Complete instability regression slice and ordered modifiers (#73)

build.gradle

@@ -17,7 +17,7 @@ tasks.named('wrapper', Wrapper).configure {
 version = mod_version
 group = mod_group_id
 
-List<String> archivedGameTestSuites = ['linking', 'environment', 'writing', 'grammar', 'generation', 'desk', 'binder', 'mixer', 'recipe']
+List<String> archivedGameTestSuites = ['linking', 'environment', 'writing', 'grammar', 'generation', 'desk', 'binder', 'mixer', 'recipe', 'instability']
 List<String> selectedArchivedGameTestSuites = providers.gradleProperty('withArchivedGameTests')
         .map { it.toBoolean() }.orElse(false).get() ? archivedGameTestSuites
         : providers.gradleProperty('archivedGameTestSuites').orElse('').get()

docs/GAMETESTS.md

@@ -18,12 +18,13 @@ core tests when investigating an issue:
 ./gradlew runGameTestServer -ParchivedGameTestSuites=desk
 ./gradlew runGameTestServer -ParchivedGameTestSuites=grammar,binder
 ./gradlew runGameTestServer -ParchivedGameTestSuites=generation
+./gradlew runGameTestServer -ParchivedGameTestSuites=instability
 ```
 
 Available suite names are `linking`, `environment`, `writing`, `grammar`,
-`generation`, `desk`, `binder`, `mixer`, and `recipe`. The `generation` archive
+`generation`, `desk`, `binder`, `mixer`, `recipe`, and `instability`. The `generation` archive
 keeps the detailed feature, structure, ore, crystal, and fissure regressions
-out of the default smoke run. Three checks formerly registered twice in the
+out of the default smoke run. The `instability` archive adds multi-player loaded-chunk selection, policy gates, and protected-block checks without rerunning the default scoring and migration tests. Three checks formerly registered twice in the
 core and their archives now run only through the core wrapper. Run all
 Rivencraft tests before a
 release or after broad cross-system changes:

docs/INSTABILITY_DIAGNOSTICS.md

@@ -0,0 +1,11 @@
+# Instability controls and diagnostics (Milestone 6, issue #72)
+
+The world-specific NeoForge server config (`serverconfig/rivencraft-server.toml`) is the global policy. `instability.enabled` stops all scheduled effects without changing a saved Age. `instability_providers.<id>` switches each Legacy card independently; these switches do not reroll frozen provider levels. The existing `instability_status_effects`, `instability_decay`, `instability_hazards`, `instability_meteor`, `instability_scorching`, and `instability_erosion` groups provide category policy and action limits. `instability.world_mutation`, hazard/meteor `block_damage`, `player_damage`, and `fire` settings control destructive behavior. `mobGriefing` and `doFireTick` still apply. Defaults retain the Legacy-active hazards; the scheduler, spawn protection, loaded-chunk checks, and per-effect caps remain Rivencraft safety adaptations. The dormant-in-Legacy erosion effect remains enabled for project testing but can be switched off.
+
+Configuration values are read during server operation, but editing the TOML on disk does not guarantee NeoForge will reload it. Restart the server or world after changing the file; `/reload` reloads data packs, not this server config. Per-Age commands below take effect on the next scheduler pass without a restart. A stopped provider does not refund or change the Age's score or saved plan. Existing owned status-effect leases are revoked on their next 20-tick check after global, category, provider, or Age disablement. In-flight meteors are cancelled when their Age or meteor provider is disabled. Existing block changes are not rolled back.
+
+Operators can inspect `/rivencraft age instability [dimension]`. The argument accepts an Age name (quote names containing spaces), a short path such as `fort`, or a full ID such as `rivencraft:age/fort`. Duplicate names require the full ID shown by `/rivencraft age list`. The command reports the frozen score and each saved contribution, the frozen provider IDs/levels and their *current* runtime eligibility, config limits, and whether this Age is enabled. "Eligible" does not promise an effect on the next tick: chance, cooldowns, loaded chunks, player presence, and protection still apply. An unavailable handler is reported as such instead of being mistaken for an active provider. Pre-scoring Ages remain neutral, and missing provider plans from older scored saves are migrated once as described in [runtime policy](INSTABILITY_RUNTIME.md). `/rivencraft age instability disable <dimension>` and `enable <dimension>` are operator-only and persist for that Age alone. Unknown dimensions are rejected. Neither command mutates a book, score, or provider plan.
+
+Newly bound Descriptive Books carry only a server-written numerical potential-instability summary for their tooltip and cover. The details and live enablement stay server-side in the operator command. Older written books receive the summary when opened through the server-approved book screen; until then, an absent tooltip score means "not yet synchronized," not zero. The score does not indicate whether effects are currently enabled.
+
+Manual check: create two scored Ages, disable one with the command, and inspect both. Only the selected Age should show "Age disabled"; its saved breakdown and plan should remain identical. Re-enable it, then switch an individual provider in the world config and restart. Its plan should remain identical while diagnostics show "provider config off." An old neutral Age should report score zero and no selected providers. A non-operator should be unable to invoke the mutation commands. Test tooltips both on a newly bound book and an older book after opening it once.

docs/INSTABILITY_RUNTIME.md

@@ -4,10 +4,21 @@ Each new Age stores an `InstabilityPlan` beside its frozen `Instability` score.
 
 The saved provider IDs are independent of installed handlers. A missing optional handler leaves its ID and level intact and is skipped at runtime. A syntactically invalid saved ID or unsupported plan version fails loading explicitly; an unknown but valid ID is preserved and logged once when encountered. Disabling instability or world mutation never rewrites a saved score or provider plan. Saves from #64 with a frozen score but no provider plan are selected once from that score and Age seed, then marked dirty for persistence. Older pre-score Ages remain neutral and inert.
 
+From 0.5.8.11, [live block profiling](LIVE_BLOCK_INSTABILITY.md) adds a separate
+effective score and provider plan once 400 Age and Overworld chunks have been
+sampled. The authored score/plan described above remain saved as the base;
+the effective provider selection can change as block abundance is observed.
+
 The server scheduler runs only for loaded `rivencraft:age/*` levels with a player present and an Age definition. It uses only chunks already loaded near those players, never requests a chunk, and rotates among eligible Ages when the per-tick cap is reached. Configuration bounds the cooldown (minimum 20 ticks), active Ages, handlers and actions per Age, effective provider level, and examined loaded chunks. A handler must claim a shared action permit before each effect. A throwing handler is logged and quarantined temporarily without stopping the server. World-mutating handlers are enabled by default to match Legacy; the setting can still disable them. These limits are guards for upcoming providers, not proof that an arbitrary third-party handler cannot misuse world APIs.
 
 Issue #67 registers the non-world-mutating potion handlers; see [status-effect policy](INSTABILITY_STATUS_EFFECTS.md). Issue #68 adds configurable [colored decay](INSTABILITY_DECAY.md), enabled by default for newly generated configs. Issue #69 adds lightning and explosions; issue #70 adds [meteor, scorching, and erosion](INSTABILITY_ENVIRONMENTAL.md). The runtime rejects Overworld and preview dimension IDs; its player requirement excludes unattended snapshot chunk loaders. GameTests cover deterministic selection, save round-trips, score-only migration, unknown IDs, scope checks, fair admission, and action caps.
 
+Issue #72 adds [server config, per-Age controls, diagnostics, and book feedback](INSTABILITY_DIAGNOSTICS.md). Its operator controls never rewrite a frozen score or provider plan.
+
+The Milestone 6 [regression and migration record](MILESTONE_6_REGRESSION.md)
+maps the automated acceptance checks and lists the in-game restart, optional-mod,
+and hazard-visual scenarios still requiring verification.
+
 # Lightning and explosions (#69)
 
 The `lightning` and `explosions` cards now run only in loaded Rivencraft Ages with players. Legacy rolled once per chunk per tick: explosions at 1/1000 and lightning at 1/5000 during thunder or 1/100000 otherwise. Each selected hazard card gets an independent roll every scheduler pass, rather than waiting for the rotating two-provider sample. The roll uses up to 81 already-loaded chunks near Age players and the exact probability of at least one Legacy opportunity over that many chunk-ticks. It permits at most one event per hazard type per pass. A per-Age saved sequence and last-event time prevent the same roll/event from replaying after a restart. Lightning also skips an existing bolt at the target.

docs/INSTABILITY_SCORE.md

@@ -6,6 +6,10 @@ The baseline is explicitly zero for page-free and Link-Panel-only random Ages, a
 
 The score is calculated after the Age plan and effective traits are chosen, then saved with the Age identity before its dimension is generated. The same UUID returns the existing definition, including the same score, on repeated use. Spawn updates preserve it. Reload only deserializes the frozen breakdown; it never reruns the current grammar or catalog. An older Age definition without `Instability` is migrated to a persisted version-1 neutral score of zero, rather than retroactively scoring its writing. A future scoring-rule change must introduce an explicit new schema/migration policy, not silently reinterpret existing Ages. Issue #66 added the frozen provider selection; issues #67–#70 added the current handlers. See the [runtime policy](INSTABILITY_RUNTIME.md).
 
+This is now the **authored base** score. [Live block profiling](LIVE_BLOCK_INSTABILITY.md)
+keeps its sample counts separately and may add a changing effective block score
+without rewriting the authored breakdown or its saved base provider plan.
+
 Unknown or unsupported pages remain invalid for *new* Ages. Their absence from a later registry does not change an already saved score. Focused GameTests cover stable/defective writing, random baseline and bright lighting, repeated identity, save round-trip, and missing-symbol/old-save behavior.
 
 `/rivencraft age instability` inspects the Age containing the command source; an optional dimension ID inspects an unloaded or different registered Age. It reports immutable base score, stability bonus, runtime penalty, and effective score. The pinned Legacy tree defines player-death and player-presence bonus classes but does not register them as default providers, so Rivencraft leaves player-driven modifiers disabled: bonus and penalty are zero and effective equals base. There is therefore no mutable bonus save to migrate in this release. No death, PvP event, player identity, or dimension transition can transfer stability between Ages. Any future opt-in mechanic must persist separately from `Instability`, define caps and reset behavior, and must not rewrite the generation plan or frozen provider plan.

docs/LEGACY_INSTABILITY_AUDIT.md

@@ -4,7 +4,7 @@ This is the behavior contract used to implement Milestone 6. It is pinned to [My
 
 ## Score, grammar, and selection in Legacy
 
-Legacy's [`AgeController`](https://github.com/Mystcraft/Mystcraft-Legacy/blob/9bc8ddc061845df0cd5ea47f4fdef773cff786ae/src/main/java/com/xcompwiz/mystcraft/world/AgeController.java) calculates `debug + symbol + block + book/base + bonus`, then applies difficulty 0/1/2/3 multipliers of 0.25/0.5/1/1.75. Global instability is enabled by default; an Age also has its own enable flag. The unmodified score is not simply “number of bad pages.” Block profiling may delay a usable score: `blockinstability` is null until **more than** 400 Age chunks are profiled, and `getInstabilityScore()` returns zero until then. It is recalculated after additional profiling. [`ChunkProfiler`](https://github.com/Mystcraft/Mystcraft-Legacy/blob/9bc8ddc061845df0cd5ea47f4fdef773cff786ae/src/main/java/com/xcompwiz/mystcraft/world/profiling/ChunkProfiler.java) compares watched block abundance with a baseline, subtracting only positive excess above each baseline. The baseline is profiled or read from balance config; [`InstabilityDataCalculator`](https://github.com/Mystcraft/Mystcraft-Legacy/blob/9bc8ddc061845df0cd5ea47f4fdef773cff786ae/src/main/java/com/xcompwiz/mystcraft/world/profiling/InstabilityDataCalculator.java) sets its default tolerance to 1.05, and default `useconfigs=false`. We should not copy its 400-chunk profiling delay or dynamic block scan into 1.21.1 without a separate performance case.
+Legacy's [`AgeController`](https://github.com/Mystcraft/Mystcraft-Legacy/blob/9bc8ddc061845df0cd5ea47f4fdef773cff786ae/src/main/java/com/xcompwiz/mystcraft/world/AgeController.java) calculates `debug + symbol + block + book/base + bonus`, then applies difficulty 0/1/2/3 multipliers of 0.25/0.5/1/1.75. Global instability is enabled by default; an Age also has its own enable flag. The unmodified score is not simply “number of bad pages.” Block profiling may delay a usable score: `blockinstability` is null until **more than** 400 Age chunks are profiled, and `getInstabilityScore()` returns zero until then. It is recalculated after additional profiling. [`ChunkProfiler`](https://github.com/Mystcraft/Mystcraft-Legacy/blob/9bc8ddc061845df0cd5ea47f4fdef773cff786ae/src/main/java/com/xcompwiz/mystcraft/world/profiling/ChunkProfiler.java) compares watched block abundance with a baseline, subtracting only positive excess above each baseline. The baseline is profiled or read from balance config; [`InstabilityDataCalculator`](https://github.com/Mystcraft/Mystcraft-Legacy/blob/9bc8ddc061845df0cd5ea47f4fdef773cff786ae/src/main/java/com/xcompwiz/mystcraft/world/profiling/InstabilityDataCalculator.java) sets its default tolerance to 1.05, and default `useconfigs=false`. Rivencraft's later [bounded implementation](LIVE_BLOCK_INSTABILITY.md) retains the threshold and tolerance, but not Legacy's spatial accessibility formula or unbounded profiling.
 
 | Input | Verified Legacy behavior | Rivencraft M6 interpretation |
 | --- | --- | --- |
@@ -15,7 +15,7 @@ Legacy's [`AgeController`](https://github.com/Mystcraft/Mystcraft-Legacy/blob/9b
 | Unsupported/unmatched page | Legacy logs unmatched symbols during reconstruction and skips their logic; its `AgeData.getBaseInstability()` still has a TODO for calculating instability from pages. This is not a sound compatibility contract. | Remains fatal for *new* books until semantic and runtime support exists; never silently erase the page or pretend its effect applied. Existing saved books retain their IDs. |
 | Other penalties/bonuses | `AgeController.addInstability(int)` is available to symbol logic. The base/book score is persisted as a `short`; Legacy's [`InstabilityBonusManager`](https://github.com/Mystcraft/Mystcraft-Legacy/blob/9bc8ddc061845df0cd5ea47f4fdef773cff786ae/src/main/java/com/xcompwiz/mystcraft/instability/bonus/InstabilityBonusManager.java) also has dynamic player death/behavior components. | Persist a versioned score breakdown for Age writing and environmental contributions. Do not infer death/troll mechanics from the mere existence of Legacy classes. |
 
-The complete Legacy `instabilityModifier` audit found direct feature-page costs only for Mineshafts, Nether Fortresses, Strongholds, and Villages. Their first three occurrences cost zero; the fourth and every later occurrence adds 100. Every other Legacy feature class inherited `SymbolBase`'s zero modifier. Rivencraft applies that exact rule to the four matching pages. By project balance decision, Bastions, Trial Chambers, Ancient Cities, Shipwrecks, Ocean Ruins, Pillager Outposts, Ruined Portals, Nether Fossils, Buried Treasure, and Trail Ruins use the same repeat rule. Matching Legacy features such as Caves, Crystal Formations, Dense Ores, Dungeons, Floating Islands, Huge Trees, Deep/Surface Lakes, Obelisks, Ravines, Skylands, Spheres, Spikes, Star Fissures, and Tendrils have no direct page cost. Legacy could still derive instability later from excess profiled blocks, especially ores, but that separate 400-chunk profiling system is intentionally not ported. Other modern-only Rivencraft features remain neutral.
+The complete Legacy `instabilityModifier` audit found direct feature-page costs only for Mineshafts, Nether Fortresses, Strongholds, and Villages. Their first three occurrences cost zero; the fourth and every later occurrence adds 100. Every other Legacy feature class inherited `SymbolBase`'s zero modifier. Rivencraft applies that exact rule to the four matching pages. By project balance decision, Bastions, Trial Chambers, Ancient Cities, Shipwrecks, Ocean Ruins, Pillager Outposts, Ruined Portals, Nether Fossils, Buried Treasure, and Trail Ruins use the same repeat rule. Matching Legacy features such as Caves, Crystal Formations, Dense Ores, Dungeons, Floating Islands, Huge Trees, Deep/Surface Lakes, Obelisks, Ravines, Skylands, Spheres, Spikes, Star Fissures, and Tendrils have no direct page cost. Legacy could still derive instability later from excess profiled blocks, especially ores. From 0.5.8.11, Rivencraft has a [bounded live block-profile adaptation](LIVE_BLOCK_INSTABILITY.md) using the 400-chunk threshold, including diamond blocks as a deliberate non-Legacy extension. Other modern-only Rivencraft features remain neutral unless they increase watched-block abundance.
 
 Bright Lighting adds 500 for every authored occurrence. A generated Bright Lighting controller also adds 500. This is independent of the 500-point extra-controller cost, so two authored Bright Lighting pages produce 1,500 total: 500 for each symbol and 500 for the repeated controller.
 

docs/LIVE_BLOCK_INSTABILITY.md

@@ -0,0 +1,94 @@
+# Live block-instability profiling (0.5.8.11–0.5.8.17)
+
+Mystcraft Legacy measures the abundance of watched blocks in generated chunks,
+compares that abundance with a baseline, and adds only positive excess to the
+Age's instability. Its `InstabilityBlockManager` and `ChunkProfiler` are
+available in the user's local 0.13.7.06 archive. Legacy's Age-side threshold
+is more than 400 profiled chunks; its default tolerance is 1.05. The Legacy watched
+blocks include coal, lapis, iron, emerald, redstone, gold and diamond ores,
+quartz ore, glowstone, and crystal blocks. Diamond **blocks** are not on that
+default list, but are included here at the player's request.
+
+Rivencraft samples up to 1,024 distinct loaded chunks per dimension,
+at most four per server tick. While a player is in an Age, it also gradually
+generates unsampled chunks around that Age's spawn and the Overworld spawn,
+at most one chunk per second across both dimensions, until their minimum
+sample counts are reached.
+The Overworld is sampled as the baseline; an Age needs 401 samples and the
+baseline needs 500 before the live block component contributes points. Counts and sampled chunk
+positions persist per dimension, preventing reloads from double-counting.
+For each watched block, Rivencraft compares average blocks per sampled chunk
+and charges `max(0, Age average − 1.05 × Overworld average) × weight`, rounded
+to the nearest point. The block component is capped at 100,000 points.
+
+Legacy weights are used for its watched blocks: coal/lapis 5, iron 60, emerald
+200, redstone 250, gold 750, diamond 4,000, quartz/crystal 20, and glowstone
+50. Deepslate variants inherit their ore's weight. Modern/high-value extensions
+include diamond, emerald, gold, iron, raw gold, raw iron and netherite storage
+blocks, plus ancient debris. Netherite blocks cost 8,000 per excess block per
+sampled chunk; ancient debris costs 4,000.
+
+Other mods remain optional. When an installed mod registers common-tagged ores
+or storage blocks, recognizable `*_ore` blocks, or source-fluid blocks,
+Rivencraft automatically includes those blocks in live profiling. The source
+fluid weight is 1.25; common mineral names such as tin,
+lead, zinc, silver, uranium, platinum, and iridium have explicit tiers, while
+other tagged ores use 60 and other tagged storage blocks use 120. The optional
+`instability_modded_materials.block_weight_overrides` list accepts a full-block
+`modid:block_id=points` entry to cover a block without common tags or replace
+its inferred weight; zero excludes it. Block entities and non-source fluid
+plants are excluded. Rivencraft never requires any particular content mod.
+
+Profiles written before 0.5.8.17 did not retain all modded material
+counts, so their block sample data resets and is collected again after upgrade.
+The saved Age definition and authored score are not changed. Later config
+changes can rescore materials already captured in the profile; a newly added
+override for a block that was not previously recognized needs fresh samples.
+
+The authored score and provider plan remain saved as the Age's immutable base.
+Only Ages created with instability schema v2 participate; existing v1 Ages
+retain their previously frozen scores/plans, including neutral pre-scoring
+Ages. This avoids silently rescoring existing worlds.
+The live block component creates a deterministic **effective** score and
+provider plan from that base plus the persisted profile; new cards can become
+active as sampled abundance rises. The command `/rivencraft age instability`
+shows both the saved base and the currently profiled block component. An
+unloaded Age has no active profile view until its dimension is loaded again.
+Turning an effect off does not delete counts or reroll the same effective plan.
+
+This is not byte-for-byte Legacy profiling. Legacy has a spatial accessibility
+map and two factors per block, actively builds a dummy-world baseline, and can
+recompute after subsequent chunk profiling. Rivencraft uses a simpler
+per-chunk abundance metric, a real-world Overworld baseline, a sample/work cap,
+and a saved authored base so modern servers remain bounded and restart-safe.
+The greater-than-400-chunk activation delay is retained. Already-explored
+chunks count when reloaded, but the bounded spawn-area pass can generate
+additional terrain. A mod that mutates blocks after the chunk-load event may
+not be reflected in the first sample.
+
+## Manual check handed to the player
+
+The first focused GameTest run after adding the chunk-load listener stalled in
+its initial 50-test batch and was stopped. It is **not** a passing test result.
+Do not retry that stalled scenario automatically. In a disposable world:
+
+1. Create one Age with an authored Diamond Block + Rocks (or Floating Islands)
+   combination and a comparison Age using Stone for the same feature. Explore
+   enough distinct chunks in each Age for `/rivencraft age instability` to show
+   a profiled-block contribution. Explore the Overworld too if its baseline has
+   not reached 400 chunks. The diamond Age should score higher and can gain
+   provider cards; the stone Age should not get a diamond-block contribution.
+2. Leave and restart the world. Re-enter both Ages and compare their scores and
+   provider IDs/levels. Reloading old chunks must not increase the sample
+   count or score by itself. Generating more diamond-rich chunks may change the
+   effective score and provider set; disabling instability must suppress their
+   effects without erasing the profile.
+3. Check a naturally generated diamond-ore Age without authored diamond-block
+   features. If its ore abundance is near the Overworld baseline, it should
+   receive little or no ore contribution. Check that profiling does not make
+   chunk loading noticeably stall, and report any exception or server hang.
+
+Do not use a valued save for this check. The player reported an in-game pass
+for the 0.5.8.18 candidate on 2026-10-12. The three detailed scenarios above
+remain useful for future regression runs; the report does not establish that
+each was exercised individually.

docs/MILESTONE_6_REGRESSION.md

@@ -0,0 +1,158 @@
+# Milestone 6 instability regression and migration check (#73)
+
+This is the release-slice acceptance record for instability, not a promise of
+general old-save compatibility. The latter remains issue #60. Run the focused
+archive with `./gradlew build runGameTestServer -ParchivedGameTestSuites=instability`;
+it includes the default smoke suite.
+For 0.5.8.10 on 2026-10-10, that dedicated GameTest server passed all 55 required tests
+with no optional content/client integrations installed (the required Dynamic
+Dimensions and Bad Packets dependencies were present). The full archive was not run;
+it has a previously documented storage stall, so do not count it as passing.
+The 0.5.8.11 run with live block profiling stalled in its initial batch and
+was stopped; it is **not** a passing result. The live profiling scenario is
+handed to the player in [the block-profile checklist](LIVE_BLOCK_INSTABILITY.md).
+
+## Automated coverage
+
+| Requirement | Existing default test or focused archive |
+| --- | --- |
+| Stable writing, defective writing, score explanations, repeated use of the same book | `AgePersistenceGameTests.instabilitySeparatesStableAndDefectiveWriting` |
+| Frozen score, age-scoped writing cost, random baseline | `AgePersistenceGameTests.randomBaselineAndBrightBalanceAreFrozen`, `auditedSymbolCostsAreCountedAndAgeScoped` |
+| Complete Age definition, score and provider-plan save/load | `AgePersistenceGameTests.authoredPlanRetainsResolvedMeaningAndAgeIdentity`; `AgeInstabilityRuntimeGameTests.selectionIsDeterministicAndFrozen` |
+| Old pre-scoring Ages, score-only saves, removed symbols, unavailable handlers | `AgePersistenceGameTests.missingRegistryEntryDoesNotReinterpretAnOldAge`, `instabilitySeparatesStableAndDefectiveWriting`; `AgeInstabilityRuntimeGameTests.savedPlanSurvivesAgeUpdatesAndMissingHandlers` |
+| Per-Age controls and changed config without score/plan reroll | `AgeInstabilityRuntimeGameTests.perAgeControlsPersistWithoutChangingScoresOrOtherAges`; `Milestone6RegressionGameTests.disablingEffectsCannotRerollFrozenPlan` |
+| Hazard cooldown and attempt sequence across saved-state reload | `AgeInstabilityRuntimeGameTests.hazardCooldownAndAttemptSequenceSurviveReload` |
+| Active-Age rotation, action/tick budget | `AgeInstabilityRuntimeGameTests.ageScopeRotationAndActionBudgetAreBounded` |
+| Multiplayer loaded-chunk-only candidate selection, deduplication and cap | `Milestone6RegressionGameTests.multiplayerCandidatesStayLoadedDeduplicatedAndCapped` |
+| Decay loaded-chunk target and spawn protection | `AgeDecayGameTests.targetMustRemainInChosenLoadedChunk`, `savedSpawnAndPlatformAreProtected` |
+| Explosion policy gates and protected blocks | `Milestone6RegressionGameTests.disabledGriefAndProtectedBlocksStayUntouched` |
+| No Overworld status or decay provider | `AgeStatusEffectGameTests.overworldCannotRunAnAgeStatusProvider`; `AgeDecayGameTests.overworldCannotRunDecayProvider` |
+| Optional-mod material weights, block overrides, and old profile migration | `Milestone6RegressionGameTests.commonModdedMaterialWeightsStayBounded`, `blockProfileSamplesPersistWithoutDoubleCounting` |
+| Ordered celestial modifier consumption, repeated modifiers, and dangling +100 per kind | `WritingGrammarGameTests.orderedGrammarAcceptsPartialWritingAndDiagnosesInvalidSequences`; `EnvironmentWritingGameTests.celestialModifiersFollowWrittenOrder` |
+
+These tests exercise saved-data serialization and deterministic policies. They
+do **not** simulate a complete process restart, an actual multiplayer server,
+optional-mod installation, or real terrain and hazard visuals. The three new
+checks live only in the `instability` archive to avoid duplicating default tests.
+
+## Migration outcome and known gaps
+
+- Pre-scoring Milestone 5 Ages load with a neutral score and no effects; they
+  are not retroactively rescored under current writing rules.
+- Score-only Ages receive a deterministic provider plan once from their saved
+  score and Age seed. An already-saved score and plan retain their meaning when
+  pages, handlers, or runtime config change. Unknown but syntactically valid
+  provider IDs are preserved and skipped if their handler is unavailable.
+- Missing symbol definitions do not reinterpret a frozen instability score.
+  That check is narrower than arbitrary missing biome, block, or worldgen
+  registry entries: loading a world with removed data packs is not guaranteed.
+  Broad save compatibility and migration remain tracked in #60.
+- Version-3 plans keep their previous stage-sorted celestial interpretation and
+  frozen writing cost. Only new version-4 plans consume period/phase modifiers
+  in authored order and charge a trailing modifier once per pending kind.
+- In-process roundtrips cannot prove that Age dimensions reload correctly
+  after a full stop/start. Check that in a real client/server world. Do not add
+  another GameTest for it if it hits the documented storage stall; hand the
+  exact scenario to the player instead.
+- The dedicated GameTest run establishes classloading with no optional runtime
+  flags. It does not establish classloading with every optional integration
+  installed, nor the reverse of removing one from an existing save.
+
+## Manual in-game matrix
+
+Use a fresh test world, then keep one save for the restart and data-pack checks.
+Record the seed, mod list, age name, and `/rivencraft age instability` output
+before and after each change. Do not deliberately remove a required registry
+entry from a valued world; copy the test save first.
+
+1. Bind a low-instability book and a deliberately unstable book. Reuse each
+   book and verify the Age name, dimension ID, score, selected providers and
+   provider levels remain unchanged. Exit the Ages, stop Minecraft completely,
+   restart and re-enter; compare the same diagnostic values.
+2. With two survival players in one unstable Age and a third player in the
+   Overworld, verify effects stay in the Age, follow the Age players, and do
+   not appear in the Overworld. Move both Age players away, let old chunks
+   unload, and confirm hazards do not keep remote chunks loaded or operate
+   there. Confirm controls on one Age do not alter a second Age.
+3. Disable global instability, then world mutation, then one provider. Verify
+   the suppressed effect stops and the frozen score/plan do not change after
+   re-enabling or restarting. With block destruction disabled, trigger an
+   explosion in an expendable Age; check that arrival platforms, portals,
+   block entities and protected blocks survive. Check lightning, explosion,
+   decay, status-effect, burning, meteor and erosion visuals where selected.
+4. With Biomes O' Plenty or another TerraBlender biome mod, confirm recognized
+   biome pages still author an Age and the instability diagnostics remain
+   stable after restart. Repeat with Serene Seasons installed, then absent in
+   a disposable copy; confirm its Age season behavior and that Rivencraft
+   itself still loads. JEI should display the relevant pages and recipes when
+   installed, while the mod works without it.
+   Separately, install a mod with common-tagged ores/storage blocks or source
+   fluids. Compare a material-rich Age with an ordinary Age after the profile
+   thresholds are reached; the installed mod's recognized blocks should affect
+   the result without a Rivencraft allowlist. Then remove that optional mod in
+   a disposable copy and confirm Rivencraft still starts. Test a single
+   `block_weight_overrides` entry and a zero-weight exclusion. This remains a
+   player-run scenario, not an automated pass.
+5. Check the book preview separately with its fallback animation, Ponder/Create,
+   and Immersive Portals when available. Opening a book should not change
+   player location, instability diagnostics, or ambient audio in the actual
+   Age. Do not install both season mods together for this matrix.
+6. On a copied save, remove or alter a **nonessential** data pack providing
+   a writing symbol or optional handler, then reload. Existing saved scores
+   and provider plans must not reroll. If a referenced worldgen registry entry
+   prevents load, record it against issue #60 rather than treating #73's
+   frozen-instability guarantee as general missing-registry support.
+
+The matrix is guidance for a player-run pass; none of these six scenarios is
+claimed as completed by the automated result above.
+The player reported an in-game pass for the 0.5.8.18 candidate on 2026-10-12.
+That is a release-slice acceptance report, not a claim that every expanded
+matrix row below was individually exercised.
+
+### Regression run record
+
+For each row, record pass/fail, world seed, Age name, Rivencraft version,
+optional-mod versions, and a short observation. "Not run" is intentional
+until a player completes the in-game check; a successful build is not a pass.
+
+| Area | Specific manual observation | Status |
+| --- | --- | --- |
+| New vs reused book | Dimension ID, score, and providers do not reroll | Not run |
+| Full process restart | Re-enter two Ages; saved traits, score, plan, and cooldowns persist | Not run |
+| Multiplayer isolation | Two Age players receive effects; Overworld player does not | Not run |
+| Loaded-chunk scope | Departing players permit unloading; hazards do not reach old chunks | Not run |
+| Controls | Global, per-Age, mutation, and provider toggles suppress effects without reroll | Not run |
+| Protected blocks | Explosion/decay/erosion spare arrival platforms, portals, and block entities | Not run |
+| Hazard visuals | Lightning, explosions, decay, status, burning, meteor, and erosion each behave when selected | Not run |
+| Third-party biomes | TerraBlender biome pages and cave classification survive Age creation/restart | Not run |
+| Optional integrations absent | Mod launches without JEI, Create/Ponder, Immersive Portals, Serene Seasons, or biome mods | Not run |
+| Optional integrations present | JEI pages/recipes, preview backends, seasonal behavior, and ambient sound work | Not run |
+| Optional-mod materials | Tagged ore/storage/source-fluid samples change live profile automatically | Not run |
+| Material overrides | Positive and zero `block_weight_overrides` values affect only named blocks | Not run |
+| Removed optional mod | Disposable copy launches without the mod; unknown sampled IDs stay serialized | Not run |
+| Removed symbol/handler | Frozen score and provider plan survive when nonessential data is removed | Not run |
+| Ordered modifiers | Five book-order cases below produce expected time and dangling costs | Not run |
+
+### Focused ordered-writing and optional-material checks for 0.5.8.18
+
+Use `/rivencraft age instability` in each newly bound Age; old Ages retain
+their original plan and score. Record each row as pass/fail with the Age name,
+world seed, installed optional mods, and the command output. The ordered
+modifier assertions are archived, not a claim that the stalled GameTest suite ran.
+
+| Book pages after Link Panel, in exact order | Expected result | Result |
+| --- | --- | --- |
+| Half Length, Double Length, Normal Time | Length combines to 1.25×, no dangling cost | Not run in game |
+| Normal Time, Zero Length | Sun keeps normal motion; one dangling +100 | Not run in game |
+| Rising, Normal Time, Setting | Rising start phase; Setting dangles +100 | Not run in game |
+| Half Length, Double Length, no celestial page | One combined pending length dangles +100; seeded clock remains | Not run in game |
+| Normal Time, Zero Length, Normal Time | Last sun consumes Zero Length; duplicate celestial cost remains separate | Not run in game |
+
+With a common-tagged ore/storage-block or source-fluid mod installed, bind
+comparable material-rich and ordinary Ages and wait for profiling thresholds.
+Verify the modded material contributes automatically, then restart and confirm
+the score/profile remains consistent. On a disposable copy, remove the mod and
+confirm Rivencraft launches without it; restore the mod before judging the
+world's registry-dependent terrain. Also check a zero-weight override and a
+positive override. These are optional-mod compatibility checks, not a new
+required dependency.

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=0.5.8.7
+mod_version=0.5.8.18
 immersive_portals_version=6.0.7
 terrablender_version=4.1.0.8
 serene_seasons_version_id=B6nTjh4b

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

@@ -62,6 +62,9 @@ public final class Rivencraft {
         NeoForge.EVENT_BUS.addListener(BookStandConversionHandler::onRightClickBlock);
         NeoForge.EVENT_BUS.addListener(AgeWeatherService::onLevelTickPost);
         NeoForge.EVENT_BUS.addListener(AgeInstabilityRuntime::onLevelTickPost);
+        NeoForge.EVENT_BUS.addListener(net.dnorberg.rivencraft.book.AgeBlockInstability::onChunkLoad);
+        NeoForge.EVENT_BUS.addListener(net.dnorberg.rivencraft.book.AgeBlockInstability::onServerTickPost);
+        NeoForge.EVENT_BUS.addListener(net.dnorberg.rivencraft.book.AgeBlockInstability::onServerStopping);
         NeoForge.EVENT_BUS.addListener(AgeEnvironmentalProviders::onLevelTickPost);
         NeoForge.EVENT_BUS.addListener(AgeEnvironmentalProviders::onLevelUnload);
         NeoForge.EVENT_BUS.addListener(AgeStatusEffectProviders::onServerTickPost);

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

@@ -0,0 +1,104 @@
+package net.dnorberg.rivencraft.book;
+
+import java.util.ArrayList;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+import net.dnorberg.rivencraft.config.RivencraftConfig;
+import net.dnorberg.rivencraft.writing.SymbolSemantics;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.SectionPos;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.chunk.LevelChunk;
+import net.minecraft.world.level.chunk.LevelChunkSection;
+import net.minecraft.util.RandomSource;
+
+/** Extra random block ticks from authored Accelerated pages, bounded to loaded player chunks. */
+final class AgeAcceleratedTicks {
+    private AgeAcceleratedTicks() {}
+
+    static void tick(ServerLevel level) {
+        int maximumAttempts = RivencraftConfig.acceleratedMaxAttempts();
+        if (maximumAttempts == 0) return;
+        AgeDefinition age = AgeRegistrySavedData.get(level)
+                .findByDimension(level.dimension().location()).orElse(null);
+        int pages = age == null || age.plan() == null ? 0 : acceleratedPages(age.plan());
+        if (pages == 0) return;
+
+        List<ChunkPos> chunks = loadedPlayerChunks(level);
+        if (chunks.isEmpty()) return;
+        int maximumChunks = Math.min(chunks.size(), RivencraftConfig.acceleratedMaxChunks());
+        int first = Math.floorMod(level.getServer().getTickCount(), chunks.size());
+        List<TickSection> eligible = new ArrayList<>();
+        for (int offset = 0; offset < maximumChunks; offset++) {
+            ChunkPos pos = chunks.get((first + offset) % chunks.size());
+            LevelChunk chunk = level.getChunkSource().getChunkNow(pos.x, pos.z);
+            if (chunk == null) continue;
+            LevelChunkSection[] sections = chunk.getSections();
+            for (int sectionIndex = 0; sectionIndex < sections.length; sectionIndex++) {
+                LevelChunkSection section = sections[sectionIndex];
+                if (!section.isRandomlyTickingBlocks()) continue;
+                int baseY = SectionPos.sectionToBlockCoord(chunk.getSectionYFromSectionIndex(sectionIndex));
+                eligible.add(new TickSection(pos, baseY, section));
+            }
+        }
+        if (eligible.isEmpty()) return;
+
+        // Legacy attempts three positions per random-ticking section per page. Divide
+        // the bounded total between sections before ticking any one of them, so a
+        // lower section cannot exhaust the entire budget ahead of surface crops.
+        int total = attemptBudget(pages, eligible.size(), maximumAttempts);
+        int perSection = total / eligible.size();
+        int remainder = total % eligible.size();
+        int firstSection = Math.floorMod(level.getServer().getTickCount(), eligible.size());
+        RandomSource random = level.getRandom();
+        for (int offset = 0; offset < eligible.size(); offset++) {
+            TickSection candidate = eligible.get((firstSection + offset) % eligible.size());
+            int samples = perSection + (offset < remainder ? 1 : 0);
+            for (int sample = 0; sample < samples; sample++) {
+                int x = random.nextInt(16);
+                int y = random.nextInt(16);
+                int z = random.nextInt(16);
+                BlockState state = candidate.section().getBlockState(x, y, z);
+                if (state.isRandomlyTicking()) {
+                    state.randomTick(level, new BlockPos(candidate.chunk().getMinBlockX() + x,
+                            candidate.baseY() + y, candidate.chunk().getMinBlockZ() + z), random);
+                }
+            }
+        }
+    }
+
+    static int attemptBudget(int pages, int sections, int maximumAttempts) {
+        if (pages < 0 || sections < 0 || maximumAttempts < 0)
+            throw new IllegalArgumentException("Negative accelerated tick budget input");
+        return (int) Math.min(maximumAttempts, Math.min(Integer.MAX_VALUE, 3L * pages * sections));
+    }
+
+    static int acceleratedPages(AgeGenerationPlan plan) {
+        return (int) plan.symbols().stream().filter(symbol ->
+                symbol.semantics().role() == SymbolSemantics.Role.ENVIRONMENT
+                        && symbol.semantics().value() instanceof SymbolSemantics.ChoiceValue choice
+                        && choice.id().equals("accelerated")).count();
+    }
+
+    private static List<ChunkPos> loadedPlayerChunks(ServerLevel level) {
+        Set<ChunkPos> chunks = new LinkedHashSet<>();
+        for (var player : level.players()) {
+            ChunkPos center = player.chunkPosition();
+            for (int x = -1; x <= 1; x++) {
+                for (int z = -1; z <= 1; z++) {
+                    int chunkX = center.x + x;
+                    int chunkZ = center.z + z;
+                    if (level.getChunkSource().hasChunk(chunkX, chunkZ)) {
+                        chunks.add(new ChunkPos(chunkX, chunkZ));
+                    }
+                }
+            }
+        }
+        return new ArrayList<>(chunks);
+    }
+
+    private record TickSection(ChunkPos chunk, int baseY, LevelChunkSection section) {}
+}

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

@@ -0,0 +1,327 @@
+package net.dnorberg.rivencraft.book;
+
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.config.RivencraftConfig;
+import net.dnorberg.rivencraft.writing.BlockSymbolPages;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.chunk.LevelChunk;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import net.neoforged.neoforge.common.Tags;
+import net.neoforged.neoforge.event.level.ChunkEvent;
+import net.neoforged.neoforge.event.server.ServerStoppingEvent;
+import net.neoforged.neoforge.event.tick.ServerTickEvent;
+
+/** Legacy-style excess-block profiling with gradual spawn-area generation. */
+public final class AgeBlockInstability {
+    // Legacy's watched blocks and factor-1 values; modern ore variants share their parent weight.
+    // Storage blocks are deliberate extensions, including the requested diamond-block case.
+    private static final Map<ResourceLocation, Double> VANILLA_WEIGHTS = weights();
+    private static final Map<String, Double> COMMON_MINERAL_WEIGHTS = Map.ofEntries(
+            Map.entry("coal", 5.0), Map.entry("sulfur", 5.0), Map.entry("sulphur", 5.0),
+            Map.entry("salt", 5.0), Map.entry("tin", 60.0), Map.entry("lead", 60.0),
+            Map.entry("aluminum", 60.0), Map.entry("aluminium", 60.0),
+            Map.entry("zinc", 60.0), Map.entry("copper", 60.0),
+            Map.entry("iron", 60.0), Map.entry("nickel", 200.0),
+            Map.entry("osmium", 200.0), Map.entry("silver", 200.0),
+            Map.entry("emerald", 200.0), Map.entry("ruby", 200.0),
+            Map.entry("sapphire", 200.0), Map.entry("redstone", 250.0),
+            Map.entry("gold", 750.0), Map.entry("uranium", 750.0),
+            Map.entry("platinum", 750.0), Map.entry("diamond", 4000.0),
+            Map.entry("iridium", 4000.0), Map.entry("netherite", 8000.0));
+    private static final int MAX_PENDING = 2048;
+    private static final int SAMPLES_PER_TICK = 4;
+    private static final int GENERATION_INTERVAL_TICKS = 20;
+    private static final List<ChunkPos> SPAWN_OFFSETS = spawnOffsets();
+    private static final Map<MinecraftServer, ArrayDeque<Pending>> PENDING = new java.util.WeakHashMap<>();
+    private static final Map<MinecraftServer, Map<ResourceLocation, Integer>> NEXT_SPAWN_SAMPLE =
+            new java.util.WeakHashMap<>();
+    private static final Map<MinecraftServer, Integer> NEXT_TARGET = new java.util.WeakHashMap<>();
+    private static final Map<MinecraftServer, Boolean> GENERATION_IN_FLIGHT =
+            new java.util.WeakHashMap<>();
+
+    private AgeBlockInstability() {}
+
+    /** Track recognized materials from installed mods without requiring any mod-specific API. */
+    static boolean tracked(ResourceLocation id) {
+        if (VANILLA_WEIGHTS.containsKey(id)) return true;
+        if (id.getNamespace().equals("minecraft") || id.getNamespace().equals("rivencraft")) return false;
+        if (!BuiltInRegistries.BLOCK.containsKey(id)) return false;
+        var block = BuiltInRegistries.BLOCK.get(id);
+        return eligibleMaterial(block) && (configuredOverride(id) != null || inferredModdedWeight(id, block) > 0);
+    }
+
+    static double weight(ResourceLocation id) {
+        Double vanilla = VANILLA_WEIGHTS.get(id);
+        if (vanilla != null) return vanilla;
+        if (id.getNamespace().equals("minecraft") || id.getNamespace().equals("rivencraft")
+                || !BuiltInRegistries.BLOCK.containsKey(id)) return 0;
+        var block = BuiltInRegistries.BLOCK.get(id);
+        if (!eligibleMaterial(block)) return 0;
+        return moddedWeight(id, inferredModdedWeight(id, block),
+                RivencraftConfig.moddedMaterialOverrides());
+    }
+
+    private static boolean eligibleMaterial(net.minecraft.world.level.block.Block block) {
+        return BlockSymbolPages.isRockMaterial(block) || BlockSymbolPages.isFluidMaterial(block);
+    }
+
+    private static Double configuredOverride(ResourceLocation id) {
+        return configuredOverride(id, RivencraftConfig.moddedMaterialOverrides());
+    }
+
+    private static Double configuredOverride(ResourceLocation id, List<? extends String> overrides) {
+        for (String entry : overrides) {
+            int separator = entry.lastIndexOf('=');
+            if (separator > 0 && entry.substring(0, separator).equals(id.toString()))
+                return (double) Integer.parseInt(entry.substring(separator + 1));
+        }
+        return null;
+    }
+
+    static double moddedWeight(ResourceLocation id, double inferred, List<? extends String> overrides) {
+        Double override = configuredOverride(id, overrides);
+        return override == null ? inferred : override;
+    }
+
+    private static double inferredModdedWeight(ResourceLocation id, net.minecraft.world.level.block.Block block) {
+        if (BlockSymbolPages.isFluidMaterial(block)) return 1.25;
+        var state = block.defaultBlockState();
+        String path = id.getPath();
+        boolean ore = state.is(Tags.Blocks.ORES) || path.endsWith("_ore") || path.contains("_ore_");
+        boolean storage = state.is(Tags.Blocks.STORAGE_BLOCKS)
+                || (path.endsWith("_block") || path.startsWith("block_of_"))
+                && namedMineralWeight(path) != null;
+        return inferredModdedWeight(id, ore, storage, false);
+    }
+
+    static double inferredModdedWeight(ResourceLocation id, boolean ore, boolean storage, boolean fluid) {
+        if (fluid) return 1.25;
+        Double named = namedMineralWeight(id.getPath());
+        if (ore) return named == null ? 60.0 : named;
+        if (storage) return named == null ? 120.0 : named;
+        return 0;
+    }
+
+    private static Double namedMineralWeight(String path) {
+        for (String part : path.split("[/_]")) {
+            Double value = COMMON_MINERAL_WEIGHTS.get(part);
+            if (value != null) return value;
+        }
+        return null;
+    }
+
+    public static void onChunkLoad(ChunkEvent.Load event) {
+        if (!(event.getLevel() instanceof ServerLevel level)
+                || !(event.getChunk() instanceof LevelChunk chunk)) return;
+        boolean overworld = level.dimension() == net.minecraft.world.level.Level.OVERWORLD;
+        if (!overworld && !AgeInstabilityRuntime.isAgeDimension(level.dimension().location())) return;
+        // Chunk-load callbacks can occur while chunk storage is updating. Defer saved-data
+        // access to a bounded server-tick lane to avoid reentering that storage path.
+        synchronized (PENDING) {
+            var queue = PENDING.computeIfAbsent(level.getServer(), ignored -> new ArrayDeque<>());
+            if (queue.size() < MAX_PENDING) queue.addLast(new Pending(level, chunk));
+        }
+    }
+
+    public static void onServerTickPost(ServerTickEvent.Post event) {
+        for (int index = 0; index < SAMPLES_PER_TICK; index++) {
+            Pending pending;
+            synchronized (PENDING) {
+                var queue = PENDING.get(event.getServer());
+                pending = queue == null ? null : queue.pollFirst();
+            }
+            if (pending == null) break;
+            var pos = pending.chunk().getPos();
+            if (pending.level().getChunkSource().hasChunk(pos.x, pos.z))
+                AgeBlockProfileSavedData.get(pending.level()).sample(pending.chunk());
+        }
+        if (event.getServer().getTickCount() % GENERATION_INTERVAL_TICKS == 0) {
+            generateNextSpawnSample(event.getServer());
+        }
+    }
+
+    public static void onServerStopping(ServerStoppingEvent event) {
+        synchronized (PENDING) { PENDING.remove(event.getServer()); }
+        NEXT_SPAWN_SAMPLE.remove(event.getServer());
+        NEXT_TARGET.remove(event.getServer());
+        GENERATION_IN_FLIGHT.remove(event.getServer());
+    }
+
+    /** Generate at most one chunk per second across the active Age and its Overworld baseline. */
+    private static void generateNextSpawnSample(MinecraftServer server) {
+        if (GENERATION_IN_FLIGHT.containsKey(server)) return;
+        List<SampleTarget> targets = new ArrayList<>();
+        for (ServerLevel level : server.getAllLevels()) {
+            if (!AgeInstabilityRuntime.isAgeDimension(level.dimension().location())
+                    || level.players().isEmpty()) continue;
+            AgeDefinition age = AgeRegistrySavedData.get(level)
+                    .findByDimension(level.dimension().location()).orElse(null);
+            if (age == null || age.instability().version() < 2) continue;
+            targets.add(new SampleTarget(level,
+                    age.spawn() == null ? level.getSharedSpawnPos() : age.spawn(),
+                    AgeBlockProfileSavedData.MIN_AGE_SAMPLES));
+        }
+        if (targets.isEmpty()) return;
+        ServerLevel overworld = server.overworld();
+        targets.add(0, new SampleTarget(overworld, overworld.getSharedSpawnPos(),
+                AgeBlockProfileSavedData.MIN_BASELINE_SAMPLES));
+        int first = Math.floorMod(NEXT_TARGET.getOrDefault(server, 0), targets.size());
+        for (int offset = 0; offset < targets.size(); offset++) {
+            int index = (first + offset) % targets.size();
+            SampleTarget target = targets.get(index);
+            if (generateNextSpawnSample(target.level(), target.origin(), target.minimum(), server)) {
+                NEXT_TARGET.put(server, index + 1);
+                return;
+            }
+        }
+    }
+
+    private static boolean generateNextSpawnSample(ServerLevel level, net.minecraft.core.BlockPos origin,
+                                                   int minimum, MinecraftServer server) {
+        AgeBlockProfileSavedData profile = AgeBlockProfileSavedData.get(level);
+        if (profile.count() >= minimum) return false;
+        Map<ResourceLocation, Integer> cursors = NEXT_SPAWN_SAMPLE.computeIfAbsent(server,
+                ignored -> new HashMap<>());
+        ResourceLocation dimension = level.dimension().location();
+        int index = cursors.getOrDefault(dimension, 0);
+        ChunkPos center = new ChunkPos(origin);
+        while (index < SPAWN_OFFSETS.size()) {
+            ChunkPos offset = SPAWN_OFFSETS.get(index++);
+            ChunkPos target = new ChunkPos(center.x + offset.x, center.z + offset.z);
+            if (profile.contains(target)) continue;
+            cursors.put(dimension, index);
+            GENERATION_IN_FLIGHT.put(server, true);
+            // getChunkFuture blocks when called on the server thread. Its off-thread
+            // path schedules generation on Minecraft's chunk executor instead.
+            CompletableFuture.supplyAsync(() -> level.getChunkSource()
+                            .getChunkFuture(target.x, target.z, ChunkStatus.FULL, true))
+                    .thenCompose(future -> future)
+                    .whenComplete((result, error) -> server.execute(() -> {
+                        GENERATION_IN_FLIGHT.remove(server);
+                        if (error != null) {
+                            Rivencraft.LOGGER.warn("Could not profile chunk {} in {}", target, dimension, error);
+                        } else if (result.orElse(null) instanceof LevelChunk chunk) {
+                            profile.sample(chunk);
+                        }
+                    }));
+            return true;
+        }
+        return false;
+    }
+
+    private static List<ChunkPos> spawnOffsets() {
+        List<ChunkPos> offsets = new ArrayList<>(AgeBlockProfileSavedData.MAX_SAMPLES);
+        offsets.add(new ChunkPos(0, 0));
+        for (int radius = 1; offsets.size() < AgeBlockProfileSavedData.MAX_SAMPLES; radius++) {
+            for (int x = -radius; x <= radius; x++) {
+                offsets.add(new ChunkPos(x, -radius));
+                offsets.add(new ChunkPos(x, radius));
+            }
+            for (int z = -radius + 1; z < radius; z++) {
+                offsets.add(new ChunkPos(-radius, z));
+                offsets.add(new ChunkPos(radius, z));
+            }
+        }
+        return List.copyOf(offsets.subList(0, AgeBlockProfileSavedData.MAX_SAMPLES));
+    }
+
+    /** Zero until the Age exceeds 400 samples and the baseline reaches 500. */
+    static int score(AgeBlockProfileSavedData age, AgeBlockProfileSavedData baseline) {
+        return score(age.totals(), age.count(), baseline.totals(), baseline.count());
+    }
+
+    static int score(Map<ResourceLocation, Long> age, int ageChunks,
+                     Map<ResourceLocation, Long> baseline, int baselineChunks) {
+        if (ageChunks < AgeBlockProfileSavedData.MIN_AGE_SAMPLES
+                || baselineChunks < AgeBlockProfileSavedData.MIN_BASELINE_SAMPLES) return 0;
+        double result = 0;
+        Set<ResourceLocation> watched = new HashSet<>(age.keySet());
+        watched.addAll(baseline.keySet());
+        for (ResourceLocation id : watched) {
+            double weight = weight(id);
+            if (weight <= 0) continue;
+            double excess = age.getOrDefault(id, 0L) / (double) ageChunks
+                    - 1.05 * baseline.getOrDefault(id, 0L) / (double) baselineChunks;
+            if (excess > 0) result += excess * weight;
+        }
+        return (int) Math.min(100_000, Math.round(result));
+    }
+
+    public static int score(ServerLevel level, AgeDefinition age) {
+        if (age.instability().version() < 2
+                || !AgeInstabilityRuntime.isAgeDimension(level.dimension().location())
+                || !age.dimensionId().equals(level.dimension().location())) return 0;
+        return score(AgeBlockProfileSavedData.get(level),
+                AgeBlockProfileSavedData.get(level.getServer().overworld()));
+    }
+
+    public static int sampledChunks(ServerLevel level) {
+        return AgeBlockProfileSavedData.get(level).count();
+    }
+
+    public static int effectiveScore(ServerLevel level, AgeDefinition age) {
+        return difficultyScore((long) age.instability().score() + score(level, age),
+                RivencraftConfig.instabilityDifficulty());
+    }
+
+    public static int difficultyScore(long rawScore, int difficulty) {
+        double multiplier = switch (difficulty) {
+            case 0 -> 0.25;
+            case 1 -> 0.5;
+            case 2 -> 1.0;
+            case 3 -> 1.75;
+            default -> throw new IllegalArgumentException("Unknown instability difficulty " + difficulty);
+        };
+        return (int) Math.min(Integer.MAX_VALUE, Math.max(0, rawScore * multiplier));
+    }
+
+    public static AgeInstabilityPlan effectivePlan(ServerLevel level, AgeDefinition age) {
+        int blockScore = score(level, age);
+        if (blockScore == 0 && RivencraftConfig.instabilityDifficulty() == 2) return age.instabilityPlan();
+        int combined = effectiveScore(level, age);
+        AgeInstability effective = new AgeInstability(AgeInstability.CURRENT_VERSION, combined,
+                java.util.List.of(new AgeInstability.Contribution("effective_block_profile", -1, combined,
+                        "Saved writing score plus sampled excess blocks")));
+        return AgeInstabilityPlan.select(effective, age.seed());
+    }
+
+    private static Map<ResourceLocation, Double> weights() {
+        Map<ResourceLocation, Double> values = new HashMap<>();
+        add(values, 5, "coal_ore", "deepslate_coal_ore", "lapis_ore", "deepslate_lapis_ore");
+        add(values, 60, "iron_ore", "deepslate_iron_ore");
+        add(values, 200, "emerald_ore", "deepslate_emerald_ore");
+        add(values, 250, "redstone_ore", "deepslate_redstone_ore");
+        add(values, 750, "gold_ore", "deepslate_gold_ore");
+        add(values, 4000, "diamond_ore", "deepslate_diamond_ore", "diamond_block");
+        add(values, 20, "nether_quartz_ore");
+        add(values, 50, "glowstone");
+        values.put(ResourceLocation.parse("rivencraft:crystal_block"), 20.0);
+        // Valuable blocks introduced after Legacy, and storage forms authorable in Rivencraft.
+        add(values, 200, "emerald_block");
+        add(values, 750, "gold_block", "raw_gold_block");
+        add(values, 4000, "ancient_debris");
+        add(values, 60, "iron_block", "raw_iron_block");
+        add(values, 8000, "netherite_block");
+        return Map.copyOf(values);
+    }
+
+    private static void add(Map<ResourceLocation, Double> values, int weight, String... paths) {
+        for (String path : paths) values.put(ResourceLocation.withDefaultNamespace(path), (double) weight);
+    }
+
+    private record Pending(ServerLevel level, LevelChunk chunk) {}
+
+    private record SampleTarget(ServerLevel level, net.minecraft.core.BlockPos origin, int minimum) {}
+}

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

@@ -0,0 +1,96 @@
+package net.dnorberg.rivencraft.book;
+
+import java.util.HashMap;
+import java.util.Map;
+import net.minecraft.core.HolderLookup;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.ListTag;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.util.datafix.DataFixTypes;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.chunk.LevelChunk;
+import net.minecraft.world.level.saveddata.SavedData;
+
+/** Persistent, bounded samples of generated block abundance for one dimension. */
+public final class AgeBlockProfileSavedData extends SavedData {
+    private static final int PROFILE_VERSION = 2;
+    static final int MIN_AGE_SAMPLES = 401;
+    static final int MIN_BASELINE_SAMPLES = 500;
+    static final int MAX_SAMPLES = 1024;
+    private static final Factory<AgeBlockProfileSavedData> FACTORY = new Factory<>(
+            AgeBlockProfileSavedData::new, AgeBlockProfileSavedData::load, DataFixTypes.SAVED_DATA_MAP_DATA);
+
+    private final Map<Long, Map<ResourceLocation, Integer>> samples = new HashMap<>();
+    private final Map<ResourceLocation, Long> totals = new HashMap<>();
+
+    AgeBlockProfileSavedData() {}
+
+    static AgeBlockProfileSavedData get(ServerLevel level) {
+        return level.getDataStorage().computeIfAbsent(FACTORY, "rivencraft_block_profile");
+    }
+
+    int count() { return samples.size(); }
+
+    boolean contains(ChunkPos pos) { return samples.containsKey(pos.toLong()); }
+
+    Map<ResourceLocation, Long> totals() { return Map.copyOf(totals); }
+
+    boolean sample(LevelChunk chunk) {
+        if (samples.size() >= MAX_SAMPLES || samples.containsKey(chunk.getPos().toLong())) return false;
+        Map<ResourceLocation, Integer> counts = new HashMap<>();
+        for (var section : chunk.getSections()) {
+            if (section.hasOnlyAir()) continue;
+            section.getStates().count((state, amount) -> {
+                ResourceLocation id = BuiltInRegistries.BLOCK.getKey(state.getBlock());
+                if (AgeBlockInstability.tracked(id)) counts.merge(id, amount, Integer::sum);
+            });
+        }
+        add(chunk.getPos(), counts);
+        return true;
+    }
+
+    void add(ChunkPos pos, Map<ResourceLocation, Integer> counts) {
+        if (samples.size() >= MAX_SAMPLES || samples.containsKey(pos.toLong())) return;
+        samples.put(pos.toLong(), Map.copyOf(counts));
+        counts.forEach((id, amount) -> totals.merge(id, amount.longValue(), Long::sum));
+        setDirty();
+    }
+
+    @Override
+    public CompoundTag save(CompoundTag tag, HolderLookup.Provider registries) {
+        tag.putInt("Version", PROFILE_VERSION);
+        ListTag entries = new ListTag();
+        for (var sample : samples.entrySet()) {
+            CompoundTag entry = new CompoundTag();
+            entry.putLong("Chunk", sample.getKey());
+            CompoundTag blocks = new CompoundTag();
+            sample.getValue().forEach((id, amount) -> blocks.putInt(id.toString(), amount));
+            entry.put("Blocks", blocks);
+            entries.add(entry);
+        }
+        tag.put("Samples", entries);
+        return tag;
+    }
+
+    static AgeBlockProfileSavedData load(CompoundTag tag, HolderLookup.Provider registries) {
+        AgeBlockProfileSavedData data = new AgeBlockProfileSavedData();
+        // Earlier profiles omitted some modded candidates. Resample rather than
+        // mixing incompatible chunk averages after installing content mods.
+        if (tag.getInt("Version") != PROFILE_VERSION) return data;
+        ListTag entries = tag.getList("Samples", CompoundTag.TAG_COMPOUND);
+        for (int index = 0; index < Math.min(entries.size(), MAX_SAMPLES); index++) {
+            CompoundTag entry = entries.getCompound(index);
+            CompoundTag blocks = entry.getCompound("Blocks");
+            Map<ResourceLocation, Integer> counts = new HashMap<>();
+            for (String key : blocks.getAllKeys()) {
+                ResourceLocation id = ResourceLocation.tryParse(key);
+                if (id != null && blocks.getInt(key) > 0)
+                    counts.put(id, blocks.getInt(key));
+            }
+            data.add(new ChunkPos(entry.getLong("Chunk")), counts);
+        }
+        return data;
+    }
+}

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

@@ -51,6 +51,8 @@ public final class AgeDecayProviders {
         AgeDefinition age = AgeRegistrySavedData.get(level).findByDimension(level.dimension().location()).orElse(null);
         if (age == null) return -1;
         ResourceLocation id = id("decay" + color.getSerializedName());
+        if (!RivencraftConfig.instabilityEnabled() || !AgeInstabilityControls.get(level).enabled(age.id())
+                || !RivencraftConfig.instabilityProviderEnabled(id)) return -1;
         int changed = 0;
         for (int i = 0; i < Math.min(count, 32); i++) {
             AgeInstabilityRuntime.Budget budget = new AgeInstabilityRuntime.Budget(1);

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

@@ -10,7 +10,17 @@ public final class AgeEnvironmentCompiler {
 
     public static AgeTraits apply(AgeGenerationPlan plan, AgeTraits seeded) {
         if (plan == null) return seeded;
+        if (plan.version() >= 4) {
+            AgeTraits base = applyLegacy(plan, seeded);
+            CelestialWriting ordered = orderedCelestial(plan, seeded);
+            return new AgeTraits(base.biomeDistribution(), base.lighting(), base.weather(),
+                    ordered.period(), base.celestialAngle(), ordered.phase());
+        }
+        return applyLegacy(plan, seeded);
+    }
 
+    /** Version-3 plans keep their frozen, stage-sorted environment interpretation. */
+    private static AgeTraits applyLegacy(AgeGenerationPlan plan, AgeTraits seeded) {
         AgeTraits.Lighting lighting = seeded.lighting();
         AgeTraits.Weather weather = seeded.weather();
         double period = seeded.celestialPeriod();
@@ -73,10 +83,45 @@ public final class AgeEnvironmentCompiler {
     }
 
     public static boolean hasWrittenPhase(AgeGenerationPlan plan) {
-        return plan != null && plan.activeSymbols().stream()
+        if (plan == null) return false;
+        if (plan.version() >= 4) return orderedCelestial(plan, null).writtenPhase();
+        return plan.activeSymbols().stream()
                 .anyMatch(symbol -> symbol.semantics().role() == SymbolSemantics.Role.PHASE_MODIFIER);
     }
 
+    private static CelestialWriting orderedCelestial(AgeGenerationPlan plan, AgeTraits seeded) {
+        double period = seeded == null ? 1.0D : seeded.celestialPeriod();
+        float phase = seeded == null ? 0.0F : seeded.celestialPhase();
+        Double pendingPeriod = null;
+        Float pendingPhase = null;
+        boolean writtenPhase = false;
+        for (AgeGenerationPlan.ResolvedSymbol symbol : plan.symbols()) {
+            SymbolSemantics semantics = symbol.semantics();
+            switch (semantics.role()) {
+                case PERIOD_MODIFIER -> {
+                    double next = ((SymbolSemantics.NumberValue) semantics.value()).amount();
+                    pendingPeriod = pendingPeriod == null ? next : (pendingPeriod + next) / 2.0D;
+                }
+                case PHASE_MODIFIER -> {
+                    float next = (float) ((SymbolSemantics.NumberValue) semantics.value()).amount();
+                    pendingPhase = pendingPhase == null ? next : circularMidpoint(pendingPhase, next);
+                }
+                case CELESTIAL -> {
+                    period = pendingPeriod == null ? 1.0D : pendingPeriod;
+                    phase = pendingPhase == null ? (seeded == null ? 0.0F : seeded.celestialPhase())
+                            : pendingPhase / 360.0F;
+                    writtenPhase = pendingPhase != null;
+                    pendingPeriod = null;
+                    pendingPhase = null;
+                }
+                default -> { }
+            }
+        }
+        return new CelestialWriting(period, phase, writtenPhase);
+    }
+
+    private record CelestialWriting(double period, float phase, boolean writtenPhase) { }
+
     public static int previewSkyColor(ResourceLocation effects, int biomeSkyColor) {
         if (effects.equals(BuiltinDimensionTypes.NETHER_EFFECTS)) return 0xFF6B2725;
         if (effects.equals(BuiltinDimensionTypes.END_EFFECTS)) return 0xFF211835;

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

@@ -60,6 +60,9 @@ public final class AgeEnvironmentalProviders {
         if (!AgeInstabilityRuntime.isAgeDimension(level.dimension().location())) return -1;
         AgeDefinition age = AgeRegistrySavedData.get(level).findByDimension(level.dimension().location()).orElse(null);
         if (age == null) return -1;
+        if (!RivencraftConfig.instabilityEnabled() || !AgeInstabilityControls.get(level).enabled(age.id())
+                || !RivencraftConfig.instabilityProviderEnabled(ResourceLocation.fromNamespaceAndPath(
+                        Rivencraft.MOD_ID, effect.equals("meteor") ? "meteors" : effect))) return 0;
         List<ChunkPos> chunks = AgeHazardProviders.loadedChunksNearPlayers(level, 16);
         if (chunks.isEmpty()) return 0;
         var context = new AgeInstabilityRuntime.Context(level, age, chunks,
@@ -77,7 +80,7 @@ public final class AgeEnvironmentalProviders {
             }
             case "erosion" -> {
                 if (!RivencraftConfig.erosionEnabled() || !AgeHazardProviders.canMutate(level)
-                        || age.instability().score() < InstabilityProviderCatalog.Deck.DESTRUCTIVE.entryCost()
+                        || AgeBlockInstability.effectiveScore(level, age) < InstabilityProviderCatalog.Deck.DESTRUCTIVE.entryCost()
                         || !(player.pick(6.0, 0.0F, false) instanceof BlockHitResult hit)) yield 0;
                 BlockPos pos = hit.getBlockPos();
                 yield erodeAt(context, pos) ? 1 : 0;
@@ -91,10 +94,10 @@ public final class AgeEnvironmentalProviders {
     }
 
     static void tickPlanned(ServerLevel level, AgeDefinition age, long tick) {
-        List<AgeInstabilityPlan.ProviderLevel> cards = age.instabilityPlan().providers().stream()
+        List<AgeInstabilityPlan.ProviderLevel> cards = AgeBlockInstability.effectivePlan(level, age).providers().stream()
                 .filter(card -> isEnvironmental(card.id())).toList();
         boolean optInErosion = RivencraftConfig.erosionEnabled()
-                && age.instability().score() >= InstabilityProviderCatalog.Deck.DESTRUCTIVE.entryCost();
+                && AgeBlockInstability.effectiveScore(level, age) >= InstabilityProviderCatalog.Deck.DESTRUCTIVE.entryCost();
         if (cards.isEmpty() && !optInErosion) return;
         List<ChunkPos> chunks = AgeHazardProviders.loadedChunksNearPlayers(level,
                 RivencraftConfig.hazardsMaxChunks());
@@ -165,7 +168,8 @@ public final class AgeEnvironmentalProviders {
             return;
         }
         AgeDefinition age = AgeRegistrySavedData.get(level).findByDimension(level.dimension().location()).orElse(null);
-        if (age == null) {
+        if (age == null || !AgeInstabilityControls.get(level).enabled(age.id())
+                || !RivencraftConfig.instabilityProviderEnabled(METEORS)) {
             ACTIVE.remove(level);
             return;
         }

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

@@ -18,7 +18,7 @@ import net.minecraft.resources.ResourceLocation;
 public record AgeGenerationPlan(int version, long ageSeed, OrderedWriting writing, List<ResolvedSymbol> symbols,
                                 AgeRuntimeProfile runtimeProfile, AgeBiomeSelection biomeSelection,
                                 List<Integer> activeSymbolIndices, int writingInstability) {
-    public static final int CURRENT_VERSION = 3;
+    public static final int CURRENT_VERSION = 4;
 
     public AgeGenerationPlan {
         if (version < 1 || version > CURRENT_VERSION) {

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

@@ -8,6 +8,7 @@ import java.util.Optional;
 import java.util.Random;
 import java.util.Set;
 import java.util.UUID;
+import java.util.function.Predicate;
 import net.dnorberg.rivencraft.Rivencraft;
 import net.dnorberg.rivencraft.config.RivencraftConfig;
 import net.minecraft.core.BlockPos;
@@ -56,7 +57,7 @@ public final class AgeHazardProviders {
     /** Roll every selected hazard card each scheduler pass, independently of other providers. */
     static void tickPlanned(ServerLevel level, AgeDefinition age, long tick) {
         if (!RivencraftConfig.hazardsEnabled()) return;
-        List<AgeInstabilityPlan.ProviderLevel> hazards = age.instabilityPlan().providers().stream()
+        List<AgeInstabilityPlan.ProviderLevel> hazards = AgeBlockInstability.effectivePlan(level, age).providers().stream()
                 .filter(provider -> isHazard(provider.id())).toList();
         if (hazards.isEmpty()) return;
         List<ChunkPos> chunks = loadedChunksNearPlayers(level, RivencraftConfig.hazardsMaxChunks());
@@ -69,18 +70,27 @@ public final class AgeHazardProviders {
     }
 
     static List<ChunkPos> loadedChunksNearPlayers(ServerLevel level, int maximum) {
+        List<ChunkPos> players = level.players().stream()
+                .sorted(Comparator.comparing(Entity::getUUID))
+                .map(ServerPlayer::chunkPosition).toList();
+        return candidateChunks(players, maximum,
+                chunk -> level.getChunkSource().hasChunk(chunk.x, chunk.z));
+    }
+
+    /** Pure candidate selection; the caller's predicate must only report already-loaded chunks. */
+    static List<ChunkPos> candidateChunks(List<ChunkPos> players, int maximum,
+                                           Predicate<ChunkPos> loaded) {
+        if (maximum <= 0) return List.of();
         Set<ChunkPos> chunks = new LinkedHashSet<>();
-        List<ServerPlayer> players = level.players().stream()
-                .sorted(Comparator.comparing(Entity::getUUID)).toList();
         for (int radius = 0; radius <= 4; radius++) {
             for (int dx = -radius; dx <= radius; dx++) {
                 for (int dz = -radius; dz <= radius; dz++) {
                     if (Math.max(Math.abs(dx), Math.abs(dz)) != radius) continue;
-                    for (ServerPlayer player : players) {
-                        ChunkPos center = player.chunkPosition();
+                    for (ChunkPos center : players) {
                         int x = center.x + dx;
                         int z = center.z + dz;
-                        if (level.getChunkSource().hasChunk(x, z)) chunks.add(new ChunkPos(x, z));
+                        ChunkPos candidate = new ChunkPos(x, z);
+                        if (loaded.test(candidate)) chunks.add(candidate);
                         if (chunks.size() >= maximum) return List.copyOf(chunks);
                     }
                 }
@@ -96,6 +106,8 @@ public final class AgeHazardProviders {
                 || !AgeInstabilityRuntime.isAgeDimension(level.dimension().location())) return -1;
         AgeDefinition age = AgeRegistrySavedData.get(level).findByDimension(level.dimension().location()).orElse(null);
         if (age == null) return -1;
+        if (!RivencraftConfig.instabilityEnabled() || !AgeInstabilityControls.get(level).enabled(age.id())
+                || !RivencraftConfig.instabilityProviderEnabled(lightning ? LIGHTNING : EXPLOSIONS)) return -1;
         AgeHazardSavedData data = AgeHazardSavedData.get(level);
         if (!data.ready(lightning, level.getGameTime(), RivencraftConfig.hazardsMinInterval())) return 0;
         ChunkPos center = player.chunkPosition();
@@ -198,7 +210,8 @@ public final class AgeHazardProviders {
     static void explodeBounded(ServerLevel level, AgeDefinition age, ChunkPos chunk, BlockPos pos,
             boolean blockDamage, boolean playerDamage, boolean ignite, int maxBlocks, int maxEntities,
             int maxDamage, int radius) {
-        boolean grief = canMutate(level) && blockDamage && maxBlocks > 0;
+        boolean grief = destructiveBlocksAllowed(RivencraftConfig.instabilityWorldMutation(),
+                level.getGameRules().getBoolean(GameRules.RULE_MOBGRIEFING), blockDamage, maxBlocks);
         boolean fire = grief && ignite
                 && level.getGameRules().getBoolean(GameRules.RULE_DOFIRETICK);
         Explosion explosion = level.explode(null, null, new BoundedExplosion(level, age, chunk, grief,
@@ -237,6 +250,19 @@ public final class AgeHazardProviders {
                 && level.getGameRules().getBoolean(GameRules.RULE_MOBGRIEFING);
     }
 
+    static boolean destructiveBlocksAllowed(boolean worldMutation, boolean mobGriefing,
+                                            boolean blockDamage, int maxBlocks) {
+        return worldMutation && mobGriefing && blockDamage && maxBlocks > 0;
+    }
+
+    static boolean protectedBlock(ServerLevel level, AgeDefinition age, BlockPos pos, BlockState state) {
+        return state.isAir() || state.hasBlockEntity() || state.is(Blocks.TNT)
+                || state.is(AgeDecayProviders.PROTECTED) || state.is(BlockTags.PORTALS)
+                || AgeDecayProviders.isSpawnProtected(age, pos)
+                || state.getDestroySpeed(level, pos) < 0
+                || BuiltInRegistries.BLOCK.getKey(state.getBlock()).getNamespace().equals(Rivencraft.MOD_ID);
+    }
+
     private static boolean eligibleEntity(Entity entity) {
         return eligibleEntity(entity, RivencraftConfig.hazardsPlayerDamage());
     }
@@ -285,12 +311,7 @@ public final class AgeHazardProviders {
         @Override
         public boolean shouldBlockExplode(Explosion explosion, BlockGetter reader, BlockPos pos,
                 BlockState state, float power) {
-            if (!grief || !inLoadedChunk(pos) || state.isAir() || state.hasBlockEntity()
-                    || state.is(Blocks.TNT)
-                    || state.is(AgeDecayProviders.PROTECTED) || state.is(BlockTags.PORTALS)
-                    || AgeDecayProviders.isSpawnProtected(age, pos)
-                    || state.getDestroySpeed(level, pos) < 0
-                    || BuiltInRegistries.BLOCK.getKey(state.getBlock()).getNamespace().equals(Rivencraft.MOD_ID)) return false;
+            if (!grief || !inLoadedChunk(pos) || protectedBlock(level, age, pos, state)) return false;
             if (approved.contains(pos)) return true;
             if (approved.size() >= maxBlocks) return false;
             var actor = FakePlayerFactory.getMinecraft(level);

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

@@ -13,7 +13,7 @@ import net.minecraft.resources.ResourceLocation;
 
 /** Frozen, server-owned score. Only new Age creation consults the current symbol catalog. */
 public record AgeInstability(int version, int score, List<Contribution> breakdown) {
-    public static final int CURRENT_VERSION = 1;
+    public static final int CURRENT_VERSION = 2;
     private static final int BRIGHT_LIGHTING_COST = 500;
     private static final int EXCESS_LEGACY_STRUCTURE_COST = 100;
     private static final int FORCED_STRUCTURE_BIOME_COST = 100;
@@ -35,7 +35,8 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
     );
 
     public AgeInstability {
-        if (version != CURRENT_VERSION) throw new IllegalArgumentException("Unsupported instability version " + version);
+        if (version < 1 || version > CURRENT_VERSION)
+            throw new IllegalArgumentException("Unsupported instability version " + version);
         breakdown = List.copyOf(breakdown);
         if (score < 0 || score != breakdown.stream().mapToInt(Contribution::points).sum()) {
             throw new IllegalArgumentException("Instability score does not match breakdown");
@@ -44,7 +45,7 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
 
     /** Pre-scoring saves are explicitly neutral, never rescored from current data packs. */
     public static AgeInstability legacyNeutral() {
-        return new AgeInstability(CURRENT_VERSION, 0,
+        return new AgeInstability(1, 0,
                 List.of(new Contribution("legacy_neutral", -1, 0, "Age predates frozen instability scoring")));
     }
 
@@ -55,13 +56,20 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
             contributions.add(new Contribution("random_baseline", -1, 0, "Page-free or Link-Panel-only Age"));
         } else {
             contributions.add(new Contribution("authored_baseline", -1, 0, "Authored Age"));
-            WritingGrammar.Result parsed = WritingGrammar.parse(plan.writing());
-            if (!parsed.canCreate() || parsed.writingInstability() != plan.writingInstability()) {
-                throw new IllegalArgumentException("Writing changed between Age compilation and scoring");
-            }
-            for (WritingGrammar.Diagnostic diagnostic : parsed.diagnostics()) {
-                contributions.add(new Contribution(diagnostic.code().name().toLowerCase(java.util.Locale.ROOT),
-                        diagnostic.index(), diagnostic.instability(), diagnostic.message()));
+            if (plan.version() < 4) {
+                // An old plan's writing cost was frozen under the previous grammar.
+                // Never validate it against the new ordered-modifier interpretation.
+                contributions.add(new Contribution("legacy_writing", -1, plan.writingInstability(),
+                        "Writing cost frozen by the original Age plan"));
+            } else {
+                WritingGrammar.Result parsed = WritingGrammar.parse(plan.writing());
+                if (!parsed.canCreate() || parsed.writingInstability() != plan.writingInstability()) {
+                    throw new IllegalArgumentException("Writing changed between Age compilation and scoring");
+                }
+                for (WritingGrammar.Diagnostic diagnostic : parsed.diagnostics()) {
+                    contributions.add(new Contribution(diagnostic.code().name().toLowerCase(java.util.Locale.ROOT),
+                            diagnostic.index(), diagnostic.instability(), diagnostic.message()));
+                }
             }
             addAuditedSymbolCosts(plan, registries, contributions);
         }
@@ -81,6 +89,24 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
                                               List<Contribution> contributions) {
         Map<ResourceLocation, Integer> structureCounts = new HashMap<>();
         for (AgeGenerationPlan.ResolvedSymbol symbol : plan.symbols()) {
+            if (symbol.semantics().role()
+                    == net.dnorberg.rivencraft.writing.SymbolSemantics.Role.ENVIRONMENT
+                    && symbol.semantics().value()
+                    instanceof net.dnorberg.rivencraft.writing.SymbolSemantics.ChoiceValue choice
+                    && choice.id().equals("accelerated")) {
+                contributions.add(new Contribution("accelerated", symbol.index(), 1000,
+                        "Authored accelerated random ticks"));
+                continue;
+            }
+            if (symbol.semantics().role()
+                    == net.dnorberg.rivencraft.writing.SymbolSemantics.Role.CORRUPTED) {
+                String size = ((net.dnorberg.rivencraft.writing.SymbolSemantics.ChoiceValue)
+                        symbol.semantics().value()).id();
+                int cost = corruptedCost(size);
+                contributions.add(new Contribution("corrupted_" + size, symbol.index(), cost,
+                        "Legacy corrupted " + size + " feature page"));
+                continue;
+            }
             if (symbol.semantics().role()
                     == net.dnorberg.rivencraft.writing.SymbolSemantics.Role.LIGHTING
                     && symbol.semantics().value()
@@ -117,6 +143,15 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
                 ? EXCESS_LEGACY_STRUCTURE_COST : 0;
     }
 
+    static int corruptedCost(String size) {
+        return switch (size) {
+            case "large" -> 0;
+            case "medium" -> 1000;
+            case "small" -> 2000;
+            default -> throw new IllegalArgumentException("Unknown corrupted page size " + size);
+        };
+    }
+
     /** Current totals exposed to diagnostics. Player-driven mutable bonuses are deliberately disabled. */
     public Totals totals() {
         return new Totals(score, 0, 0, score);

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

@@ -0,0 +1,55 @@
+package net.dnorberg.rivencraft.book;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+import net.minecraft.core.HolderLookup;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.ListTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.util.datafix.DataFixTypes;
+import net.minecraft.world.level.saveddata.SavedData;
+
+/** Per-world operator overrides. Absence means enabled; scores and plans stay immutable. */
+public final class AgeInstabilityControls extends SavedData {
+    private static final String DATA_NAME = "rivencraft_instability_controls";
+    private static final Factory<AgeInstabilityControls> FACTORY = new Factory<>(
+            AgeInstabilityControls::new, AgeInstabilityControls::load, DataFixTypes.SAVED_DATA_MAP_DATA);
+    private final Set<UUID> disabled = new HashSet<>();
+
+    public static AgeInstabilityControls get(ServerLevel level) {
+        return level.getServer().overworld().getDataStorage().computeIfAbsent(FACTORY, DATA_NAME);
+    }
+
+    public boolean enabled(UUID ageId) {
+        return !disabled.contains(ageId);
+    }
+
+    public boolean setEnabled(UUID ageId, boolean enabled) {
+        boolean changed = enabled ? disabled.remove(ageId) : disabled.add(ageId);
+        if (changed) setDirty();
+        return changed;
+    }
+
+    static AgeInstabilityControls load(CompoundTag tag, HolderLookup.Provider registries) {
+        AgeInstabilityControls controls = new AgeInstabilityControls();
+        ListTag entries = tag.getList("DisabledAges", CompoundTag.TAG_COMPOUND);
+        for (int index = 0; index < entries.size(); index++) {
+            CompoundTag entry = entries.getCompound(index);
+            if (entry.hasUUID("Id")) controls.disabled.add(entry.getUUID("Id"));
+        }
+        return controls;
+    }
+
+    @Override
+    public CompoundTag save(CompoundTag tag, HolderLookup.Provider registries) {
+        ListTag entries = new ListTag();
+        disabled.stream().sorted().forEach(id -> {
+            CompoundTag entry = new CompoundTag();
+            entry.putUUID("Id", id);
+            entries.add(entry);
+        });
+        tag.put("DisabledAges", entries);
+        return tag;
+    }
+}

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

@@ -38,8 +38,11 @@ public final class AgeInstabilityRuntime {
     }
 
     public static void onLevelTickPost(LevelTickEvent.Post event) {
-        if (!(event.getLevel() instanceof ServerLevel level) || !RivencraftConfig.instabilityEnabled()
+        if (!(event.getLevel() instanceof ServerLevel level)
                 || !isAgeDimension(level.dimension().location()) || level.players().isEmpty()) return;
+        // Authored environmental pages are active Age rules, not selected instability cards.
+        AgeAcceleratedTicks.tick(level);
+        if (!RivencraftConfig.instabilityEnabled()) return;
         MinecraftServer server = level.getServer();
         long tick = server.getTickCount();
         int cooldown = RivencraftConfig.instabilityCooldown();
@@ -52,7 +55,8 @@ public final class AgeInstabilityRuntime {
         if (!admitted(state.eligible, level.dimension().location(), tick / cooldown,
                 RivencraftConfig.instabilityMaxAges())) return;
         AgeDefinition age = AgeRegistrySavedData.get(level).findByDimension(level.dimension().location()).orElse(null);
-        if (age == null || age.instabilityPlan().providers().isEmpty()) return;
+        if (age == null || AgeBlockInstability.effectivePlan(level, age).providers().isEmpty()
+                || !AgeInstabilityControls.get(level).enabled(age.id())) return;
         // Legacy's per-chunk hazards must not wait for the rotating two-provider sample.
         AgeHazardProviders.tickPlanned(level, age, tick);
         AgeEnvironmentalProviders.tickPlanned(level, age, tick);
@@ -60,7 +64,7 @@ public final class AgeInstabilityRuntime {
         if (chunks.isEmpty()) return;
         Budget budget = new Budget(RivencraftConfig.instabilityMaxActions());
         Context context = new Context(level, age, chunks, tick, budget);
-        List<AgeInstabilityPlan.ProviderLevel> providers = age.instabilityPlan().providers();
+        List<AgeInstabilityPlan.ProviderLevel> providers = AgeBlockInstability.effectivePlan(level, age).providers();
         int first = (int) Math.floorMod(tick / cooldown + age.seed(), providers.size());
         int ran = 0;
         for (int offset = 0; offset < providers.size() && ran < RivencraftConfig.instabilityMaxProviders()
@@ -74,6 +78,8 @@ public final class AgeInstabilityRuntime {
 
     /** Shared handler guard, including quarantine, for rotating and per-chunk provider lanes. */
     static boolean invoke(Context context, ResourceLocation id, int level) {
+        if (!RivencraftConfig.instabilityEnabled()
+                || !AgeInstabilityControls.get(context.level()).enabled(context.age().id())) return false;
         Handler handler = HANDLERS.get(id);
         if (handler == null) {
             if (!InstabilityProviderCatalog.contains(id) && UNKNOWN_LOGGED.add(id)) {
@@ -81,7 +87,8 @@ public final class AgeInstabilityRuntime {
             }
             return false;
         }
-        if (handler.worldMutating() && !RivencraftConfig.instabilityWorldMutation()) return false;
+        if (!policyAllowsProvider(RivencraftConfig.instabilityProviderEnabled(id),
+                RivencraftConfig.instabilityWorldMutation(), handler.worldMutating())) return false;
         long retryAfter = FAILURES.computeIfAbsent(context.level(), ignored -> new HashMap<>())
                 .getOrDefault(id, 0L);
         if (context.serverTick() < retryAfter) return false;
@@ -107,6 +114,45 @@ public final class AgeInstabilityRuntime {
         return id.getNamespace().equals(Rivencraft.MOD_ID) && id.getPath().startsWith("age/");
     }
 
+    static boolean policyAllowsProvider(boolean providerEnabled, boolean worldMutation,
+                                        boolean mutatingHandler) {
+        return providerEnabled && (!mutatingHandler || worldMutation);
+    }
+
+    /** Current runtime state, distinct from the Age's immutable score and provider selection. */
+    public static String providerStatus(ServerLevel level, AgeDefinition age, ResourceLocation id) {
+        if (!RivencraftConfig.instabilityEnabled()) return "global config off";
+        if (!AgeInstabilityControls.get(level).enabled(age.id())) return "Age disabled";
+        Handler handler = HANDLERS.get(id);
+        if (handler == null) return "handler unavailable";
+        if (!RivencraftConfig.instabilityProviderEnabled(id)) return "provider config off";
+        if (handler.worldMutating() && !RivencraftConfig.instabilityWorldMutation()) return "world mutation off";
+        String path = id.getPath();
+        if (path.startsWith("decay") && !RivencraftConfig.decayEnabled()) return "decay config off";
+        if ((path.equals("lightning") || path.equals("explosions")) && !RivencraftConfig.hazardsEnabled())
+            return "hazards config off";
+        if (path.equals("meteors") && !RivencraftConfig.meteorEnabled()) return "meteor config off";
+        if (path.equals("burning") && !RivencraftConfig.scorchEnabled()) return "burning config off";
+        if (path.equals("erosion") && !RivencraftConfig.erosionEnabled()) return "erosion config off";
+        if (!path.startsWith("decay") && !path.equals("lightning") && !path.equals("explosions")
+                && !path.equals("meteors") && !path.equals("burning") && !path.equals("erosion")
+                && !path.equals("crumble") && !RivencraftConfig.statusEffectsEnabled())
+            return "status effects config off";
+        if (path.startsWith("enemy") && !RivencraftConfig.statusEffectsHostiles())
+            return "hostile status effects config off";
+        if (!path.startsWith("enemy") && !path.startsWith("decay") && !path.equals("lightning")
+                && !path.equals("explosions") && !path.equals("meteors") && !path.equals("burning")
+                && !path.equals("erosion") && !RivencraftConfig.statusEffectsPlayers()
+                && !RivencraftConfig.statusEffectsNonplayers())
+            return "status effect targets disabled";
+        ServerLevel ageLevel = level.getServer().getLevel(AgeDimensionService.dimensionKey(age));
+        if (ageLevel == null) return "Age unloaded";
+        if (ageLevel.players().isEmpty()) return "no players in Age";
+        long retryAfter = FAILURES.getOrDefault(ageLevel, Map.of()).getOrDefault(id, 0L);
+        if (ageLevel.getServer().getTickCount() < retryAfter) return "quarantined until tick " + retryAfter;
+        return "eligible; chance, cooldown, and protection still apply";
+    }
+
     static boolean admitted(List<ResourceLocation> eligible, ResourceLocation id, long run,
                             int maximum) {
         int index = eligible.indexOf(id);
@@ -121,7 +167,8 @@ public final class AgeInstabilityRuntime {
         for (ServerLevel level : server.getAllLevels()) {
             ResourceLocation id = level.dimension().location();
             if (isAgeDimension(id) && !level.players().isEmpty()
-                    && registry.findByDimension(id).filter(age -> !age.instabilityPlan().providers().isEmpty())
+                    && registry.findByDimension(id).filter(age -> !AgeBlockInstability.effectivePlan(level, age).providers().isEmpty())
+                    .filter(age -> AgeInstabilityControls.get(level).enabled(age.id()))
                     .isPresent()) eligible.add(id);
         }
         eligible.sort(Comparator.comparing(ResourceLocation::toString));

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

@@ -59,6 +59,53 @@ public final class AgeInstabilityRuntimeGameTests {
         helper.succeed();
     }
 
+    @GameTest(template = "empty")
+    public static void perAgeControlsPersistWithoutChangingScoresOrOtherAges(GameTestHelper helper) {
+        UUID first = UUID.randomUUID();
+        UUID second = UUID.randomUUID();
+        AgeInstabilityControls controls = new AgeInstabilityControls();
+        helper.assertTrue(controls.enabled(first) && controls.enabled(second),
+                "Ages must be enabled by default");
+        helper.assertTrue(controls.setEnabled(first, false) && !controls.enabled(first)
+                        && controls.enabled(second), "Disabling one Age must not change another");
+        AgeInstabilityControls restored = AgeInstabilityControls.load(
+                controls.save(new CompoundTag(), helper.getLevel().registryAccess()),
+                helper.getLevel().registryAccess());
+        helper.assertTrue(!restored.enabled(first) && restored.enabled(second),
+                "The per-Age override must survive a save round trip");
+        helper.assertTrue(restored.setEnabled(first, true) && restored.enabled(first),
+                "Re-enabling must remove the override");
+
+        var oldAge = new AgeDefinition(first, "Old Age", 1L, AgeGenerationProfiles.STANDARD,
+                AgeDefinition.CURRENT_GENERATION_VERSION, 0L, AgeDefinition.dimensionId(first), null,
+                AgeTraits.LEGACY_DEFAULTS);
+        helper.assertValueEqual(oldAge.instability().score(), 0,
+                "A pre-scoring Age must remain neutral regardless of runtime controls");
+        helper.assertTrue(oldAge.instabilityPlan().providers().isEmpty(),
+                "Runtime controls must not generate providers for old Ages");
+        AgeInstabilityControls live = AgeInstabilityControls.get(helper.getLevel());
+        live.setEnabled(first, false);
+        helper.assertValueEqual(AgeInstabilityRuntime.providerStatus(helper.getLevel(), oldAge,
+                        ResourceLocation.parse("rivencraft:poison")), "Age disabled",
+                "Diagnostics must distinguish an Age override from the saved plan");
+        live.setEnabled(first, true);
+        helper.assertValueEqual(AgeInstabilityRuntime.providerStatus(helper.getLevel(), oldAge,
+                        ResourceLocation.parse("example:missing_handler")), "handler unavailable",
+                "Unknown saved providers must not be reported as active");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void instabilityControlCommandsRequireOperatorPermission(GameTestHelper helper) {
+        var server = helper.getLevel().getServer();
+        var command = server.getCommands().getDispatcher().getRoot().getChild("rivencraft");
+        helper.assertTrue(command != null, "Rivencraft commands must be registered on a dedicated server");
+        helper.assertTrue(!command.canUse(server.createCommandSourceStack().withPermission(0))
+                        && command.canUse(server.createCommandSourceStack().withPermission(2)),
+                "Non-operators cannot reach Age instability enable/disable commands");
+        helper.succeed();
+    }
+
     @GameTest(template = "empty")
     public static void ageScopeRotationAndActionBudgetAreBounded(GameTestHelper helper) {
         ResourceLocation first = ResourceLocation.parse("rivencraft:age/first");

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

@@ -75,7 +75,7 @@ public final class AgeStatusEffectProviders {
         candidates.sort(Comparator.comparing(Entity::getUUID));
         LivingEntity target = candidates.get(random.nextInt(candidates.size()));
         if (!context.budget().claim() || !target.addEffect(instance)) return;
-        leases.add(new Lease(new WeakReference<>(target), instance,
+        leases.add(new Lease(id, new WeakReference<>(target), instance,
                 context.serverTick() + duration, spec.target()));
     }
 
@@ -100,7 +100,12 @@ public final class AgeStatusEffectProviders {
         if (event.getServer().getTickCount() % 20 != 0) return;
         boolean disabled = !RivencraftConfig.instabilityEnabled() || !RivencraftConfig.statusEffectsEnabled();
         long tick = event.getServer().getTickCount();
-        for (var entry : LEASES.entrySet()) prune(entry.getKey(), entry.getValue(), tick, disabled);
+        for (var entry : LEASES.entrySet()) {
+            AgeDefinition age = AgeRegistrySavedData.get(entry.getKey())
+                    .findByDimension(entry.getKey().dimension().location()).orElse(null);
+            prune(entry.getKey(), entry.getValue(), tick, disabled || age == null
+                    || !AgeInstabilityControls.get(entry.getKey()).enabled(age.id()));
+        }
         LEASES.values().removeIf(List::isEmpty);
     }
 
@@ -146,7 +151,8 @@ public final class AgeStatusEffectProviders {
                 iterator.remove();
                 continue;
             }
-            boolean revoke = removeAll || entity.level() != level
+            boolean revoke = removeAll || !RivencraftConfig.instabilityProviderEnabled(lease.provider())
+                    || entity.level() != level
                     || !allowedByPolicy(lease.target(), entity);
             if (revoke || tick >= lease.expiresAt()) {
                 removeOwnedEffect(entity, lease);
@@ -208,11 +214,11 @@ public final class AgeStatusEffectProviders {
 
     private enum Target { GENERAL, HOSTILE }
     private record Spec(Holder<MobEffect> effect, int legacyDuration, boolean global, Target target) {}
-    private record Lease(WeakReference<LivingEntity> entity, MobEffectInstance instance, long expiresAt,
+    private record Lease(ResourceLocation provider, WeakReference<LivingEntity> entity, MobEffectInstance instance, long expiresAt,
                          Target target, int amplifier, int originalDuration) {
-        private Lease(WeakReference<LivingEntity> entity, MobEffectInstance instance, long expiresAt,
+        private Lease(ResourceLocation provider, WeakReference<LivingEntity> entity, MobEffectInstance instance, long expiresAt,
                       Target target) {
-            this(entity, instance, expiresAt, target, instance.getAmplifier(), instance.getDuration());
+            this(provider, entity, instance, expiresAt, target, instance.getAmplifier(), instance.getDuration());
         }
     }
 }

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

@@ -193,6 +193,48 @@ public final class EnvironmentWritingGameTests {
         });
     }
 
+    @GameTest(template = "empty")
+    public static void celestialModifiersFollowWrittenOrder(GameTestHelper helper) {
+        AgeTraits seeded = AgeTraits.select(42L);
+        OrderedWriting consumed = new OrderedWriting(List.of(WritingEntry.linkPanel(),
+                page("period/half"), page("period/double"), page("phase/rising"),
+                page("celestial/normal_time")));
+        AgeGenerationPlan consumedPlan = AgeGenerationPlan.compile(consumed, 42L,
+                AgeGenerationProfiles.STANDARD, seeded, helper.getLevel().registryAccess());
+        AgeTraits consumedTraits = AgeEnvironmentCompiler.apply(consumedPlan, seeded);
+        helper.assertValueEqual(consumedTraits.celestialPeriod(), 1.25D,
+                "Repeated period pages must combine before Normal Time consumes them");
+        helper.assertValueEqual(consumedTraits.celestialPhase(), 0.25F,
+                "A preceding phase page must be consumed by Normal Time");
+        helper.assertValueEqual(consumedPlan.writingInstability(), 0,
+                "Consumed modifiers must not be charged as dangling");
+
+        OrderedWriting dangling = new OrderedWriting(List.of(WritingEntry.linkPanel(),
+                page("celestial/normal_time"), page("period/zero"), page("phase/rising")));
+        AgeGenerationPlan danglingPlan = AgeGenerationPlan.compile(dangling, 42L,
+                AgeGenerationProfiles.STANDARD, seeded, helper.getLevel().registryAccess());
+        AgeTraits danglingTraits = AgeEnvironmentCompiler.apply(danglingPlan, seeded);
+        helper.assertValueEqual(danglingTraits.celestialPeriod(), 1.0D,
+                "A period after Normal Time must not change the already-written sun");
+        helper.assertValueEqual(danglingTraits.celestialPhase(), seeded.celestialPhase(),
+                "A phase after Normal Time must not change the already-written sun");
+        helper.assertFalse(AgeEnvironmentCompiler.hasWrittenPhase(danglingPlan),
+                "An unconsumed phase page must not set the Age's start time");
+        helper.assertValueEqual(danglingPlan.writingInstability(), 200,
+                "Each unconsumed modifier kind must contribute Legacy's +100");
+        helper.assertValueEqual(AgeEnvironmentCompiler.apply(AgeGenerationPlan.load(danglingPlan.save()), seeded),
+                danglingTraits, "Ordered modifier behavior must survive reload");
+        AgeGenerationPlan previousVersion = new AgeGenerationPlan(3, danglingPlan.ageSeed(),
+                danglingPlan.writing(), danglingPlan.symbols(), danglingPlan.runtimeProfile(),
+                danglingPlan.biomeSelection(), danglingPlan.activeSymbolIndices(), danglingPlan.writingInstability());
+        helper.assertTrue(AgeEnvironmentCompiler.apply(previousVersion, seeded).hasStoppedCelestialCycle(),
+                "An existing version-3 Age must retain its earlier stage-sorted time behavior");
+        helper.assertTrue(AgeInstability.compute(previousVersion, seeded, helper.getLevel().registryAccess())
+                        .breakdown().stream().anyMatch(entry -> entry.reason().equals("legacy_writing")),
+                "Version-3 writing cost must not be revalidated under version-4 grammar");
+        helper.succeed();
+    }
+
     private static WritingEntry page(String path) {
         return WritingEntry.symbol(new SymbolReference(ResourceLocation.fromNamespaceAndPath("rivencraft", path)));
     }

src/main/java/net/dnorberg/rivencraft/book/Milestone6RegressionGameTests.java

@@ -0,0 +1,158 @@
+package net.dnorberg.rivencraft.book;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+import net.dnorberg.rivencraft.registry.ModBlocks;
+import net.minecraft.core.BlockPos;
+import net.minecraft.gametest.framework.GameTest;
+import net.minecraft.gametest.framework.GameTestHelper;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.block.Blocks;
+import net.neoforged.neoforge.gametest.GameTestHolder;
+import net.neoforged.neoforge.gametest.PrefixGameTestTemplate;
+
+/** Focused safety gaps; score and migration cases remain in the default suite. */
+@GameTestHolder("rivencraft_archive_instability")
+@PrefixGameTestTemplate(false)
+public final class Milestone6RegressionGameTests {
+    private Milestone6RegressionGameTests() {}
+
+    @GameTest(template = "empty")
+    public static void multiplayerCandidatesStayLoadedDeduplicatedAndCapped(GameTestHelper helper) {
+        ChunkPos first = new ChunkPos(0, 0);
+        ChunkPos second = new ChunkPos(8, 0);
+        ChunkPos unloaded = new ChunkPos(0, 1);
+        Set<ChunkPos> loaded = Set.of(first, second, new ChunkPos(1, 0));
+        var selected = AgeHazardProviders.candidateChunks(List.of(first, second, first), 2, loaded::contains);
+        helper.assertValueEqual(selected, List.of(first, second),
+                "Two players in different loaded areas must each contribute one candidate before expansion");
+        helper.assertTrue(!selected.contains(unloaded) && selected.stream().distinct().count() == 2,
+                "Unloaded and duplicate chunks must never enter the effect context");
+        helper.assertValueEqual(AgeHazardProviders.candidateChunks(List.of(first, second), 1, loaded::contains),
+                List.of(first), "The per-attempt chunk cap must be obeyed with multiple players");
+        helper.assertTrue(AgeHazardProviders.candidateChunks(List.of(first), 0, loaded::contains).isEmpty(),
+                "A zero work budget must not inspect chunks");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void disablingEffectsCannotRerollFrozenPlan(GameTestHelper helper) {
+        AgeInstability score = new AgeInstability(AgeInstability.CURRENT_VERSION, 20_000,
+                List.of(new AgeInstability.Contribution("fixture", -1, 20_000, "regression score")));
+        AgeInstabilityPlan plan = AgeInstabilityPlan.select(score, 741L);
+        UUID id = UUID.randomUUID();
+        AgeDefinition age = new AgeDefinition(id, "Policy fixture", 741L, AgeGenerationProfiles.STANDARD,
+                AgeDefinition.CURRENT_GENERATION_VERSION, 0L, AgeDefinition.dimensionId(id), null,
+                AgeTraits.LEGACY_DEFAULTS, null, null, List.of(), score, plan);
+        AgeInstabilityControls controls = new AgeInstabilityControls();
+        controls.setEnabled(id, false);
+        helper.assertTrue(!controls.enabled(id) && controls.enabled(UUID.randomUUID()),
+                "An Age override must not spill into another Age");
+        helper.assertTrue(!AgeInstabilityRuntime.policyAllowsProvider(false, true, false)
+                        && !AgeInstabilityRuntime.policyAllowsProvider(true, false, true)
+                        && AgeInstabilityRuntime.policyAllowsProvider(true, false, false),
+                "Per-provider disable and world-mutation disable must block only their intended effects");
+        controls.setEnabled(id, true);
+        helper.assertValueEqual(age.instability(), score, "Controls must not change the frozen score");
+        helper.assertValueEqual(age.instabilityPlan(), plan, "Controls must not reroll the frozen provider plan");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void disabledGriefAndProtectedBlocksStayUntouched(GameTestHelper helper) {
+        helper.assertTrue(!AgeHazardProviders.destructiveBlocksAllowed(false, true, true, 16)
+                        && !AgeHazardProviders.destructiveBlocksAllowed(true, false, true, 16)
+                        && !AgeHazardProviders.destructiveBlocksAllowed(true, true, false, 16)
+                        && !AgeHazardProviders.destructiveBlocksAllowed(true, true, true, 0),
+                "Every disabled destructive policy must prevent block damage");
+        helper.assertTrue(AgeHazardProviders.destructiveBlocksAllowed(true, true, true, 1),
+                "The enabled path must still have a bounded block budget");
+        BlockPos spawn = helper.absolutePos(new BlockPos(1, 1, 1));
+        BlockPos far = spawn.offset(12, 0, 12);
+        UUID id = UUID.randomUUID();
+        AgeDefinition age = new AgeDefinition(id, "Protected fixture", 1L, AgeGenerationProfiles.STANDARD,
+                AgeDefinition.CURRENT_GENERATION_VERSION, 0L, AgeDefinition.dimensionId(id), spawn,
+                AgeTraits.LEGACY_DEFAULTS);
+        var level = helper.getLevel();
+        helper.assertTrue(AgeHazardProviders.protectedBlock(level, age, spawn, Blocks.STONE.defaultBlockState()),
+                "Arrival blocks must be protected from an explosion");
+        for (var state : List.of(Blocks.CHEST.defaultBlockState(), Blocks.NETHER_PORTAL.defaultBlockState(),
+                Blocks.BEDROCK.defaultBlockState(), ModBlocks.CLOUD_PLATFORM.get().defaultBlockState())) {
+            helper.assertTrue(AgeHazardProviders.protectedBlock(level, age, far, state),
+                    "Block entities, portals, unbreakable blocks, and Rivencraft blocks must be protected");
+        }
+        helper.assertTrue(!AgeHazardProviders.protectedBlock(level, age, far, Blocks.STONE.defaultBlockState()),
+                "Ordinary stone outside the protected arrival area remains eligible");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void generatedDiamondBlocksIncreaseLiveInstability(GameTestHelper helper) {
+        var diamond = net.minecraft.resources.ResourceLocation.parse("minecraft:diamond_block");
+        var ore = net.minecraft.resources.ResourceLocation.parse("minecraft:diamond_ore");
+        helper.assertValueEqual(AgeBlockInstability.score(Map.of(diamond, 4000L), 400,
+                Map.of(ore, 2000L), 500), 0,
+                "Legacy's 400-chunk threshold must gate the live block component");
+        int score = AgeBlockInstability.score(Map.of(diamond, 4010L, ore, 1604L), 401,
+                Map.of(ore, 2000L), 500);
+        helper.assertValueEqual(score, 40_000,
+                "Ten generated diamond blocks per sampled chunk add substantial instability");
+        helper.assertValueEqual(AgeBlockInstability.score(Map.of(ore, 1604L), 401,
+                Map.of(ore, 2000L), 500), 0,
+                "Natural ore abundance equal to the baseline must remain free");
+        var effective = new AgeInstability(AgeInstability.CURRENT_VERSION, score,
+                List.of(new AgeInstability.Contribution("block_profile", -1, score, "sampled excess")));
+        helper.assertTrue(!AgeInstabilityPlan.select(effective, 64L).providers().isEmpty(),
+                "A new effective score must unlock providers without replacing the authored base plan");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void commonModdedMaterialWeightsStayBounded(GameTestHelper helper) {
+        var tin = net.minecraft.resources.ResourceLocation.parse("examplemod:deepslate_tin_ore");
+        var uranium = net.minecraft.resources.ResourceLocation.parse("examplemod:raw_uranium_block");
+        var oil = net.minecraft.resources.ResourceLocation.parse("examplemod:oil");
+        var unknown = net.minecraft.resources.ResourceLocation.parse("examplemod:unknown_ore");
+        helper.assertValueEqual(AgeBlockInstability.inferredModdedWeight(tin, true, false, false), 60.0,
+                "Common tin ore should use the low mineral tier");
+        helper.assertValueEqual(AgeBlockInstability.inferredModdedWeight(uranium, false, true, false), 750.0,
+                "A common radioactive mineral block should use its material tier");
+        helper.assertValueEqual(AgeBlockInstability.inferredModdedWeight(oil, false, false, true), 1.25,
+                "Modded source fluids should use the Legacy fluid factor");
+        helper.assertValueEqual(AgeBlockInstability.inferredModdedWeight(unknown, true, false, false), 60.0,
+                "Unknown but tagged ores should use a conservative fallback");
+        helper.assertValueEqual(AgeBlockInstability.inferredModdedWeight(unknown, false, false, false), 0.0,
+                "Uncategorized modded blocks must not be watched automatically");
+        helper.assertValueEqual(AgeBlockInstability.moddedWeight(tin, 60.0, List.of()), 60.0,
+                "Recognized ore from an installed mod should be scored automatically");
+        helper.assertValueEqual(AgeBlockInstability.moddedWeight(tin, 60.0,
+                List.of("examplemod:deepslate_tin_ore=750")), 750.0,
+                "A block override should replace the discovered weight");
+        helper.assertValueEqual(AgeBlockInstability.moddedWeight(tin, 60.0,
+                List.of("examplemod:deepslate_tin_ore=0")), 0.0,
+                "A zero-weight override should exclude a discovered block");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void blockProfileSamplesPersistWithoutDoubleCounting(GameTestHelper helper) {
+        var data = new AgeBlockProfileSavedData();
+        var diamond = net.minecraft.resources.ResourceLocation.parse("minecraft:diamond_block");
+        data.add(new ChunkPos(3, 4), Map.of(diamond, 12));
+        data.add(new ChunkPos(3, 4), Map.of(diamond, 100));
+        helper.assertValueEqual(data.count(), 1, "A reloaded chunk must not be sampled twice");
+        helper.assertValueEqual(data.totals().get(diamond), 12L, "Duplicate loads cannot inflate abundance");
+        var restored = AgeBlockProfileSavedData.load(data.save(new net.minecraft.nbt.CompoundTag(),
+                helper.getLevel().registryAccess()), helper.getLevel().registryAccess());
+        helper.assertValueEqual(restored.count(), 1, "The profiled chunk set must survive restart");
+        helper.assertValueEqual(restored.totals(), data.totals(), "Block counts must survive restart");
+        var oldProfile = data.save(new net.minecraft.nbt.CompoundTag(), helper.getLevel().registryAccess());
+        oldProfile.remove("Version");
+        helper.assertValueEqual(AgeBlockProfileSavedData.load(oldProfile,
+                helper.getLevel().registryAccess()).count(), 0,
+                "Profiles lacking modded candidate counts must resample after migration");
+        helper.succeed();
+    }
+}

src/main/java/net/dnorberg/rivencraft/client/ClientBookInteractionHandler.java

@@ -5,6 +5,7 @@ import net.dnorberg.rivencraft.client.screen.DescriptiveBookScreen;
 import net.dnorberg.rivencraft.block.entity.BookStandBlockEntity;
 import net.dnorberg.rivencraft.registry.ModBlocks;
 import net.dnorberg.rivencraft.registry.ModItems;
+import net.dnorberg.rivencraft.registry.ModDataComponents;
 import net.minecraft.client.Minecraft;
 import net.minecraft.core.BlockPos;
 import net.minecraft.world.InteractionHand;
@@ -87,8 +88,12 @@ public final class ClientBookInteractionHandler {
                 currentBook = minecraft.player.getItemInHand(hand);
             }
             // Ignore delayed replies if the player has moved or replaced the book.
+            ItemStack currentWithoutSummary = currentBook.copy();
+            ItemStack replyWithoutSummary = payload.book().copy();
+            currentWithoutSummary.remove(ModDataComponents.AGE_INSTABILITY_SCORE.get());
+            replyWithoutSummary.remove(ModDataComponents.AGE_INSTABILITY_SCORE.get());
             if (!currentBook.is(ModItems.DESCRIPTIVE_BOOK.get())
-                    || !ItemStack.isSameItemSameComponents(currentBook, payload.book())) {
+                    || !ItemStack.isSameItemSameComponents(currentWithoutSummary, replyWithoutSummary)) {
                 return;
             }
             minecraft.setScreen(payload.fromStand()

src/main/java/net/dnorberg/rivencraft/client/screen/DescriptiveBookScreen.java

@@ -250,7 +250,7 @@ public final class DescriptiveBookScreen extends Screen implements ExplorableBoo
         int detailsY = drawWrappedWithoutShadow(graphics,
                 author == null || author.isBlank()
                         ? Component.translatable("screen.rivencraft.age.unknown_author")
-                        : Component.literal(author), x + 10, nameEnd + 2, 100) + 10;
+                        : Component.literal(author), x + 10, nameEnd + 2, 100) + 4;
         if (!pageFree) return;
         if (generationProfile != null) {
             Component profileName = generationProfile.getNamespace().equals("rivencraft")

src/main/java/net/dnorberg/rivencraft/client/screen/WritingDeskScreen.java

@@ -266,9 +266,17 @@ public final class WritingDeskScreen extends AbstractContainerScreen<WritingDesk
         if (selectedPage >= source.size() || source.get(selectedPage).isEmpty()) return;
         ItemStack selected = source.get(selectedPage);
         drawPage(graphics, selected, leftPos + 265, topPos + 26);
-        String title = font.plainSubstrByWidth(selected.getHoverName().getString(), 95);
         graphics.fill(leftPos + 261, topPos + 81, leftPos + 360, topPos + 95, 0xFF202020);
-        graphics.drawString(font, title, leftPos + 263, topPos + 84, 0xFFE0E0E0, false);
+        var symbol = PageItem.content(selected).symbol();
+        if (symbol.isPresent() && PageItem.isCorrupted(symbol.orElseThrow())) {
+            graphics.enableScissor(leftPos + 263, topPos + 82, leftPos + 358, topPos + 94);
+            graphics.drawString(font, selected.getHoverName(), leftPos + 263, topPos + 84,
+                    0xFFE0E0E0, false);
+            graphics.disableScissor();
+        } else {
+            String title = font.plainSubstrByWidth(selected.getHoverName().getString(), 95);
+            graphics.drawString(font, title, leftPos + 263, topPos + 84, 0xFFE0E0E0, false);
+        }
     }
 
     private void drawPage(GuiGraphics graphics, ItemStack page, int x, int y) {

src/main/java/net/dnorberg/rivencraft/command/RivencraftCommands.java

@@ -9,12 +9,17 @@ import net.dnorberg.rivencraft.book.AgeHazardProviders;
 import net.dnorberg.rivencraft.book.AgeEnvironmentalProviders;
 import net.dnorberg.rivencraft.book.AgeDimensionService;
 import net.dnorberg.rivencraft.book.AgeRegistrySavedData;
+import net.dnorberg.rivencraft.book.AgeInstabilityControls;
+import net.dnorberg.rivencraft.book.AgeInstabilityRuntime;
+import net.dnorberg.rivencraft.config.RivencraftConfig;
 import net.minecraft.commands.Commands;
 import net.minecraft.commands.CommandSourceStack;
 import com.mojang.brigadier.builder.LiteralArgumentBuilder;
 import net.minecraft.network.chat.Component;
 import net.minecraft.resources.ResourceLocation;
 import net.neoforged.neoforge.event.RegisterCommandsEvent;
+import java.util.List;
+import java.util.Locale;
 
 /** Administrative commands for inspecting and safely unloading persistent Ages. */
 public final class RivencraftCommands {
@@ -30,21 +35,23 @@ public final class RivencraftCommands {
                         .then(Commands.literal("instability")
                                 .executes(context -> inspectInstability(context.getSource(),
                                         context.getSource().getLevel().dimension().location().toString()))
+                                .then(Commands.literal("enable")
+                                        .then(Commands.argument("dimension", StringArgumentType.string())
+                                                .suggests((context, builder) -> suggestAges(context.getSource(), builder))
+                                                .executes(context -> setInstability(context.getSource(),
+                                                        StringArgumentType.getString(context, "dimension"), true))))
+                                .then(Commands.literal("disable")
+                                        .then(Commands.argument("dimension", StringArgumentType.string())
+                                                .suggests((context, builder) -> suggestAges(context.getSource(), builder))
+                                                .executes(context -> setInstability(context.getSource(),
+                                                        StringArgumentType.getString(context, "dimension"), false))))
                                 .then(Commands.argument("dimension", StringArgumentType.string())
-                                        .suggests((context, builder) -> {
-                                            AgeRegistrySavedData.get(context.getSource().getLevel()).definitions()
-                                                    .forEach(age -> builder.suggest(age.dimensionId().toString()));
-                                            return builder.buildFuture();
-                                        })
+                                        .suggests((context, builder) -> suggestAges(context.getSource(), builder))
                                         .executes(context -> inspectInstability(context.getSource(),
                                                 StringArgumentType.getString(context, "dimension")))))
                         .then(Commands.literal("unload")
                                 .then(Commands.argument("dimension", StringArgumentType.string())
-                                        .suggests((context, builder) -> {
-                                            AgeRegistrySavedData.get(context.getSource().getLevel()).definitions()
-                                                    .forEach(age -> builder.suggest(age.dimensionId().toString()));
-                                            return builder.buildFuture();
-                                        })
+                                        .suggests((context, builder) -> suggestAges(context.getSource(), builder))
                                         .executes(context -> unloadAge(
                                                 context.getSource(),
                                                 StringArgumentType.getString(context, "dimension")
@@ -100,16 +107,8 @@ public final class RivencraftCommands {
     }
 
     private static int unloadAge(net.minecraft.commands.CommandSourceStack source, String requestedDimension) {
-        ResourceLocation dimension = ResourceLocation.tryParse(requestedDimension);
-        if (dimension == null) {
-            source.sendFailure(Component.literal("Invalid dimension id: " + requestedDimension));
-            return 0;
-        }
-        AgeDefinition age = AgeRegistrySavedData.get(source.getLevel()).findByDimension(dimension).orElse(null);
-        if (age == null) {
-            source.sendFailure(Component.literal("Unknown Rivencraft Age: " + dimension));
-            return 0;
-        }
+        AgeDefinition age = resolveAge(source, requestedDimension);
+        if (age == null) return 0;
 
         AgeDimensionService.UnloadResult result = AgeDimensionService.unload(source.getServer(), age);
         return switch (result) {
@@ -131,25 +130,115 @@ public final class RivencraftCommands {
     }
 
     private static int inspectInstability(CommandSourceStack source, String requestedDimension) {
-        ResourceLocation dimension = ResourceLocation.tryParse(requestedDimension);
-        if (dimension == null) {
-            source.sendFailure(Component.literal("Invalid dimension id: " + requestedDimension));
-            return 0;
-        }
-        AgeDefinition age = AgeRegistrySavedData.get(source.getLevel()).findByDimension(dimension).orElse(null);
-        if (age == null) {
-            source.sendFailure(Component.literal("Unknown Rivencraft Age: " + dimension));
-            return 0;
-        }
+        AgeDefinition age = resolveAge(source, requestedDimension);
+        if (age == null) return 0;
+        var ageLevel = source.getServer().getLevel(net.minecraft.resources.ResourceKey.create(
+                net.minecraft.core.registries.Registries.DIMENSION, age.dimensionId()));
+        int blockScore = ageLevel == null ? 0 : net.dnorberg.rivencraft.book.AgeBlockInstability.score(ageLevel, age);
+        var selectedPlan = ageLevel == null ? age.instabilityPlan()
+                : net.dnorberg.rivencraft.book.AgeBlockInstability.effectivePlan(ageLevel, age);
         var totals = age.instability().totals();
+        int effectiveScore = net.dnorberg.rivencraft.book.AgeBlockInstability.difficultyScore(
+                (long) totals.effectiveScore() + blockScore, RivencraftConfig.instabilityDifficulty());
         source.sendSuccess(() -> Component.literal(age.name() + " — " + age.dimensionId()), false);
         source.sendSuccess(() -> Component.literal("Instability: base " + totals.baseScore()
                 + ", stability bonus " + totals.stabilityBonus()
                 + ", penalty " + totals.instabilityPenalty()
-                + ", effective " + totals.effectiveScore()), false);
+                + ", profiled blocks +" + blockScore
+                + ", effective " + effectiveScore
+                + " (difficulty " + RivencraftConfig.instabilityDifficulty() + ")"), false);
+        if (age.instability().version() >= 2) {
+            int ageSamples = ageLevel == null ? 0
+                    : net.dnorberg.rivencraft.book.AgeBlockInstability.sampledChunks(ageLevel);
+            int baselineSamples = net.dnorberg.rivencraft.book.AgeBlockInstability.sampledChunks(
+                    source.getServer().overworld());
+            source.sendSuccess(() -> Component.literal("Block profile: Age " + ageSamples
+                    + "/401, Overworld baseline " + baselineSamples + "/500"
+                    + (ageLevel == null ? " (Age unloaded)" : "")), false);
+            source.sendSuccess(() -> Component.literal("Modded materials: automatic when installed, "
+                    + RivencraftConfig.moddedMaterialOverrides().size() + " exact block override(s)"), false);
+        }
+        boolean enabled = AgeInstabilityControls.get(source.getLevel()).enabled(age.id());
+        source.sendSuccess(() -> Component.literal("Runtime: " + (enabled ? "Age enabled" : "Age disabled")
+                + ", global " + (RivencraftConfig.instabilityEnabled() ? "enabled" : "disabled")
+                + "; saved score and plan are unchanged by controls"), false);
+        source.sendSuccess(() -> Component.literal("Score breakdown (saved schema v"
+                + age.instability().version() + "):"), false);
+        age.instability().breakdown().forEach(part -> source.sendSuccess(() -> Component.literal(
+                "  " + (part.pageIndex() < 0 ? "Age" : "page " + (part.pageIndex() + 1))
+                        + " +" + part.points() + " " + part.reason() + ": " + part.detail()), false));
+        source.sendSuccess(() -> Component.literal("Selected providers (effective plan v"
+                + selectedPlan.version() + "): " + selectedPlan.providers().size()), false);
+        selectedPlan.providers().forEach(provider -> source.sendSuccess(() -> Component.literal(
+                "  " + provider.id() + " level " + provider.level() + " — "
+                        + AgeInstabilityRuntime.providerStatus(ageLevel == null ? source.getLevel() : ageLevel,
+                        age, provider.id())), false));
+        if (selectedPlan.providers().isEmpty()) source.sendSuccess(() -> Component.literal(
+                "  No providers selected; an old neutral Age stays neutral."), false);
+        source.sendSuccess(() -> Component.literal("Limits: cooldown " + RivencraftConfig.instabilityCooldown()
+                + " ticks, " + RivencraftConfig.instabilityMaxAges() + " Ages/tick, "
+                + RivencraftConfig.instabilityMaxProviders() + " providers/Age, "
+                + RivencraftConfig.instabilityMaxActions() + " actions/Age, level cap "
+                + RivencraftConfig.instabilityMaxLevel()), false);
         source.sendSuccess(() -> Component.literal("Mutable player bonuses: disabled (no active Legacy registration)"),
                 false);
-        return totals.effectiveScore();
+        return effectiveScore;
+    }
+
+    private static java.util.concurrent.CompletableFuture<com.mojang.brigadier.suggestion.Suggestions> suggestAges(
+            CommandSourceStack source, com.mojang.brigadier.suggestion.SuggestionsBuilder builder) {
+        AgeRegistrySavedData.get(source.getLevel()).definitions()
+                .forEach(age -> {
+                    builder.suggest(age.dimensionId().toString());
+                    if (!age.name().contains(" ")) builder.suggest(age.name());
+                });
+        return builder.buildFuture();
+    }
+
+    /** Bare input is an Age name or short path, never a minecraft-namespace resource ID. */
+    static List<AgeDefinition> matchingAges(List<AgeDefinition> ages, String requested) {
+        String input = requested.strip();
+        if (input.isEmpty()) return List.of();
+        if (input.contains(":")) {
+            ResourceLocation id = ResourceLocation.tryParse(input);
+            return id == null ? List.of() : ages.stream()
+                    .filter(age -> age.dimensionId().equals(id)).toList();
+        }
+        List<AgeDefinition> names = ages.stream()
+                .filter(age -> age.name().equalsIgnoreCase(input)).toList();
+        if (!names.isEmpty()) return names;
+        String path = input.toLowerCase(Locale.ROOT);
+        if (!path.startsWith("age/")) path = "age/" + path;
+        String expectedPath = path;
+        return ages.stream().filter(age -> age.dimensionId().getPath().equals(expectedPath)).toList();
+    }
+
+    private static AgeDefinition resolveAge(CommandSourceStack source, String requested) {
+        List<AgeDefinition> matches = matchingAges(
+                AgeRegistrySavedData.get(source.getLevel()).definitions(), requested);
+        if (matches.size() == 1) return matches.getFirst();
+        if (matches.size() > 1) {
+            source.sendFailure(Component.literal("Ambiguous Age name '" + requested
+                    + "'. Use its full dimension ID from /rivencraft age list."));
+        } else {
+            source.sendFailure(Component.literal("Unknown Rivencraft Age '" + requested
+                    + "'. Use its name or dimension ID from /rivencraft age list."));
+        }
+        return null;
+    }
+
+    private static int setInstability(CommandSourceStack source, String requestedDimension, boolean enabled) {
+        if (!source.hasPermission(2)) {
+            source.sendFailure(Component.literal("Operator permission is required to change Age instability."));
+            return 0;
+        }
+        AgeDefinition age = resolveAge(source, requestedDimension);
+        if (age == null) return 0;
+        boolean changed = AgeInstabilityControls.get(source.getLevel()).setEnabled(age.id(), enabled);
+        source.sendSuccess(() -> Component.literal(age.name() + " instability "
+                + (enabled ? "enabled" : "disabled") + (changed ? "" : " (already set)")
+                + ". The saved score and provider plan are unchanged."), true);
+        return 1;
     }
 
     private static int pulseDecay(net.minecraft.commands.CommandSourceStack source, String colorName, int attempts) {

src/main/java/net/dnorberg/rivencraft/command/RivencraftCommandsGameTests.java

@@ -0,0 +1,53 @@
+package net.dnorberg.rivencraft.command;
+
+import java.util.List;
+import java.util.UUID;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.book.AgeDefinition;
+import net.dnorberg.rivencraft.book.AgeGenerationProfiles;
+import net.dnorberg.rivencraft.book.AgeTraits;
+import net.minecraft.gametest.framework.GameTest;
+import net.minecraft.gametest.framework.GameTestHelper;
+import net.neoforged.neoforge.gametest.GameTestHolder;
+import net.neoforged.neoforge.gametest.PrefixGameTestTemplate;
+
+/** Command-facing Age lookup regression checks. */
+@GameTestHolder(Rivencraft.MOD_ID)
+@PrefixGameTestTemplate(false)
+public final class RivencraftCommandsGameTests {
+    private RivencraftCommandsGameTests() {}
+
+    @GameTest(template = "empty")
+    public static void bareAgeNameDoesNotBecomeMinecraftResourceId(GameTestHelper helper) {
+        AgeDefinition fort = age("Fort", "fort");
+        AgeDefinition tower = age("Tower", "tower");
+        List<AgeDefinition> ages = List.of(fort, tower);
+        for (String query : List.of("fort", "Fort", "age/fort", "rivencraft:age/fort")) {
+            helper.assertValueEqual(RivencraftCommands.matchingAges(ages, query), List.of(fort),
+                    "Age lookup must accept its name, short path, and full dimension ID");
+        }
+        helper.assertTrue(RivencraftCommands.matchingAges(ages, "minecraft:fort").isEmpty(),
+                "An explicit wrong namespace must not resolve to a Rivencraft Age");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void duplicateNamesRequireFullDimensionId(GameTestHelper helper) {
+        AgeDefinition first = age("Fort", "fort");
+        AgeDefinition second = age("Fort", "fort_2");
+        List<AgeDefinition> ages = List.of(first, second);
+        helper.assertValueEqual(RivencraftCommands.matchingAges(ages, "fort").size(), 2,
+                "Duplicate display names must remain ambiguous, not silently pick an Age");
+        helper.assertValueEqual(RivencraftCommands.matchingAges(ages, "rivencraft:age/fort_2"),
+                List.of(second), "A full dimension ID must select the intended duplicate");
+        helper.succeed();
+    }
+
+    private static AgeDefinition age(String name, String path) {
+        UUID id = UUID.randomUUID();
+        return new AgeDefinition(id, name, 1L, AgeGenerationProfiles.STANDARD,
+                AgeDefinition.CURRENT_GENERATION_VERSION, 0L,
+                net.minecraft.resources.ResourceLocation.parse("rivencraft:age/" + path), null,
+                AgeTraits.LEGACY_DEFAULTS);
+    }
+}

src/main/java/net/dnorberg/rivencraft/config/RivencraftConfig.java

@@ -1,5 +1,9 @@
 package net.dnorberg.rivencraft.config;
 
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import net.minecraft.resources.ResourceLocation;
 import net.neoforged.neoforge.common.ModConfigSpec;
 
 /** Server-configurable gameplay policies. */
@@ -19,6 +23,7 @@ public final class RivencraftConfig {
     private static final ModConfigSpec.IntValue LINK_PANEL_INK_COST;
     private static final ModConfigSpec.BooleanValue AUTO_WHITELIST_SERENE_AGES;
     private static final ModConfigSpec.BooleanValue INSTABILITY_ENABLED;
+    private static final ModConfigSpec.IntValue INSTABILITY_DIFFICULTY;
     private static final ModConfigSpec.BooleanValue INSTABILITY_WORLD_MUTATION;
     private static final ModConfigSpec.IntValue INSTABILITY_COOLDOWN;
     private static final ModConfigSpec.IntValue INSTABILITY_MAX_AGES;
@@ -26,6 +31,9 @@ public final class RivencraftConfig {
     private static final ModConfigSpec.IntValue INSTABILITY_MAX_ACTIONS;
     private static final ModConfigSpec.IntValue INSTABILITY_MAX_LEVEL;
     private static final ModConfigSpec.IntValue INSTABILITY_MAX_CHUNKS;
+    private static final ModConfigSpec.IntValue ACCELERATED_MAX_CHUNKS;
+    private static final ModConfigSpec.IntValue ACCELERATED_MAX_ATTEMPTS;
+    private static final ModConfigSpec.ConfigValue<List<? extends String>> MODDED_MATERIAL_OVERRIDES;
     private static final ModConfigSpec.BooleanValue STATUS_EFFECTS_ENABLED;
     private static final ModConfigSpec.BooleanValue STATUS_EFFECTS_PLAYERS;
     private static final ModConfigSpec.BooleanValue STATUS_EFFECTS_NONPLAYERS;
@@ -56,6 +64,7 @@ public final class RivencraftConfig {
     private static final ModConfigSpec.BooleanValue SCORCH_PLAYERS;
     private static final ModConfigSpec.IntValue SCORCH_MAX_TARGETS;
     private static final ModConfigSpec.BooleanValue EROSION_ENABLED;
+    private static final Map<String, ModConfigSpec.BooleanValue> INSTABILITY_PROVIDERS = new HashMap<>();
 
     static {
         ModConfigSpec.Builder builder = new ModConfigSpec.Builder();
@@ -81,6 +90,8 @@ public final class RivencraftConfig {
         builder.push("instability");
         INSTABILITY_ENABLED = builder.comment("Run selected instability providers in loaded Ages. Disabling does not alter saved plans.")
                 .define("enabled", true);
+        INSTABILITY_DIFFICULTY = builder.comment("Legacy instability difficulty: 0=quarter, 1=half, 2=normal, 3=1.75x. Changes affect active effects, not saved writing.")
+                .defineInRange("difficulty", 2, 0, 3);
         INSTABILITY_WORLD_MUTATION = builder.comment("Allow selected instability providers to change blocks or create explosions, as in Legacy.")
                 .define("world_mutation", true);
         INSTABILITY_COOLDOWN = builder.comment("Minimum ticks between instability runs for each loaded Age.")
@@ -96,6 +107,19 @@ public final class RivencraftConfig {
         INSTABILITY_MAX_CHUNKS = builder.comment("Maximum already-loaded candidate chunks inspected per Age run.")
                 .defineInRange("max_loaded_chunks", 16, 1, 64);
         builder.pop();
+        builder.push("accelerated_age");
+        ACCELERATED_MAX_CHUNKS = builder.comment("Maximum already-loaded chunks given extra random ticks per Age tick.")
+                .defineInRange("max_loaded_chunks", 8, 1, 64);
+        ACCELERATED_MAX_ATTEMPTS = builder.comment("Maximum extra random-tick positions sampled per Age tick, shared fairly across loaded sections; zero disables the Accelerated page effect. The previous 1024-attempt default capped heavily accelerated Ages too early.")
+                .defineInRange("max_random_tick_attempts_per_tick", 16384, 0, 65536);
+        builder.pop();
+        builder.push("instability_modded_materials");
+        MODDED_MATERIAL_OVERRIDES = builder.comment(
+                        "Installed mods' recognized ores, mineral blocks and source fluids are scored automatically without requiring those mods.",
+                        "Optional exact block weights use modid:block_id=points; zero excludes a block. Example: [\"examplemod:rare_ore=4000\"].")
+                .defineList("block_weight_overrides", List.<String>of(), () -> "examplemod:rare_ore=4000",
+                        RivencraftConfig::validModdedMaterialOverride);
+        builder.pop();
         builder.push("instability_status_effects");
         STATUS_EFFECTS_ENABLED = builder.comment("Allow bounded instability status effects in loaded Ages.")
                 .define("enabled", true);
@@ -170,6 +194,19 @@ public final class RivencraftConfig {
                         "Ages with a destructive instability score may spread adjacent fluid into one safe block per pass.")
                 .define("enabled", true);
         builder.pop();
+        builder.push("instability_providers");
+        for (String provider : new String[] {
+                "blindness", "blindness_global", "enemyregen_global", "enemyresist_global",
+                "fatigue", "fatigue_global", "hunger", "hunger_global", "nausea", "nausea_global",
+                "poison", "poison_global", "slow", "slow_global", "weakness", "weakness_global",
+                "wither", "wither_global", "burning", "crumble", "decayblue", "decaypurple",
+                "decayred", "decaywhite", "explosions", "lightning", "meteors", "erosion"
+        }) {
+            INSTABILITY_PROVIDERS.put(provider, builder.comment(
+                    "Allow this saved provider to run. Disabling it does not change an Age's frozen plan.")
+                    .define(provider, true));
+        }
+        builder.pop();
         SPEC = builder.build();
     }
 
@@ -193,6 +230,12 @@ public final class RivencraftConfig {
     }
 
     public static boolean instabilityEnabled() { return INSTABILITY_ENABLED.get(); }
+    public static int instabilityDifficulty() { return INSTABILITY_DIFFICULTY.get(); }
+    public static boolean instabilityProviderEnabled(ResourceLocation id) {
+        ModConfigSpec.BooleanValue value = id.getNamespace().equals("rivencraft")
+                ? INSTABILITY_PROVIDERS.get(id.getPath()) : null;
+        return value != null && value.get();
+    }
     public static boolean instabilityWorldMutation() { return INSTABILITY_WORLD_MUTATION.get(); }
     public static int instabilityCooldown() { return INSTABILITY_COOLDOWN.get(); }
     public static int instabilityMaxAges() { return INSTABILITY_MAX_AGES.get(); }
@@ -200,6 +243,24 @@ public final class RivencraftConfig {
     public static int instabilityMaxActions() { return INSTABILITY_MAX_ACTIONS.get(); }
     public static int instabilityMaxLevel() { return INSTABILITY_MAX_LEVEL.get(); }
     public static int instabilityMaxChunks() { return INSTABILITY_MAX_CHUNKS.get(); }
+    public static int acceleratedMaxChunks() { return ACCELERATED_MAX_CHUNKS.get(); }
+    public static int acceleratedMaxAttempts() { return ACCELERATED_MAX_ATTEMPTS.get(); }
+    public static List<? extends String> moddedMaterialOverrides() { return MODDED_MATERIAL_OVERRIDES.get(); }
+
+    private static boolean validModdedMaterialOverride(Object value) {
+        if (!(value instanceof String entry)) return false;
+        int separator = entry.lastIndexOf('=');
+        if (separator < 1) return false;
+        ResourceLocation id = ResourceLocation.tryParse(entry.substring(0, separator));
+        if (id == null || !entry.substring(0, separator).contains(":")
+                || id.getNamespace().equals("minecraft") || id.getNamespace().equals("rivencraft")) return false;
+        try {
+            int weight = Integer.parseInt(entry.substring(separator + 1));
+            return weight >= 0 && weight <= 100_000;
+        } catch (NumberFormatException ignored) {
+            return false;
+        }
+    }
     public static boolean statusEffectsEnabled() { return STATUS_EFFECTS_ENABLED.get(); }
     public static boolean statusEffectsPlayers() { return STATUS_EFFECTS_PLAYERS.get(); }
     public static boolean statusEffectsNonplayers() { return STATUS_EFFECTS_NONPLAYERS.get(); }

src/main/java/net/dnorberg/rivencraft/gametest/WritingGrammarGameTests.java

@@ -87,6 +87,12 @@ public final class WritingGrammarGameTests {
         WritingGrammar.Result repeatedModifiers = parse(resolver, WritingEntry.linkPanel(),
                 WritingEntry.symbol(periodHalf), WritingEntry.symbol(periodFull), WritingEntry.symbol(celestial));
         helper.assertTrue(repeatedModifiers.canCreate(), "Repeated period modifiers must remain legal");
+        helper.assertValueEqual(repeatedModifiers.writingInstability(), 0,
+                "Repeated same-kind modifiers combine before the celestial page consumes them");
+        WritingGrammar.Result unconsumed = parse(resolver, WritingEntry.linkPanel(),
+                WritingEntry.symbol(periodHalf), WritingEntry.symbol(periodFull));
+        helper.assertValueEqual(unconsumed.writingInstability(), 100,
+                "Only the final combined modifier dangles when no celestial page follows");
         assertPenalty(helper, parse(resolver, WritingEntry.linkPanel(), WritingEntry.symbol(terrain),
                 WritingEntry.symbol(terrain)), WritingGrammar.Code.DUPLICATE);
         WritingGrammar.Result replacedTerrain = parse(resolver, WritingEntry.linkPanel(), WritingEntry.symbol(terrain),
@@ -96,8 +102,11 @@ public final class WritingGrammarGameTests {
                 "The last supported controller must supply the effective terrain");
         assertPenalty(helper, parse(resolver, WritingEntry.linkPanel(), WritingEntry.symbol(weather),
                 WritingEntry.symbol(terrain)), WritingGrammar.Code.OUT_OF_ORDER);
-        assertPenalty(helper, parse(resolver, WritingEntry.linkPanel(), WritingEntry.symbol(celestial),
-                WritingEntry.symbol(periodHalf)), WritingGrammar.Code.MISPLACED_MODIFIER);
+        WritingGrammar.Result afterCelestial = parse(resolver, WritingEntry.linkPanel(), WritingEntry.symbol(celestial),
+                WritingEntry.symbol(periodHalf));
+        assertPenalty(helper, afterCelestial, WritingGrammar.Code.DANGLING_MODIFIER);
+        helper.assertValueEqual(afterCelestial.writingInstability(), 100,
+                "A modifier after the last celestial page must be charged only once");
         assertPenalty(helper, parse(resolver, WritingEntry.linkPanel(), WritingEntry.symbol(nativeBiomes),
                 WritingEntry.symbol(plains)), WritingGrammar.Code.OUT_OF_ORDER);
         assertPenalty(helper, parse(resolver, WritingEntry.linkPanel(), WritingEntry.symbol(plains),

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

@@ -290,13 +290,17 @@ public final class PageItem extends Item {
                 : SymbolDisplayMetadata.unresolved(reference);
         if (metadata.resolved()) {
             tooltipComponents.add(Component.translatable(metadata.descriptionTranslationKey())
-                    .withStyle(ChatFormatting.GRAY));
+                    .withStyle(isCorrupted(reference)
+                            ? style -> style.applyFormats(ChatFormatting.GRAY, ChatFormatting.OBFUSCATED)
+                            : style -> style.applyFormat(ChatFormatting.GRAY)));
         } else {
             tooltipComponents.add(Component.translatable(
                     "symbol.rivencraft.unresolved.description", reference.unresolvedName())
                     .withStyle(ChatFormatting.RED));
         }
-        tooltipComponents.add(Component.literal(reference.id().toString()).withStyle(ChatFormatting.DARK_GRAY));
+        if (!isCorrupted(reference)) {
+            tooltipComponents.add(Component.literal(reference.id().toString()).withStyle(ChatFormatting.DARK_GRAY));
+        }
     }
 
     private static ItemStack create(PageContent content) {
@@ -313,6 +317,9 @@ public final class PageItem extends Item {
         SymbolDisplayMetadata metadata = stack.getOrDefault(
                 ModDataComponents.PAGE_SYMBOL_DISPLAY.get(), SymbolCatalog.display(reference));
         if (!metadata.resolved()) return Component.translatable("item.rivencraft.page.unresolved");
+        if (isCorrupted(reference)) {
+            return Component.translatable(metadata.nameTranslationKey()).withStyle(ChatFormatting.OBFUSCATED);
+        }
         return reference.id().getNamespace().equals(Rivencraft.MOD_ID)
                 && reference.id().getPath().startsWith("biome/")
                 ? Component.translatableWithFallback(metadata.nameTranslationKey(),
@@ -324,4 +331,9 @@ public final class PageItem extends Item {
                 : Component.translatable(metadata.nameTranslationKey());
     }
 
+    public static boolean isCorrupted(SymbolReference reference) {
+        return reference.id().getNamespace().equals(Rivencraft.MOD_ID)
+                && reference.id().getPath().startsWith("corrupted/");
+    }
+
 }

src/main/java/net/dnorberg/rivencraft/network/ModNetworking.java

@@ -170,8 +170,9 @@ public final class ModNetworking {
 
             access.stack().set(ModDataComponents.AGE_REFERENCE.get(), reference);
             access.stack().set(ModDataComponents.BOOK_AUTHOR.get(), player.getGameProfile().getName());
-            AgeRegistrySavedData.get(player.serverLevel()).find(reference.id()).ifPresent(definition ->
-                    access.stack().set(ModDataComponents.AGE_GENERATION_PROFILE.get(), definition.generationProfile()));
+            AgeRegistrySavedData.get(player.serverLevel()).find(reference.id()).ifPresent(definition -> {
+                access.stack().set(ModDataComponents.AGE_GENERATION_PROFILE.get(), definition.generationProfile());
+            });
             access.stack().set(DataComponents.CUSTOM_NAME, Component.literal(title));
             access.sync().run();
             player.level().playSound(null, player.blockPosition(), SoundEvents.BOOK_PAGE_TURN, SoundSource.PLAYERS, 1.0F, 1.0F);

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

@@ -50,7 +50,7 @@ public final class ModCreativeTabs {
                     .build());
 
     private static final List<String> CATEGORY_ORDER = List.of(
-            "terrain", "biome", "cave_biome", "biome_generation", "weather", "season", "lighting", "sky", "celestial", "block", "fluid", "feature");
+            "terrain", "biome", "cave_biome", "biome_generation", "weather", "season", "lighting", "sky", "celestial", "block", "fluid", "feature", "environment", "corrupted");
 
     public static final Map<ResourceLocation, DeferredHolder<CreativeModeTab, CreativeModeTab>> SYMBOL_PAGES =
             registerSymbolPageTabs();

src/main/java/net/dnorberg/rivencraft/registry/ModDataComponents.java

@@ -81,6 +81,13 @@ public final class ModDataComponents {
                     .networkSynchronized(ByteBufCodecs.STRING_UTF8)
                     .cacheEncoding()
                     .build());
+    /** Server-written display summary only; detailed scoring and provider plans remain server-owned. */
+    public static final DeferredHolder<DataComponentType<?>, DataComponentType<Integer>> AGE_INSTABILITY_SCORE =
+            DATA_COMPONENTS.register("age_instability_score", () -> DataComponentType.<Integer>builder()
+                    .persistent(Codec.intRange(0, Integer.MAX_VALUE))
+                    .networkSynchronized(ByteBufCodecs.VAR_INT)
+                    .cacheEncoding()
+                    .build());
     public static final DeferredHolder<DataComponentType<?>, DataComponentType<Integer>> INK_REMAINING =
             DATA_COMPONENTS.register("ink_remaining", () -> DataComponentType.<Integer>builder()
                     .persistent(Codec.intRange(0, 16))

src/main/java/net/dnorberg/rivencraft/writing/SymbolSemantics.java

@@ -87,7 +87,9 @@ public record SymbolSemantics(Role role, Value value) {
         ANGLE_MODIFIER("angle_modifier", Kind.NUMBER),
         PHASE_MODIFIER("phase_modifier", Kind.NUMBER),
         BLOCK("block", Kind.RESOURCE),
-        FEATURE("feature", Kind.RESOURCE);
+        FEATURE("feature", Kind.RESOURCE),
+        ENVIRONMENT("environment", Kind.CHOICE, "accelerated"),
+        CORRUPTED("corrupted", Kind.CHOICE, "large", "medium", "small");
 
         private final String id;
         private final Kind kind;

src/main/java/net/dnorberg/rivencraft/writing/WritingGrammar.java

@@ -40,6 +40,7 @@ public final class WritingGrammar {
         if (writing.entries().isEmpty()) return new Result(symbols, diagnostics);
 
         EnumMap<Role, ParsedSymbol> singular = new EnumMap<>(Role.class);
+        EnumMap<Role, ParsedSymbol> pendingModifiers = new EnumMap<>(Role.class);
         int panels = 0;
         int lastStage = -1;
         int biomeCount = 0;
@@ -72,6 +73,13 @@ public final class WritingGrammar {
             Role role = semantics.orElseThrow().role();
             ParsedSymbol parsed = new ParsedSymbol(index, reference, semantics.orElseThrow());
             symbols.add(parsed);
+            if (modifier(role)) {
+                // Legacy modifier pages pop and combine an earlier modifier of the same
+                // kind. Only the final pending value can be left dangling.
+                pendingModifiers.put(role, parsed);
+            } else if (role == Role.CELESTIAL) {
+                pendingModifiers.clear();
+            }
             if (pendingBlock != null && role != Role.FEATURE) {
                 // A material page without a following feature receives a seeded compatible
                 // feature when the Age plan is compiled.
@@ -107,8 +115,8 @@ public final class WritingGrammar {
             }
             if (role == Role.BIOME) biomeCount++;
             int stage = stage(role);
-            if (stage < lastStage) {
-                diagnostics.add(new Diagnostic(modifier(role) ? Code.MISPLACED_MODIFIER : Code.OUT_OF_ORDER,
+            if (stage < lastStage && !modifier(role)) {
+                diagnostics.add(new Diagnostic(Code.OUT_OF_ORDER,
                         index, "Move this " + role.id() + " page before later grammar categories"));
             } else {
                 lastStage = stage;
@@ -116,6 +124,10 @@ public final class WritingGrammar {
         }
         if (panels == 0) diagnostics.add(new Diagnostic(Code.MISSING_PANEL, -1,
                 "Add a Link Panel as the first page"));
+        for (ParsedSymbol dangling : pendingModifiers.values()) {
+            diagnostics.add(new Diagnostic(Code.DANGLING_MODIFIER, dangling.index(),
+                    "This " + dangling.semantics().role().id() + " page has no later celestial page to consume it"));
+        }
         if (symbols.isEmpty()) return new Result(symbols, diagnostics);
 
         ParsedSymbol controller = singular.get(Role.BIOME_CONTROLLER);
@@ -168,20 +180,20 @@ public final class WritingGrammar {
             case SKY -> 6;
             case PERIOD_MODIFIER, ANGLE_MODIFIER, PHASE_MODIFIER -> 7;
             case CELESTIAL -> 8;
-            case BLOCK, FEATURE -> 9;
+            case BLOCK, FEATURE, ENVIRONMENT, CORRUPTED -> 9;
         };
     }
 
     public enum Code {
         TOO_MANY, MISSING_PANEL, PANEL_ORDER, DUPLICATE_PANEL, UNRESOLVED, UNSUPPORTED,
-        DUPLICATE, CONFLICT, OUT_OF_ORDER, MISPLACED_MODIFIER, INCOMPLETE, UNSUPPORTED_PROFILE,
+        DUPLICATE, CONFLICT, OUT_OF_ORDER, MISPLACED_MODIFIER, DANGLING_MODIFIER, INCOMPLETE, UNSUPPORTED_PROFILE,
         UNKNOWN_BIOME, UNSUPPORTED_BIOME, UNSUPPORTED_ENVIRONMENT, UNSUPPORTED_FEATURE,
         UNSUPPORTED_COMBINATION;
 
         public Severity severity() {
             return switch (this) {
                 case INCOMPLETE -> Severity.SEEDED_COMPLETION;
-                case DUPLICATE, CONFLICT, OUT_OF_ORDER, MISPLACED_MODIFIER -> Severity.INSTABILITY;
+                case DUPLICATE, CONFLICT, OUT_OF_ORDER, MISPLACED_MODIFIER, DANGLING_MODIFIER -> Severity.INSTABILITY;
                 default -> Severity.FATAL;
             };
         }
@@ -205,7 +217,7 @@ public final class WritingGrammar {
         public int instability() {
             return switch (code) {
                 case DUPLICATE, CONFLICT -> 500;
-                case OUT_OF_ORDER, MISPLACED_MODIFIER -> 100;
+                case OUT_OF_ORDER, MISPLACED_MODIFIER, DANGLING_MODIFIER -> 100;
                 default -> 0;
             };
         }

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

@@ -2,6 +2,7 @@
   "item.rivencraft.descriptive_book": "Descriptive Book",
   "item.rivencraft.descriptive_book.unwritten": "Unwritten",
   "item.rivencraft.descriptive_book.age": "%s",
+  "item.rivencraft.descriptive_book.instability": "Instability: %s (potential)",
   "item.rivencraft.linking_book": "Linking Book",
   "item.rivencraft.linking_book.unbound": "Unbound — sneak-use to bind",
   "item.rivencraft.linking_book.destination": "%s (%s, %s, %s)",
@@ -350,5 +351,15 @@
   "itemGroup.rivencraft.pages.celestial": "Rivencraft Celestial Pages",
   "itemGroup.rivencraft.pages.block": "Rivencraft Block Pages",
   "itemGroup.rivencraft.pages.fluid": "Rivencraft Fluid Pages",
-  "itemGroup.rivencraft.pages.feature": "Rivencraft Feature Pages"
+  "itemGroup.rivencraft.pages.feature": "Rivencraft Feature Pages",
+  "itemGroup.rivencraft.pages.corrupted": "Rivencraft Corrupted Pages",
+  "itemGroup.rivencraft.pages.environment": "Rivencraft Environment Pages",
+  "symbol.rivencraft.environment.accelerated": "Accelerated",
+  "symbol.rivencraft.environment.accelerated.description": "Causes blocks in this Age to receive extra random ticks.",
+  "symbol.rivencraft.corrupted.large": "Corrupted Page",
+  "symbol.rivencraft.corrupted.large.description": "The writing shifts beyond comprehension.",
+  "symbol.rivencraft.corrupted.medium": "Corrupted Page",
+  "symbol.rivencraft.corrupted.medium.description": "The writing shifts beyond comprehension.",
+  "symbol.rivencraft.corrupted.small": "Corrupted Page",
+  "symbol.rivencraft.corrupted.small.description": "The writing shifts beyond comprehension."
 }

src/main/resources/data/rivencraft/rivencraft/symbols/corrupted/large.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.corrupted.large",
+  "description": "symbol.rivencraft.corrupted.large.description",
+  "category": "rivencraft:corrupted",
+  "semantics": { "role": "corrupted", "value": "large" },
+  "poem": "Contradict Chaos Exist Terrain"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/corrupted/medium.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.corrupted.medium",
+  "description": "symbol.rivencraft.corrupted.medium.description",
+  "category": "rivencraft:corrupted",
+  "semantics": { "role": "corrupted", "value": "medium" },
+  "poem": "Contradict Chaos Exist Balance"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/corrupted/small.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.corrupted.small",
+  "description": "symbol.rivencraft.corrupted.small.description",
+  "category": "rivencraft:corrupted",
+  "semantics": { "role": "corrupted", "value": "small" },
+  "poem": "Contradict Chaos Exist Form"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/environment/accelerated.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.environment.accelerated",
+  "description": "symbol.rivencraft.environment.accelerated.description",
+  "category": "rivencraft:environment",
+  "semantics": { "role": "environment", "value": "accelerated" },
+  "poem": "Environment Dynamic Change Spur"
+}