in [docs/AGES.md](docs/AGES.md).
-Data-pack runtime profiles are documented in
-[docs/AGE_PROFILES.md](docs/AGE_PROFILES.md).
-
-## Requirements
-
-- A Java 21 JDK
-- Minecraft 1.21.1
-- NeoForge 21.1.264 or newer in the 21.1 line
-- Dynamic Dimensions AR Edition 0.9.1 and Bad Packets 0.8.2 (client and server)
-
-Create is optional. When installed, Rivencraft uses its Ponder renderer for
-book previews when Immersive Portals is absent. Immersive Portals is also
-optional and takes priority in the default `AUTO` mode, providing a live
-rotating destination view. Its Explore button enables WASD and jump/sneak
-camera movement plus left-drag camera look; right-click returns to the rotating
-view. Without either integration, Rivencraft uses its built-in animated linking
-panel. Clients can set `book_preview.mode` in
-`rivencraft-client.toml` to `AUTO`, `IMMERSIVE_PORTALS`, `PONDER`, or `LEGACY`.
-Unavailable optional renderers safely fall back to `LEGACY`.
-The complete backend matrix, supported combinations, cleanup behavior, and
-known upstream limits are documented in
-[docs/PREVIEW_COMPATIBILITY.md](docs/PREVIEW_COMPATIBILITY.md).
-
-## Build and run
-
-```shell
+```sh
 ./gradlew build
-./gradlew runClient
+./gradlew runGameTestServer
 ```
 
-The built mod is written to `build/libs/`.
-The default dedicated-server GameTest run is deliberately small. Use
-`./gradlew runGameTestServer -PwithArchivedGameTests=true` for the complete
-regression suite before a release or when investigating a related issue. See
-[docs/GAMETESTS.md](docs/GAMETESTS.md).
+The JAR is written to `build/libs/`. Development runs need the required mods;
+see [GameTest guidance](docs/GAMETESTS.md) for focused archived suites.
+Versions use `x.y.z.b`: major release, completed milestone, release slice,
+then fixes/additional work within that slice.
 
-## Versioning
-
-Rivencraft versions use `x.y.z.b`:
-
-- `x` changes for a major public release.
-- `y` changes when a development milestone is completed.
-- `z` changes for each release slice within the current milestone.
-- `b` changes for bug fixes and additional work within that release slice.
-
-The build component resets to zero when a new release slice begins. Completing
-a milestone increments `y` and resets both `z` and `b` to zero. For example,
-milestone 2 development can progress from `0.1.1.0` to `0.1.1.1`, then
-`0.1.2.0`; completing the milestone produces `0.2.0.0`.
-
-## Porting approach
-
-Mystcraft Legacy targets Forge for Minecraft 1.12.2. Rivencraft therefore
-ports one subsystem at a time onto current registries, codecs, data packs, and
-NeoForge APIs instead of importing the legacy source tree wholesale.
-
-See [docs/PORTING.md](docs/PORTING.md) for the roadmap, live Gitea tracking
-links, architectural direction, and provenance rules.
-
-## License
-
-Rivencraft is licensed under LGPL-3.0-or-later. Mystcraft Legacy is also
-LGPL-3.0; copied or adapted upstream code must retain its copyright and license
-notices. See [LICENSE](LICENSE) and [NOTICE](NOTICE).
+Rivencraft is licensed under LGPL-3.0-or-later. Legacy-derived material is
+credited in [NOTICE](NOTICE) and [asset provenance](docs/ASSET_PROVENANCE.md).

build.gradle

@@ -245,6 +245,11 @@ dependencies {
     // Keep them on the compile classpath without forcing either mod at runtime.
     compileOnly "net.createmod.ponder:ponder-neoforge:${ponder_version}+mc${minecraft_version}"
     compileOnly "maven.modrinth:immersive-portals-neoforge:${immersive_portals_version}"
+    // Ruins is optional; its pre-spawn event is only registered when Ruins is loaded.
+    compileOnly 'curse.maven:ruins-227873:6391825'
+    if (providers.gradleProperty('withRuins').map { it.toBoolean() }.orElse(false).get()) {
+        localRuntime 'curse.maven:ruins-227873:6391825'
+    }
     // TerraBlender's region API is only used by the guarded compat adapter.
     compileOnly "com.github.glitchfiend:TerraBlender-neoforge:${minecraft_version}-${terrablender_version}"
     if (providers.gradleProperty('withTerraBlender').map { it.toBoolean() }.orElse(false).get()) {

docs/AGES.md

@@ -11,7 +11,7 @@ suffixes such as `_2` and `_3`.
 
 The selected terrain profile, biome distribution, lighting, weather, celestial
 period, celestial angle, and phase are deterministic and become part of the
-saved definition. A five-by-five cobblestone platform with clear headroom is
+saved definition. A five-by-five non-dropping Crystal Platform with clear headroom is
 prepared at a safe arrival point. The completed book and every copy carrying
 the same UUID resolve to that definition.
 
@@ -42,10 +42,11 @@ on demand when an administrator previously unloaded it. Unloading retains the
 definition and world folder, so existing books continue to reference the same
 Age and later reload the same terrain.
 
-Rivencraft does not automatically delete Ages. Safe permanent deletion needs a
-complete reference index for books in inventories, containers, Book Stands,
-and unloaded chunks. Until that exists, retaining the definition prevents an
-administrator action from silently orphaning books.
+Rivencraft does not automatically delete Ages. The operator-only creative Link
+Modifier can deliberately retire an unoccupied Age: it unloads the dimension,
+moves its data to a sibling `<world>-retired-ages/<uuid>` archive, and records
+the UUID as dead so existing books cannot silently regenerate it. Back up the
+whole world first.
 
 Destination-preview chunk loaders are temporary. Rivencraft releases them when
 the book closes, the player travels, the player disconnects, the destination
@@ -101,8 +102,8 @@ Use this sequence when a book cannot load an existing Age:
    matching dimension data and authoritative world saved data from the same
    backup generation. Do not combine them from different backups.
 
-There is intentionally no delete command in Milestone 3. Do not manually
-delete an Age definition or rename its dimension folder: books may exist in
-inventories, containers, Book Stands, or unloaded chunks, and would be
-orphaned. `/rivencraft age unload` is the supported reversible maintenance
-operation.
+Do not manually delete an Age definition or rename its dimension folder:
+books may exist in inventories, containers, Book Stands, or unloaded chunks.
+`/rivencraft age unload` remains the reversible maintenance operation. The
+Link Modifier's retirement control is not reversible through a book UI;
+recover its archived data and registry together from a full-world backup.

docs/CURRENT_IMPLEMENTATION.md

@@ -0,0 +1,98 @@
+# Current implementation (Milestone 7 development)
+
+This is the maintained technical overview of Rivencraft as of the 1.0.0.2
+slice. It describes implemented behavior, not every behavior in Mystcraft
+Legacy. [The README](../README.md) is the player introduction;
+[milestone summaries](MILESTONES.md) explain how the implementation arrived
+here. The linked deep dives are retained as historical audits and should be
+read with their version dates in mind.
+
+## Books, linking, and previews
+
+- Linking Books bind a named position and direction. Same-dimension use needs
+  Intra Linking. Descriptive Books refer to a persistent Age UUID and keep
+  their authored page order. Copies keep that identity.
+- Book screens use Legacy-inspired page spreads and destination panels. `AUTO`
+  selects optional Immersive Portals first, then Create/Ponder, then the built-in
+  animation. Travel is validated on the server regardless of renderer.
+- Handheld travel drops the active book at its departure point as a visible
+  book entity. Book Stands and crystal portals keep the book in place. Disarm
+  drops carried items; Maintain Momentum rotates and carries velocity.
+- A vanilla Lectern converts to a Book Stand when given a Rivencraft book or
+  page. A Book Receptacle in a connected Crystal Block frame activates a
+  vertical or horizontal portal. Immersive Portals can display a live view;
+  otherwise the Legacy-style animated surface remains. Portal arrivals use
+  existing safe footing; a Descriptive portal does not generate a platform.
+- Automatic Return Links default to `DISABLED`, with `ON_CREATION` and `ALWAYS`
+  server options. Linking Books do not generate platforms by default; a
+  creative Link Modifier can explicitly enable that property.
+
+See [preview modes](PREVIEW_COMPATIBILITY.md), [Legacy M7 audit](LEGACY_M7_AUDIT.md),
+and [Age administration](AGES.md).
+
+## Ages, writing, and structures
+
+- Dynamic Dimensions AR Edition creates Age worlds. Each Age has a saved UUID,
+  safe dimension ID, seed, spawn, traits, versioned generation plan, and
+  optional season mode. Page-free or Link-Panel-only books get seeded random
+  choices. Authored supported pages override the appropriate choices.
+- Terrain choices are Standard, Amplified, Island, Cave, Flat, and Void. Cave
+  terrain uses cave/Nether biomes and an appropriate spawn search; normal
+  terrain starts from exposed surfaces. If no safe arrival site exists, the
+  Age-creation path can construct a non-dropping Crystal Platform at Y=63.
+- The server catalog accepts typed data-pack symbols. The Binder preserves
+  written order and diagnoses conflicts. Its status readout is off by default;
+  `/rivencraft binder messages enable` makes it visible only to OPs. Symbol
+  Pages are composed at runtime from Legacy glyph assets. Number pages 0–24
+  set color strength or, immediately before a Length, Angle, Phase, or Size
+  modifier, its numeric value.
+  Celestial pages can create multiple suns/moons with independent color, size,
+  angle, period, phase, and direction; authored eclipses affect light.
+- The Writing Desk stores tabs and copies known Symbol Pages with paper and
+  ink. Notebooks hold ordered pages; the Binder consumes a Link Panel and cover
+  to make a finished Descriptive Book. The Ink Mixer makes Link Panels and
+  rolls Disarm, Intra Linking, and Maintain Momentum from additives. Blank
+  Pages are internal bases, not a craftable or JEI-listed output.
+- Features include terrain additions, decorations, configurable block/fluid
+  materials, ores, vanilla structures including newer 1.21 structures,
+  Legacy-style libraries, crystals, obelisks, and star fissures. Optional Ruins
+  templates gain authorable pages. Some biome/terrain combinations or feature
+  placements are deliberately unsupported and are diagnosed during binding.
+
+See [symbol semantics](SYMBOL_SEMANTICS.md), [writing data](WRITING_DATA.md),
+[generation profiles](AGE_PROFILES.md), and [library/Ruins rules](RUINS_COMPATIBILITY.md).
+
+## Instability and optional mods
+
+Invalid or excessive writing and valuable generated blocks can add
+instability. Block abundance is profiled in loaded chunks, so its contribution
+and selected effects can change as the Age is explored; the authored plan is
+not rewritten. Effects are bounded to loaded Ages and include status effects,
+colored decay, lightning, explosions, meteors, burning, and erosion. Operator
+commands expose the score and providers; the book GUI does not. See
+[scoring](INSTABILITY_SCORE.md) and [runtime policy](INSTABILITY_RUNTIME.md).
+
+JEI, Create/Ponder, Immersive Portals, TerraBlender, Serene Seasons with
+GlitchCore, and Ruins are optional. TerraBlender can supply biomes from any mod
+using its eligible regions; Biomes O' Plenty is a test example. Serene Seasons
+has per-Age normal/no/eternal modes and live Age enrollment. Ecliptic Seasons
+is not integrated because its 1.21.1 API lacks supported live registration and
+per-Age calendar control. See the [optional-mod matrix](MILESTONE_7_REGRESSION.md).
+
+## Persistence and boundaries
+
+An Age registry definition and its dimension folder belong to the **same
+whole-world backup**. Known older book/writing, plan, workstation, and Age
+formats have migration or stable-default handling. Unknown symbol IDs remain
+in books; missing registry objects or removed dimension mods can still prevent
+world loading. The OP-only Link Modifier can retire an unoccupied Age. That
+operation marks its UUID dead and moves its dimension data to a sibling
+`<world>-retired-ages/<uuid>` folder; it is not ordinary book maintenance.
+Do not use it without a backup.
+
+This is not an exact port of every Legacy generator, page, hazard, or client
+renderer. Modern safety budgets and NeoForge's dimension/biome APIs require
+adaptations. The [Milestone 7 regression matrix](MILESTONE_7_REGRESSION.md)
+separates tested behavior from unverified multiplayer/restart/optional-mod
+combinations. The [Milestone 7 acceptance record](MILESTONE_7_ACCEPTANCE.md)
+records release evidence and remaining validation limits.

docs/GAMETESTS.md

@@ -1,5 +1,9 @@
 # GameTest suites
 
+The current Milestone 7 results and manual handoffs are in the
+[regression matrix](MILESTONE_7_REGRESSION.md). This file documents the test
+mechanics and older scenario-specific handoffs.
+
 The default dedicated-server run is a small smoke suite. Its Rivencraft tests
 cover core linking, deterministic Age definition, writing persistence, legacy
 data migration, workstation transactions, and forged/replayed menu actions.

docs/MILESTONES.md

@@ -0,0 +1,66 @@
+# Milestones at a glance
+
+This is the condensed milestone history. The [current implementation](CURRENT_IMPLEMENTATION.md)
+is authoritative for what the latest development build does; older acceptance
+and audit files remain available as dated evidence, not competing current
+instructions. [Gitea milestones](https://truenas-scale.tail180fb1.ts.net:8443/dnorberg/rivencraft/milestones)
+hold the live issue status.
+
+## 1 — Bootstrap (complete)
+
+Established the NeoForge 1.21.1/Java 21 project, mod identity, registries,
+assets, build, and first automated checks. The port deliberately shares
+Mystcraft's concepts while maintaining its own modern package and data model.
+See [porting principles](PORTING.md) and [asset provenance](ASSET_PROVENANCE.md).
+
+## 2 — Books and linking (complete)
+
+Introduced persistent Linking and Descriptive Books, conversion of vanilla
+Lecterns into Book Stands, named books and Ages, safe travel, destination
+previews, and a configurable Return Link policy. Later milestones refined
+renderer selection and portal travel. See [preview compatibility](PREVIEW_COMPATIBILITY.md).
+
+## 3 — Ages (complete)
+
+Added persistent runtime dimensions, deterministic random Age traits,
+name-derived unique dimension folders, terrain/biome choices, spawn recovery,
+and Age lifecycle commands. See [Age administration](AGES.md),
+[runtime profiles](AGE_PROFILES.md), and [random weights](RANDOM_AGE_WEIGHTS.md).
+
+## 4 — Writing system (complete)
+
+Introduced Symbol Pages, Link Panels, Notebooks, the Writing Desk, Book Binder,
+and Ink Mixer. Writing order and unknown symbol references persist instead of
+being inferred from UI text. See [writing data](WRITING_DATA.md),
+[descriptive-book presentation](DESCRIPTIVE_BOOK_PRESENTATION.md), and
+[Ink Mixer audit](INK_MIXER_MODIFIER_AUDIT.md).
+
+## 5 — Age grammar (complete for the supported subset)
+
+Compiled supported pages into frozen Age plans: terrain, biome distribution,
+environment, features, block/fluid materials, structures, crystals, and
+fissures. Added optional TerraBlender and Serene Seasons adapters. This was
+not a claim of complete Legacy grammar parity. See [M5 acceptance](MILESTONE_5_ACCEPTANCE.md),
+[Legacy grammar audit](LEGACY_AGE_GRAMMAR_AUDIT.md),
+[symbol schema](SYMBOL_SEMANTICS.md), [TerraBlender](TERRABLENDER_COMPATIBILITY.md),
+and [Serene Seasons](SERENE_SEASONS_COMPATIBILITY.md).
+
+## 6 — Instability (complete)
+
+Added authored and live block-abundance scoring, frozen provider plans,
+operator diagnostics, bounded status effects, decay, lightning, explosions,
+meteors, burning, and erosion. Safety budgets are deliberate modern
+adaptations. See [M6 acceptance](MILESTONE_6_ACCEPTANCE.md),
+[Legacy instability audit](LEGACY_INSTABILITY_AUDIT.md), and
+[runtime policy](INSTABILITY_RUNTIME.md).
+
+## 7 — Structures and polish (complete in 1.0.0.2)
+
+Added Legacy-layout Age libraries, page-bearing stands, crystal portals and
+receptacles, the handheld dropped-book entity, data-driven recipes,
+advancements, asset/audio polish, optional Ruins, compatibility updates, and
+expanded sky/glyph pages. Issue #83 covered regression, migration, and document
+consolidation; issue #84 records the final milestone acceptance. See the
+[M7 acceptance](MILESTONE_7_ACCEPTANCE.md), [M7 Legacy audit](LEGACY_M7_AUDIT.md),
+[M7 regression matrix](MILESTONE_7_REGRESSION.md), and
+[M7 compatibility review](MILESTONE_7_COMPATIBILITY_REVIEW.md).

docs/MILESTONE_7_ACCEPTANCE.md

@@ -0,0 +1,72 @@
+# Milestone 7 acceptance — 1.0.0.2
+
+Milestone 7 is complete for the supported NeoForge 1.21.1 feature set. This is
+not a claim of total Mystcraft Legacy parity or exhaustive optional-mod
+certification. The [current implementation](CURRENT_IMPLEMENTATION.md) is the
+up-to-date behavior summary; the [regression matrix](MILESTONE_7_REGRESSION.md)
+separates automated evidence from manual scenarios.
+
+## Scope and issue gate
+
+The Gitea audit for issue #84 found no other open issues. Required existing
+#14 (cave terrain), #43 (glyph numbers), #44 (sky), and #60 (old-save policy)
+were closed. M7 implementation and review issues #75–#83, #85–#90, and
+later additions #91–#94 were closed before this acceptance. No required
+issue was silently deferred.
+
+| Legacy concept | Rivencraft implementation or deliberate difference |
+| --- | --- |
+| Cave terrain and writing | Cave terrain uses its cave/Nether biome set and a modern Y=64-start spawn search. Existing non-cave terrain still supports caves as features. See [Age profiles](AGE_PROFILES.md) and [grammar](WRITING_GRAMMAR.md). |
+| Libraries | The recognizable Legacy small-library layout and sparse candidate spacing are ported as a structure template with a chest and up to five page-bearing Book Stands. It generates only in Ages and only on suitable surfaces; player-selectable Legacy or Age-only loot is supported. See [Legacy M7 audit](LEGACY_M7_AUDIT.md). |
+| Crystal portal and Receptacle | Connected Crystal Blocks support vertical and horizontal portals. The held book stays in the Receptacle; removing it removes the surface. Rivencraft validates loaded bounds and block protection, saves owner pointers, and uses book-travel rules. Optional Immersive Portals supplies a live destination view, with an animated fallback while unavailable. |
+| Handheld Linking/Descriptive Books | The used book remains behind as a rendered book entity at the origin. The exact Legacy entity pickup rule is not copied: modern contact pickup is used. Return Links default to disabled but remain configurable. |
+| Recipes and discovery | JSON crafting recipes and recipe-book unlocks cover the supported writing/crystal progression. Optional JEI covers the Binder, Writing Desk, and Ink Mixer; a Lectern conversion has no JEI guide. Blank Pages are not craftable. Optional Create/Ponder teaches portal construction. See [JEI review](MILESTONE_7_JEI_REVIEW.md). |
+| Models, sounds, and advancements | Legacy-sourced assets are credited in [asset provenance](ASSET_PROVENANCE.md); 1.21.1-compatible models and renderer adaptations are documented in the [visual audit](MILESTONE_7_VISUAL_AUDIT.md). Server-owned advancements cover book, writing, Age, and portal progress; the unimplemented Quinn equivalent is explicitly omitted in [advancement notes](MILESTONE_7_ADVANCEMENTS.md). |
+| Numbers, sky, and extra items | Base-25 number glyphs, celestial modifiers and eclipses, Symbol Portfolios, the OP-only Link Modifier, and optional Ruins pages were follow-up additions. Legacy page semantics are adapted to the modern authoring plan rather than a binary copy of 1.12.2 worldgen. |
+
+## Compatibility and migration
+
+NeoForge **21.1.264** is the minimum 21.1 build. A player passed the
+singleplayer client with the optional stack, then a local dedicated server
+including Immersive Portals, before the minimum was raised. See the
+[compatibility decision](MILESTONE_7_COMPATIBILITY_REVIEW.md). JEI
+19.69.0.457 and Serene Seasons 10.1.0.9 received their own player checks;
+Create/Ponder, Immersive Portals, TerraBlender/biome add-ons, Serene Seasons,
+JEI, and Ruins remain optional. Ecliptic Seasons is deliberately not
+integrated: its 1.21.1 public API does not support the required live Age
+registration and per-Age calendar control. Missing optional mods must not
+prevent the core mod from loading.
+
+Known older writing/book, Age-plan, and workstation formats have explicit
+migration or stable-default handling. An Age registry and its dimension
+folders must be backed up together. Removed mods, missing custom registry
+objects, and arbitrary prerelease saves are **not** guaranteed to load.
+Retiring an Age through the creative Link Modifier archives its data and
+invalidates its UUID; that intentional destructive operation is not a
+migration. See the [old-save boundary](MILESTONE_7_REGRESSION.md#old-save-boundary-60).
+
+## Release validation and limits
+
+The 0.6.11.0 regression candidate passed `./gradlew --offline build` and
+fresh-world GameTest runs: core **91/91**, generation **129/129**, and
+environment **103/103**. The player reported an in-game pass for that
+candidate. The 1.0.0.1 release candidate additionally allows Number Pages to
+set Celestial Size. The 1.0.0.2 release makes Binder status diagnostics an
+OP-only, default-off world setting. Its offline build and core GameTests
+passed (93/93), and the player reported an in-game pass. The
+preceding 1.0.0.0 candidate passed core and generation GameTests. Its
+environment archive stalled in the first 50-test batch, repeatedly printing
+its field without completing; it was stopped and is **not** counted as a
+1.0.0.0–1.0.0.2 pass. The previous 0.6.11.0 run of that same suite passed 103/103.
+The focused sky, season, and number-page in-game checks in the regression
+matrix remain useful regression checks, not claimed full-matrix passes. The
+Gitea release changelog records the tested JAR and verified SHA-256.
+
+These results do not prove every two-player race, full restart, migration
+from every development world, or optional-mod combination. The specific
+manual matrix remains in [M7 regression](MILESTONE_7_REGRESSION.md); those
+broader combinations are known validation limits, not claimed passes. Modern
+chunk and tick budgets, safer portal validation, 1.21.1 world-height and
+biome APIs, and the dynamic-dimension backend are deliberate deviations from
+Legacy. A complete Legacy worldgen or link-property port is outside this
+milestone.

docs/MILESTONE_7_REGRESSION.md

@@ -0,0 +1,79 @@
+# Milestone 7 regression and migration matrix (issue #83)
+
+This is the dated regression record for the 0.6.11.0 candidate. The
+[Milestone 7 acceptance](MILESTONE_7_ACCEPTANCE.md) owns the final sign-off. A passing
+GameTest is server-side evidence; it is not proof of client rendering,
+multiplayer timing, or every optional-mod combination.
+
+## Automated evidence
+
+| Area | Focused check | Candidate result |
+| --- | --- | --- |
+| Dedicated server, core linking, book/Age identity, old writing and workstation formats | `./gradlew --offline runGameTestServer`; includes `CoreGameTests`, `AgePersistenceGameTests`, `CrystalPortalGameTests`, M7 crafting/advancement checks | 91/91 required GameTests passed on NeoForge 21.1.264; clean shutdown and fresh-world removal. |
+| Deterministic structures and terrain | `./gradlew --offline runGameTestServer -ParchivedGameTestSuites=generation`; includes library template/spacing/loot/stand checks, cave profiles, vanilla structures, crystal formations, fissures | 129/129 passed after correcting one village test to assert its own contribution rather than a seed-dependent total; fresh-world removal. |
+| Sky, glyph numbers, seasons, creative/JEI page feed | `./gradlew --offline runGameTestServer -ParchivedGameTestSuites=environment` | 103/103 passed on the 0.6.11.0 candidate, including issue #94's number-page check; fresh-world removal. |
+| Packaged models and data | `Milestone7ResourceGameTests.coreModelsResolveBundledTextures` in the core suite; parses critical block models, checks their Rivencraft texture references and the library NBT resource | Passed in the 91-test core run. This checks resource presence, not visual orientation or transparency. |
+| Recipe behavior | `Milestone7CraftingGameTests` and `LinkingBookRecipeGameTests` through the loaded Recipe Manager | Passed in the core run; confirms crystal and receptacle quantities, ink bucket return, no Blank Page crafting, and Linking Book ingredients. |
+| Portal state/save-load | `CrystalPortalGameTests` plus `AgePersistenceGameTests` in the core suite | Passed; covers activation/release, fallback orientation, horizontal/underside placement, uninterrupted surface, cooldown, retired Age and seed/plan identity. Full server restart remains manual. |
+
+The generation archive initially failed
+`AgeStructureGameTests.mixedEndAndTaigaVillagesChargeForEndPortion` because it
+compared the total instability score (1200) with the village-only expectation
+(200). A seed-completed sky legitimately supplied an extra sun (+1000). The
+production scoring was unchanged; the check now isolates the
+`forced_biome_villages` contribution. The rerun passed 129/129. This is a
+repaired assertion, not a hidden feature failure.
+
+Every default GameTest run creates a new world with Minecraft's fixed seed 0
+and deletes it after pass or fail. See [GameTest guidance](GAMETESTS.md).
+Do not retry a storage-stalled GameTest: stop it, remove that automated
+scenario, and give its exact steps to the player. No run in this issue has
+stalled so far. The older full-archive storage stall is historical and is not
+counted as a current pass. On the subsequent **1.0.0.0 release candidate**,
+the environment archive stalled during its first 50-test batch and was
+stopped. The 103/103 result above applies to 0.6.11.0 only, not to 1.0.0.0
+or the later 1.0.0.1–1.0.0.2 candidates. For the 1.0.0.2 manual handoff, create an Age
+with Number Pages immediately before Celestial Angle, Phase, and Size pages;
+confirm each affects the intended body rather than becoming a stray page. Also verify a
+fixed-season Age remains fixed across a restart while the Overworld remains
+independent. Do not rerun the stalled suite merely to obtain a green count.
+
+## Old-save boundary (#60)
+
+Issue #60 established a policy of preserving old saves where practical. Tests
+cover bare-list `OrderedWriting`, page-free books, unknown symbol IDs, older
+Age definitions with stable defaults, plan-v3/plan-v4 interpretation, and
+workstation inventory migration. A bound book's UUID and its Age's registered
+dimension remain stable through ordinary load. This does **not** imply every
+pre-public-release world, removed biome mod, missing dimension provider, or
+changed datapack can be opened. Back up the full world; the Age registry and
+dimension folders are a unit. The creative Link Modifier can intentionally
+retire an Age, archiving its data and marking the UUID dead. That is an explicit
+administrative boundary, not a silent migration.
+
+## Manual matrix for the player
+
+Use a backup or disposable save. Record the exact mod list and jar version.
+These checks are **pending for 0.6.11.0** unless a later note records an actual
+pass. Historical passes on earlier slices should not be silently promoted to
+this candidate.
+
+| Scenario | What to verify |
+| --- | --- |
+| Full restart | Create a random and an authored Age, a library with a looted chest/page stand, an active portal, and a bound book. Stop and restart the server; UUID, terrain, loot removal, stand contents, portal activation, and return travel must persist. |
+| Two players | Cross the same portal at nearly the same time, return independently, and use separate book previews. Cooldowns, destination positions, dropped-book ownership/retrieval, and preview chunk loaders must not interfere. |
+| Cross-dimension travel | Compare the same Descriptive Book by hand, stand, and portal. Check footing/platform rules, arrival coordinates and facing, Disarm, Maintain Momentum, Intra Linking, and Return Link mode. |
+| Client visuals/audio | Compare book spreads, glyphs, D'ni numbers, page/desk/binder/mixer models, 16×16 crystal buds and translucent elements, portal frame/surface order, skies/eclipses, page turns, and Legacy link sounds. A server test cannot observe pixels or audio. |
+| Optional renderers | With neither Create nor Immersive Portals, confirm Legacy fallback. With Create alone, confirm Ponder snapshots and portal guide. With Immersive Portals, confirm live view, Explore exit, sky/sound isolation, portal travel, and fallback while chunks load. With both, `AUTO` should choose Immersive Portals. |
+| Optional world/recipe mods | Test JEI guides/search, TerraBlender with a biome-producing addon (for example Biomes O' Plenty), Serene's six season modes plus Overworld independence/restart, and Ruins template selection/spawn weighting. Repeat startup without optional mods. |
+| Migration | Copy a backed-up older development world. Verify books and Notebooks retain their Age/page IDs, a desk and stand keep contents, old Ages load or provide a clear error, and removing a custom symbol retains its unresolved ID. Do not test by modifying the only copy. |
+| Binder diagnostics | As a non-OP, verify the Binder still creates books but shows no instability/seeded/status messages. As an OP, run `/rivencraft binder messages enable`, reopen the Binder, and verify those messages appear only for the OP. Disable them and restart the world; the setting should remain disabled. |
+
+Historical evidence: the player approved NeoForge 21.1.264 on singleplayer
+and a dedicated server with Immersive Portals; JEI 19.69.0.457 guides, Serene
+Seasons 10.1.0.9's full per-Age matrix, Ruins generation, and issue #94's
+numbered celestials each received an in-game pass on their respective earlier
+release slices. See [compatibility review](MILESTONE_7_COMPATIBILITY_REVIEW.md),
+[JEI review](MILESTONE_7_JEI_REVIEW.md), [Serene review](MILESTONE_7_SERENE_REVIEW.md),
+and [Ruins notes](RUINS_COMPATIBILITY.md). The current candidate's broad
+multiplayer/restart/optional-mod matrix remains unverified until tested.

docs/MINECRAFT_26_3_ALPHA_1.md

@@ -0,0 +1,42 @@
+# Rivencraft 1.0.1.2-alpha.1 — Minecraft 26.3
+
+Experimental **NeoForge 26.3** port preview. This is a separate artifact from
+the supported Minecraft 1.21.1 release, and it does **not** have feature
+parity. Use a disposable test world or make a backup first. Do not migrate a
+1.21.1 Rivencraft world to this alpha.
+
+## Working in this alpha
+
+- Rivencraft loads on Minecraft 26.3 / NeoForge 26.3.0.99 with Java 25.
+- The first-party runtime Age backend creates separately seeded, persistent
+  prototype dimensions. The operator-only `/rivencraft_port age` commands can
+  create and inspect them.
+- Runtime Age catalogs are synchronized and acknowledged before cross-dimension
+  travel. A missing or unacknowledged destination is refused.
+- Operator-created Descriptive Books can enter prototype Ages.
+- Handheld Linking Books can be named and bound to a location, then used from
+  their book GUI to return there. The destination data survives a restart.
+- The Crystal Block and Crystal Shard are registered with reused art.
+
+## Not yet ported
+
+Normal authored Age generation, book crafting and workstations, Page symbols,
+most blocks and items, portal systems, Link modifiers, the rotating destination
+preview, instability, and optional mod integrations. The Linking Book GUI shows
+a placeholder destination panel rather than a live scene. Generated Ages use
+prototype vanilla terrain, not the player's authored Pages.
+
+The [26.3 port status](MINECRAFT_26_3_PORT.md) and [open port issues](https://git.paddedcell.org/dnorberg/rivencraft/issues)
+track the remaining work. The stable 1.21.1 release remains available
+separately. Please file alpha bugs with the exact Minecraft, NeoForge and
+Rivencraft versions, plus the relevant client/server log.
+
+## Verification
+
+- Clean 26.3 Gradle build passed.
+- Disposable dedicated-server smoke test passed: two distinct Age seeds and
+  their terrain persisted across a restart.
+- The user verified the handheld Linking Book GUI click and travel in-game on
+  2026-10-27.
+
+These checks are **not** the full port acceptance matrix or a stability claim.

docs/MINECRAFT_26_3_ALPHA_2.md

@@ -0,0 +1,37 @@
+# Rivencraft 1.0.1.3-alpha.1 — Minecraft 26.3
+
+Experimental **NeoForge 26.3** port preview. This is separate from the
+supported Minecraft 1.21.1 release and does **not** have feature parity. Use
+a disposable test world or make a backup first. Do not migrate a 1.21.1
+Rivencraft world to this alpha.
+
+## Changes since 1.0.1.2-alpha.1
+
+- An unbound Descriptive Book now opens a naming screen. Binding it creates a
+  distinct prototype Age with a random seed; duplicate names receive a
+  numbered suffix.
+- A bound Descriptive Book opens a book screen whose destination panel can be
+  clicked to enter its Age. The server validates the held book and waits for
+  the client's Age catalog acknowledgement before travel.
+- Retired Age IDs are excluded when assigning a new book's Age name, so an
+  archived world cannot be silently reused.
+
+## Still experimental
+
+These Ages use prototype vanilla terrain. Page-authored generation, crafting
+and workstations, most items and blocks, portals, Link modifiers, instability,
+live destination previews, and optional mod integrations are not ported. The
+book panel is a placeholder, not a rendered destination view. The
+[port status](MINECRAFT_26_3_PORT.md) and [open port issues](https://git.paddedcell.org/dnorberg/rivencraft/issues)
+track the remaining work. The stable 1.21.1 release remains available
+separately.
+
+## Verification
+
+- Clean 26.3 Gradle build passed.
+- Disposable dedicated-server smoke test passed: two distinct Age seeds and
+  their terrain persisted across restart.
+- The player verified Descriptive Book binding and travel in game on
+  2026-10-29.
+
+These checks are **not** the full port acceptance matrix or a stability claim.

docs/MINECRAFT_26_3_PORT.md

@@ -0,0 +1,429 @@
+# Minecraft 26.3 port status (issue #96)
+
+Checked 2026-10-26. Minecraft Java 26.3 is the newest stable Java release with
+NeoForge support. This is an engineering audit and the start of the port, **not
+a claim that a 26.3 Rivencraft JAR is ready**. The 1.21.1 build remains the
+release target until a separate 26.3 client and dedicated-server build passes.
+The user wants both Minecraft lines maintained after the port, not a one-time
+26.3 release. Gitea milestone "Dual-version support: 1.21.1 and 26.3"
+tracks issues #97–#103 under parent #96.
+
+## Version boundary
+
+Minecraft 26.3/NeoForge uses Java 25, while Rivencraft 1.21.1 uses Java 21.
+Build and publish separate artifacts; do not widen the Minecraft dependency
+range of the 1.21.1 JAR. The official [26.3 release notes](https://www.minecraft.net/en-us/article/minecraft-java-edition-26-3),
+[NeoForge 26.3 Maven metadata](https://maven.neoforged.net/releases/net/neoforged/neoforge/maven-metadata.xml),
+[NeoForge Java 25 setting](https://github.com/neoforged/NeoForge/blob/26.3.x/gradle.properties),
+and [NeoForge migration primers](https://docs.neoforged.net/primer/docs/)
+are the version sources. NeoForge 26.3.0.99 is the newest listed stable build
+at the time of this check.
+
+## Dependency availability
+
+The entries below mean that a NeoForge 26.3 version is advertised by the
+project, not that its API or runtime behavior has been validated with
+Rivencraft. Recheck immediately before choosing versions for a port build.
+
+| Integration | Role in 1.21.1 | 26.3 availability | Port decision |
+| --- | --- | --- | --- |
+| [Dynamic Dimensions AR Edition](https://modrinth.com/mod/dynamic-dimensions-ar-edition) | Required runtime Age loading | No; 1.21.1 only | Keep it for 1.21.1. Use a Rivencraft-owned runtime-dimension backend for 26.3. |
+| [bad packets](https://modrinth.com/mod/badpackets) | Declared runtime dependency; no direct Java imports in Rivencraft | No advertised 26.3 version | Determine whether the new dimension backend needs it; otherwise remove it from the 26.3 artifact. Use NeoForge's own networking for Rivencraft packets. |
+| [JEI](https://modrinth.com/mod/jei) | Optional recipe/page guides | Yes | Port and test its plugin against the 26.3 API. |
+| [TerraBlender](https://modrinth.com/mod/terrablender) | Optional modded biome support | Yes | Port and verify biome discovery and Age generation. |
+| [Serene Seasons](https://modrinth.com/mod/serene-seasons) and [GlitchCore](https://modrinth.com/mod/glitchcore) | Optional seasons | Yes | Port and repeat the per-Age seasonal matrix. |
+| [Biomes O' Plenty](https://modrinth.com/mod/biomes-o-plenty) | Optional TerraBlender test addon | Yes | Test modded biome registration and decoration. |
+| [Ruins (Structure Spawning System)](https://www.curseforge.com/minecraft/mc-mods/ruins-structure-spawning-system) | Optional authored ruins integration | Yes | Port and verify its generation hooks. |
+| [Create](https://modrinth.com/mod/create) / bundled Ponder | Optional scene renderer | No advertised 26.3 version | Use Rivencraft's existing legacy-animation preview fallback for this target until a compatible release exists. |
+| [Immersive Portals for (Neo)Forge](https://modrinth.com/mod/immersive-portals-neoforge) | Optional live views and portal teleport integration | No advertised 26.3 version | Use the fallback portal surface and normal Rivencraft linking. Do not claim live destination views on 26.3. |
+
+Ecliptic Seasons publishes 26.3, but Rivencraft's Ecliptic integration was
+deferred and is not a replacement for the current Serene integration.
+
+The alternatives checked for runtime Age loading do not meet the 26.3
+NeoForge requirement: [upstream Dynamic Dimensions](https://github.com/TeamGalacticraft/DynamicDimensions)
+and its [AR fork](https://github.com/dercodeKoenig/DynamicDimensions)
+have no published 26.3 branch or artifact;
+[DimLib](https://modrinth.com/mod/dimlib) is Fabric-only and stops at 1.21.1;
+and [DimensionsCore](https://www.curseforge.com/minecraft/mc-mods/dimensionscore-dynamic-dimension-world-management)
+currently publishes only a Forge 1.20.1 file. Mods that add fixed dimensions
+or portals do not supply the arbitrary per-book runtime worlds Rivencraft
+needs. This is a search result, not proof that no other project exists.
+
+## 26.3 backend design
+
+The 26.3 port is a **fresh-save target**. It does not need to import 1.21.1
+Age worlds or migrate Dynamic Dimensions' saved registry data. The 1.21.1
+artifact will continue using that library. Within 26.3, however, a created
+Age must retain its identity, seed, chunks and access across save/restart.
+
+1. Keep the existing `AgeDimensionService`/`AgeDimensionBackend` boundary.
+   Implement a target-specific 26.3 backend without importing Dynamic
+   Dimensions or its seed mixin. The backend contract needs registration at
+   server start, create/load, unload and delete. Return a failure without
+   publishing a half-created Age if any step fails.
+2. At server startup, reconstruct all non-retired Ages from Rivencraft's
+   `AgeRegistrySavedData` **before** players can join. For a newly bound book,
+   register its unique `rivencraft:age/...` dimension and construct a
+   `ServerLevel` from its authored chunk generator, dimension type and saved
+   Age seed. The seed must feed chunk random state, not only `getSeed()`.
+3. Register the level with the server's level map and the appropriate
+   dimension registries, then synchronize the new dimension definition to
+   already-connected clients before sending a travel packet. Handle a
+   connecting client receiving every existing Age. Determine the minimal
+   26.3 registry and network hooks from the current NeoForge source; do not
+   assume `/reload` creates new running levels.
+4. Initialize world border, view/simulation distance, forced chunks, spawn
+   settings, per-Age data storage and tick/save lifecycle as a normal level.
+   On unload or retirement, refuse while players occupy the Age, move any
+   remaining entities safely, flush pending chunk writes, detach the level,
+   and synchronize removal. Retirement must not delete another Age's data.
+5. Review the MIT-licensed Dynamic Dimensions code as an implementation
+   reference. If any code is adapted, retain its copyright/license notice and
+   identify the derived files. Prefer the smallest backend Rivencraft needs
+   over a general-purpose library fork.
+
+The release gate is a 26.3 integrated-client **and** dedicated-server matrix:
+create two Ages with distinct seeds, explore chunks, travel while another
+client remains online, reconnect, restart, revisit saved chunks, reseed for
+future chunks, unload/reload, retire one Age without harming the other, and
+verify normal travel without optional mods. Then repeat relevant paths with
+available integrations. A failed synchronization must be reported and leave
+the player in their current level, not crash or strand them.
+
+## Implementation order
+
+1. Keep `AgeDimensionService` independent of a concrete runtime-dimension
+   implementation. The 1.21.1 Dynamic Dimensions calls now live in
+   `AgeDimensionBackend`; the `AgeDimensionSeedMixin` is 1.21.1-only.
+2. Create a separate 26.3/Java 25 build target. Replace the dimension backend,
+   then migrate the main sources through the official NeoForge primers. Do not
+   publish a partial JAR with missing Age generation.
+3. Port optional integration classes one at a time. Keep unavailable mods
+   optional and preserve their existing fallbacks. Upgrade JEI, TerraBlender,
+   Serene Seasons/GlitchCore, Biomes O' Plenty, and Ruins only in the 26.3
+   target; do not change the validated 1.21.1 dependency set.
+4. Run compile, data/resource validation, new-world Age generation, Age
+   save/restart/reload, direct and portal/book travel, client rendering, and
+   dedicated-server tests on both targets. Test without optional mods, then
+   with each available integration. Require an in-game check before release.
+
+The core blocker is **not** a version number change: 26.3 makes a major API
+jump and the required 1.21.1 runtime-dimension library has no 26.3 build.
+
+## Build isolation started in #97
+
+The repository root remains the playable 1.21.1/Java 21 build. A separate
+`ports/mc263` Gradle build now resolves NeoForge 26.3.0.99 and compiles with
+Java 25. The build workflow has separate Java 21 and Java 25 jobs. Its JAR
+task remains disabled; this does not satisfy #97's final artifact criteria.
+
+## First core slice in #98
+
+The 26.3 target now has real Rivencraft metadata and an entrypoint. It
+registers the Crystal Shard and Crystal Block with their reused 1.21.1
+textures/models plus the 26.3 item-model definitions. `build` passed, and a
+dedicated development server loaded the mod and reached `Done` with a new
+world and no optional mods. The server was then stopped. This validates only
+the entrypoint/registry/resource foundation. A development client also loaded
+Rivencraft and reloaded its resources without reported missing models or
+textures. The client logged the host's missing `libflite.so` narrator library;
+this is unrelated to Rivencraft. Both test processes were stopped after
+startup. This does **not** validate in-world client rendering or Age
+functionality. Age generators, data, networking, and client code still
+need migration; #98 remains open.
+
+## Runtime-level prototype in #99
+
+The 26.3 target has a first-party server-side runtime-level loader and a
+SavedData seed index. It constructs each level with a `LevelStem` seed override,
+publishes the level only after construction, and restores indexed Ages when
+the Overworld loads. A dedicated-server probe created two separate Ages with
+seeds `123456789` and `987654321`; after generating chunks, their terrain
+fingerprints differed (`2865094` and `3227421`). Both levels, their region
+files, seeds, and fingerprints survived a server restart, and the startup log
+shows restoration before `Done`. The temporary operator-only
+`rivencraft_port age` command exists solely to test this non-distributable
+port workspace.
+
+This is **not** issue #99 completion. The loader currently reuses the vanilla
+Overworld generator because issue #98 has not ported authored generators or
+Age definitions. The synchronized operator travel probe below does not port
+normal book travel. The 26.3 JAR task remains disabled.
+
+## Runtime client-catalog prototype in #100
+
+The 26.3 target now sends the current dimension-key catalog to each joining
+client and broadcasts a new catalog when a prototype Age is created or
+retired. Clients update their known-level set and acknowledge a version; the
+server's `rivencraft_port age enter <name>` probe refuses travel until that
+acknowledgement arrives and the target is still loaded. A stale acknowledgement
+does not satisfy the gate. This follows NeoForge's play-payload registration
+and client-handler separation. It is not a general dynamic-registry sync for
+authored dimension types, which have not been ported.
+
+The dedicated-server probe used two simultaneous 26.3 clients. Both
+acknowledged a newly created Age without reconnecting; a second client entered
+an existing runtime Age; a player saved inside an Age reconnected after server
+restart and remained there. The operator travel probe searches near origin for
+safe footing and creates a small Crystal Block platform if none is found.
+This probe is not the final book landing implementation.
+
+`rivencraft_port age retire <name>` refuses to retire an Age containing a
+player, then saves and closes it, removes it from the active index, and
+broadcasts the reduced catalog. On the dedicated test server, the client
+acknowledged creation and retirement even when they happened back-to-back; a
+late acknowledgement for the intermediate catalog was ignored. Travel to the
+retired Age was refused without moving the player, and retiring an occupied
+Age was refused. The #101 lifecycle slice below now archives exact Age data.
+
+This remains a **prototype**, not completion of #100: normal Linking and
+Descriptive Book travel, authored dimension-type/generator registration, full
+client registry synchronization, and an integrated-client regression pass
+must follow the core port. The 26.3 JAR remains disabled. The local test
+server was stopped after verification.
+
+## Runtime lifecycle prototype in #101
+
+The operator-only backend probe now supports `age unload`, `reload`, `reseed`,
+and `retire` in addition to `create`, `list`, `sample`, and `enter`. Unload and
+retirement refuse a level containing players. A full chunk/entity save and
+close handles other entities; Minecraft's shutdown-style ticket deactivation
+and startup-style activation preserve forced chunks across runtime reloads.
+The loaded-dimension catalog is rebroadcast after unload/reload/reseed and
+retirement, with stale acknowledgements ignored.
+
+On the dedicated server, a generated Age unloaded and reloaded with the same
+terrain fingerprint. Reseeding `lifetest` from `24680` to `13579` kept the
+previously generated origin fingerprint `2898472`; previously ungenerated
+chunks at offset 100 produced fingerprint `2897795`, identical to a fresh
+`13579` control Age and different from a fresh `24680` control (`2863099`).
+After restart, `lifetest` still reported seed `13579` and its original origin
+fingerprint. Three consecutive unload/reload cycles with a connected client
+completed; that client acknowledged the final catalog and intermediate stale
+acknowledgements were ignored. Unloading the player's current Age was refused.
+
+A force-loaded chunk and a summoned armor stand with UUID
+`[I; -872307724, 883641011, -1239011659, 796091120]` survived repeated
+runtime unload/reload and server restart. The entity could be queried again
+after its chunk finished loading. The probe retired a different Age,
+`seedcontrol`: only its directory moved to the sibling `world-retired-ages`
+archive, other Age directories stayed in place, and reloading/recreating the
+retired ID was refused after restart. A second archival probe exercised the
+tombstone-before-move sequence and again moved only its own directory. The
+tombstone is persisted before the archive move so an interrupted archival
+cannot silently revive an old Age; an ordinary move failure attempts to
+restore the index and level. Ten more consecutive unload/reload cycles
+completed on the dedicated server, with its open file-descriptor count steady
+at 218 before and after. That is a narrow smoke check, not proof of no leak.
+
+This still does **not** close #101. The prototype has not been integrated with
+normal books or the full 26.3 Age definition, nor has a long-running resource
+leak test or interrupted-archive recovery drill been completed. Its dev world
+and archive are under ignored `ports/mc263/build`, not a release save.
+
+## Optional-integration probe in #102
+
+On 2026-10-27, the published NeoForge 26.3 versions checked were JEI
+31.17.0.95, TerraBlender 26.3.0.0.9, Biomes O' Plenty 26.3.0.0.15,
+GlitchCore 26.3.0.0.5, and Serene Seasons 26.1.2.0.7 (its file is labelled
+for Minecraft 26.3). Ruins advertises 26.3.1NF. Create/Ponder and
+Immersive Portals still had no advertised compatible version. These are
+availability checks, not API-compatibility claims.
+
+The 26.3 development target now has the operator-only
+`/rivencraft_port compat` command. It reports loaded optional mod IDs and
+the count of registered biome keys by namespace, so integration smoke tests
+can distinguish a missing addon from a missing biome registration. It does
+not change Age generation. A clean dedicated server loaded with no optional
+mods and reported 67 vanilla biomes. A separate dedicated-server launch with
+TerraBlender, Biomes O' Plenty, GlitchCore, and Serene Seasons loaded all four;
+the probe reported 68 `biomesoplenty` biome keys, and TerraBlender logged its
+Overworld and Nether regions. Both launches stopped cleanly.
+
+Issue #102 remains open. The 26.3 target still lacks authored Ages, JEI
+guides, per-Age season policy, Ruins hooks, book previews and crystal portals,
+so the relevant integration and fallback acceptance tests cannot yet pass.
+The probe must not be mistaken for feature support. The existing 1.21.1
+integration code and dependencies remain unchanged.
+
+## First player-facing bridge in #104
+
+The 26.3 port now registers a Descriptive Book with the Legacy item texture
+and a persistent, network-synchronized Age-ID data component. The operator-only
+`/rivencraft_port age book <name>` probe grants a book for an already indexed
+Age; an unbound book does not create a world. Using the bound book calls the
+same server-authoritative, catalog-acknowledged landing path as the existing
+`age enter` probe. A missing or unloaded Age refuses travel. This avoids
+trusting a book-supplied seed or creating a new Age from a forged item.
+
+The dedicated-server smoke test still passed after this bridge, and a 26.3
+development client loaded the new item model and texture without a missing
+resource warning. The host still reports a missing Linux `libflite.so`
+narrator library; this is not a Rivencraft item error. The client was stopped.
+The player confirmed right-click travel in game. Book component persistence
+across restart still needs a player test; the headless smoke test cannot
+exercise it. To test the
+bridge in a disposable 26.3 world as an operator:
+
+1. `/rivencraft_port age create booktest 123456789`
+2. Wait for the Age catalog acknowledgement, then
+   `/rivencraft_port age book booktest`.
+3. Right-click the granted book and verify arrival in
+   `rivencraft:age/booktest`. Restart client and server, then use the same
+   book again and verify it targets the same saved Age.
+
+This is deliberately a **port probe**, not the final book workflow: the Book
+Binder, naming UI, GUI preview, automatic return link, dropped-book entity, authored Age
+plan, and Legacy landing rules are not yet connected. The bound book currently
+remains in hand after travel. Do not distribute this target or mark #104 done.
+For a local player test only, the normally disabled port JAR can be built with
+`./gradlew -p ports/mc263 build -PallowIncompletePortJar=true`; its filename
+retains `26.3-INCOMPLETE` and a `port-dev` version marker. This does not enable the normal
+release artifact or imply that the full mod has been ported.
+
+The first Prism test exposed a production-only catalog bug: Minecraft 26.3's
+`ClientPacketListener.levels()` returned an immutable set, and the client
+handler attempted to clear it. That threw `UnsupportedOperationException`
+before the client could acknowledge the Age, so book travel was refused. The
+handler now replaces the entire level set through a narrow access transformer
+and acknowledges only after replacement. The corrected local test JAR is
+`rivencraft-26.3-INCOMPLETE-0.0.0.1-port-dev.jar`. It built successfully;
+the player used that JAR to verify actual travel in game on 2026-10-27.
+
+### Linking Book return-path slice
+
+The separate 26.3 target now registers a Linking Book using the Legacy bound
+book sprite. `/rivencraft_port link book` grants an operator-only probe book
+bound to the player's exact current dimension, coordinates, and facing. Its
+destination is a persistent data component resolved by the server on use. A
+missing dimension, unacknowledged catalog, same-dimension target without
+Intra-Linking, out-of-bounds target, or obstructed arrival is rejected without
+moving the player. This path does **not** generate a landing platform.
+
+For a test, stand at an unobstructed spot in the Overworld and run
+`/rivencraft_port link book`. Create and bind an Age Descriptive Book using the
+steps above, travel into that Age, then right-click the Linking Book. It
+should return to the exact bound spot and facing. Same-dimension use should
+refuse. Repeat after a server restart to check component persistence. This
+slice is `0.0.0.2-port-dev` and remains explicitly incomplete: normal
+crafting/binding, modifiers, book GUI, origin-drop entity, and safe fallback
+are still unported. The probe book remains in inventory after travel.
+
+### Age-index durability after the first in-game return-link check
+
+The first return-link test exposed a recoverable prototype failure: Seamless
+Portals rejected a newly added runtime Age, the integrated server exited
+abnormally, and a second Age created just before the exit was not present in
+Rivencraft's saved index on restart. Its directory contained no saved chunks.
+The `0.0.0.3-port-dev` slice flushes the index synchronously before announcing
+newly created Ages to clients. It also flushes reseed changes. The dedicated
+server smoke test now checks that both new Age IDs are already in the on-disk
+index **before** it issues `stop`, then verifies both seeds/terrain after a
+restart. This closes the ordinary interrupted-shutdown gap but is not a
+substitute for a power-loss durability test or integration with other mods'
+dynamic-dimension catalogs.
+
+### Handheld Linking Book binding slice
+
+The `0.0.0.4-port-dev` target adds a client-only book screen using the Legacy
+book artwork. An unbound Linking Book accepts a player-chosen title; a
+serverbound packet binds the held book to the player's *current* dimension,
+coordinates and facing only after checking the book, title length and empty
+target. A bound book opens the same screen and uses a server-validated
+destination-panel click for travel. This replaces the earlier direct item-use
+probe. The panel is a visible placeholder, **not** a live snapshot. The
+rotating preview, completed book behavior (including origin drop), recipe,
+modifiers, stand handling and other port systems remain unported.
+
+To test this slice, use `/give @s rivencraft:linking_book` in a 26.3 test
+world, stand at the intended return point, right-click the unbound book, enter
+a name and bind. Travel to an Age, right-click the book again and click its
+right-hand destination panel. Verify the named book persists across restart,
+same-dimension travel is refused, and a replaced/removed held book cannot be
+bound or used by a delayed screen packet. Do not treat this partial target as
+a playable release.
+
+The first `0.0.0.4-port-dev` in-game right-click exposed a 26.3 screen API
+mistake: `Screen.extractRenderStateWithTooltipAndSubtitles` already calls
+`extractBackground`, so the screen's second call raised `Can only blur once per
+frame`. The `0.0.0.5-port-dev` fix removes that duplicate background call.
+The next in-game check found that a bound Linking Book's right-hand panel did
+not trigger travel: its target component was persistent but lacked a network
+codec, so the client screen could not identify the book as bound. The
+`0.0.0.6-port-dev` slice adds stream codecs for the Linking Book target and
+Descriptive Book Age ID. Server-side held-item and destination checks remain
+authoritative. This needs another in-game check before considering the slice
+validated.
+The `0.0.0.6-port-dev` retest showed the bound-book panel but left-clicking
+did not even close the GUI. Minecraft 26.3's primary mouse button is
+`InputConstants.MOUSE_BUTTON_LEFT` (value 1), while the port handler still
+checked the 1.21.1 value 0. The `0.0.0.7-port-dev` slice uses the 26.3
+constant. This still requires in-game verification of the full click/travel
+path.
+The player confirmed the `0.0.0.7-port-dev` bound Linking Book click/travel
+path passes in game on 2026-10-27. The 26.3 target remains incomplete and is
+not ready for a public release or closure of the parent port issue.
+
+### Explicit technical alpha exception
+
+At the player's request, `1.0.1.2-alpha.1` packages this limited 26.3 port as
+an experimental alpha. It is **not** the full mod and does not pass the stable
+release gate above. The alpha label and release notes must state that Ages use
+prototype vanilla terrain, normal authoring and most content are absent, and
+worlds should be disposable or backed up. The 1.21.1 stable release remains
+independent; issues #96–#104 stay open until the full port and validation pass.
+
+The next development slice, `1.0.1.3-alpha.1`, adds a basic Descriptive Book
+screen and server-validated binding. Naming an unbound book creates a unique
+prototype Age with a random seed; clicking the bound book's placeholder panel
+uses the acknowledged-catalog travel gate. This is not authored Page binding
+or a live destination preview. The player confirmed the Descriptive Book
+binding and travel interaction in game on 2026-10-29.
+
+The following `1.0.1.4-alpha.1` development iteration registers a small
+Rivencraft creative tab for the two Books, Crystal Block, and Crystal Shard.
+It builds and passes the dedicated-server Age smoke test. The player confirmed
+the tab and four entries in game on 2026-10-29. No Page categories or
+unported items are advertised in the 26.3 tab.
+
+The next local `1.0.1.5-alpha.1` iteration selects Legacy's unwritten
+Linking Book sprite until a target is bound, then the bound sprite. It also
+restores the four-Crystal-Shard crafting recipe for a Crystal Block. Both
+changes passed the player's in-game visual/crafting check on 2026-10-29.
+
+The local `1.0.1.6-alpha.1` iteration ports Budding Crystal and the four
+blue crystal growth stages, reusing the 1.21.1 sprites and vanilla amethyst
+growth/harvest rules. Crystal clusters yield Shards, but natural crystal
+formation generation remains unported. Test growth with a Creative or
+command-placed Budding Crystal; the player passed the in-game check.
+
+The local `1.0.1.7-alpha.1` iteration adds one persistent Page item with
+unwritten and Link Panel variants. It reuses the existing Page/Link Panel
+artwork and exposes only the Link Panel variant in its own creative tab,
+matching the 1.21.1 separation of Link Pages from symbol pages. Blank Pages
+remain command-only bases; the Ink Mixer, Book Binder and symbol writing are
+not yet ported. The player passed the in-game visual and persistence check.
+
+The local `1.0.1.8-alpha.1` iteration ports the Ink Vial item, its animated
+sprite, and the black-dye/glass-bottle/water-bucket crafting recipe. Using
+it with paper in the other hand prepares a Link Panel at the current 1.21.1
+default cost of 2 ink from a 16-use vial. Ink remaining persists per vial;
+an empty vial yields a glass bottle. The Ink Mixer, configurable ink cost,
+and Book Binder remain unported. The player passed the in-game craft/use check.
+
+The local `1.0.1.9-alpha.1` iteration ports the special shapeless leather +
+Link Panel recipe for an unwritten Linking Book. The 26.3 recipe serializer
+rejects blank Pages and extra ingredients and preserves a panel's custom name
+without carrying its Page identity onto the Book. No Link Panel modifiers are
+ported yet. The player passed the in-game crafting check on 2026-10-29. The
+full Book Binder GUI and Age authoring remain the next larger port step.
+
+## Verification of this first slice
+
+The 1.21.1 `compileJava` and `build` tasks passed offline after the backend
+extraction. The GameTest server ran 93 tests; 92 passed, while
+`twoblockdeskdropsonce` failed because breaking either desk half dropped zero
+desks instead of one. That desk failure is outside the dimension-backend edit
+and must be resolved or rechecked before a release. The 1.21.1 `build` task
+passed again after the 26.3 registry slice.

docs/PORTING.md

@@ -1,5 +1,9 @@
 # Porting roadmap
 
+For a concise current status, start with [current implementation](CURRENT_IMPLEMENTATION.md)
+and [milestone summaries](MILESTONES.md). This file retains the original
+roadmap and architectural rationale.
+
 Rivencraft ports Mystcraft Legacy from Minecraft 1.12.2 to NeoForge 1.21.1.
 The world-generation, dimension, registry, networking, and rendering APIs have
 changed substantially, so the work is divided into independently testable
@@ -62,8 +66,9 @@ acceptance issue and all required implementation issues are complete.
    **Complete.** See the [Legacy instability audit](LEGACY_INSTABILITY_AUDIT.md)
    and [Milestone 6 acceptance](MILESTONE_6_ACCEPTANCE.md).
 7. **Structures and polish** — libraries, crystals, portals, recipes, models,
-   sounds, advancements, compatibility, and migration tests. Start with the
-   [Milestone 7 Legacy audit](LEGACY_M7_AUDIT.md).
+   sounds, advancements, compatibility, and migration tests. **In progress.**
+   See the [Milestone 7 regression matrix](MILESTONE_7_REGRESSION.md) and
+   [Legacy audit](LEGACY_M7_AUDIT.md).
 
 ## Architectural direction
 

docs/PREVIEW_COMPATIBILITY.md

@@ -66,8 +66,11 @@ unstable in a particular graphics or mod configuration.
 
 For preview-related releases:
 
-1. Run `./gradlew runGameTestServer -PwithArchivedGameTests=true` to verify the complete selection matrix,
-   core Age creation, persistence, and travel without optional renderers.
+1. Run `./gradlew runGameTestServer` for the core selection matrix, Age
+   creation, persistence, and travel without optional renderers. Add the
+   relevant archives from [GameTest guidance](GAMETESTS.md); if a scenario
+   stalls, stop it and hand that exact check to a real client rather than
+   treating the interrupted run as a pass.
 2. Open held Linking and Descriptive Books once with each available backend.
 3. Open both book types from a Book Stand and confirm Explore is disabled.
 4. With Immersive Portals, enter and leave Explore, travel between dimensions,

docs/README.md

@@ -0,0 +1,21 @@
+# Documentation map
+
+Start with the player-facing [project README](../README.md). The two maintained
+technical entry points are [current implementation](CURRENT_IMPLEMENTATION.md)
+and [milestone summaries](MILESTONES.md). Use [GameTest guidance](GAMETESTS.md)
+to run checks. The files below retain detailed design, provenance, and
+version-specific test evidence; an older milestone record may describe a
+former behavior or loader version.
+
+| Milestone | Detailed records |
+| --- | --- |
+| M1–M3 | [Porting roadmap](PORTING.md), [Age administration](AGES.md), [Age profiles](AGE_PROFILES.md), [preview compatibility](PREVIEW_COMPATIBILITY.md), [random Age weights](RANDOM_AGE_WEIGHTS.md) |
+| M4 | [Writing data](WRITING_DATA.md), [book presentation](DESCRIPTIVE_BOOK_PRESENTATION.md), [Ink Mixer audit](INK_MIXER_MODIFIER_AUDIT.md) |
+| M5 | [Acceptance](MILESTONE_5_ACCEPTANCE.md), [Legacy grammar audit](LEGACY_AGE_GRAMMAR_AUDIT.md), [writing grammar](WRITING_GRAMMAR.md), [symbol semantics](SYMBOL_SEMANTICS.md), [TerraBlender](TERRABLENDER_COMPATIBILITY.md), [Serene Seasons](SERENE_SEASONS_COMPATIBILITY.md) |
+| M6 | [Acceptance](MILESTONE_6_ACCEPTANCE.md), [regression](MILESTONE_6_REGRESSION.md), [Legacy audit](LEGACY_INSTABILITY_AUDIT.md), [score](INSTABILITY_SCORE.md), [live blocks](LIVE_BLOCK_INSTABILITY.md), [runtime](INSTABILITY_RUNTIME.md), [diagnostics](INSTABILITY_DIAGNOSTICS.md), [status effects](INSTABILITY_STATUS_EFFECTS.md), [decay](INSTABILITY_DECAY.md), [environmental hazards](INSTABILITY_ENVIRONMENTAL.md), [cloud platform](AGE_CLOUD_PLATFORM.md) |
+| M7 | [Acceptance](MILESTONE_7_ACCEPTANCE.md), [regression and manual matrix](MILESTONE_7_REGRESSION.md), [Legacy audit](LEGACY_M7_AUDIT.md), [visual/audio](MILESTONE_7_VISUAL_AUDIT.md), [advancements](MILESTONE_7_ADVANCEMENTS.md), [JEI](MILESTONE_7_JEI_REVIEW.md), [Serene review](MILESTONE_7_SERENE_REVIEW.md), [compatibility](MILESTONE_7_COMPATIBILITY_REVIEW.md), [Ruins](RUINS_COMPATIBILITY.md) |
+
+[Asset provenance](ASSET_PROVENANCE.md) applies across milestones. Detailed
+audits are intentionally retained for source attribution and migration
+history; these three entry points replace the former practice of treating
+every dated task note as a current installation guide.

docs/RUINS_COMPATIBILITY.md

@@ -0,0 +1,66 @@
+# Optional Ruins template pages (issue #91)
+
+Rivencraft supports Ruins 1.21.1.2NF as an optional mod. When it is installed,
+every `.tml` template in Ruins' active `config/ruins_config/<generic-or-biome>/`
+folders receives a separate Ruins page in Rivencraft's creative and JEI page
+feeds. New templates added to Ruins' config appear after a restart; removing a
+template makes its page unavailable to new books. With Ruins absent, no Ruins
+pages or structure integration are active.
+
+An authored Age with Ruins pages is admitted through Ruins' dimension gate.
+Rivencraft also admits the authored templates through their individual
+`dimensionsToSpawnIn` gates, which usually list only `overworld` and would
+otherwise prevent them from loading in an Age. Ruins still owns chunk
+inspection, spawn chance, surface validation, biome pools, and spacing.
+Rivencraft filters Ruins' weighted
+template choice to the exact pages in that Age and vetoes an unauthorized
+template in Ruins' pre-spawn event. A page therefore selects *which* template
+may appear; it does not guarantee a structure in every chunk. Manual
+`/testruin` placements are unaffected.
+
+Repeating a template page multiplies that template's Ruins selection weight by
+its page count and adds one spawn attempt per chunk for each duplicate page.
+The extra attempts are capped at 32 per chunk (or Ruins' configured count if
+higher). Distinct template pages do not add attempts, and Ruins' spacing and
+surface checks still apply. As with Rivencraft's standard
+structure pages, the first three copies of each template are instability-free;
+each additional copy adds 100 instability. Ruins retains its own biome and
+surface checks, so the standard structure forced-biome penalty does not apply.
+
+Ruins' event identifies a template only by its filename. If two active folders
+contain the same `.tml` basename, Rivencraft cannot distinguish them and
+disables all Ruins pages for that configuration. Give each template a unique
+filename to restore support. Ruins must also be able to parse the template and
+find a suitable surface in the selected biome; a page cannot repair an invalid
+or biome-incompatible template.
+
+The adapter and dimension/selection mixin are version-sensitive to Ruins
+1.21.1.2NF. The published Rivencraft jar does not include Ruins. To include it
+in a development run, use `-PwithRuins=true`.
+
+## Manual check
+
+1. Start a client with Ruins 1.21.1.2NF and Rivencraft 0.6.9.3. Confirm the
+   Ruins Pages tab contains one page per configured `.tml` file, and search a
+   distinctive template name in JEI.
+2. Bind a new Descriptive Book with a Link Panel, Standard Terrain, a suitable
+   surface biome, and one Ruins page (for example ZombieHut). Enter the Age and
+   explore *unvisited* chunks. Ruins marks inspected chunks and will not retry
+   chunks explored under the earlier broken build. Only the selected Ruins
+   template should appear. Ruins'
+   own chance and distance settings still determine how far exploration takes.
+3. For duplicate weighting, bind an Age with one copy of one template page and
+   three copies of a second template page valid in the same biome. Across enough
+   new candidate chunks, the second should be selected more often relative to
+   the first, and there should be two additional spawn attempts per inspected
+   chunk. Four copies of one template should add 100 instability, visible
+   through the OP Age instability diagnostic, while three copies add none.
+4. Make another Age without a Ruins page and confirm Ruins structures do not
+   appear there. Restart the game and confirm the authored Age keeps its page
+   selection. Then remove Ruins and confirm Rivencraft starts normally without
+   a Ruins tab.
+
+The Ruins-enabled GameTest server passed all 90 required tests and loaded the
+template-dimension and attempt mixins. Its test world was removed afterward.
+Use the client check above to verify actual Ruins generation and the increased
+attempt rate.

docs/SYMBOL_SEMANTICS.md

@@ -32,9 +32,10 @@ The Writing Desk retains 88 collection tabs, numbered from zero as in Legacy. Le
 | `weather` | `normal`, `fast`, `slow`, `off`, `always`, `cloudy`, `rain`, `snow`, or `storm`. |
 | `season` | `no_seasons`, `seasons`, `eternal_winter`, `eternal_summer`, `eternal_fall`, or `eternal_spring`. Seasonal effects other than No Seasons require optional Serene Seasons. |
 | `celestial` | `normal_time` (the first representable single-cycle behavior). |
-| `period_modifier` | JSON number in `[0, 2]`; zero is stopped time. |
-| `angle_modifier` | JSON number in `[0, 360)` degrees. |
-| `phase_modifier` | JSON number in `[0, 360)` degrees; the compiler will convert to turns. |
+| `period_modifier` | JSON number in `[0, 2]`; zero is stopped time. An immediately preceding D'ni number page overrides it with digit × 0.08. |
+| `angle_modifier` | JSON number in `[0, 360)` degrees. An immediately preceding D'ni number page overrides it with digit × 15°, wrapping 360° to 0°. |
+| `phase_modifier` | JSON number in `[0, 360)` degrees; the compiler converts it to turns. An immediately preceding D'ni number page overrides it with digit × 15°, wrapping 360° to 0°. |
+| `size_modifier` | JSON scale in `[0.25, 3]`. An immediately preceding D'ni number page overrides it with a linear 0.25×–3× scale: digit 0 is 0.25× and digit 24 is 3×. Without a number, Small/Normal/Large remain 0.5×/1×/2×. |
 | `block` | Canonical namespaced material ID for a compatible following feature; registered full-collision blocks and source fluids receive generated Pages. |
 | `feature` | Canonical namespaced feature-effect ID; the compiler must recognize and validate it. This includes supported decorations and structures. |
 

gradle.properties

@@ -36,7 +36,7 @@ mod_name=Rivencraft
 # The license of the mod. Review your options at https://choosealicense.com/. All Rights Reserved is the default.
 mod_license=LGPL-3.0-or-later
 # The mod version. Rivencraft uses the x.y.z.b policy documented in README.md.
-mod_version=0.6.8.7
+mod_version=1.0.1.1
 immersive_portals_version=6.0.7
 terrablender_version=4.1.0.8
 serene_seasons_version_id=pHEgQQUE

ports/mc263/README.md

@@ -0,0 +1,53 @@
+# Minecraft 26.3 port workspace
+
+This is an **experimental alpha port** for issues #97–#104, not gameplay parity
+with the Minecraft 1.21.1 release. It registers basic items and a runtime Age
+prototype with persisted seeds. The operator-only `rivencraft_port age`
+commands create and inspect separate vanilla-terrain levels. The current
+development slice can name an unbound Descriptive Book to create a prototype
+Age, then enter it from the book GUI; the player verified this interaction in game.
+Named Linking Book binding/travel works as a limited probe. Authored
+generation, most content, recipes, workstations, portal systems, modifiers and
+the destination preview renderer remain unported. 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.
+
+The creative tab contains the two Books, Crystal Block and Crystal Shard;
+the player verified these in game. Unbound Linking Books use the Legacy
+sprite, and four Crystal Shards craft into a Crystal Block; both were also
+verified in game. The current local iteration adds Budding Crystal and all
+four blue crystal growth stages with vanilla-style harvesting. Natural crystal
+formation generation is not yet ported; use Creative or commands to obtain a
+Budding Crystal for this test. The player verified the growth chain in game.
+The next local slice adds the Link Panel Page as a separate creative entry,
+using the existing item texture. Blank Pages remain unavailable in Creative;
+the player verified the Link Panel's appearance in game. Ink Vials now use
+the existing crafting recipe and animated sprite. With paper in the other
+hand, an Ink Vial prepares a Link Panel for two of its sixteen ink uses, as
+in the current 1.21.1 default. The Book Binder and symbol-writing systems
+are still unported. The player verified the Ink Vial interaction in game.
+A prepared Link Panel can now be combined shapelessly with leather to craft
+an unwritten Linking Book, as in 1.21.1. This custom recipe rejects a blank
+Page and extra ingredients. The Book Binder remains the next larger step for
+assembling Descriptive Books from authored pages.
+
+From the repository root:
+
+```sh
+./gradlew -p ports/mc263 build
+```
+
+This standalone Gradle build uses Minecraft 26.3, NeoForge 26.3.0.99,
+ModDevGradle 2.0.148, and Java 25. The repository root remains the independent
+Minecraft 1.21.1/Java 21 build:
+
+```sh
+./gradlew build
+```
+
+The alpha JAR is under `ports/mc263/build/libs`. Continue the port and its
+full dual-version validation in issues #98–#104 before calling 26.3 stable.
+
+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.

ports/mc263/build.gradle

@@ -0,0 +1,115 @@
+plugins {
+    id 'java-library'
+    id 'net.neoforged.moddev' version '2.0.148'
+}
+
+group = 'net.dnorberg.rivencraft'
+version = mod_version
+
+base {
+    archivesName = "rivencraft-${minecraft_version}"
+}
+
+java.toolchain.languageVersion = JavaLanguageVersion.of(25)
+
+neoForge {
+    version = project.neo_version
+    runs {
+        client {
+            client()
+            if (project.hasProperty('connectAddress')) {
+                programArgument '--quickPlayMultiplayer'
+                programArgument project.property('connectAddress').toString()
+            }
+            if (project.hasProperty('clientName')) {
+                programArgument '--username'
+                programArgument project.property('clientName').toString()
+                gameDirectory = project.layout.buildDirectory.dir('run-client-' + project.property('clientName')).get().asFile
+            }
+        }
+        server {
+            server()
+            gameDirectory = project.hasProperty('serverRunDir')
+                    ? file(project.property('serverRunDir').toString())
+                    : project.layout.buildDirectory.dir('run-server').get().asFile
+            programArgument '--nogui'
+        }
+    }
+    mods {
+        rivencraft {
+            sourceSet(sourceSets.main)
+        }
+    }
+}
+
+def generateModMetadata = tasks.register('generateModMetadata', ProcessResources) {
+    def replaceProperties = [
+            mod_id: mod_id,
+            mod_name: mod_name,
+            mod_license: mod_license,
+            mod_version: mod_version,
+            neo_version: neo_version,
+            minecraft_version_range: minecraft_version_range,
+    ]
+    inputs.properties replaceProperties
+    expand replaceProperties
+    from 'src/main/templates'
+    into 'build/generated/sources/modMetadata'
+}
+sourceSets.main.resources.srcDir generateModMetadata
+neoForge.ideSyncTask generateModMetadata
+
+tasks.named('processResources', ProcessResources).configure {
+    // Reuse the existing sprite and base model without copying binary assets.
+    from('../../src/main/resources') {
+        include 'assets/rivencraft/textures/item/crystal_shard.png'
+        include 'assets/rivencraft/textures/item/page.png'
+        include 'assets/rivencraft/textures/item/page_link_panel.png'
+        include 'assets/rivencraft/models/item/page_link_panel.json'
+        include 'assets/rivencraft/textures/item/ink_vial.png'
+        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'
+        include 'assets/rivencraft/textures/item/descriptive_book.png'
+        include 'assets/rivencraft/models/item/descriptive_book.json'
+        include 'assets/rivencraft/textures/item/linking_book.png'
+        include 'assets/rivencraft/textures/item/linking_book_unwritten.png'
+        include 'assets/rivencraft/models/item/linking_book_bound.json'
+        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/block/crystal_block.png'
+        include 'assets/rivencraft/models/block/crystal_block.json'
+        include 'assets/rivencraft/blockstates/crystal_block.json'
+        include 'assets/rivencraft/blockstates/budding_crystal.json'
+        include 'assets/rivencraft/blockstates/small_crystal_bud.json'
+        include 'assets/rivencraft/blockstates/medium_crystal_bud.json'
+        include 'assets/rivencraft/blockstates/large_crystal_bud.json'
+        include 'assets/rivencraft/blockstates/crystal_cluster.json'
+        include 'assets/rivencraft/models/block/budding_crystal.json'
+        include 'assets/rivencraft/models/block/small_crystal_bud.json'
+        include 'assets/rivencraft/models/block/medium_crystal_bud.json'
+        include 'assets/rivencraft/models/block/large_crystal_bud.json'
+        include 'assets/rivencraft/models/block/crystal_cluster.json'
+        include 'assets/rivencraft/models/item/budding_crystal.json'
+        include 'assets/rivencraft/models/item/small_crystal_bud.json'
+        include 'assets/rivencraft/models/item/medium_crystal_bud.json'
+        include 'assets/rivencraft/models/item/large_crystal_bud.json'
+        include 'assets/rivencraft/models/item/crystal_cluster.json'
+        include 'assets/rivencraft/textures/block/small_crystal_bud.png'
+        include 'assets/rivencraft/textures/block/medium_crystal_bud.png'
+        include 'assets/rivencraft/textures/block/large_crystal_bud.png'
+        include 'assets/rivencraft/textures/block/crystal_cluster.png'
+        include 'data/rivencraft/loot_table/blocks/crystal_block.json'
+        include 'data/minecraft/tags/block/mineable/pickaxe.json'
+        include 'data/minecraft/tags/item/cluster_max_harvestables.json'
+    }
+}
+
+tasks.withType(JavaCompile).configureEach {
+    options.encoding = 'UTF-8'
+}
+
+tasks.named('runServer').configure {
+    standardInput = System.in
+}

ports/mc263/gradle.properties

@@ -0,0 +1,10 @@
+org.gradle.jvmargs=-Xmx2G
+org.gradle.caching=true
+
+minecraft_version=26.3
+minecraft_version_range=[26.3]
+neo_version=26.3.0.99
+mod_id=rivencraft
+mod_name=Rivencraft
+mod_license=LGPL-3.0-or-later
+mod_version=1.0.1.9-alpha.1

ports/mc263/settings.gradle

@@ -0,0 +1,11 @@
+pluginManagement {
+    repositories {
+        gradlePluginPortal()
+    }
+}
+
+plugins {
+    id 'org.gradle.toolchains.foojay-resolver-convention' version '1.0.0'
+}
+
+rootProject.name = 'rivencraft-mc263-port'

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

@@ -0,0 +1,113 @@
+package net.dnorberg.rivencraft;
+
+import com.mojang.logging.LogUtils;
+import com.mojang.serialization.Codec;
+import net.dnorberg.rivencraft.age.RuntimeAgeBackend;
+import net.dnorberg.rivencraft.age.PortAgeCommands;
+import net.dnorberg.rivencraft.age.AgeCatalogSync;
+import net.dnorberg.rivencraft.block.BuddingCrystalBlock;
+import net.dnorberg.rivencraft.item.DescriptiveBookItem;
+import net.dnorberg.rivencraft.item.LinkBookTarget;
+import net.dnorberg.rivencraft.item.InkVialItem;
+import net.dnorberg.rivencraft.item.LinkingBookItem;
+import net.dnorberg.rivencraft.item.PageItem;
+import net.dnorberg.rivencraft.network.PortBookNetworking;
+import net.dnorberg.rivencraft.registry.ModCreativeTabs;
+import net.dnorberg.rivencraft.writing.LinkingBookRecipe;
+import net.minecraft.core.component.DataComponentType;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.network.codec.ByteBufCodecs;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.AmethystClusterBlock;
+import net.minecraft.world.level.block.state.BlockBehaviour;
+import net.minecraft.world.level.material.MapColor;
+import net.minecraft.world.item.BlockItem;
+import net.minecraft.world.item.Item;
+import net.minecraft.world.item.crafting.RecipeSerializer;
+import net.neoforged.bus.api.IEventBus;
+import net.neoforged.fml.common.Mod;
+import net.neoforged.neoforge.registries.DeferredBlock;
+import net.neoforged.neoforge.registries.DeferredItem;
+import net.neoforged.neoforge.registries.DeferredRegister;
+import java.util.function.Supplier;
+import net.neoforged.neoforge.common.NeoForge;
+import org.slf4j.Logger;
+
+/** First 26.3 registry slice; gameplay remains in the 1.21.1 target for now. */
+@Mod(Rivencraft.MOD_ID)
+public final class Rivencraft {
+    public static final String MOD_ID = "rivencraft";
+    public static final Logger LOGGER = LogUtils.getLogger();
+    private static final DeferredRegister.Blocks BLOCKS = DeferredRegister.createBlocks(MOD_ID);
+    private static final DeferredRegister.Items ITEMS = DeferredRegister.createItems(MOD_ID);
+    private static final DeferredRegister<RecipeSerializer<?>> RECIPE_SERIALIZERS =
+            DeferredRegister.create(Registries.RECIPE_SERIALIZER, MOD_ID);
+    private static final DeferredRegister.DataComponents COMPONENTS =
+            DeferredRegister.createDataComponents(Registries.DATA_COMPONENT_TYPE, MOD_ID);
+
+    public static final Supplier<DataComponentType<Identifier>> AGE_BOOK_ID = COMPONENTS.registerComponentType(
+            "age_book_id", builder -> builder.persistent(Identifier.CODEC)
+                    .networkSynchronized(Identifier.STREAM_CODEC));
+    public static final Supplier<DataComponentType<LinkBookTarget>> LINK_BOOK_TARGET = COMPONENTS.registerComponentType(
+            "link_book_target", builder -> builder.persistent(LinkBookTarget.CODEC)
+                    .networkSynchronized(LinkBookTarget.STREAM_CODEC));
+    /** A present component distinguishes Link Panels from unwritten base Pages. */
+    public static final Supplier<DataComponentType<Boolean>> LINK_PANEL_PAGE = COMPONENTS.registerComponentType(
+            "link_panel_page", builder -> builder.persistent(Codec.BOOL)
+                    .networkSynchronized(ByteBufCodecs.BOOL));
+    public static final Supplier<DataComponentType<Integer>> INK_REMAINING = COMPONENTS.registerComponentType(
+            "ink_remaining", builder -> builder.persistent(Codec.INT)
+                    .networkSynchronized(ByteBufCodecs.VAR_INT));
+
+    public static final DeferredBlock<Block> CRYSTAL_BLOCK = BLOCKS.registerBlock("crystal_block",
+            Block::new, () -> BlockBehaviour.Properties.ofFullCopy(Blocks.AMETHYST_BLOCK));
+    public static final DeferredItem<BlockItem> CRYSTAL_BLOCK_ITEM = ITEMS.registerSimpleBlockItem(CRYSTAL_BLOCK);
+    public static final DeferredBlock<BuddingCrystalBlock> BUDDING_CRYSTAL = BLOCKS.registerBlock(
+            "budding_crystal", BuddingCrystalBlock::new,
+            () -> BlockBehaviour.Properties.ofFullCopy(Blocks.BUDDING_AMETHYST).mapColor(MapColor.COLOR_BLUE));
+    public static final DeferredItem<BlockItem> BUDDING_CRYSTAL_ITEM = ITEMS.registerSimpleBlockItem(BUDDING_CRYSTAL);
+    public static final DeferredBlock<AmethystClusterBlock> SMALL_CRYSTAL_BUD = BLOCKS.registerBlock(
+            "small_crystal_bud", properties -> new AmethystClusterBlock(3.0F, 4.0F, properties),
+            () -> BlockBehaviour.Properties.ofFullCopy(Blocks.SMALL_AMETHYST_BUD));
+    public static final DeferredItem<BlockItem> SMALL_CRYSTAL_BUD_ITEM = ITEMS.registerSimpleBlockItem(SMALL_CRYSTAL_BUD);
+    public static final DeferredBlock<AmethystClusterBlock> MEDIUM_CRYSTAL_BUD = BLOCKS.registerBlock(
+            "medium_crystal_bud", properties -> new AmethystClusterBlock(4.0F, 3.0F, properties),
+            () -> BlockBehaviour.Properties.ofFullCopy(Blocks.MEDIUM_AMETHYST_BUD));
+    public static final DeferredItem<BlockItem> MEDIUM_CRYSTAL_BUD_ITEM = ITEMS.registerSimpleBlockItem(MEDIUM_CRYSTAL_BUD);
+    public static final DeferredBlock<AmethystClusterBlock> LARGE_CRYSTAL_BUD = BLOCKS.registerBlock(
+            "large_crystal_bud", properties -> new AmethystClusterBlock(5.0F, 3.0F, properties),
+            () -> BlockBehaviour.Properties.ofFullCopy(Blocks.LARGE_AMETHYST_BUD));
+    public static final DeferredItem<BlockItem> LARGE_CRYSTAL_BUD_ITEM = ITEMS.registerSimpleBlockItem(LARGE_CRYSTAL_BUD);
+    public static final DeferredBlock<AmethystClusterBlock> CRYSTAL_CLUSTER = BLOCKS.registerBlock(
+            "crystal_cluster", properties -> new AmethystClusterBlock(7.0F, 3.0F, properties),
+            () -> BlockBehaviour.Properties.ofFullCopy(Blocks.AMETHYST_CLUSTER));
+    public static final DeferredItem<BlockItem> CRYSTAL_CLUSTER_ITEM = ITEMS.registerSimpleBlockItem(CRYSTAL_CLUSTER);
+    public static final DeferredItem<Item> CRYSTAL_SHARD = ITEMS.registerSimpleItem("crystal_shard");
+    public static final DeferredItem<PageItem> PAGE = ITEMS.registerItem("page", PageItem::new);
+    public static final DeferredItem<InkVialItem> INK_VIAL = ITEMS.registerItem(
+            "ink_vial", InkVialItem::new, properties -> properties.stacksTo(16));
+    public static final DeferredItem<DescriptiveBookItem> DESCRIPTIVE_BOOK = ITEMS.registerItem(
+            "descriptive_book", DescriptiveBookItem::new, properties -> properties.stacksTo(1));
+    public static final DeferredItem<LinkingBookItem> LINKING_BOOK = ITEMS.registerItem(
+            "linking_book", LinkingBookItem::new, properties -> properties.stacksTo(1));
+    public static final Supplier<RecipeSerializer<LinkingBookRecipe>> LINKING_BOOK_RECIPE =
+            RECIPE_SERIALIZERS.register("linking_book", () -> LinkingBookRecipe.SERIALIZER);
+
+    public Rivencraft(IEventBus modEventBus) {
+        BLOCKS.register(modEventBus);
+        ITEMS.register(modEventBus);
+        COMPONENTS.register(modEventBus);
+        RECIPE_SERIALIZERS.register(modEventBus);
+        ModCreativeTabs.register(modEventBus);
+        NeoForge.EVENT_BUS.addListener(RuntimeAgeBackend::onLevelLoad);
+        NeoForge.EVENT_BUS.addListener(PortAgeCommands::register);
+        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);
+        LOGGER.info("Initializing Rivencraft 26.3 port slice (not release-ready)");
+    }
+}

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

@@ -0,0 +1,22 @@
+package net.dnorberg.rivencraft.age;
+
+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;
+
+/** Acknowledges the exact catalog version applied on the client main thread. */
+public record AgeCatalogAckPayload(int version) implements CustomPacketPayload {
+    public static final Type<AgeCatalogAckPayload> TYPE = new Type<>(
+            Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "age_catalog_ack"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, AgeCatalogAckPayload> STREAM_CODEC = StreamCodec.composite(
+            ByteBufCodecs.VAR_INT, AgeCatalogAckPayload::version, AgeCatalogAckPayload::new
+    );
+
+    @Override
+    public Type<AgeCatalogAckPayload> type() {
+        return TYPE;
+    }
+}

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

@@ -0,0 +1,29 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.List;
+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;
+
+/** Full server level catalog, sent on login and after a runtime Age is added. */
+public record AgeCatalogPayload(int version, List<Identifier> dimensions) implements CustomPacketPayload {
+    public static final Type<AgeCatalogPayload> TYPE = new Type<>(
+            Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "age_catalog"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, AgeCatalogPayload> STREAM_CODEC = StreamCodec.composite(
+            ByteBufCodecs.VAR_INT, AgeCatalogPayload::version,
+            Identifier.STREAM_CODEC.apply(ByteBufCodecs.list()), AgeCatalogPayload::dimensions,
+            AgeCatalogPayload::new
+    );
+
+    public AgeCatalogPayload {
+        dimensions = List.copyOf(dimensions);
+    }
+
+    @Override
+    public Type<AgeCatalogPayload> type() {
+        return TYPE;
+    }
+}

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

@@ -0,0 +1,102 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.HashMap;
+import java.util.IdentityHashMap;
+import java.util.Map;
+import java.util.UUID;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerPlayer;
+import net.neoforged.neoforge.event.entity.player.PlayerEvent;
+import net.neoforged.neoforge.event.server.ServerStoppedEvent;
+import net.neoforged.neoforge.network.PacketDistributor;
+import net.neoforged.neoforge.network.event.RegisterPayloadHandlersEvent;
+
+/** Refuses runtime-Age travel until the connected client confirms its catalog. */
+public final class AgeCatalogSync {
+    private static final Map<MinecraftServer, State> STATES = new IdentityHashMap<>();
+
+    private AgeCatalogSync() {
+    }
+
+    public static void registerPayloads(RegisterPayloadHandlersEvent event) {
+        var registrar = event.registrar("1");
+        registrar.playToClient(AgeCatalogPayload.TYPE, AgeCatalogPayload.STREAM_CODEC);
+        registrar.playToServer(AgeCatalogAckPayload.TYPE, AgeCatalogAckPayload.STREAM_CODEC,
+                (payload, context) -> {
+                    if (context.player() instanceof ServerPlayer player) acknowledge(player, payload.version());
+                });
+    }
+
+    public static void onLogin(PlayerEvent.PlayerLoggedInEvent event) {
+        if (event.getEntity() instanceof ServerPlayer player) {
+            try {
+                send(player);
+            } catch (RuntimeException exception) {
+                Rivencraft.LOGGER.error("Could not send initial Age catalog to {}; travel remains blocked",
+                        player.getName().getString(), exception);
+            }
+        }
+    }
+
+    public static void onLogout(PlayerEvent.PlayerLoggedOutEvent event) {
+        if (event.getEntity() instanceof ServerPlayer player) {
+            State state = STATES.get(player.level().getServer());
+            if (state != null) state.acknowledged.remove(player.getUUID());
+        }
+    }
+
+    public static void onServerStopped(ServerStoppedEvent event) {
+        STATES.remove(event.getServer());
+    }
+
+    public static void onCatalogChanged(MinecraftServer server) {
+        State state = state(server);
+        state.version++;
+        state.acknowledged.clear();
+        for (ServerPlayer player : server.getPlayerList().getPlayers()) {
+            try {
+                send(player);
+            } catch (RuntimeException exception) {
+                Rivencraft.LOGGER.error("Could not send Age catalog to {}; travel remains blocked",
+                        player.getName().getString(), exception);
+            }
+        }
+    }
+
+    public static boolean ready(ServerPlayer player, Identifier target) {
+        MinecraftServer server = player.level().getServer();
+        State state = state(server);
+        return state.version == state.acknowledged.getOrDefault(player.getUUID(), -1)
+                && server.levelKeys().stream().anyMatch(key -> key.identifier().equals(target));
+    }
+
+    private static void send(ServerPlayer player) {
+        MinecraftServer server = player.level().getServer();
+        State state = state(server);
+        state.acknowledged.remove(player.getUUID());
+        var dimensions = server.levelKeys().stream().map(key -> key.identifier()).sorted().toList();
+        PacketDistributor.sendToPlayer(player, new AgeCatalogPayload(state.version, dimensions));
+    }
+
+    private static void acknowledge(ServerPlayer player, int version) {
+        State state = state(player.level().getServer());
+        if (version != state.version) {
+            Rivencraft.LOGGER.warn("Ignoring stale Age catalog acknowledgement {} from {} (current {})",
+                    version, player.getName().getString(), state.version);
+            return;
+        }
+        state.acknowledged.put(player.getUUID(), version);
+        Rivencraft.LOGGER.info("Age catalog {} acknowledged by {}", version, player.getName().getString());
+    }
+
+    private static State state(MinecraftServer server) {
+        return STATES.computeIfAbsent(server, ignored -> new State());
+    }
+
+    private static final class State {
+        private int version = 1;
+        private final Map<UUID, Integer> acknowledged = new HashMap<>();
+    }
+}

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

@@ -0,0 +1,79 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.resources.Identifier;
+import net.minecraft.world.level.saveddata.SavedData;
+import net.minecraft.world.level.saveddata.SavedDataType;
+
+/** Server-owned seed index for the first-party 26.3 runtime-level prototype. */
+final class AgeLevelIndex extends SavedData {
+    private static final Codec<AgeLevelIndex> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+            Codec.unboundedMap(Identifier.CODEC, Codec.LONG).fieldOf("ages").forGetter(index -> index.ages),
+            Identifier.CODEC.listOf().optionalFieldOf("retired", List.of())
+                    .forGetter(index -> List.copyOf(index.retired))
+    ).apply(instance, AgeLevelIndex::new));
+
+    static final SavedDataType<AgeLevelIndex> TYPE = new SavedDataType<>(
+            Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "runtime_ages"),
+            AgeLevelIndex::new,
+            CODEC
+    );
+
+    private final Map<Identifier, Long> ages;
+    private final Set<Identifier> retired;
+
+    private AgeLevelIndex() {
+        this.ages = new LinkedHashMap<>();
+        this.retired = new LinkedHashSet<>();
+    }
+
+    private AgeLevelIndex(Map<Identifier, Long> ages, List<Identifier> retired) {
+        this.ages = new LinkedHashMap<>(ages);
+        this.retired = new LinkedHashSet<>(retired);
+    }
+
+    Map<Identifier, Long> entries() {
+        return Map.copyOf(ages);
+    }
+
+    boolean contains(Identifier id) {
+        return ages.containsKey(id) || retired.contains(id);
+    }
+
+    Long seed(Identifier id) {
+        return ages.get(id);
+    }
+
+    void add(Identifier id, long seed) {
+        if (contains(id)) {
+            throw new IllegalArgumentException("Age already exists: " + id);
+        }
+        ages.put(id, seed);
+        setDirty();
+    }
+
+    void retire(Identifier id) {
+        if (ages.remove(id) == null) throw new IllegalArgumentException("Age not indexed: " + id);
+        retired.add(id);
+        setDirty();
+    }
+
+    void restoreAfterFailedRetirement(Identifier id, long seed) {
+        if (!retired.remove(id)) throw new IllegalStateException("Age is not retired: " + id);
+        ages.put(id, seed);
+        setDirty();
+    }
+
+    void reseed(Identifier id, long seed) {
+        if (!ages.containsKey(id)) throw new IllegalArgumentException("Age not indexed: " + id);
+        ages.put(id, seed);
+        setDirty();
+    }
+}

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

@@ -0,0 +1,221 @@
+package net.dnorberg.rivencraft.age;
+
+import com.mojang.brigadier.arguments.LongArgumentType;
+import com.mojang.brigadier.arguments.IntegerArgumentType;
+import com.mojang.brigadier.arguments.StringArgumentType;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.item.LinkBookTarget;
+import net.minecraft.commands.Commands;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.Identifier;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.util.Prediction;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.neoforged.neoforge.event.RegisterCommandsEvent;
+import net.neoforged.fml.ModList;
+import java.util.Map;
+import java.util.TreeMap;
+
+/** Operator-only backend and synchronized-travel probes, not normal book behavior. */
+public final class PortAgeCommands {
+    private PortAgeCommands() {
+    }
+
+    public static void register(RegisterCommandsEvent event) {
+        event.getDispatcher().register(Commands.literal("rivencraft_port")
+                .requires(Commands.hasPermission(Commands.LEVEL_ADMINS))
+                .then(Commands.literal("compat")
+                        .executes(context -> {
+                            StringBuilder mods = new StringBuilder("Optional mods: ");
+                            for (String id : new String[]{"jei", "terrablender", "biomesoplenty",
+                                    "sereneseasons", "glitchcore", "ruins", "create",
+                                    "ponder", "immersive_portals_core"}) {
+                                if (mods.length() > "Optional mods: ".length()) mods.append(", ");
+                                mods.append(id).append('=').append(ModList.get().isLoaded(id));
+                            }
+                            context.getSource().sendSuccess(() -> Component.literal(mods.toString()), false);
+                            Map<String, Integer> biomeCounts = new TreeMap<>();
+                            context.getSource().getServer().registryAccess()
+                                    .lookupOrThrow(Registries.BIOME).listElementIds()
+                                    .forEach(key -> biomeCounts.merge(key.identifier().getNamespace(), 1, Integer::sum));
+                            context.getSource().sendSuccess(() -> Component.literal(
+                                    "Registered biomes by namespace: " + biomeCounts), false);
+                            return 1;
+                        }))
+                .then(Commands.literal("link")
+                        .then(Commands.literal("book")
+                                .executes(context -> {
+                                    ServerPlayer player = context.getSource().getPlayerOrException();
+                                    ItemStack book = new ItemStack(Rivencraft.LINKING_BOOK.get());
+                                    LinkBookTarget target = LinkBookTarget.at(player);
+                                    book.set(Rivencraft.LINK_BOOK_TARGET.get(), target);
+                                    book.set(DataComponents.CUSTOM_NAME, Component.literal(
+                                            "Link to " + target.dimension()));
+                                    if (!player.getInventory().add(book)) player.drop(book, false, Prediction.SERVER_ONLY);
+                                    context.getSource().sendSuccess(() -> Component.literal(
+                                            "Granted Linking Book bound to " + target.dimension() + " at "
+                                                    + player.blockPosition()), false);
+                                    return 1;
+                                })))
+                .then(Commands.literal("age")
+                        .then(Commands.literal("create")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .then(Commands.argument("seed", LongArgumentType.longArg())
+                                                .executes(context -> {
+                                                    String name = StringArgumentType.getString(context, "name");
+                                                    Identifier id = Identifier.fromNamespaceAndPath(
+                                                            Rivencraft.MOD_ID, "age/" + name);
+                                                    long seed = LongArgumentType.getLong(context, "seed");
+                                                    ServerLevel level;
+                                                    try {
+                                                        level = RuntimeAgeBackend.create(
+                                                                context.getSource().getServer(), id, seed);
+                                                    } catch (IllegalArgumentException | IllegalStateException exception) {
+                                                        context.getSource().sendFailure(Component.literal(exception.getMessage()));
+                                                        return 0;
+                                                    }
+                                                    context.getSource().sendSuccess(() -> Component.literal(
+                                                            "Created " + id + " with seed " + level.getSeed()), true);
+                                                    return 1;
+                                                }))))
+                        .then(Commands.literal("list")
+                                .executes(context -> {
+                                    var ages = RuntimeAgeBackend.savedAges(context.getSource().getServer());
+                                    context.getSource().sendSuccess(() -> Component.literal(
+                                            "Saved prototype Ages: " + ages), false);
+                                    return ages.size();
+                                }))
+                        .then(Commands.literal("retire")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .executes(context -> {
+                                            String name = StringArgumentType.getString(context, "name");
+                                            Identifier id = Identifier.fromNamespaceAndPath(
+                                                    Rivencraft.MOD_ID, "age/" + name);
+                                            try {
+                                                RuntimeAgeBackend.retire(context.getSource().getServer(), id);
+                                            } catch (IllegalArgumentException | IllegalStateException exception) {
+                                                context.getSource().sendFailure(Component.literal(exception.getMessage()));
+                                                return 0;
+                                            }
+                                            context.getSource().sendSuccess(() -> Component.literal(
+                                                    "Retired " + id + "; exact Age data archived"), true);
+                                            return 1;
+                                        })))
+                        .then(Commands.literal("unload")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .executes(context -> {
+                                            Identifier id = ageId(context);
+                                            try {
+                                                RuntimeAgeBackend.unload(context.getSource().getServer(), id);
+                                            } catch (IllegalArgumentException | IllegalStateException exception) {
+                                                context.getSource().sendFailure(Component.literal(exception.getMessage()));
+                                                return 0;
+                                            }
+                                            context.getSource().sendSuccess(() -> Component.literal("Unloaded " + id), true);
+                                            return 1;
+                                        })))
+                        .then(Commands.literal("reload")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .executes(context -> {
+                                            Identifier id = ageId(context);
+                                            try {
+                                                RuntimeAgeBackend.reload(context.getSource().getServer(), id);
+                                            } catch (IllegalArgumentException | IllegalStateException exception) {
+                                                context.getSource().sendFailure(Component.literal(exception.getMessage()));
+                                                return 0;
+                                            }
+                                            context.getSource().sendSuccess(() -> Component.literal("Reloaded " + id), true);
+                                            return 1;
+                                        })))
+                        .then(Commands.literal("reseed")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .then(Commands.argument("seed", LongArgumentType.longArg())
+                                                .executes(context -> {
+                                                    Identifier id = ageId(context);
+                                                    long seed = LongArgumentType.getLong(context, "seed");
+                                                    try {
+                                                        RuntimeAgeBackend.reseed(context.getSource().getServer(), id, seed);
+                                                    } catch (IllegalArgumentException | IllegalStateException exception) {
+                                                        context.getSource().sendFailure(Component.literal(exception.getMessage()));
+                                                        return 0;
+                                                    }
+                                                    context.getSource().sendSuccess(() -> Component.literal(
+                                                            "Reseeded " + id + " to " + seed + " for future chunks"), true);
+                                                    return 1;
+                                                }))))
+                        .then(Commands.literal("enter")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .executes(context -> {
+                                            ServerPlayer player = context.getSource().getPlayerOrException();
+                                            Identifier id = ageId(context);
+                                            String failure = PortAgeTravel.enter(player, id);
+                                            if (failure != null) {
+                                                context.getSource().sendFailure(Component.literal(failure));
+                                                return 0;
+                                            }
+                                            context.getSource().sendSuccess(() -> Component.literal(
+                                                    "Entered " + id + " after Age catalog acknowledgement"), false);
+                                            return 1;
+                                        })))
+                        .then(Commands.literal("book")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .executes(context -> {
+                                            ServerPlayer player = context.getSource().getPlayerOrException();
+                                            Identifier id = ageId(context);
+                                            if (!RuntimeAgeBackend.savedAges(context.getSource().getServer()).containsKey(id)) {
+                                                context.getSource().sendFailure(Component.literal("Age not active: " + id));
+                                                return 0;
+                                            }
+                                            ItemStack book = new ItemStack(Rivencraft.DESCRIPTIVE_BOOK.get());
+                                            book.set(Rivencraft.AGE_BOOK_ID.get(), id);
+                                            book.set(DataComponents.CUSTOM_NAME, Component.literal(
+                                                    StringArgumentType.getString(context, "name")));
+                                            if (!player.getInventory().add(book)) player.drop(book, false, Prediction.SERVER_ONLY);
+                                            context.getSource().sendSuccess(() -> Component.literal(
+                                                    "Granted bound Descriptive Book for " + id), false);
+                                            return 1;
+                                        })))
+                        .then(Commands.literal("sample")
+                                .then(Commands.argument("name", StringArgumentType.word())
+                                        .executes(context -> sampleAge(context, 0))
+                                        .then(Commands.argument("chunkOffset", IntegerArgumentType.integer(0))
+                                                .executes(context -> sampleAge(context,
+                                                        IntegerArgumentType.getInteger(context, "chunkOffset"))))))));
+    }
+
+    private static int sampleAge(com.mojang.brigadier.context.CommandContext<net.minecraft.commands.CommandSourceStack> context,
+                                 int chunkOffset) {
+        Identifier id = ageId(context);
+        ServerLevel level = context.getSource().getServer().getLevel(
+                ResourceKey.create(Registries.DIMENSION, id));
+        if (level == null) {
+            context.getSource().sendFailure(Component.literal("Age not loaded: " + id));
+            return 0;
+        }
+        int fingerprint = 1;
+        for (int x = 0; x < 2; x++) {
+            for (int z = 0; z < 2; z++) {
+                int chunkX = chunkOffset + x * 4;
+                int chunkZ = chunkOffset + z * 4;
+                level.getChunk(chunkX, chunkZ);
+                fingerprint = 31 * fingerprint + level.getHeight(
+                        Heightmap.Types.WORLD_SURFACE, chunkX * 16, chunkZ * 16);
+            }
+        }
+        int result = fingerprint;
+        context.getSource().sendSuccess(() -> Component.literal(
+                id + " seed=" + level.getSeed() + " chunkOffset=" + chunkOffset + " terrain=" + result), false);
+        return 1;
+    }
+
+    private static Identifier ageId(com.mojang.brigadier.context.CommandContext<net.minecraft.commands.CommandSourceStack> context) {
+        return Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID,
+                "age/" + StringArgumentType.getString(context, "name"));
+    }
+
+}

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

@@ -0,0 +1,63 @@
+package net.dnorberg.rivencraft.age;
+
+import java.util.Set;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.levelgen.Heightmap;
+
+/** Shared, server-authoritative landing for the 26.3 book and operator probe. */
+public final class PortAgeTravel {
+    private PortAgeTravel() {
+    }
+
+    public static String enter(ServerPlayer player, Identifier id) {
+        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 = findLanding(target);
+        if (landing == null) return "No safe test 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";
+    }
+
+    private static BlockPos findLanding(ServerLevel target) {
+        for (int radius = 0; radius <= 16; radius++) {
+            for (int x = -radius; x <= radius; x++) {
+                for (int z = -radius; z <= radius; z++) {
+                    if (Math.max(Math.abs(x), Math.abs(z)) != radius) continue;
+                    int y = target.getHeight(Heightmap.Types.MOTION_BLOCKING, x, z);
+                    BlockPos foot = new BlockPos(x, y, z);
+                    BlockPos floor = foot.below();
+                    if (target.getBlockState(floor).isFaceSturdy(target, floor, Direction.UP)
+                            && target.getBlockState(foot).getCollisionShape(target, foot).isEmpty()
+                            && target.getBlockState(foot.above()).getCollisionShape(target, foot.above()).isEmpty()) {
+                        return foot;
+                    }
+                }
+            }
+        }
+        // The operator/book probe needs a deterministic landing even when
+        // origin is ocean or foliage. Final book landing rules are ported later.
+        int y = Math.max(64, target.getHeight(Heightmap.Types.MOTION_BLOCKING, 0, 0) + 2);
+        if (y + 2 >= target.getMaxY()) return null;
+        BlockPos foot = new BlockPos(0, y, 0);
+        for (int x = -1; x <= 1; x++) {
+            for (int z = -1; z <= 1; z++) {
+                target.setBlock(new BlockPos(x, y - 1, z), Rivencraft.CRYSTAL_BLOCK.get().defaultBlockState(), 3);
+            }
+        }
+        target.setBlock(foot, Blocks.AIR.defaultBlockState(), 3);
+        target.setBlock(foot.above(), Blocks.AIR.defaultBlockState(), 3);
+        return foot;
+    }
+}

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

@@ -0,0 +1,276 @@
+package net.dnorberg.rivencraft.age;
+
+import java.io.IOException;
+import java.nio.file.AtomicMoveNotSupportedException;
+import java.nio.file.Files;
+import java.nio.file.LinkOption;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.util.List;
+import java.util.Map;
+import java.util.OptionalLong;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.TicketStorage;
+import net.minecraft.world.level.biome.BiomeManager;
+import net.minecraft.world.level.dimension.LevelStem;
+import net.minecraft.world.level.storage.DerivedLevelData;
+import net.minecraft.world.level.storage.LevelResource;
+import net.neoforged.neoforge.common.NeoForge;
+import net.neoforged.neoforge.common.world.chunk.ForcedChunkManager;
+import net.neoforged.neoforge.event.level.LevelEvent;
+
+/**
+ * Server-side runtime-level foundation for 26.3. Authored generators and
+ * dynamic client registry synchronization remain separate migration steps.
+ */
+public final class RuntimeAgeBackend {
+    private RuntimeAgeBackend() {
+    }
+
+    public static void onLevelLoad(LevelEvent.Load event) {
+        if (!(event.getLevel() instanceof ServerLevel overworld) || overworld.dimension() != Level.OVERWORLD) {
+            return;
+        }
+        MinecraftServer server = overworld.getServer();
+        AgeLevelIndex index = index(server);
+        for (Map.Entry<Identifier, Long> age : index.entries().entrySet()) {
+            try {
+                load(server, age.getKey(), age.getValue());
+            } catch (RuntimeException exception) {
+                Rivencraft.LOGGER.error("Could not restore Age {}. Its saved index remains intact.", age.getKey(), exception);
+            }
+        }
+    }
+
+    /** Creates a server level, then commits its identity only after successful construction. */
+    public static ServerLevel create(MinecraftServer server, Identifier id, long seed) {
+        checkServerThread(server);
+        ageName(id);
+        AgeLevelIndex index = index(server);
+        if (index.contains(id)) throw new IllegalArgumentException("Age already exists: " + id);
+        ServerLevel level = load(server, id, seed);
+        index.add(id, seed);
+        // 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.
+        server.overworld().getDataStorage().saveAndJoin();
+        AgeCatalogSync.onCatalogChanged(server);
+        return level;
+    }
+
+    /** Unloads an Age only when no player remains; save(true) flushes other entities. */
+    public static void unload(MinecraftServer server, Identifier id) {
+        checkServerThread(server);
+        requireSeed(server, id);
+        unloadLoaded(server, id);
+        AgeCatalogSync.onCatalogChanged(server);
+    }
+
+    public static ServerLevel reload(MinecraftServer server, Identifier id) {
+        checkServerThread(server);
+        long seed = requireSeed(server, id);
+        ServerLevel level = load(server, id, seed);
+        AgeCatalogSync.onCatalogChanged(server);
+        return level;
+    }
+
+    /** Existing saved chunks stay in place; the replacement level uses the new seed. */
+    public static void reseed(MinecraftServer server, Identifier id, long seed) {
+        checkServerThread(server);
+        AgeLevelIndex index = index(server);
+        long previousSeed = requireSeed(server, id);
+        if (previousSeed == seed) return;
+        boolean loaded = server.getLevel(dimensionKey(id)) != null;
+        if (loaded) unloadLoaded(server, id);
+        try {
+            if (loaded) load(server, id, seed);
+            index.reseed(id, seed);
+            server.overworld().getDataStorage().saveAndJoin();
+            if (loaded) AgeCatalogSync.onCatalogChanged(server);
+        } catch (RuntimeException exception) {
+            if (loaded) {
+                try {
+                    load(server, id, previousSeed);
+                    AgeCatalogSync.onCatalogChanged(server);
+                } catch (RuntimeException rollbackFailure) {
+                    exception.addSuppressed(rollbackFailure);
+                }
+            }
+            throw exception;
+        }
+    }
+
+    /** Retires one unloaded Age and moves only its own storage to a recoverable archive. */
+    public static void retire(MinecraftServer server, Identifier id) {
+        checkServerThread(server);
+        String name = ageName(id);
+        AgeLevelIndex index = index(server);
+        long seed = requireSeed(server, id);
+        boolean loaded = server.getLevel(dimensionKey(id)) != null;
+        ArchivePaths paths = archivePaths(server, name);
+        if (loaded) unloadLoaded(server, id);
+        // Persist the tombstone before moving files: a crash mid-archive must
+        // not let an old book silently regenerate this identity.
+        index.retire(id);
+        try {
+            server.overworld().getDataStorage().saveAndJoin();
+            if (Files.exists(paths.live(), LinkOption.NOFOLLOW_LINKS)) {
+                Files.createDirectories(paths.archive().getParent());
+                try {
+                    Files.move(paths.live(), paths.archive(), StandardCopyOption.ATOMIC_MOVE);
+                } catch (AtomicMoveNotSupportedException exception) {
+                    Files.move(paths.live(), paths.archive());
+                }
+            }
+        } catch (IOException | RuntimeException exception) {
+            try {
+                index.restoreAfterFailedRetirement(id, seed);
+                server.overworld().getDataStorage().saveAndJoin();
+            } catch (RuntimeException rollbackFailure) {
+                exception.addSuppressed(rollbackFailure);
+            }
+            if (loaded) {
+                try {
+                    load(server, id, seed);
+                } catch (RuntimeException rollbackFailure) {
+                    exception.addSuppressed(rollbackFailure);
+                }
+            }
+            throw new IllegalStateException("Could not archive Age " + id, exception);
+        }
+        AgeCatalogSync.onCatalogChanged(server);
+        Rivencraft.LOGGER.info("Retired 26.3 prototype Age {} (archived at {})", id, paths.archive());
+    }
+
+    public static Map<Identifier, Long> savedAges(MinecraftServer server) {
+        checkServerThread(server);
+        return index(server).entries();
+    }
+
+    /** Includes retired IDs, which must never be silently reused by a new book. */
+    public static boolean isNameTaken(MinecraftServer server, Identifier id) {
+        checkServerThread(server);
+        ageName(id);
+        return index(server).contains(id);
+    }
+
+    private static AgeLevelIndex index(MinecraftServer server) {
+        return server.overworld().getDataStorage().computeIfAbsent(AgeLevelIndex.TYPE);
+    }
+
+    private static void checkServerThread(MinecraftServer server) {
+        if (!server.isSameThread()) throw new IllegalStateException("Runtime Age operation outside server thread");
+    }
+
+    private static long requireSeed(MinecraftServer server, Identifier id) {
+        ageName(id);
+        Long seed = index(server).seed(id);
+        if (seed == null) throw new IllegalArgumentException("Age not active: " + id);
+        return seed;
+    }
+
+    private static String ageName(Identifier id) {
+        if (!id.getNamespace().equals(Rivencraft.MOD_ID) || !id.getPath().startsWith("age/")) {
+            throw new IllegalArgumentException("Expected a rivencraft:age/* dimension ID: " + id);
+        }
+        String name = id.getPath().substring("age/".length());
+        if (name.isBlank() || name.contains("/") || name.equals(".") || name.equals("..")) {
+            throw new IllegalArgumentException("Expected a single safe Age path segment: " + id);
+        }
+        return name;
+    }
+
+    private static ResourceKey<Level> dimensionKey(Identifier id) {
+        return ResourceKey.create(Registries.DIMENSION, id);
+    }
+
+    private static void unloadLoaded(MinecraftServer server, Identifier id) {
+        ResourceKey<Level> key = dimensionKey(id);
+        ServerLevel level = server.getLevel(key);
+        if (level == null) throw new IllegalStateException("Age not loaded: " + id);
+        if (!level.players().isEmpty()) {
+            throw new IllegalStateException("Age still contains players; move them before unloading: " + id);
+        }
+        // Match the server shutdown sequence so forced tickets are persisted
+        // as inactive, rather than holding stale references to this level.
+        level.getChunkSource().deactivateTicketsOnClosing();
+        level.getChunkSource().tick(() -> true, false);
+        level.save(null, true, false);
+        try {
+            level.close();
+        } catch (IOException exception) {
+            throw new IllegalStateException("Could not close Age: " + id, exception);
+        }
+        server.levels.remove(key);
+        NeoForge.EVENT_BUS.post(new LevelEvent.Unload(level));
+        Rivencraft.LOGGER.info("Unloaded 26.3 prototype Age {}", id);
+    }
+
+    private static ArchivePaths archivePaths(MinecraftServer server, String name) {
+        Path world = server.getWorldPath(LevelResource.ROOT).toAbsolutePath().normalize();
+        Path dimensions = world.resolve("dimensions");
+        Path namespace = dimensions.resolve(Rivencraft.MOD_ID);
+        Path ageRoot = namespace.resolve("age");
+        Path live = ageRoot.resolve(name).normalize();
+        Path archiveRoot = world.getParent().resolve(world.getFileName() + "-retired-ages").normalize();
+        Path archive = archiveRoot.resolve(name).normalize();
+        if (!live.getParent().equals(ageRoot) || !archive.getParent().equals(archiveRoot)
+                || Files.isSymbolicLink(world) || Files.isSymbolicLink(dimensions)
+                || Files.isSymbolicLink(namespace) || Files.isSymbolicLink(ageRoot)
+                || Files.isSymbolicLink(live) || Files.isSymbolicLink(archiveRoot)
+                || Files.exists(archive, LinkOption.NOFOLLOW_LINKS)) {
+            throw new IllegalStateException("Unsafe or existing Age archive path for " + name);
+        }
+        return new ArchivePaths(live, archive);
+    }
+
+    private record ArchivePaths(Path live, Path archive) {
+    }
+
+    private static ServerLevel load(MinecraftServer server, Identifier id, long seed) {
+        ResourceKey<Level> key = ResourceKey.create(Registries.DIMENSION, id);
+        if (server.getLevel(key) != null) throw new IllegalArgumentException("Level already loaded: " + id);
+
+        // This prototype uses vanilla Overworld terrain until issue #98 ports
+        // authored ChunkGenerators. LevelStem.seedOverride controls chunk random
+        // state as well as ServerLevel.getSeed() in NeoForge 26.3.
+        LevelStem overworldStem = server.registryAccess().lookupOrThrow(Registries.LEVEL_STEM)
+                .getValue(LevelStem.OVERWORLD);
+        if (overworldStem == null) throw new IllegalStateException("Missing Overworld LevelStem");
+        LevelStem stem = new LevelStem(overworldStem.type(), overworldStem.generator(), OptionalLong.of(seed));
+        long biomeZoomSeed = BiomeManager.obfuscateSeed(server.getWorldGenSettings().options().seed());
+        ServerLevel level = new ServerLevel(server, server.executor, server.storageSource,
+                new DerivedLevelData(server.getWorldData(), server.getWorldData().overworldData()),
+                key, stem, server.getWorldData().isDebugWorld(), biomeZoomSeed, List.of(), false);
+
+        // Publish only after the constructor succeeds. If the load event fails,
+        // roll back the map and close the newly opened chunk/entity stores.
+        try {
+            server.levels.put(key, level);
+            level.getWorldBorder().setAbsoluteMaxSize(server.getAbsoluteMaxWorldSize());
+            server.getPlayerList().addWorldborderListener(level);
+            NeoForge.EVENT_BUS.post(new LevelEvent.Load(level));
+            TicketStorage tickets = level.getDataStorage().get(TicketStorage.TYPE);
+            if (tickets != null) {
+                tickets.activateAllDeactivatedTickets();
+                ForcedChunkManager.activateAllDeactivatedTickets(level, tickets);
+            }
+            Rivencraft.LOGGER.info("Loaded 26.3 prototype Age {} with seed {}", id, seed);
+            return level;
+        } catch (RuntimeException exception) {
+            server.levels.remove(key);
+            try {
+                level.close();
+            } catch (IOException closeException) {
+                exception.addSuppressed(closeException);
+            }
+            throw exception;
+        }
+    }
+}

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

@@ -0,0 +1,45 @@
+package net.dnorberg.rivencraft.block;
+
+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.level.block.AmethystBlock;
+import net.minecraft.world.level.block.AmethystClusterBlock;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.BuddingAmethystBlock;
+import net.minecraft.world.level.block.state.BlockBehaviour;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.material.Fluids;
+
+/** Vanilla amethyst growth, using Rivencraft's blue crystal stages. */
+public final class BuddingCrystalBlock extends AmethystBlock {
+    public BuddingCrystalBlock(BlockBehaviour.Properties properties) {
+        super(properties);
+    }
+
+    @Override
+    protected void randomTick(BlockState state, ServerLevel level, BlockPos pos, RandomSource random) {
+        if (random.nextInt(5) != 0) return;
+        Direction direction = Direction.values()[random.nextInt(Direction.values().length)];
+        BlockPos target = pos.relative(direction);
+        BlockState existing = level.getBlockState(target);
+        Block next = nextStage(existing, direction);
+        if (next == null) return;
+        level.setBlockAndUpdate(target, next.defaultBlockState()
+                .setValue(AmethystClusterBlock.FACING, direction)
+                .setValue(AmethystClusterBlock.WATERLOGGED,
+                        existing.getFluidState().getType() == Fluids.WATER));
+    }
+
+    public static Block nextStage(BlockState existing, Direction direction) {
+        if (BuddingAmethystBlock.canClusterGrowAtState(existing)) return Rivencraft.SMALL_CRYSTAL_BUD.get();
+        if (!existing.hasProperty(AmethystClusterBlock.FACING)
+                || existing.getValue(AmethystClusterBlock.FACING) != direction) return null;
+        if (existing.is(Rivencraft.SMALL_CRYSTAL_BUD)) return Rivencraft.MEDIUM_CRYSTAL_BUD.get();
+        if (existing.is(Rivencraft.MEDIUM_CRYSTAL_BUD)) return Rivencraft.LARGE_CRYSTAL_BUD.get();
+        if (existing.is(Rivencraft.LARGE_CRYSTAL_BUD)) return Rivencraft.CRYSTAL_CLUSTER.get();
+        return null;
+    }
+}

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

@@ -0,0 +1,31 @@
+package net.dnorberg.rivencraft.client;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.age.AgeCatalogAckPayload;
+import net.dnorberg.rivencraft.age.AgeCatalogPayload;
+import net.minecraft.client.multiplayer.ClientPacketListener;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.world.level.Level;
+import net.neoforged.api.distmarker.Dist;
+import net.neoforged.bus.api.SubscribeEvent;
+import net.neoforged.fml.common.EventBusSubscriber;
+import net.neoforged.neoforge.client.network.event.RegisterClientPayloadHandlersEvent;
+import java.util.stream.Collectors;
+
+@EventBusSubscriber(modid = Rivencraft.MOD_ID, value = Dist.CLIENT)
+public final class AgeCatalogClient {
+    private AgeCatalogClient() {
+    }
+
+    @SubscribeEvent
+    public static void register(RegisterClientPayloadHandlersEvent event) {
+        event.register(AgeCatalogPayload.TYPE, (payload, context) -> {
+            if (!(context.listener() instanceof ClientPacketListener listener)) return;
+            listener.levels = payload.dimensions().stream()
+                    .map(id -> ResourceKey.<Level>create(Registries.DIMENSION, id))
+                    .collect(Collectors.toUnmodifiableSet());
+            context.reply(new AgeCatalogAckPayload(payload.version()));
+        });
+    }
+}

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

@@ -0,0 +1,29 @@
+package net.dnorberg.rivencraft.client;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.client.Minecraft;
+import net.minecraft.world.InteractionResult;
+import net.neoforged.api.distmarker.Dist;
+import net.neoforged.bus.api.SubscribeEvent;
+import net.neoforged.fml.common.EventBusSubscriber;
+import net.neoforged.neoforge.event.entity.player.PlayerInteractEvent;
+
+/** Opens screens only on the physical client, including integrated singleplayer. */
+@EventBusSubscriber(modid = Rivencraft.MOD_ID, value = Dist.CLIENT)
+public final class PortBookInteractionHandler {
+    private PortBookInteractionHandler() {
+    }
+
+    @SubscribeEvent
+    public static void onRightClickItem(PlayerInteractEvent.RightClickItem event) {
+        if (!event.getEntity().level().isClientSide()) return;
+        boolean linking = event.getItemStack().is(Rivencraft.LINKING_BOOK.get());
+        boolean descriptive = event.getItemStack().is(Rivencraft.DESCRIPTIVE_BOOK.get());
+        if (!linking && !descriptive) return;
+        event.setCanceled(true);
+        event.setCancellationResult(InteractionResult.SUCCESS);
+        Minecraft.getInstance().setScreenAndShow(linking
+                ? new PortLinkingBookScreen(event.getHand(), event.getItemStack().copy())
+                : new PortDescriptiveBookScreen(event.getHand(), event.getItemStack().copy()));
+    }
+}

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

@@ -0,0 +1,116 @@
+package net.dnorberg.rivencraft.client;
+
+import com.mojang.blaze3d.platform.InputConstants;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.network.BindDescriptiveBookPayload;
+import net.dnorberg.rivencraft.network.PortBookNetworking;
+import net.dnorberg.rivencraft.network.UseDescriptiveBookPayload;
+import net.minecraft.client.gui.GuiGraphicsExtractor;
+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. */
+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 EditBox titleInput;
+
+    public PortDescriptiveBookScreen(InteractionHand hand, ItemStack book) {
+        super(book.getHoverName());
+        this.hand = hand;
+        bound = book.has(Rivencraft.AGE_BOOK_ID.get());
+    }
+
+    @Override
+    protected void init() {
+        if (bound) 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"));
+        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());
+    }
+
+    @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);
+        }
+        super.extractRenderState(graphics, mouseX, mouseY, partialTick);
+    }
+
+    @Override
+    public boolean mouseClicked(MouseButtonEvent event, boolean doubleClick) {
+        if (bound && 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));
+                onClose();
+                return true;
+            }
+        }
+        return super.mouseClicked(event, doubleClick);
+    }
+
+    @Override
+    public boolean isPauseScreen() {
+        return false;
+    }
+
+    private void bind() {
+        if (titleInput == null) return;
+        String name = titleInput.getValue().strip();
+        if (name.isEmpty()) return;
+        ClientPacketDistributor.sendToServer(new BindDescriptiveBookPayload(hand == InteractionHand.OFF_HAND, name));
+        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/PortLinkingBookScreen.java

@@ -0,0 +1,114 @@
+package net.dnorberg.rivencraft.client;
+
+import com.mojang.blaze3d.platform.InputConstants;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.network.BindLinkingBookPayload;
+import net.dnorberg.rivencraft.network.PortBookNetworking;
+import net.dnorberg.rivencraft.network.UseLinkingBookPayload;
+import net.minecraft.client.gui.GuiGraphicsExtractor;
+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. */
+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 EditBox titleInput;
+
+    public PortLinkingBookScreen(InteractionHand hand, ItemStack book) {
+        super(book.getHoverName());
+        this.hand = hand;
+        bound = book.has(Rivencraft.LINK_BOOK_TARGET.get());
+    }
+
+    @Override
+    protected void init() {
+        if (bound) return;
+        int left = (width - WIDTH) / 2;
+        int top = (height - HEIGHT) / 2;
+        titleInput = new EditBox(font, left + 40, top + 69, 110, 20,
+                Component.literal("Linking Book name"));
+        titleInput.setMaxLength(PortBookNetworking.MAX_BOOK_TITLE_LENGTH);
+        titleInput.setHint(Component.literal("Name this link"));
+        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());
+    }
+
+    @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);
+        } else {
+            graphics.text(font, Component.literal("Name this Linking Book"), left + 183, top + 39,
+                    TEXT_COLOR, false);
+        }
+        super.extractRenderState(graphics, mouseX, mouseY, partialTick);
+    }
+
+    @Override
+    public boolean mouseClicked(MouseButtonEvent event, boolean doubleClick) {
+        if (bound && 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));
+                onClose();
+                return true;
+            }
+        }
+        return super.mouseClicked(event, doubleClick);
+    }
+
+    @Override
+    public boolean isPauseScreen() {
+        return false;
+    }
+
+    private void bind() {
+        if (titleInput == null) return;
+        String name = titleInput.getValue().strip();
+        if (name.isEmpty()) return;
+        ClientPacketDistributor.sendToServer(new BindLinkingBookPayload(hand == InteractionHand.OFF_HAND, name));
+        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/item/DescriptiveBookItem.java

@@ -0,0 +1,40 @@
+package net.dnorberg.rivencraft.item;
+
+import java.util.function.Consumer;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.Identifier;
+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.TooltipFlag;
+import net.minecraft.world.item.component.TooltipDisplay;
+import net.minecraft.world.level.Level;
+
+/** Descriptive Book shell for the 26.3 prototype Age backend. */
+public final class DescriptiveBookItem extends Item {
+    public DescriptiveBookItem(Properties properties) {
+        super(properties);
+    }
+
+    @Override
+    public boolean isFoil(ItemStack stack) {
+        return stack.has(Rivencraft.AGE_BOOK_ID.get()) || super.isFoil(stack);
+    }
+
+    @Override
+    public InteractionResult use(Level level, Player player, InteractionHand hand) {
+        // The client opens the GUI. Binding and travel are validated on the
+        // server through dedicated packets; item use cannot bypass them.
+        return InteractionResult.SUCCESS;
+    }
+
+    @Override
+    public void appendHoverText(ItemStack stack, TooltipContext context, TooltipDisplay display,
+                                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));
+    }
+}

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

@@ -0,0 +1,76 @@
+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.minecraft.world.item.TooltipFlag;
+import net.minecraft.world.item.component.TooltipDisplay;
+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);
+    }
+
+    public static int remaining(ItemStack vial) {
+        return vial.getOrDefault(Rivencraft.INK_REMAINING.get(), CAPACITY);
+    }
+
+    @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()) 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;
+    }
+
+    @Override
+    public void appendHoverText(ItemStack stack, TooltipContext context, TooltipDisplay display,
+                                Consumer<Component> tooltip, TooltipFlag flag) {
+        tooltip.accept(Component.translatable("item.rivencraft.ink_vial.remaining", remaining(stack), CAPACITY));
+        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/LinkBookTarget.java

@@ -0,0 +1,40 @@
+package net.dnorberg.rivencraft.item;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.ByteBufCodecs;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerPlayer;
+
+/** Persistent destination captured when a 26.3 prototype Linking Book is bound. */
+public record LinkBookTarget(Identifier dimension, double x, double y, double z, float yaw, float pitch) {
+    public static final Codec<LinkBookTarget> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+            Identifier.CODEC.fieldOf("dimension").forGetter(LinkBookTarget::dimension),
+            Codec.DOUBLE.fieldOf("x").forGetter(LinkBookTarget::x),
+            Codec.DOUBLE.fieldOf("y").forGetter(LinkBookTarget::y),
+            Codec.DOUBLE.fieldOf("z").forGetter(LinkBookTarget::z),
+            Codec.FLOAT.fieldOf("yaw").forGetter(LinkBookTarget::yaw),
+            Codec.FLOAT.fieldOf("pitch").forGetter(LinkBookTarget::pitch)
+    ).apply(instance, LinkBookTarget::new));
+    public static final StreamCodec<RegistryFriendlyByteBuf, LinkBookTarget> STREAM_CODEC = StreamCodec.composite(
+            Identifier.STREAM_CODEC, LinkBookTarget::dimension,
+            ByteBufCodecs.DOUBLE, LinkBookTarget::x,
+            ByteBufCodecs.DOUBLE, LinkBookTarget::y,
+            ByteBufCodecs.DOUBLE, LinkBookTarget::z,
+            ByteBufCodecs.FLOAT, LinkBookTarget::yaw,
+            ByteBufCodecs.FLOAT, LinkBookTarget::pitch,
+            LinkBookTarget::new);
+
+    public static LinkBookTarget at(ServerPlayer player) {
+        return new LinkBookTarget(player.level().dimension().identifier(),
+                player.getX(), player.getY(), player.getZ(), player.getYRot(), player.getXRot());
+    }
+
+    public boolean valid() {
+        return Double.isFinite(x) && Double.isFinite(y) && Double.isFinite(z)
+                && Float.isFinite(yaw) && Float.isFinite(pitch)
+                && Math.abs(x) <= 30_000_000 && Math.abs(z) <= 30_000_000;
+    }
+}

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

@@ -0,0 +1,77 @@
+package net.dnorberg.rivencraft.item;
+
+import java.util.Set;
+import java.util.function.Consumer;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.age.AgeCatalogSync;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+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.TooltipFlag;
+import net.minecraft.world.item.component.TooltipDisplay;
+import net.minecraft.world.level.Level;
+
+/** Handheld Linking Book; destination binding and travel are server-authoritative packets. */
+public final class LinkingBookItem extends Item {
+    public LinkingBookItem(Properties properties) {
+        super(properties);
+    }
+
+    @Override
+    public boolean isFoil(ItemStack stack) {
+        return stack.has(Rivencraft.LINK_BOOK_TARGET.get()) || super.isFoil(stack);
+    }
+
+    @Override
+    public InteractionResult use(Level level, Player player, InteractionHand hand) {
+        // Client-side interaction opens the book screen. A direct server-side
+        // item-use packet must never bypass the screen's validated payloads.
+        return InteractionResult.SUCCESS;
+    }
+
+    public static String travel(ServerPlayer player, LinkBookTarget destination) {
+        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())) {
+            return "Same-dimension linking requires an Intra-Linking page";
+        }
+        ServerLevel target = player.level().getServer().getLevel(
+                ResourceKey.create(Registries.DIMENSION, destination.dimension()));
+        if (target == null) return "Destination dimension is unavailable: " + destination.dimension();
+        if (!AgeCatalogSync.ready(player, destination.dimension())) {
+            return "Destination catalog not acknowledged by client";
+        }
+        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";
+        }
+        // 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(
+                destination.x() - player.getX(), destination.y() - player.getY(),
+                destination.z() - player.getZ()))) {
+            return "Linked destination is obstructed";
+        }
+        boolean moved = player.teleportTo(target, destination.x(), destination.y(), destination.z(),
+                Set.of(), destination.yaw(), destination.pitch(), true);
+        return moved ? null : "Teleportation failed";
+    }
+
+    @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() + ")"));
+    }
+}

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

@@ -0,0 +1,43 @@
+package net.dnorberg.rivencraft.item;
+
+import java.util.function.Consumer;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.network.chat.Component;
+import net.minecraft.world.item.Item;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.TooltipFlag;
+import net.minecraft.world.item.component.TooltipDisplay;
+
+/** One Page item with a persistent Link Panel variant; symbol writing is not ported yet. */
+public final class PageItem extends Item {
+    public PageItem(Properties properties) {
+        super(properties);
+    }
+
+    public static ItemStack createLinkPanelPage() {
+        ItemStack stack = new ItemStack(Rivencraft.PAGE.get());
+        stack.set(Rivencraft.LINK_PANEL_PAGE.get(), true);
+        return stack;
+    }
+
+    public static boolean isLinkPanel(ItemStack stack) {
+        return stack.is(Rivencraft.PAGE.get()) && stack.getOrDefault(Rivencraft.LINK_PANEL_PAGE.get(), false);
+    }
+
+    @Override
+    public Component getName(ItemStack stack) {
+        Component customName = stack.get(DataComponents.CUSTOM_NAME);
+        if (customName != null) return customName;
+        return Component.translatable(isLinkPanel(stack)
+                ? "item.rivencraft.page.link_panel" : "item.rivencraft.page.blank");
+    }
+
+    @Override
+    public void appendHoverText(ItemStack stack, TooltipContext context, TooltipDisplay display,
+                                Consumer<Component> tooltip, TooltipFlag flag) {
+        tooltip.accept(Component.translatable(isLinkPanel(stack)
+                ? "item.rivencraft.page.link_panel.port_status"
+                : "item.rivencraft.page.blank.port_status"));
+    }
+}

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

@@ -0,0 +1,22 @@
+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 BindDescriptiveBookPayload(boolean offhand, String title) implements CustomPacketPayload {
+    public static final Type<BindDescriptiveBookPayload> TYPE = new Type<>(
+            Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "bind_descriptive_book"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, BindDescriptiveBookPayload> STREAM_CODEC =
+            StreamCodec.composite(ByteBufCodecs.BOOL, BindDescriptiveBookPayload::offhand,
+                    ByteBufCodecs.stringUtf8(32), BindDescriptiveBookPayload::title,
+                    BindDescriptiveBookPayload::new);
+
+    @Override
+    public Type<BindDescriptiveBookPayload> type() {
+        return TYPE;
+    }
+}

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

@@ -0,0 +1,22 @@
+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 BindLinkingBookPayload(boolean offhand, String title) implements CustomPacketPayload {
+    public static final Type<BindLinkingBookPayload> TYPE = new Type<>(
+            Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "bind_linking_book"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, BindLinkingBookPayload> STREAM_CODEC = StreamCodec.composite(
+            ByteBufCodecs.BOOL, BindLinkingBookPayload::offhand,
+            ByteBufCodecs.stringUtf8(32), BindLinkingBookPayload::title,
+            BindLinkingBookPayload::new);
+
+    @Override
+    public Type<BindLinkingBookPayload> type() {
+        return TYPE;
+    }
+}

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

@@ -0,0 +1,108 @@
+package net.dnorberg.rivencraft.network;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.age.PortAgeTravel;
+import net.dnorberg.rivencraft.age.RuntimeAgeBackend;
+import net.dnorberg.rivencraft.item.LinkBookTarget;
+import net.dnorberg.rivencraft.item.LinkingBookItem;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.network.chat.Component;
+import net.minecraft.resources.Identifier;
+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.item.ItemStack;
+import net.neoforged.neoforge.network.event.RegisterPayloadHandlersEvent;
+import java.util.Locale;
+
+/** Server-authoritative handheld Linking Book binding and travel. */
+public final class PortBookNetworking {
+    public static final int MAX_BOOK_TITLE_LENGTH = 32;
+
+    private PortBookNetworking() {
+    }
+
+    public static void registerPayloads(RegisterPayloadHandlersEvent event) {
+        var registrar = event.registrar("1");
+        registrar.playToServer(BindLinkingBookPayload.TYPE, BindLinkingBookPayload.STREAM_CODEC,
+                (payload, context) -> {
+                    if (context.player() instanceof ServerPlayer player) bind(player, payload);
+                });
+        registrar.playToServer(UseLinkingBookPayload.TYPE, UseLinkingBookPayload.STREAM_CODEC,
+                (payload, context) -> {
+                    if (context.player() instanceof ServerPlayer player) use(player, payload);
+                });
+        registrar.playToServer(BindDescriptiveBookPayload.TYPE, BindDescriptiveBookPayload.STREAM_CODEC,
+                (payload, context) -> {
+                    if (context.player() instanceof ServerPlayer player) bindAge(player, payload);
+                });
+        registrar.playToServer(UseDescriptiveBookPayload.TYPE, UseDescriptiveBookPayload.STREAM_CODEC,
+                (payload, context) -> {
+                    if (context.player() instanceof ServerPlayer player) enterAge(player, payload);
+                });
+    }
+
+    private static void bind(ServerPlayer player, BindLinkingBookPayload payload) {
+        ItemStack stack = player.getItemInHand(hand(payload.offhand()));
+        if (!stack.is(Rivencraft.LINKING_BOOK.get()) || stack.has(Rivencraft.LINK_BOOK_TARGET.get())) return;
+        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(DataComponents.CUSTOM_NAME, Component.literal(title));
+        player.level().playSound(null, player.blockPosition(), SoundEvents.BOOK_PAGE_TURN,
+                SoundSource.PLAYERS, 1.0F, 1.0F);
+        player.sendOverlayMessage(Component.literal("Bound Linking Book: " + title));
+        player.containerMenu.broadcastChanges();
+    }
+
+    private static void use(ServerPlayer player, UseLinkingBookPayload payload) {
+        ItemStack stack = player.getItemInHand(hand(payload.offhand()));
+        if (!stack.is(Rivencraft.LINKING_BOOK.get())) return;
+        String failure = LinkingBookItem.travel(player, stack.get(Rivencraft.LINK_BOOK_TARGET.get()));
+        if (failure != null) player.sendOverlayMessage(Component.literal(failure));
+    }
+
+    private static void bindAge(ServerPlayer player, BindDescriptiveBookPayload payload) {
+        ItemStack stack = player.getItemInHand(hand(payload.offhand()));
+        if (!stack.is(Rivencraft.DESCRIPTIVE_BOOK.get()) || stack.has(Rivencraft.AGE_BOOK_ID.get())) return;
+        String title = payload.title().strip();
+        if (title.isEmpty() || title.length() > MAX_BOOK_TITLE_LENGTH) return;
+        String base = title.toLowerCase(Locale.ROOT).replaceAll("[^a-z0-9._-]+", "_")
+                .replaceAll("^[_\\.-]+|[_\\.-]+$", "");
+        if (base.isEmpty()) base = "age";
+        var server = player.level().getServer();
+        String name = base;
+        int suffix = 2;
+        Identifier id = Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "age/" + name);
+        while (RuntimeAgeBackend.isNameTaken(server, id)) {
+            name = base + "_" + suffix++;
+            id = Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "age/" + name);
+        }
+        try {
+            RuntimeAgeBackend.create(server, id, player.getRandom().nextLong());
+        } catch (IllegalArgumentException | IllegalStateException exception) {
+            player.sendOverlayMessage(Component.literal("Age creation failed: " + exception.getMessage()));
+            return;
+        }
+        stack.set(Rivencraft.AGE_BOOK_ID.get(), id);
+        stack.set(DataComponents.CUSTOM_NAME, Component.literal(title));
+        player.level().playSound(null, player.blockPosition(), SoundEvents.BOOK_PAGE_TURN,
+                SoundSource.PLAYERS, 1.0F, 1.0F);
+        player.sendOverlayMessage(Component.literal("Bound Descriptive Book: " + title));
+        player.containerMenu.broadcastChanges();
+    }
+
+    private static void enterAge(ServerPlayer player, UseDescriptiveBookPayload payload) {
+        ItemStack stack = player.getItemInHand(hand(payload.offhand()));
+        if (!stack.is(Rivencraft.DESCRIPTIVE_BOOK.get())) return;
+        Identifier id = stack.get(Rivencraft.AGE_BOOK_ID.get());
+        if (id == null) return;
+        String failure = PortAgeTravel.enter(player, id);
+        if (failure != null) player.sendOverlayMessage(Component.literal(failure));
+    }
+
+    private static InteractionHand hand(boolean offhand) {
+        return offhand ? InteractionHand.OFF_HAND : InteractionHand.MAIN_HAND;
+    }
+}

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

@@ -0,0 +1,21 @@
+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 UseDescriptiveBookPayload(boolean offhand) implements CustomPacketPayload {
+    public static final Type<UseDescriptiveBookPayload> TYPE = new Type<>(
+            Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "use_descriptive_book"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, UseDescriptiveBookPayload> STREAM_CODEC =
+            StreamCodec.composite(ByteBufCodecs.BOOL, UseDescriptiveBookPayload::offhand,
+                    UseDescriptiveBookPayload::new);
+
+    @Override
+    public Type<UseDescriptiveBookPayload> type() {
+        return TYPE;
+    }
+}

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

@@ -0,0 +1,20 @@
+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 UseLinkingBookPayload(boolean offhand) implements CustomPacketPayload {
+    public static final Type<UseLinkingBookPayload> TYPE = new Type<>(
+            Identifier.fromNamespaceAndPath(Rivencraft.MOD_ID, "use_linking_book"));
+    public static final StreamCodec<RegistryFriendlyByteBuf, UseLinkingBookPayload> STREAM_CODEC = StreamCodec.composite(
+            ByteBufCodecs.BOOL, UseLinkingBookPayload::offhand, UseLinkingBookPayload::new);
+
+    @Override
+    public Type<UseLinkingBookPayload> type() {
+        return TYPE;
+    }
+}

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

@@ -0,0 +1,46 @@
+package net.dnorberg.rivencraft.registry;
+
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.item.PageItem;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.network.chat.Component;
+import net.minecraft.world.item.CreativeModeTab;
+import net.neoforged.bus.api.IEventBus;
+import net.neoforged.neoforge.registries.DeferredRegister;
+
+/** Only items already ported to 26.3 appear here. */
+public final class ModCreativeTabs {
+    private static final DeferredRegister<CreativeModeTab> TABS =
+            DeferredRegister.create(Registries.CREATIVE_MODE_TAB, Rivencraft.MOD_ID);
+
+    static {
+        TABS.register("rivencraft", () -> CreativeModeTab.builder()
+                .title(Component.translatable("itemGroup.rivencraft"))
+                .icon(() -> Rivencraft.DESCRIPTIVE_BOOK.get().getDefaultInstance())
+                .displayItems((parameters, output) -> {
+                    output.accept(Rivencraft.DESCRIPTIVE_BOOK.get());
+                    output.accept(Rivencraft.LINKING_BOOK.get());
+                    output.accept(Rivencraft.CRYSTAL_BLOCK_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());
+                    output.accept(Rivencraft.LARGE_CRYSTAL_BUD_ITEM.get());
+                    output.accept(Rivencraft.CRYSTAL_CLUSTER_ITEM.get());
+                    output.accept(Rivencraft.CRYSTAL_SHARD.get());
+                    output.accept(Rivencraft.INK_VIAL.get());
+                })
+                .build());
+        TABS.register("rivencraft_link_pages", () -> CreativeModeTab.builder()
+                .title(Component.translatable("itemGroup.rivencraft.pages.link"))
+                .icon(PageItem::createLinkPanelPage)
+                .displayItems((parameters, output) -> output.accept(PageItem.createLinkPanelPage()))
+                .build());
+    }
+
+    private ModCreativeTabs() {
+    }
+
+    public static void register(IEventBus modEventBus) {
+        TABS.register(modEventBus);
+    }
+}

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

@@ -0,0 +1,63 @@
+package net.dnorberg.rivencraft.writing;
+
+import com.mojang.serialization.MapCodec;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.item.PageItem;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+import net.minecraft.world.item.crafting.CraftingInput;
+import net.minecraft.world.item.crafting.CustomRecipe;
+import net.minecraft.world.item.crafting.RecipeSerializer;
+import net.minecraft.world.level.Level;
+
+/** Legacy's shapeless leather + Link Panel recipe; never accepts a blank Page. */
+public final class LinkingBookRecipe extends CustomRecipe {
+    private static final LinkingBookRecipe INSTANCE = new LinkingBookRecipe();
+    public static final MapCodec<LinkingBookRecipe> MAP_CODEC = MapCodec.unit(INSTANCE);
+    public static final StreamCodec<RegistryFriendlyByteBuf, LinkingBookRecipe> STREAM_CODEC = StreamCodec.unit(INSTANCE);
+    public static final RecipeSerializer<LinkingBookRecipe> SERIALIZER = new RecipeSerializer<>(MAP_CODEC, STREAM_CODEC);
+
+    private LinkingBookRecipe() {
+    }
+
+    private static ItemStack findPanel(CraftingInput input) {
+        if (input.ingredientCount() != 2) return ItemStack.EMPTY;
+        ItemStack panel = ItemStack.EMPTY;
+        boolean leather = false;
+        for (ItemStack stack : input.items()) {
+            if (stack.isEmpty()) continue;
+            if (PageItem.isLinkPanel(stack) && panel.isEmpty()) {
+                panel = stack;
+            } else if (stack.is(Items.LEATHER) && !leather) {
+                leather = true;
+            } else {
+                return ItemStack.EMPTY;
+            }
+        }
+        return leather ? panel : ItemStack.EMPTY;
+    }
+
+    @Override
+    public boolean matches(CraftingInput input, Level level) {
+        return !findPanel(input).isEmpty();
+    }
+
+    @Override
+    public ItemStack assemble(CraftingInput input) {
+        ItemStack panel = findPanel(input);
+        if (panel.isEmpty()) return ItemStack.EMPTY;
+        ItemStack book = new ItemStack(Rivencraft.LINKING_BOOK.get());
+        if (panel.has(DataComponents.CUSTOM_NAME)) {
+            book.set(DataComponents.CUSTOM_NAME, panel.get(DataComponents.CUSTOM_NAME));
+        }
+        return book;
+    }
+
+    @Override
+    public RecipeSerializer<LinkingBookRecipe> getSerializer() {
+        return SERIALIZER;
+    }
+}

ports/mc263/src/main/resources/META-INF/accesstransformer.cfg

@@ -0,0 +1,8 @@
+# The 26.3 server has no public runtime-Level insertion API. Keep the
+# access surface restricted to the three fields used by RuntimeAgeBackend.
+public net.minecraft.server.MinecraftServer levels
+public net.minecraft.server.MinecraftServer storageSource
+public net.minecraft.server.MinecraftServer executor
+# Minecraft 26.3 may expose an immutable level catalog. Replace the field
+# atomically when the server announces new runtime Ages instead of mutating it.
+public net.minecraft.client.multiplayer.ClientPacketListener levels

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

@@ -0,0 +1,15 @@
+{
+  "model": {
+    "type": "minecraft:condition",
+    "property": "minecraft:has_component",
+    "component": "rivencraft:link_book_target",
+    "on_true": {
+      "type": "minecraft:model",
+      "model": "rivencraft:item/linking_book_bound"
+    },
+    "on_false": {
+      "type": "minecraft:model",
+      "model": "rivencraft:item/linking_book_unwritten"
+    }
+  }
+}

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

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

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

@@ -0,0 +1,9 @@
+{
+  "model": {
+    "type": "minecraft:condition",
+    "property": "minecraft:has_component",
+    "component": "rivencraft:link_panel_page",
+    "on_true": {"type": "minecraft:model", "model": "rivencraft:item/page_link_panel"},
+    "on_false": {"type": "minecraft:model", "model": "rivencraft:item/page"}
+  }
+}

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

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

ports/mc263/src/main/resources/assets/rivencraft/lang/en_us.json

@@ -0,0 +1,21 @@
+{
+  "item.rivencraft.crystal_shard": "Crystal Shard",
+  "item.rivencraft.descriptive_book": "Descriptive Book",
+  "item.rivencraft.linking_book": "Linking Book",
+  "item.rivencraft.page": "Page",
+  "item.rivencraft.page.blank": "Blank Page",
+  "item.rivencraft.page.link_panel": "Link Panel Page",
+  "item.rivencraft.ink_vial": "Ink Vial",
+  "item.rivencraft.ink_vial.remaining": "Ink: %s/%s",
+  "item.rivencraft.ink_vial.usage": "Use with paper in the other hand to prepare a Link Panel.",
+  "item.rivencraft.page.blank.port_status": "Base for future symbol writing; not yet usable in this port.",
+  "item.rivencraft.page.link_panel.port_status": "Prepared for book binding; the Book Binder is not yet ported.",
+  "block.rivencraft.crystal_block": "Crystal Block",
+  "block.rivencraft.budding_crystal": "Budding Crystal",
+  "block.rivencraft.small_crystal_bud": "Small Crystal Bud",
+  "block.rivencraft.medium_crystal_bud": "Medium Crystal Bud",
+  "block.rivencraft.large_crystal_bud": "Large Crystal Bud",
+  "block.rivencraft.crystal_cluster": "Crystal Cluster",
+  "itemGroup.rivencraft": "Rivencraft",
+  "itemGroup.rivencraft.pages.link": "Rivencraft Link Pages"
+}

ports/mc263/src/main/resources/assets/rivencraft/models/item/linking_book_unwritten.json

@@ -0,0 +1,6 @@
+{
+  "parent": "minecraft:item/generated",
+  "textures": {
+    "layer0": "rivencraft:item/linking_book_unwritten"
+  }
+}

ports/mc263/src/main/resources/assets/rivencraft/models/item/page.json

@@ -0,0 +1 @@
+{"parent":"minecraft:item/generated","textures":{"layer0":"rivencraft:item/page"}}

ports/mc263/src/main/resources/data/rivencraft/loot_table/blocks/budding_crystal.json

@@ -0,0 +1 @@
+{"type":"minecraft:block","random_sequence":"rivencraft:blocks/budding_crystal"}

ports/mc263/src/main/resources/data/rivencraft/loot_table/blocks/crystal_cluster.json

@@ -0,0 +1,23 @@
+{
+  "type": "minecraft:block",
+  "pools": [{
+    "entries": [{
+      "type": "minecraft:alternatives",
+      "children": [
+        {"type": "minecraft:item", "condition": "minecraft:tool/can_silk_touch", "name": "rivencraft:crystal_cluster"},
+        {"type": "minecraft:alternatives", "children": [
+          {"type": "minecraft:item", "condition": {"type": "minecraft:match_tool", "predicate": {"items": "#minecraft:cluster_max_harvestables"}}, "modifier": [
+            {"type": "minecraft:set_count", "count": 4},
+            {"type": "minecraft:apply_bonus", "enchantment": "minecraft:fortune", "formula": "minecraft:ore_drops"}
+          ], "name": "rivencraft:crystal_shard"},
+          {"type": "minecraft:item", "modifier": [
+            {"type": "minecraft:set_count", "count": 2},
+            {"type": "minecraft:explosion_decay"}
+          ], "name": "rivencraft:crystal_shard"}
+        ]}
+      ]
+    }],
+    "rolls": 1
+  }],
+  "random_sequence": "rivencraft:blocks/crystal_cluster"
+}

ports/mc263/src/main/resources/data/rivencraft/loot_table/blocks/large_crystal_bud.json

@@ -0,0 +1 @@
+{"type":"minecraft:block","pools":[{"condition":"minecraft:tool/can_silk_touch","entries":[{"type":"minecraft:item","name":"rivencraft:large_crystal_bud"}],"rolls":1}],"random_sequence":"rivencraft:blocks/large_crystal_bud"}

ports/mc263/src/main/resources/data/rivencraft/loot_table/blocks/medium_crystal_bud.json

@@ -0,0 +1 @@
+{"type":"minecraft:block","pools":[{"condition":"minecraft:tool/can_silk_touch","entries":[{"type":"minecraft:item","name":"rivencraft:medium_crystal_bud"}],"rolls":1}],"random_sequence":"rivencraft:blocks/medium_crystal_bud"}

ports/mc263/src/main/resources/data/rivencraft/loot_table/blocks/small_crystal_bud.json

@@ -0,0 +1 @@
+{"type":"minecraft:block","pools":[{"condition":"minecraft:tool/can_silk_touch","entries":[{"type":"minecraft:item","name":"rivencraft:small_crystal_bud"}],"rolls":1}],"random_sequence":"rivencraft:blocks/small_crystal_bud"}

ports/mc263/src/main/resources/data/rivencraft/recipe/crystal_block.json

@@ -0,0 +1,12 @@
+{
+  "type": "minecraft:crafting_shaped",
+  "category": "misc",
+  "pattern": ["SS", "SS"],
+  "key": {
+    "S": "rivencraft:crystal_shard"
+  },
+  "result": {
+    "id": "rivencraft:crystal_block",
+    "count": 1
+  }
+}

ports/mc263/src/main/resources/data/rivencraft/recipe/ink_vial.json

@@ -0,0 +1,11 @@
+{
+  "type": "minecraft:crafting_shapeless",
+  "category": "misc",
+  "ingredients": [
+    "minecraft:black_dye",
+    "minecraft:black_dye",
+    "minecraft:glass_bottle",
+    "minecraft:water_bucket"
+  ],
+  "result": {"id": "rivencraft:ink_vial", "count": 1}
+}

ports/mc263/src/main/resources/data/rivencraft/recipe/linking_book.json

@@ -0,0 +1 @@
+{"type":"rivencraft:linking_book"}

ports/mc263/src/main/templates/META-INF/neoforge.mods.toml

@@ -0,0 +1,28 @@
+license="${mod_license}"
+issueTrackerURL="https://git.paddedcell.org/dnorberg/rivencraft/issues"
+
+[[mods]]
+modId="${mod_id}"
+version="${mod_version}"
+displayName="${mod_name} 26.3 Alpha"
+displayURL="https://git.paddedcell.org/dnorberg/rivencraft"
+authors="dnorberg and contributors"
+description='''
+Experimental Minecraft 26.3 alpha. Provides a runtime Age prototype and basic
+Linking Book travel. Most Rivencraft gameplay has not yet been ported. Use a
+test world and keep backups; this alpha is not compatible with 1.21.1 worlds.
+'''
+
+[[dependencies.${mod_id}]]
+modId="neoforge"
+type="required"
+versionRange="[${neo_version},)"
+ordering="NONE"
+side="BOTH"
+
+[[dependencies.${mod_id}]]
+modId="minecraft"
+type="required"
+versionRange="${minecraft_version_range}"
+ordering="NONE"
+side="BOTH"

scripts/smoke_server_263.sh

@@ -0,0 +1,103 @@
+#!/usr/bin/env bash
+# Disposable, headless smoke check for the incomplete 26.3 runtime Age backend.
+set -euo pipefail
+
+repo_dir=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+smoke_dir=$(mktemp -d "${TMPDIR:-/tmp}/rivencraft-263-smoke.XXXXXX")
+server_dir="$smoke_dir/server"
+server_pid=
+input_fd=
+
+cleanup() {
+    if [[ -n "$server_pid" ]] && kill -0 "$server_pid" 2>/dev/null; then
+        if [[ -n "$input_fd" ]]; then printf 'stop\n' >&"$input_fd" || true; fi
+        wait "$server_pid" 2>/dev/null || true
+    fi
+    if [[ -n "$input_fd" ]]; then exec {input_fd}>&-; fi
+    rm -rf -- "$smoke_dir"
+}
+trap cleanup EXIT
+
+mkdir -p "$server_dir"
+printf 'eula=true\n' > "$server_dir/eula.txt"
+printf 'server-port=0\nonline-mode=false\nwhite-list=false\n' > "$server_dir/server.properties"
+
+wait_for_log() {
+    local log_file=$1 pattern=$2 seconds=$3
+    local tries=$((seconds * 4))
+    for ((i = 0; i < tries; i++)); do
+        if grep -Fq -- "$pattern" "$log_file" 2>/dev/null; then return 0; fi
+        if ! kill -0 "$server_pid" 2>/dev/null; then
+            printf 'Server exited before: %s\n' "$pattern" >&2
+            tail -80 "$log_file" >&2
+            return 1
+        fi
+        sleep 0.25
+    done
+    printf 'Timed out waiting for: %s\n' "$pattern" >&2
+    tail -80 "$log_file" >&2
+    return 1
+}
+
+start_server() {
+    local phase=$1
+    log_file="$smoke_dir/$phase.log"
+    fifo="$smoke_dir/$phase.stdin"
+    mkfifo "$fifo"
+    exec {input_fd}<>"$fifo"
+    "$repo_dir/gradlew" -p "$repo_dir/ports/mc263" runServer \
+        -PserverRunDir="$server_dir" --no-daemon < "$fifo" > "$log_file" 2>&1 &
+    server_pid=$!
+    wait_for_log "$log_file" 'Done (' 120
+}
+
+stop_server() {
+    printf 'stop\n' >&"$input_fd"
+    wait "$server_pid"
+    server_pid=
+    exec {input_fd}>&-
+    rm -- "$fifo"
+}
+
+send_and_wait() {
+    local command=$1 result=$2
+    printf '%s\n' "$command" >&"$input_fd"
+    wait_for_log "$log_file" "$result" 60
+}
+
+start_server first
+send_and_wait 'rivencraft_port compat' 'Registered biomes by namespace:'
+send_and_wait 'rivencraft_port age create smoke_alpha 123456789' 'Created rivencraft:age/smoke_alpha with seed 123456789'
+send_and_wait 'rivencraft_port age create smoke_beta 987654321' 'Created rivencraft:age/smoke_beta with seed 987654321'
+# The index must reach disk while the server is still running. A graceful
+# shutdown would hide the interrupted-save regression this checks.
+index_file="$server_dir/world/dimensions/minecraft/overworld/data/rivencraft/runtime_ages.dat"
+[[ -s "$index_file" ]] || {
+    printf 'Age index was not persisted before shutdown: %s\n' "$index_file" >&2
+    exit 1
+}
+gzip -dc "$index_file" | strings | grep -Fq 'rivencraft:age/smoke_alpha'
+gzip -dc "$index_file" | strings | grep -Fq 'rivencraft:age/smoke_beta'
+send_and_wait 'rivencraft_port age sample smoke_alpha' 'rivencraft:age/smoke_alpha seed=123456789 chunkOffset=0 terrain='
+send_and_wait 'rivencraft_port age sample smoke_beta' 'rivencraft:age/smoke_beta seed=987654321 chunkOffset=0 terrain='
+alpha_before=$(grep -F 'rivencraft:age/smoke_alpha seed=123456789 chunkOffset=0 terrain=' "$log_file" | tail -1 | sed 's/.*terrain=//')
+beta_before=$(grep -F 'rivencraft:age/smoke_beta seed=987654321 chunkOffset=0 terrain=' "$log_file" | tail -1 | sed 's/.*terrain=//')
+if [[ "$alpha_before" == "$beta_before" ]]; then
+    printf 'Different Age seeds produced the same terrain probe: %s\n' "$alpha_before" >&2
+    exit 1
+fi
+stop_server
+
+start_server restart
+send_and_wait 'rivencraft_port age list' 'smoke_alpha'
+send_and_wait 'rivencraft_port age sample smoke_alpha' 'rivencraft:age/smoke_alpha seed=123456789 chunkOffset=0 terrain='
+send_and_wait 'rivencraft_port age sample smoke_beta' 'rivencraft:age/smoke_beta seed=987654321 chunkOffset=0 terrain='
+alpha_after=$(grep -F 'rivencraft:age/smoke_alpha seed=123456789 chunkOffset=0 terrain=' "$log_file" | tail -1 | sed 's/.*terrain=//')
+beta_after=$(grep -F 'rivencraft:age/smoke_beta seed=987654321 chunkOffset=0 terrain=' "$log_file" | tail -1 | sed 's/.*terrain=//')
+[[ "$alpha_before" == "$alpha_after" && "$beta_before" == "$beta_after" ]] || {
+    printf 'Age terrain changed across restart: %s/%s -> %s/%s\n' \
+        "$alpha_before" "$beta_before" "$alpha_after" "$beta_after" >&2
+    exit 1
+}
+stop_server
+printf '26.3 dedicated-server smoke passed: two distinct Ages persisted across restart.\n'

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

@@ -20,6 +20,7 @@ import net.dnorberg.rivencraft.network.ModNetworking;
 import net.dnorberg.rivencraft.config.RivencraftConfig;
 import net.dnorberg.rivencraft.config.RivencraftClientConfig;
 import net.dnorberg.rivencraft.compat.SereneSeasonsCompatibility;
+import net.dnorberg.rivencraft.compat.RuinsCompatibility;
 import net.dnorberg.rivencraft.book.AgeDimensionService;
 import net.dnorberg.rivencraft.book.AgeWeatherService;
 import net.dnorberg.rivencraft.book.AgeInstabilityRuntime;
@@ -43,6 +44,7 @@ public final class Rivencraft {
 
     public Rivencraft(IEventBus modEventBus, ModContainer modContainer) {
         AgeDimensionService.register();
+        RuinsCompatibility.register();
         AgeStatusEffectProviders.register();
         AgeDecayProviders.register();
         AgeHazardProviders.register();
@@ -82,6 +84,8 @@ public final class Rivencraft {
         NeoForge.EVENT_BUS.addListener(AgeInstabilityRuntime::onServerStopping);
         NeoForge.EVENT_BUS.addListener(AgeEnvironmentalProviders::onServerStopping);
         NeoForge.EVENT_BUS.addListener(AgeStatusEffectProviders::onServerStopping);
+        NeoForge.EVENT_BUS.addListener((net.neoforged.neoforge.event.server.ServerStoppingEvent event) ->
+                RuinsCompatibility.onServerStopping());
         NeoForge.EVENT_BUS.addListener(RivencraftCommands::register);
         NeoForge.EVENT_BUS.addListener(LibraryLocateService::onServerTickPost);
         NeoForge.EVENT_BUS.addListener(LibraryLocateService::onServerStopping);

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

@@ -36,6 +36,7 @@ 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.DirectionProperty;
+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;
@@ -44,10 +45,11 @@ import net.minecraft.world.phys.shapes.VoxelShape;
 public final class BookReceptacleBlock extends BaseEntityBlock {
     public static final MapCodec<BookReceptacleBlock> CODEC = simpleCodec(BookReceptacleBlock::new);
     public static final DirectionProperty 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));
+        registerDefaultState(stateDefinition.any().setValue(FACING, Direction.NORTH).setValue(HAS_BOOK, false));
     }
 
     @Override protected MapCodec<? extends BaseEntityBlock> codec() { return CODEC; }
@@ -64,7 +66,7 @@ public final class BookReceptacleBlock extends BaseEntityBlock {
         };
     }
     @Override protected void createBlockStateDefinition(StateDefinition.Builder<Block, BlockState> builder) {
-        builder.add(FACING);
+        builder.add(FACING, HAS_BOOK);
     }
     @Override public BlockEntity newBlockEntity(BlockPos pos, BlockState state) {
         return new BookReceptacleBlockEntity(pos, state);
@@ -153,7 +155,7 @@ public final class BookReceptacleBlock extends BaseEntityBlock {
         if (!state.is(replacement.getBlock()) && level instanceof ServerLevel server) {
             CrystalPortalNetwork.shutdown(server, pos);
             if (level.getBlockEntity(pos) instanceof BookReceptacleBlockEntity holder) {
-                ItemStack book = holder.takeBook();
+                ItemStack book = holder.takeBookOnBreak();
                 if (!book.isEmpty()) level.addFreshEntity(new ItemEntity(level, pos.getX()+0.5, pos.getY()+0.5,
                         pos.getZ()+0.5, book));
             }

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

@@ -2,7 +2,9 @@ package net.dnorberg.rivencraft.block.entity;
 
 import net.dnorberg.rivencraft.book.LinkTarget;
 import net.dnorberg.rivencraft.book.AgeEnvironmentCompiler;
+import net.dnorberg.rivencraft.block.BookReceptacleBlock;
 import net.dnorberg.rivencraft.registry.ModBlockEntities;
+import net.dnorberg.rivencraft.registry.ModBlocks;
 import net.dnorberg.rivencraft.portal.CrystalPortalNetwork;
 import net.minecraft.nbt.NbtOps;
 import net.minecraft.core.BlockPos;
@@ -52,18 +54,36 @@ public final class BookReceptacleBlockEntity extends BlockEntity {
     }
 
     public ItemStack takeBook() {
+        return removeBook(true);
+    }
+
+    /** The block is already being replaced, so do not write its state back into the world. */
+    public ItemStack takeBookOnBreak() {
+        return removeBook(false);
+    }
+
+    private ItemStack removeBook(boolean notify) {
         ItemStack result = book;
         book = ItemStack.EMPTY;
         destination = null;
         skyColor = 0xFFFFFF;
-        sync();
+        if (notify) sync();
+        else setChanged();
         return result;
     }
 
     private void sync() {
         setChanged();
-        if (level != null && !level.isClientSide)
-            level.sendBlockUpdated(worldPosition, getBlockState(), getBlockState(), 2);
+        if (level instanceof ServerLevel server) {
+            BlockState state = server.getBlockState(worldPosition);
+            if (!state.is(ModBlocks.BOOK_RECEPTACLE.get())) return;
+            boolean hasBook = !book.isEmpty();
+            if (state.getValue(BookReceptacleBlock.HAS_BOOK) != hasBook) {
+                state = state.setValue(BookReceptacleBlock.HAS_BOOK, hasBook);
+                server.setBlock(worldPosition, state, 2);
+            }
+            server.sendBlockUpdated(worldPosition, state, state, 2);
+        }
     }
 
     @Override
@@ -98,6 +118,10 @@ public final class BookReceptacleBlockEntity extends BlockEntity {
     public static void serverTick(net.minecraft.world.level.Level world, BlockPos pos, BlockState state,
                                   BookReceptacleBlockEntity holder) {
         if (!(world instanceof ServerLevel level)) return;
+        // Reconcile receptacles saved before HAS_BOOK existed, including an
+        // occupied receptacle restored from an older pre-release world.
+        boolean hasBook = !holder.book.isEmpty();
+        if (state.getValue(BookReceptacleBlock.HAS_BOOK) != hasBook) holder.sync();
         if (holder.book.isEmpty() || (!holder.restoreView && level.getGameTime() % 200 != 0)) return;
         // Startup maintenance must never turn a saved portal off while its
         // chunks and block entities are still arriving. Structural edits are

src/main/java/net/dnorberg/rivencraft/book/AgeBiomeSelection.java

@@ -8,6 +8,7 @@ import java.util.Random;
 import java.util.Set;
 import net.dnorberg.rivencraft.Rivencraft;
 import net.dnorberg.rivencraft.compat.TerraBlenderBiomes;
+import net.dnorberg.rivencraft.writing.BiomeSymbolPages;
 import net.dnorberg.rivencraft.writing.SymbolSemantics;
 import net.dnorberg.rivencraft.writing.WritingGrammar;
 import net.minecraft.core.Holder;
@@ -34,6 +35,12 @@ public record AgeBiomeSelection(AgeTraits.BiomeDistribution distribution, List<R
 
     public static AgeBiomeSelection compile(WritingGrammar.Result writing, AgeTraits traits,
                                              AgeRuntimeProfile profile, long seed, RegistryAccess registries) {
+        return compile(writing, traits, profile, seed, registries, RandomPagePolicy.UNRESTRICTED);
+    }
+
+    public static AgeBiomeSelection compile(WritingGrammar.Result writing, AgeTraits traits,
+                                             AgeRuntimeProfile profile, long seed, RegistryAccess registries,
+                                             RandomPagePolicy policy) {
         List<ResourceLocation> authored = writing.symbols().stream()
                 .filter(symbol -> symbol.semantics().role() == SymbolSemantics.Role.BIOME)
                 .map(symbol -> ((SymbolSemantics.ResourceValue) symbol.semantics().value()).id()).toList();
@@ -67,10 +74,26 @@ public record AgeBiomeSelection(AgeTraits.BiomeDistribution distribution, List<R
                         + " or a TerraBlender Nether region");
             }
         }
-        List<ResourceLocation> availableBiomes = eligible(registries, profile);
-        if (availableBiomes.isEmpty()) throw new IllegalArgumentException("No eligible biomes for terrain " + profile.noiseSettings());
+        List<ResourceLocation> terrainBiomes = eligible(registries, profile);
+        if (terrainBiomes.isEmpty()) throw new IllegalArgumentException("No eligible biomes for terrain " + profile.noiseSettings());
+        List<ResourceLocation> availableBiomes = distribution == AgeTraits.BiomeDistribution.NATIVE
+                ? terrainBiomes : new ArrayList<>(policy.eligible(terrainBiomes, BiomeSymbolPages::symbolId));
+        if (distribution != AgeTraits.BiomeDistribution.NATIVE
+                && new LinkedHashSet<>(availableBiomes).size() < minimum(distribution)) {
+            ResourceLocation preferred = profile.terrain() == AgeRuntimeProfile.Terrain.VOID
+                    ? ResourceLocation.withDefaultNamespace("the_void")
+                    : cave ? ResourceLocation.withDefaultNamespace("deep_dark")
+                    : ResourceLocation.withDefaultNamespace("plains");
+            if (terrainBiomes.contains(preferred) && !availableBiomes.contains(preferred))
+                availableBiomes.add(preferred);
+            for (ResourceLocation fallback : terrainBiomes) {
+                if (new LinkedHashSet<>(availableBiomes).size() >= minimum(distribution)) break;
+                if (!availableBiomes.contains(fallback)) availableBiomes.add(fallback);
+            }
+        }
         if (distribution == AgeTraits.BiomeDistribution.NATIVE) {
             if (!authored.isEmpty()) throw new IllegalArgumentException("Native biome distribution cannot use biome pages");
+            // Native noise biomes are supplied by Minecraft's preset, not chosen as Pages.
             return new AgeBiomeSelection(distribution, profile.terrain() == AgeRuntimeProfile.Terrain.FLAT
                     ? List.of(ResourceLocation.withDefaultNamespace("plains"))
                     : isCave(profile) ? availableBiomes : presetBiomes(registries, profile));

src/main/java/net/dnorberg/rivencraft/book/AgeDefinition.java

@@ -23,7 +23,8 @@ public record AgeDefinition(
         @Nullable AgeSeasonMode seasonMode,
         List<AgeFeatureSelection.Choice> randomFeatures,
         AgeInstability instability,
-        AgeInstabilityPlan instabilityPlan
+        AgeInstabilityPlan instabilityPlan,
+        RandomPagePolicy randomPagePolicy
 ) {
     public static final ResourceLocation RANDOM_VANILLA_PROFILE = ResourceLocation.fromNamespaceAndPath(
             Rivencraft.MOD_ID, "random_vanilla"
@@ -39,6 +40,7 @@ public record AgeDefinition(
         Objects.requireNonNull(traits, "traits");
         Objects.requireNonNull(instability, "instability");
         Objects.requireNonNull(instabilityPlan, "instabilityPlan");
+        Objects.requireNonNull(randomPagePolicy, "randomPagePolicy");
         randomFeatures = List.copyOf(randomFeatures);
         if (plan != null && !randomFeatures.isEmpty()) {
             throw new IllegalArgumentException("Authored Ages cannot also have random features");
@@ -88,6 +90,16 @@ public record AgeDefinition(
                 AgeInstabilityPlan.empty());
     }
 
+    public AgeDefinition(UUID id, String name, long seed, ResourceLocation generationProfile,
+                         int generationVersion, long createdGameTime, ResourceLocation dimensionId,
+                         BlockPos spawn, AgeTraits traits, AgeGenerationPlan plan,
+                         @Nullable AgeSeasonMode seasonMode, List<AgeFeatureSelection.Choice> randomFeatures,
+                         AgeInstability instability, AgeInstabilityPlan instabilityPlan) {
+        this(id, name, seed, generationProfile, generationVersion, createdGameTime,
+                dimensionId, spawn, traits, plan, seasonMode, randomFeatures, instability,
+                instabilityPlan, RandomPagePolicy.UNRESTRICTED);
+    }
+
     public static ResourceLocation dimensionId(UUID ageId) {
         return ResourceLocation.fromNamespaceAndPath(Rivencraft.MOD_ID, "age/" + ageId);
     }
@@ -117,7 +129,7 @@ public record AgeDefinition(
     public AgeDefinition withSpawn(BlockPos spawn) {
         return new AgeDefinition(id, name, seed, generationProfile, generationVersion,
                 createdGameTime, dimensionId, spawn.immutable(), traits, plan, seasonMode,
-                randomFeatures, instability, instabilityPlan);
+                randomFeatures, instability, instabilityPlan, randomPagePolicy);
     }
 
     /** A frozen authored profile takes precedence over the profile ID on old books. */

src/main/java/net/dnorberg/rivencraft/book/AgeDimensionService.java

@@ -16,6 +16,7 @@ import net.dnorberg.rivencraft.Rivencraft;
 import net.dnorberg.rivencraft.registry.ModBlocks;
 import net.dnorberg.rivencraft.compat.ImmersivePortalsChunkLoaders;
 import net.dnorberg.rivencraft.compat.SereneSeasonsCompatibility;
+import net.dnorberg.rivencraft.compat.RuinsCompatibility;
 import net.dnorberg.rivencraft.compat.TerraBlenderBiomes;
 import net.dnorberg.rivencraft.writing.BiomeSymbolPages;
 import net.dnorberg.rivencraft.writing.BlockSymbolPages;
@@ -84,6 +85,7 @@ public final class AgeDimensionService {
                 if (level != null) {
                     applyCelestialClock(level, age);
                     SereneSeasonsCompatibility.registerAge(server, age);
+                    RuinsCompatibility.registerAge(age);
                 }
             }
             synchronizeImmersivePortals(server);
@@ -141,6 +143,7 @@ public final class AgeDimensionService {
         if (existing != null) {
             applyCelestialClock(existing, definition);
             SereneSeasonsCompatibility.registerAge(server, definition);
+            RuinsCompatibility.registerAge(definition);
             return existing;
         }
 
@@ -157,6 +160,7 @@ public final class AgeDimensionService {
         } else {
             applyCelestialClock(loaded, definition);
             SereneSeasonsCompatibility.registerAge(server, definition);
+            RuinsCompatibility.registerAge(definition);
             synchronizeImmersivePortals(server);
         }
         return loaded;
@@ -461,7 +465,7 @@ public final class AgeDimensionService {
         AgeBiomeSelection selection = age.plan() != null && age.plan().biomeSelection() != null
                 ? age.plan().biomeSelection()
                 : AgeBiomeSelection.compile(net.dnorberg.rivencraft.writing.WritingGrammar.parse(OrderedWriting.EMPTY),
-                        age.traits(), profile, age.seed(), server.registryAccess());
+                        age.traits(), profile, age.seed(), server.registryAccess(), age.randomPagePolicy());
         var registry = server.registryAccess().lookupOrThrow(Registries.BIOME);
         List<Holder<Biome>> biomes = new ArrayList<>();
         List<ResourceLocation> fallbacks = AgeBiomeSelection.eligible(server.registryAccess(), profile);

src/main/java/net/dnorberg/rivencraft/book/AgeEnvironmentCompiler.java

@@ -108,11 +108,7 @@ public final class AgeEnvironmentCompiler {
 
     /** An authored color is fixed; -1 means the biome or selected vanilla sky supplies it. */
     public static int skyColor(AgeGenerationPlan plan) {
-        if (plan == null) return -1;
-        return AgeSkyProfile.mixColors(plan.activeSymbols().stream()
-                .filter(symbol -> symbol.semantics().role() == SymbolSemantics.Role.SKY_COLOR)
-                .map(symbol -> ((SymbolSemantics.ChoiceValue) symbol.semantics().value()).id())
-                .map(AgeSkyProfile::color).toList());
+        return AgeSkyProfile.authoredSkyColor(plan);
     }
 
     public static int selectedSkyColor(AgeGenerationPlan plan, ResourceLocation fallback, int biomeSkyColor) {
@@ -159,15 +155,19 @@ public final class AgeEnvironmentCompiler {
         Double pendingPeriod = null;
         Float pendingPhase = null;
         boolean writtenPhase = false;
+        Double pendingNumber = null;
         for (AgeGenerationPlan.ResolvedSymbol symbol : plan.symbols()) {
             SymbolSemantics semantics = symbol.semantics();
+            Double number = pendingNumber;
+            if (semantics.role() != SymbolSemantics.Role.COLOR_NUMBER) pendingNumber = null;
             switch (semantics.role()) {
+                case COLOR_NUMBER -> pendingNumber = ((SymbolSemantics.NumberValue) semantics.value()).amount();
                 case PERIOD_MODIFIER -> {
-                    double next = ((SymbolSemantics.NumberValue) semantics.value()).amount();
+                    double next = CelestialPageValues.value(semantics, number);
                     pendingPeriod = pendingPeriod == null ? next : (pendingPeriod + next) / 2.0D;
                 }
                 case PHASE_MODIFIER -> {
-                    float next = (float) ((SymbolSemantics.NumberValue) semantics.value()).amount();
+                    float next = (float) CelestialPageValues.value(semantics, number);
                     pendingPhase = pendingPhase == null ? next : circularMidpoint(pendingPhase, next);
                 }
                 case CELESTIAL -> {

src/main/java/net/dnorberg/rivencraft/book/AgeFeatureSelection.java

@@ -10,6 +10,7 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.Random;
 import net.dnorberg.rivencraft.writing.BlockSymbolPages;
+import net.dnorberg.rivencraft.compat.RuinsTemplatePages;
 import net.dnorberg.rivencraft.writing.OrderedWriting;
 import net.dnorberg.rivencraft.writing.SymbolSemantics;
 import net.dnorberg.rivencraft.writing.WritingGrammar;
@@ -157,12 +158,19 @@ public final class AgeFeatureSelection {
 
     /** Page-free Ages roll up to two material features, plus rare Skylands, once at creation. */
     public static List<Choice> randomChoices(long ageSeed, AgeRuntimeProfile profile, RegistryAccess registries) {
+        return randomChoices(ageSeed, profile, registries, RandomPagePolicy.UNRESTRICTED);
+    }
+
+    public static List<Choice> randomChoices(long ageSeed, AgeRuntimeProfile profile, RegistryAccess registries,
+                                             RandomPagePolicy policy) {
         Random random = new Random(ageSeed ^ 0x4D4154455249414CL);
         int count = random.nextInt(3);
         List<LegacyRankChoice.Option<ResourceLocation>> features = new ArrayList<>();
-        for (ResourceLocation id : BLOCK_FEATURES) if (error(id, profile, registries) == null)
+        for (ResourceLocation id : BLOCK_FEATURES) if (error(id, profile, registries) == null
+                && policy.allows(featurePage(id)))
             features.add(new LegacyRankChoice.Option<>(id, randomMaterialRank(id)));
-        for (ResourceLocation id : FLUID_FEATURES) if (error(id, profile, registries) == null)
+        for (ResourceLocation id : FLUID_FEATURES) if (error(id, profile, registries) == null
+                && policy.allows(featurePage(id)))
             features.add(new LegacyRankChoice.Option<>(id, randomMaterialRank(id)));
         List<Choice> choices = new ArrayList<>();
         while (choices.size() < count && !features.isEmpty()) {
@@ -171,23 +179,30 @@ public final class AgeFeatureSelection {
             var category = solidFeature(feature)
                     ? BlockSymbolPages.CATEGORY : BlockSymbolPages.FLUID_CATEGORY;
             List<ResourceLocation> materials = BlockSymbolPages.availableBlocks(category).stream()
+                    .filter(id -> policy.allows(BlockSymbolPages.symbolId(id)))
                     .filter(id -> materialError(new Choice(feature, Optional.of(id))) == null).toList();
             if (!materials.isEmpty()) choices.add(new Choice(feature,
                     Optional.of(materials.get(random.nextInt(materials.size())))));
         }
         if (profile.terrain() == AgeRuntimeProfile.Terrain.NOISE
+                && policy.allows(featurePage(id("skylands")))
                 && Math.floorMod(mix(ageSeed ^ RANDOM_SKYLANDS_SALT), 8) == 0)
             choices.add(new Choice(id("skylands"), Optional.empty()));
-        if (error(CRYSTAL_FORMATIONS, profile, registries) == null && random.nextInt(10) == 0)
+        if (error(CRYSTAL_FORMATIONS, profile, registries) == null
+                && policy.allows(featurePage(CRYSTAL_FORMATIONS)) && random.nextInt(10) == 0)
             choices.add(new Choice(CRYSTAL_FORMATIONS, Optional.empty()));
-        if (randomStarFissure(ageSeed))
+        if (policy.allows(featurePage(STAR_FISSURES)) && randomStarFissure(ageSeed))
             choices.add(new Choice(STAR_FISSURES, Optional.empty()));
         AgeBiomeSelection biomes = AgeBiomeSelection.compile(WritingGrammar.parse(OrderedWriting.EMPTY),
-                AgeTraits.select(ageSeed), profile, ageSeed, registries);
-        choices.addAll(AgeStructureSelection.randomChoices(ageSeed, profile, biomes, registries));
+                AgeTraits.select(ageSeed, policy), profile, ageSeed, registries, policy);
+        choices.addAll(AgeStructureSelection.randomChoices(ageSeed, profile, biomes, registries, policy));
         return List.copyOf(choices);
     }
 
+    private static ResourceLocation featurePage(ResourceLocation id) {
+        return ResourceLocation.fromNamespaceAndPath("rivencraft", "feature/" + id.getPath());
+    }
+
     static int randomMaterialRank(ResourceLocation feature) {
         if (feature.equals(id("surface_lakes")) || feature.equals(id("deep_lakes"))) return 1;
         if (feature.equals(id("lava_lakes"))) return 2; // New separate fluid choice.
@@ -235,6 +250,9 @@ public final class AgeFeatureSelection {
     }
 
     public static String error(ResourceLocation choice, AgeRuntimeProfile profile, RegistryAccess registries) {
+        if (RuinsTemplatePages.isSymbol(choice))
+            return RuinsTemplatePages.contains(choice) ? null : "Ruins template " + choice
+                    + " is unavailable; restore Ruins and its template before loading this Age";
         if (AgeStructureSelection.feature(choice))
             return AgeStructureSelection.error(choice, profile, null, registries);
         if (choice.equals(AgeDenseOres.ID))

src/main/java/net/dnorberg/rivencraft/book/AgeGenerationPlan.java

@@ -188,7 +188,7 @@ public record AgeGenerationPlan(int version, long ageSeed, OrderedWriting writin
             String raw = item.getString("Value");
             SymbolSemantics.Value value = switch (role) {
                 case TERRAIN, BIOME, BLOCK, FEATURE -> new SymbolSemantics.ResourceValue(ResourceLocation.parse(raw));
-                case PERIOD_MODIFIER, ANGLE_MODIFIER, PHASE_MODIFIER, SIZE_MODIFIER ->
+                case PERIOD_MODIFIER, ANGLE_MODIFIER, PHASE_MODIFIER, SIZE_MODIFIER, COLOR_NUMBER ->
                         new SymbolSemantics.NumberValue(Double.parseDouble(raw));
                 default -> new SymbolSemantics.ChoiceValue(raw);
             };

src/main/java/net/dnorberg/rivencraft/book/AgeInstability.java

@@ -6,6 +6,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import net.dnorberg.rivencraft.writing.WritingGrammar;
+import net.dnorberg.rivencraft.compat.RuinsTemplatePages;
 import net.minecraft.core.RegistryAccess;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.nbt.ListTag;
@@ -55,6 +56,11 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
     }
 
     static AgeInstability compute(AgeGenerationPlan plan, AgeTraits traits, RegistryAccess registries, long ageSeed) {
+        return compute(plan, traits, registries, ageSeed, RandomPagePolicy.UNRESTRICTED);
+    }
+
+    static AgeInstability compute(AgeGenerationPlan plan, AgeTraits traits, RegistryAccess registries,
+                                  long ageSeed, RandomPagePolicy policy) {
         Objects.requireNonNull(traits, "traits");
         List<Contribution> contributions = new ArrayList<>();
         if (plan == null) {
@@ -86,7 +92,7 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
             contributions.add(new Contribution("bright_lighting", -1, BRIGHT_LIGHTING_COST,
                     "Seeded bright lighting"));
         }
-        AgeSkyProfile sky = plan == null && ageSeed != Long.MIN_VALUE ? AgeSkyProfile.random(ageSeed, traits)
+        AgeSkyProfile sky = plan == null && ageSeed != Long.MIN_VALUE ? AgeSkyProfile.random(ageSeed, traits, policy)
                 : plan == null ? new AgeSkyProfile(AgeSkyProfile.Style.INHERITED, -1, List.of())
                 : AgeSkyProfile.compile(plan, traits);
         int seenSuns = 0;
@@ -150,9 +156,12 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
                     || !(symbol.semantics().value()
                     instanceof net.dnorberg.rivencraft.writing.SymbolSemantics.ResourceValue resource)) continue;
             String name = COUNTED_STRUCTURES.get(resource.id());
+            if (name == null && RuinsTemplatePages.isSymbol(resource.id()))
+                name = RuinsTemplatePages.fallbackName(resource.id());
             if (name == null) continue;
             int count = structureCounts.merge(resource.id(), 1, Integer::sum);
-            if (AgeStructureSelection.requiresBiomeOverride(resource.id(), plan.biomeSelection(), registries)) {
+            if (COUNTED_STRUCTURES.containsKey(resource.id())
+                    && AgeStructureSelection.requiresBiomeOverride(resource.id(), plan.biomeSelection(), registries)) {
                 contributions.add(new Contribution("forced_biome_" + resource.id().getPath(), symbol.index(),
                         FORCED_STRUCTURE_BIOME_COST,
                         name + " occurrence " + count + " is forced into an unsupported biome"));
@@ -168,7 +177,7 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
 
     static int featureCost(ResourceLocation feature, int occurrence) {
         if (occurrence < 1) throw new IllegalArgumentException("Feature occurrence must be positive");
-        return COUNTED_STRUCTURES.containsKey(feature) && occurrence > 3
+        return (COUNTED_STRUCTURES.containsKey(feature) || RuinsTemplatePages.isSymbol(feature)) && occurrence > 3
                 ? EXCESS_LEGACY_STRUCTURE_COST : 0;
     }
 

src/main/java/net/dnorberg/rivencraft/book/AgePersistenceGameTests.java

@@ -125,9 +125,9 @@ public final class AgePersistenceGameTests {
                 new AgeReference(UUID.randomUUID(), "Stable Writing"), stable);
         AgeDefinition defectiveAge = AgeRegistrySavedData.resolveOrCreate(helper.getLevel(),
                 new AgeReference(UUID.randomUUID(), "Defective Writing"), defective);
-        helper.assertValueEqual(stableAge.instability().score(), 0,
+        helper.assertValueEqual(nonCelestialInstability(stableAge), 0,
                 "Missing seeded branches do not add instability");
-        helper.assertValueEqual(defectiveAge.instability().score(), 600,
+        helper.assertValueEqual(nonCelestialInstability(defectiveAge), 600,
                 "Out-of-order and repeated terrain pages each add their saved penalty");
         helper.assertTrue(defectiveAge.instability().breakdown().stream()
                         .anyMatch(part -> part.reason().equals("duplicate") && part.pageIndex() == 3),
@@ -184,9 +184,9 @@ public final class AgePersistenceGameTests {
                     new AgeReference(UUID.randomUUID(), "Three " + structure), structureWriting(structure, 3));
             AgeDefinition four = AgeRegistrySavedData.resolveOrCreate(helper.getLevel(),
                     new AgeReference(UUID.randomUUID(), "Four " + structure), structureWriting(structure, 4));
-            helper.assertValueEqual(three.instability().score(), 0,
+            helper.assertValueEqual(nonCelestialInstability(three), 0,
                     "The first three " + structure + " pages retain Legacy's zero cost");
-            helper.assertValueEqual(four.instability().score(), 100,
+            helper.assertValueEqual(nonCelestialInstability(four), 100,
                     "The fourth " + structure + " page must add Legacy's 100-point cost");
             helper.assertTrue(four.instability().breakdown().stream().anyMatch(part ->
                             part.reason().equals("excess_" + structure) && part.pageIndex() == 8),
@@ -207,6 +207,13 @@ public final class AgePersistenceGameTests {
                 "Modern repeated structures must use the same deterministic scoring path");
         helper.assertValueEqual(AgeInstability.featureCost(ResourceLocation.parse("rivencraft:dungeons"), 4), 0,
                 "A Legacy-neutral feature must remain neutral when repeated");
+        ResourceLocation ruin = net.dnorberg.rivencraft.compat.RuinsTemplatePages.symbolId("ZombieHut.tml");
+        helper.assertValueEqual(AgeInstability.featureCost(ruin, 1), 0,
+                "The first Ruins template page is free like a standard structure");
+        helper.assertValueEqual(AgeInstability.featureCost(ruin, 3), 0,
+                "The first three copies of a Ruins page are free");
+        helper.assertValueEqual(AgeInstability.featureCost(ruin, 4), 100,
+                "Each Ruins page beyond the third adds 100 instability");
 
         OrderedWriting duplicateBright = new OrderedWriting(List.of(
                 WritingEntry.linkPanel(),
@@ -216,7 +223,7 @@ public final class AgePersistenceGameTests {
         ));
         AgeDefinition bright = AgeRegistrySavedData.resolveOrCreate(helper.getLevel(),
                 new AgeReference(UUID.randomUUID(), "Double Bright"), duplicateBright);
-        helper.assertValueEqual(bright.instability().score(), 1500,
+        helper.assertValueEqual(nonCelestialInstability(bright), 1500,
                 "Each Bright Lighting page costs 500 and the extra controller costs another 500");
         helper.assertValueEqual(bright.instability().breakdown().stream()
                         .filter(part -> part.reason().equals("bright_lighting")).count(), 2L,
@@ -420,6 +427,13 @@ public final class AgePersistenceGameTests {
         helper.succeed();
     }
 
+    /** Isolate the writing-cost assertion from seed-completed extra-sun instability. */
+    private static int nonCelestialInstability(AgeDefinition age) {
+        return age.instability().breakdown().stream()
+                .filter(part -> !part.reason().equals("extra_sun"))
+                .mapToInt(AgeInstability.Contribution::points).sum();
+    }
+
     private static CompoundTag entry(
             UUID id,
             String name,

src/main/java/net/dnorberg/rivencraft/book/AgeRegistrySavedData.java

@@ -39,6 +39,7 @@ public final class AgeRegistrySavedData extends SavedData {
     private static final String TRAITS_TAG = "Traits";
     private static final String PLAN_TAG = "GenerationPlan";
     private static final String RANDOM_FEATURES_TAG = "RandomFeatures";
+    private static final String RANDOM_PAGE_POLICY_TAG = "RandomPagePolicy";
     private static final String SEASON_MODE_TAG = "SeasonMode";
     private static final String INSTABILITY_TAG = "Instability";
     private static final String INSTABILITY_PLAN_TAG = "InstabilityPlan";
@@ -77,9 +78,19 @@ public final class AgeRegistrySavedData extends SavedData {
         ServerLevel overworld = level.getServer().overworld();
         AgeRegistrySavedData data = get(overworld);
         long seed = ageSeed(overworld.getSeed(), data.availableDimensionId(normalizedName(name)));
-        AgeGenerationPlan.compile(writing, seed,
+        AgeGenerationPlan plan = AgeGenerationPlan.compile(writing, seed,
                 AgeRuntimeProfiles.selectForWriting(seed, writing, overworld.registryAccess()), AgeTraits.select(seed),
                 overworld.registryAccess());
+        if (plan == null) {
+            RandomPagePolicy policy = RandomPagePolicy.configured();
+            ResourceLocation profileId = AgeRuntimeProfiles.select(seed, policy);
+            AgeRuntimeProfile profile = AgeRuntimeProfiles.resolve(profileId);
+            AgeTraits traits = AgeTraits.select(seed, policy);
+            AgeBiomeSelection.compile(net.dnorberg.rivencraft.writing.WritingGrammar.parse(OrderedWriting.EMPTY),
+                    traits, profile, seed, overworld.registryAccess(), policy);
+            AgeSkyProfile.random(seed, traits, policy);
+            AgeSeasonMode.select(null, seed, ModList.get().isLoaded("sereneseasons"), profile, policy);
+        }
     }
 
     public static ResourceLocation previewGenerationProfile(ServerLevel level, String name) {
@@ -155,7 +166,8 @@ public final class AgeRegistrySavedData extends SavedData {
         AgeDefinition changed = new AgeDefinition(previous.id(), previous.name(), seed,
                 previous.generationProfile(), previous.generationVersion(), previous.createdGameTime(),
                 previous.dimensionId(), previous.spawn(), previous.traits(), plan, previous.seasonMode(),
-                previous.randomFeatures(), previous.instability(), previous.instabilityPlan());
+                previous.randomFeatures(), previous.instability(), previous.instabilityPlan(),
+                previous.randomPagePolicy());
         if (AgeDimensionService.unload(server, previous) == AgeDimensionService.UnloadResult.FAILED)
             return false;
         ages.put(ageId, changed);
@@ -173,13 +185,19 @@ public final class AgeRegistrySavedData extends SavedData {
         String name = normalizedName(reference.name());
         ResourceLocation dimensionId = availableDimensionId(name);
         long seed = ageSeed(worldSeed, dimensionId);
+        RandomPagePolicy policy = RandomPagePolicy.configured();
         ResourceLocation seedProfile = AgeRuntimeProfiles.selectForWriting(seed, writing, registries);
         AgeTraits traits = AgeTraits.select(seed);
         AgeGenerationPlan plan = AgeGenerationPlan.compile(writing, seed, seedProfile, traits, registries);
+        if (plan == null) {
+            seedProfile = AgeRuntimeProfiles.select(seed, policy);
+            traits = AgeTraits.select(seed, policy);
+        }
         AgeTraits effectiveTraits = plan == null
                 ? AgeEnvironmentCompiler.forTerrain(traits, AgeRuntimeProfiles.resolve(seedProfile))
                 : AgeEnvironmentCompiler.apply(plan, traits);
-        AgeInstability instability = AgeInstability.compute(plan, effectiveTraits, registries, seed);
+        AgeInstability instability = AgeInstability.compute(plan, effectiveTraits, registries, seed,
+                plan == null ? policy : RandomPagePolicy.UNRESTRICTED);
         AgeInstabilityPlan instabilityPlan = AgeInstabilityPlan.select(instability, seed);
         AgeDefinition created = new AgeDefinition(
                 reference.id(),
@@ -193,11 +211,13 @@ public final class AgeRegistrySavedData extends SavedData {
                 effectiveTraits,
                 plan,
                 AgeSeasonMode.select(plan, seed, ModList.get().isLoaded("sereneseasons"),
-                        plan == null ? AgeRuntimeProfiles.resolve(seedProfile) : plan.runtimeProfile()),
+                        plan == null ? AgeRuntimeProfiles.resolve(seedProfile) : plan.runtimeProfile(),
+                        plan == null ? policy : RandomPagePolicy.UNRESTRICTED),
                 plan == null ? AgeFeatureSelection.randomChoices(seed,
-                        AgeRuntimeProfiles.resolve(seedProfile), registries) : List.of(),
+                        AgeRuntimeProfiles.resolve(seedProfile), registries, policy) : List.of(),
                 instability,
-                instabilityPlan
+                instabilityPlan,
+                plan == null ? policy : RandomPagePolicy.UNRESTRICTED
         );
         ages.put(created.id(), created);
         setDirty();
@@ -264,7 +284,10 @@ public final class AgeRegistrySavedData extends SavedData {
                             ? AgeSeasonMode.parseOrNull(entry.getString(SEASON_MODE_TAG)) : null,
                     readRandomFeatures(entry),
                     instability,
-                    instabilityPlan
+                    instabilityPlan,
+                    entry.contains(RANDOM_PAGE_POLICY_TAG, CompoundTag.TAG_COMPOUND)
+                            ? RandomPagePolicy.load(entry.getCompound(RANDOM_PAGE_POLICY_TAG))
+                            : RandomPagePolicy.UNRESTRICTED
             ));
         }
         return data;
@@ -309,6 +332,7 @@ public final class AgeRegistrySavedData extends SavedData {
                         entry.put(RANDOM_FEATURES_TAG, featureTags);
                     }
                     if (age.seasonMode() != null) entry.putString(SEASON_MODE_TAG, age.seasonMode().name());
+                    if (age.plan() == null) entry.put(RANDOM_PAGE_POLICY_TAG, age.randomPagePolicy().save());
                     entry.put(INSTABILITY_TAG, age.instability().save());
                     entry.put(INSTABILITY_PLAN_TAG, age.instabilityPlan().save());
                     serializedAges.add(entry);

src/main/java/net/dnorberg/rivencraft/book/AgeRuntimeProfiles.java

@@ -57,20 +57,39 @@ public final class AgeRuntimeProfiles {
 
     /** Selects from all valid loaded profiles in stable resource-ID order. */
     public static ResourceLocation select(long seed) {
+        return select(seed, RandomPagePolicy.UNRESTRICTED);
+    }
+
+    public static ResourceLocation select(long seed, RandomPagePolicy policy) {
         if (PROFILES.isEmpty()) {
-            return AgeGenerationProfiles.select(seed);
+            List<LegacyRankChoice.Option<ResourceLocation>> profiles = policy.required(
+                    AgeGenerationProfiles.all().stream().sorted()
+                            .map(id -> new LegacyRankChoice.Option<>(id, AgeGenerationProfiles.randomRank(id)))
+                            .toList(), option -> terrainPage(option.value()),
+                    new LegacyRankChoice.Option<>(AgeGenerationProfiles.STANDARD, 1));
+            return LegacyRankChoice.choose(new Random(seed ^ 0x5445525241494E4CL), profiles);
         }
-        List<LegacyRankChoice.Option<ResourceLocation>> profiles = PROFILES.keySet().stream().sorted()
+        List<LegacyRankChoice.Option<ResourceLocation>> available = PROFILES.keySet().stream().sorted()
                 .map(id -> new LegacyRankChoice.Option<>(id, AgeGenerationProfiles.randomRank(id))).toList();
+        LegacyRankChoice.Option<ResourceLocation> fallback = available.stream()
+                .filter(option -> option.value().equals(AgeGenerationProfiles.STANDARD))
+                .findFirst().orElse(available.getFirst());
+        List<LegacyRankChoice.Option<ResourceLocation>> profiles = policy.required(available,
+                option -> terrainPage(option.value()), fallback);
         return LegacyRankChoice.choose(new Random(seed ^ 0x5445525241494E4CL), profiles);
     }
 
+    private static ResourceLocation terrainPage(ResourceLocation profile) {
+        return ResourceLocation.fromNamespaceAndPath("rivencraft", "terrain/" + profile.getPath());
+    }
+
     /** Keep seed-selected terrain random, but only among profiles able to host authored features. */
     public static ResourceLocation selectForWriting(long seed, OrderedWriting writing, RegistryAccess registries) {
-        ResourceLocation selected = select(seed);
         WritingGrammar.Result parsed = WritingGrammar.parse(writing);
-        if (parsed.activeSymbols().stream().anyMatch(symbol ->
-                symbol.semantics().role() == SymbolSemantics.Role.TERRAIN)) return selected;
+        boolean authoredTerrain = parsed.activeSymbols().stream().anyMatch(symbol ->
+                symbol.semantics().role() == SymbolSemantics.Role.TERRAIN);
+        ResourceLocation selected = select(seed);
+        if (authoredTerrain) return selected;
         List<ResourceLocation> features = parsed.activeSymbols().stream()
                 .filter(symbol -> symbol.semantics().role() == SymbolSemantics.Role.FEATURE)
                 .map(symbol -> ((SymbolSemantics.ResourceValue) symbol.semantics().value()).id()).toList();

src/main/java/net/dnorberg/rivencraft/book/AgeSeasonMode.java

@@ -24,15 +24,23 @@ public enum AgeSeasonMode {
 
     public static AgeSeasonMode select(AgeGenerationPlan plan, long ageSeed, boolean sereneInstalled,
                                        AgeRuntimeProfile profile) {
+        return select(plan, ageSeed, sereneInstalled, profile, RandomPagePolicy.UNRESTRICTED);
+    }
+
+    public static AgeSeasonMode select(AgeGenerationPlan plan, long ageSeed, boolean sereneInstalled,
+                                       AgeRuntimeProfile profile, RandomPagePolicy policy) {
         if (profile != null && AgeBiomeSelection.isCave(profile)) return NO_SEASONS;
         if (hasAuthoredPage(plan)) return from(plan);
-        return sereneInstalled ? LegacyRankChoice.choose(new Random(ageSeed ^ RANDOM_SALT), List.of(
+        return sereneInstalled ? LegacyRankChoice.choose(new Random(ageSeed ^ RANDOM_SALT), policy.required(List.of(
                 new LegacyRankChoice.Option<>(SEASONS, 1),
                 new LegacyRankChoice.Option<>(NO_SEASONS, 2),
                 new LegacyRankChoice.Option<>(ETERNAL_WINTER, 3),
                 new LegacyRankChoice.Option<>(ETERNAL_SUMMER, 3),
                 new LegacyRankChoice.Option<>(ETERNAL_FALL, 3),
-                new LegacyRankChoice.Option<>(ETERNAL_SPRING, 3))) : null;
+                new LegacyRankChoice.Option<>(ETERNAL_SPRING, 3)),
+                option -> net.minecraft.resources.ResourceLocation.fromNamespaceAndPath("rivencraft",
+                        "season/" + option.value().name().toLowerCase(Locale.ROOT)),
+                new LegacyRankChoice.Option<>(NO_SEASONS, 2))) : null;
     }
 
     /** Existing Ages without a stored choice retain their old cycling behavior. */