Expose instability controls and diagnostics (#72)

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

@@ -8,6 +8,8 @@ The server scheduler runs only for loaded `rivencraft:age/*` levels with a playe
 
 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.
+
 # 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

@@ -2,7 +2,7 @@
 
 Every newly created Age now gets a version-1 `Instability` compound inside its server-owned `rivencraft_ages` saved definition. It contains the total `Score` and an ordered `Breakdown` of reason, original page index (zero-based, or -1 for an Age-wide cause), points, and explanation. `AgeRegistrySavedData.instability(UUID)` is the read-only server query. No client tooltip or live data-pack lookup is needed to read a saved score.
 
-The baseline is explicitly zero for page-free and Link-Panel-only random Ages, and for authored Ages. Incomplete writing receives seed-based completion and a zero-point explanatory entry. Supported writing defects use the provisional Milestone 6 grammar costs: duplicate/conflicting single-choice pages +500, out-of-order or misplaced pages +100. Legacy's audited Bright Lighting symbol adds +500 for every occurrence, including a seed-generated controller. Mineshafts, Nether Fortresses, Strongholds, and Villages add +100 for the fourth and every later occurrence. By project balance decision, Bastions, Trial Chambers, Ancient Cities, Shipwrecks, Ocean Ruins, Pillager Outposts, Ruined Portals, Nether Fossils, Buried Treasure, and Trail Ruins follow that same rule. The first three occurrences and all other audited Legacy feature symbols have no direct page cost. An authored structure may override its vanilla biome eligibility; every structure-page occurrence forced into an unsupported selected biome adds +100. Seed completion still prefers compatible biomes and therefore avoids that cost when it can. Other modern-only features remain neutral. The frozen score selects a deterministic, persisted provider plan through the Milestone 6 runtime. Registered handlers apply that plan only inside loaded Rivencraft Ages and remain subject to the documented scheduler and effect-specific safety bounds.
+The baseline is explicitly zero for page-free and Link-Panel-only random Ages, and for authored Ages. Incomplete writing receives seed-based completion and a zero-point explanatory entry. Supported writing defects use the provisional Milestone 6 grammar costs: duplicate/conflicting single-choice pages +500, out-of-order or misplaced pages +100. Legacy's audited Bright Lighting symbol adds +500 for every occurrence, including a seed-generated controller. Mineshafts, Nether Fortresses, Strongholds, and Villages add +100 for the fourth and every later occurrence. By project balance decision, Bastions, Trial Chambers, Ancient Cities, Shipwrecks, Ocean Ruins, Pillager Outposts, Ruined Portals, Nether Fossils, Buried Treasure, and Trail Ruins follow that same rule. The first three occurrences and all other audited Legacy feature symbols have no direct page cost. An authored structure may override its vanilla biome eligibility; every structure-page occurrence adds +100 if **any** selected biome is unsupported, even when another selected biome is compatible. Seed completion still prefers compatible biomes and therefore avoids that cost when it can. Other modern-only features remain neutral. The frozen score selects a deterministic, persisted provider plan through the Milestone 6 runtime. Registered handlers apply that plan only inside loaded Rivencraft Ages and remain subject to the documented scheduler and effect-specific safety bounds.
 
 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).
 

docs/WRITING_GRAMMAR.md

@@ -8,7 +8,7 @@ The supported order follows the representable subset of the [Legacy grammar audi
 
 Missing terrain, controller, weather, lighting, celestial, or the controller's minimum biome count is an **incomplete** warning, not an error: the compiler retains seed-selected traits for missing branches. An omitted terrain page uses a seed-selected profile compatible with authored feature pages, so changing the Age name cannot accidentally select Flat, Void, or Cave terrain for Rocks or Lakes. If no profile can support the writing, binding still rejects it. Native consumes no authored biome pages; Single consumes one; Tiled/Grid and Tiny–Huge require two, with seeded filler when pages are missing. From 0.5.1.0, known misplaced or repeated pages no longer block creation: the book keeps its original order, while the server repairs category order, uses the last single-choice controller, and stores a writing-instability score in the Age plan. A conflicting/repeated choice adds 500; an out-of-order page or misplaced modifier adds 100. Native ignores surplus authored biome pages and Single uses the first, with the conflict recorded as instability. Audited Legacy symbol modifiers also add 500 for each Bright Lighting page and 100 for each Mineshafts, Nether Fortresses, Strongholds, or Villages occurrence after the third. Modern structures configured with the same rule are Bastions, Trial Chambers, Ancient Cities, Shipwrecks, Ocean Ruins, Pillager Outposts, Ruined Portals, Nether Fossils, Buried Treasure, and Trail Ruins. Every repeated structure page increases that structure's placement rate: probability-based structures multiply their chance, grid-based structures use a denser grid, and Strongholds add more positions to each ring and more positions overall. One page retains the vanilla placement rate. Authored structures can generate outside their vanilla biome set; each structure-page occurrence that requires this override adds 100 instability. Seed completion selects compatible biomes where possible. Other feature pages have no direct symbol cost. Incorrectly placed pages are **not** red-highlighted; their warning remains available as a tooltip. Unknown IDs, schema-v1 display-only symbols, unavailable dependencies/profiles, unsupported semantic effects or feature/material pairs, missing/extra Link Panels, and oversized writing still reject a new Age. The Binder disables output for those fatal errors and shows a red page indication where applicable. Rejected inputs remain removable.
 
-The plan stores the original writing order, the authoritative semantic value of each resolved symbol, the active repaired-page indexes, the writing-instability score, the Age seed, and a copy of the selected runtime profile. An explicit terrain page overrides random terrain selection; an omitted terrain uses a seed-selected compatible profile. The built-in Standard, Amplified, Cave, Island, Flat, and Void terrain pages select their matching generation resources. Age loading uses the frozen runtime profile and does not need the original symbol definition or runtime-profile JSON, though its referenced noise, biome-preset, and dimension-type registry entries must remain available. Existing bound books without plans are not reinterpreted. Page-free and Link-Panel-only books keep the pre-existing random path. Biome and environment pages affect new Ages, and the supported feature subset below is compiled into the same frozen plan. Runtime effects for a nonzero writing-instability score are not implemented yet.
+The plan stores the original writing order, the authoritative semantic value of each resolved symbol, the active repaired-page indexes, the writing-instability score, the Age seed, and a copy of the selected runtime profile. An explicit terrain page overrides random terrain selection; an omitted terrain uses a seed-selected compatible profile. The built-in Standard, Amplified, Cave, Island, Flat, and Void terrain pages select their matching generation resources. Age loading uses the frozen runtime profile and does not need the original symbol definition or runtime-profile JSON, though its referenced noise, biome-preset, and dimension-type registry entries must remain available. Existing bound books without plans are not reinterpreted. Page-free and Link-Panel-only books keep the pre-existing random path. Biome and environment pages affect new Ages, and the supported feature subset below is compiled into the same frozen plan. Nonzero instability can select a persisted provider plan; status effects, decay, lightning, explosions, meteors, burning, and test-enabled erosion run through the bounded Age-scoped scheduler described in [the runtime policy](INSTABILITY_RUNTIME.md).
 
 ## Supported feature pages (issue #35)
 

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=0.5.8.4
+mod_version=0.5.8.9
 immersive_portals_version=6.0.7
 terrablender_version=4.1.0.8
 serene_seasons_version_id=B6nTjh4b

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/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,
@@ -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/AgeHazardProviders.java

@@ -96,6 +96,8 @@ 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();

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

@@ -97,7 +97,7 @@ public record AgeInstability(int version, int score, List<Contribution> breakdow
             String name = COUNTED_STRUCTURES.get(resource.id());
             if (name == null) continue;
             int count = structureCounts.merge(resource.id(), 1, Integer::sum);
-            if (!AgeStructureSelection.biomeCompatible(resource.id(), plan.biomeSelection(), registries)) {
+            if (AgeStructureSelection.requiresBiomeOverride(resource.id(), plan.biomeSelection(), registries)) {
                 contributions.add(new Contribution("forced_biome_" + resource.id().getPath(), symbol.index(),
                         FORCED_STRUCTURE_BIOME_COST,
                         name + " occurrence " + count + " is forced into an unsupported biome"));

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

@@ -52,7 +52,8 @@ 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 || age.instabilityPlan().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);
@@ -74,6 +75,8 @@ 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)) {
@@ -81,6 +84,7 @@ public final class AgeInstabilityRuntime {
             }
             return false;
         }
+        if (!RivencraftConfig.instabilityProviderEnabled(id)) return false;
         if (handler.worldMutating() && !RivencraftConfig.instabilityWorldMutation()) return false;
         long retryAfter = FAILURES.computeIfAbsent(context.level(), ignored -> new HashMap<>())
                 .getOrDefault(id, 0L);
@@ -107,6 +111,40 @@ public final class AgeInstabilityRuntime {
         return id.getNamespace().equals(Rivencraft.MOD_ID) && id.getPath().startsWith("age/");
     }
 
+    /** 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);
@@ -122,6 +160,7 @@ public final class AgeInstabilityRuntime {
             ResourceLocation id = level.dimension().location();
             if (isAgeDimension(id) && !level.players().isEmpty()
                     && registry.findByDimension(id).filter(age -> !age.instabilityPlan().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/AgeStructureGameTests.java

@@ -9,6 +9,9 @@ import net.dnorberg.rivencraft.writing.OrderedWriting;
 import net.dnorberg.rivencraft.writing.SymbolReference;
 import net.dnorberg.rivencraft.writing.WritingEntry;
 import net.minecraft.core.registries.Registries;
+import net.minecraft.world.level.biome.Biomes;
+import net.minecraft.world.level.biome.FixedBiomeSource;
+import net.minecraft.world.level.chunk.ChunkGeneratorStructureState;
 import net.minecraft.gametest.framework.GameTest;
 import net.minecraft.gametest.framework.GameTestHelper;
 import net.minecraft.resources.ResourceKey;
@@ -165,6 +168,88 @@ public final class AgeStructureGameTests {
         helper.succeed();
     }
 
+    @GameTest(template = "empty")
+    public static void mixedEndAndTaigaVillagesChargeForEndPortion(GameTestHelper helper) {
+        for (String firstBiome : List.of("the_end", "plains")) {
+            var writing = new OrderedWriting(List.of(WritingEntry.linkPanel(),
+                    page("terrain/standard"), page("biome/" + firstBiome), page("biome/taiga"),
+                    page("biome/tiled"), page("lighting/normal"),
+                    page("feature/villages"), page("feature/villages")));
+            var age = AgeRegistrySavedData.resolveOrCreate(helper.getLevel(),
+                    new AgeReference(java.util.UUID.randomUUID(), "Mixed " + firstBiome), writing);
+            int expected = firstBiome.equals("the_end") ? 200 : 0;
+            helper.assertValueEqual(age.instability().score(), expected,
+                    "Each Village page must charge 100 if any selected biome needs the override");
+            helper.assertValueEqual(age.instability().breakdown().stream()
+                            .filter(part -> part.reason().equals("forced_biome_villages")).count(),
+                    firstBiome.equals("the_end") ? 2L : 0L,
+                    "Compatible Taiga must not erase the End portion's forced-biome charges");
+        }
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void forcedVillageSurvivesStructureStateBiomeGate(GameTestHelper helper) {
+        var registries = helper.getLevel().registryAccess();
+        var sets = registries.lookupOrThrow(Registries.STRUCTURE_SET);
+        var end = new FixedBiomeSource(registries.lookupOrThrow(Registries.BIOME).getOrThrow(Biomes.THE_END));
+        var villages = repeated("villages", 1);
+        var random = helper.getLevel().getChunkSource().randomState();
+        var baseline = ChunkGeneratorStructureState.createForNormal(random, 42L, end,
+                AgeStructureSelection.filteredLookup(sets, villages, end));
+        helper.assertTrue(baseline.possibleStructureSets().stream()
+                        .noneMatch(holder -> holder.unwrapKey().filter(BuiltinStructureSets.VILLAGES::equals).isPresent()),
+                "Vanilla rejects a Village structure set in a single End biome before the biome mixin runs");
+
+        var planned = ChunkGeneratorStructureState.createForNormal(random, 42L,
+                AgeStructureSelection.planningBiomes(end, sets, villages),
+                AgeStructureSelection.filteredLookup(sets, villages, end));
+        helper.assertTrue(planned.possibleStructureSets().stream()
+                        .anyMatch(holder -> holder.unwrapKey().filter(BuiltinStructureSets.VILLAGES::equals).isPresent()),
+                "The authored Village must survive the structure-state biome gate");
+        var village = sets.getOrThrow(BuiltinStructureSets.VILLAGES).value().structures().getFirst().structure();
+        helper.assertTrue(!planned.getPlacementsForStructure(village).isEmpty(),
+                "The forced Village must have an actual placement in the Age structure state");
+        helper.assertTrue(planned.possibleStructureSets().stream().noneMatch(holder -> holder.unwrapKey()
+                        .filter(BuiltinStructureSets.DESERT_PYRAMIDS::equals).isPresent()),
+                "Planning biomes must not enable unrelated desert structures in the End Age");
+        helper.assertTrue(end.possibleBiomes().size() == 1 && end.possibleBiomes().contains(
+                        registries.lookupOrThrow(Registries.BIOME).getOrThrow(Biomes.THE_END)),
+                "The actual Age biome source must remain End-only");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void otherAuthoredStructuresOverrideBiomeWithInstability(GameTestHelper helper) {
+        var registries = helper.getLevel().registryAccess();
+        var sets = registries.lookupOrThrow(Registries.STRUCTURE_SET);
+        var end = new FixedBiomeSource(registries.lookupOrThrow(Registries.BIOME).getOrThrow(Biomes.THE_END));
+        var random = helper.getLevel().getChunkSource().randomState();
+        for (var entry : Map.of("shipwrecks", BuiltinStructureSets.SHIPWRECKS,
+                "trial_chambers", BuiltinStructureSets.TRIAL_CHAMBERS).entrySet()) {
+            String feature = entry.getKey();
+            var choices = repeated(feature, 1);
+            var planned = ChunkGeneratorStructureState.createForNormal(random, 42L,
+                    AgeStructureSelection.planningBiomes(end, sets, choices),
+                    AgeStructureSelection.filteredLookup(sets, choices, end));
+            helper.assertTrue(planned.possibleStructureSets().stream()
+                            .anyMatch(holder -> holder.unwrapKey().filter(entry.getValue()::equals).isPresent()),
+                    "Authored " + feature + " must survive the structure-state biome gate");
+            var structure = sets.getOrThrow(entry.getValue()).value().structures().getFirst().structure();
+            helper.assertTrue(!planned.getPlacementsForStructure(structure).isEmpty(),
+                    "Authored " + feature + " must have a placement in the End Age");
+
+            var writing = new OrderedWriting(List.of(WritingEntry.linkPanel(),
+                    page("terrain/standard"), page("biome/the_end"), page("biome/single"),
+                    page("feature/" + feature)));
+            var age = AgeRegistrySavedData.resolveOrCreate(helper.getLevel(),
+                    new AgeReference(java.util.UUID.randomUUID(), "Forced " + feature), writing);
+            helper.assertValueEqual(age.instability().score(), 100,
+                    "An authored " + feature + " outside its normal biomes must add 100 instability");
+        }
+        helper.succeed();
+    }
+
     private static List<AgeFeatureSelection.Choice> repeated(String feature, int count) {
         return java.util.stream.IntStream.range(0, count)
                 .mapToObj(ignored -> new AgeFeatureSelection.Choice(id(feature), Optional.<ResourceLocation>empty()))

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

@@ -1,5 +1,6 @@
 package net.dnorberg.rivencraft.book;
 
+import com.mojang.serialization.MapCodec;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -18,6 +19,9 @@ import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.tags.TagKey;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.BiomeSource;
+import net.minecraft.world.level.biome.Climate;
 import net.minecraft.world.level.levelgen.structure.BuiltinStructureSets;
 import net.minecraft.world.level.levelgen.structure.Structure;
 import net.minecraft.world.level.levelgen.structure.StructureSet;
@@ -133,6 +137,13 @@ public final class AgeStructureSelection {
         return compatible.isEmpty() || biomes.biomes().stream().anyMatch(compatible::contains);
     }
 
+    /** A mixed pool still needs the authored override wherever its structure is not normally allowed. */
+    public static boolean requiresBiomeOverride(ResourceLocation feature, AgeBiomeSelection biomes,
+                                                RegistryAccess registries) {
+        Set<ResourceLocation> compatible = compatibleBiomes(feature, registries);
+        return !compatible.isEmpty() && biomes.biomes().stream().anyMatch(biome -> !compatible.contains(biome));
+    }
+
     /** True when this exact registered structure belongs to an authored structure page. */
     public static boolean authoredStructure(Structure structure, RegistryAccess registries,
                                             List<AgeFeatureSelection.Choice> choices) {
@@ -177,22 +188,38 @@ public final class AgeStructureSelection {
 
     public static Stream<Holder<StructureSet>> allowedSets(Stream<Holder<StructureSet>> sets,
                                                             List<AgeFeatureSelection.Choice> choices) {
+        return allowedSets(sets, choices, null);
+    }
+
+    public static Stream<Holder<StructureSet>> allowedSets(Stream<Holder<StructureSet>> sets,
+                                                            List<AgeFeatureSelection.Choice> choices,
+                                                            BiomeSource actualBiomes) {
         Map<ResourceLocation, Integer> enabled = enabledSets(choices);
         return sets.filter(holder -> holder.unwrapKey()
-                        .map(key -> allowed(key.location(), enabled.keySet())).orElse(false))
+                        .map(key -> allowed(key.location(), enabled.keySet())
+                                && (actualBiomes == null || enabled.containsKey(key.location())
+                                || hasActualBiome(holder.value(), actualBiomes))).orElse(false))
                 .map(holder -> scaledHolder(holder, enabled));
     }
 
     public static HolderLookup<StructureSet> filteredLookup(HolderLookup<StructureSet> lookup,
                                                              List<AgeFeatureSelection.Choice> choices) {
+        return filteredLookup(lookup, choices, null);
+    }
+
+    public static HolderLookup<StructureSet> filteredLookup(HolderLookup<StructureSet> lookup,
+                                                             List<AgeFeatureSelection.Choice> choices,
+                                                             BiomeSource actualBiomes) {
         Map<ResourceLocation, Integer> enabled = enabledSets(choices);
         Map<ResourceKey<StructureSet>, Holder.Reference<StructureSet>> scaled = new HashMap<>();
         return new HolderLookup<>() {
             @Override
             public Optional<Holder.Reference<StructureSet>> get(ResourceKey<StructureSet> key) {
                 if (!allowed(key.location(), enabled.keySet())) return Optional.empty();
-                return lookup.get(key).map(holder -> scaled.computeIfAbsent(key,
-                        ignored -> scaledReference(holder, enabled.getOrDefault(key.location(), 1))));
+                return lookup.get(key).filter(holder -> actualBiomes == null || enabled.containsKey(key.location())
+                        || hasActualBiome(holder.value(), actualBiomes))
+                        .map(holder -> scaled.computeIfAbsent(key,
+                                ignored -> scaledReference(holder, enabled.getOrDefault(key.location(), 1))));
             }
 
             @Override
@@ -204,6 +231,8 @@ public final class AgeStructureSelection {
             public Stream<Holder.Reference<StructureSet>> listElements() {
                 return lookup.listElements()
                         .filter(holder -> allowed(holder.key().location(), enabled.keySet()))
+                        .filter(holder -> actualBiomes == null || enabled.containsKey(holder.key().location())
+                                || hasActualBiome(holder.value(), actualBiomes))
                         .map(holder -> scaled.computeIfAbsent(holder.key(),
                                 ignored -> scaledReference(holder,
                                         enabled.getOrDefault(holder.key().location(), 1))));
@@ -220,6 +249,50 @@ public final class AgeStructureSelection {
         return !CONTROLLED_SETS.contains(set) || enabled.contains(set);
     }
 
+    private static boolean hasActualBiome(StructureSet set, BiomeSource actualBiomes) {
+        Set<Holder<Biome>> present = actualBiomes.possibleBiomes();
+        return set.structures().stream().flatMap(entry -> entry.structure().value().biomes().stream())
+                .anyMatch(present::contains);
+    }
+
+    /** Only the structure planner sees these extra biomes; terrain and weather keep the real source. */
+    public static BiomeSource planningBiomes(BiomeSource actual, HolderLookup<StructureSet> sets,
+                                             List<AgeFeatureSelection.Choice> choices) {
+        Set<ResourceLocation> enabled = enabledSets(choices).keySet();
+        List<Holder<Biome>> structureBiomes = enabled.stream()
+                .map(id -> sets.get(ResourceKey.create(Registries.STRUCTURE_SET, id)))
+                .flatMap(Optional::stream)
+                .flatMap(holder -> holder.value().structures().stream())
+                .flatMap(entry -> entry.structure().value().biomes().stream())
+                .distinct().toList();
+        return structureBiomes.isEmpty() ? actual : new PlanningBiomeSource(actual, structureBiomes);
+    }
+
+    private static final class PlanningBiomeSource extends BiomeSource {
+        private final BiomeSource actual;
+        private final List<Holder<Biome>> structureBiomes;
+
+        private PlanningBiomeSource(BiomeSource actual, List<Holder<Biome>> structureBiomes) {
+            this.actual = actual;
+            this.structureBiomes = structureBiomes;
+        }
+
+        @Override
+        protected MapCodec<? extends BiomeSource> codec() {
+            throw new UnsupportedOperationException("Structure-planning biome sources are never serialized");
+        }
+
+        @Override
+        protected Stream<Holder<Biome>> collectPossibleBiomes() {
+            return Stream.concat(actual.possibleBiomes().stream(), structureBiomes.stream());
+        }
+
+        @Override
+        public Holder<Biome> getNoiseBiome(int x, int y, int z, Climate.Sampler sampler) {
+            return actual.getNoiseBiome(x, y, z, sampler);
+        }
+    }
+
     private static Holder<StructureSet> scaledHolder(Holder<StructureSet> holder,
                                                       Map<ResourceLocation, Integer> enabled) {
         int occurrences = holder.unwrapKey().map(key -> enabled.getOrDefault(key.location(), 1)).orElse(1);

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

@@ -54,6 +54,7 @@ public final class DescriptiveBookScreen extends Screen implements ExplorableBoo
     private final List<SymbolDisplayMetadata> writingSymbols;
     private final boolean pageFree;
     private final String author;
+    private final Integer instabilityScore;
     private final InteractionHand hand;
     private final BlockPos bookStandPos;
     private DestinationPreviewRenderer preview;
@@ -74,6 +75,7 @@ public final class DescriptiveBookScreen extends Screen implements ExplorableBoo
         this.writingSymbols = List.copyOf(writingSymbols);
         pageFree = writing.entries().stream().noneMatch(entry -> entry.kind() == WritingEntry.Kind.SYMBOL);
         author = book.get(ModDataComponents.BOOK_AUTHOR.get());
+        instabilityScore = book.get(ModDataComponents.AGE_INSTABILITY_SCORE.get());
         this.hand = hand;
         bookStandPos = null;
     }
@@ -88,6 +90,7 @@ public final class DescriptiveBookScreen extends Screen implements ExplorableBoo
         this.writingSymbols = List.copyOf(writingSymbols);
         pageFree = writing.entries().stream().noneMatch(entry -> entry.kind() == WritingEntry.Kind.SYMBOL);
         author = book.get(ModDataComponents.BOOK_AUTHOR.get());
+        instabilityScore = book.get(ModDataComponents.AGE_INSTABILITY_SCORE.get());
         hand = InteractionHand.MAIN_HAND;
         this.bookStandPos = bookStandPos.immutable();
     }
@@ -250,7 +253,12 @@ 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 (instabilityScore != null) {
+            detailsY = drawWrappedWithoutShadow(graphics,
+                    Component.translatable("item.rivencraft.descriptive_book.instability", instabilityScore),
+                    x, detailsY, 110, instabilityScore > 0 ? UNRESOLVED_TEXT_COLOR : BOOK_TEXT_COLOR) + 6;
+        }
         if (!pageFree) return;
         if (generationProfile != null) {
             Component profileName = generationProfile.getNamespace().equals("rivencraft")

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) {
@@ -131,27 +130,96 @@ 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 totals = age.instability().totals();
         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);
+        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 (saved plan v"
+                + age.instabilityPlan().version() + "): " + age.instabilityPlan().providers().size()), false);
+        age.instabilityPlan().providers().forEach(provider -> source.sendSuccess(() -> Component.literal(
+                "  " + provider.id() + " level " + provider.level() + " — "
+                        + AgeInstabilityRuntime.providerStatus(source.getLevel(), age, provider.id())), false));
+        if (age.instabilityPlan().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();
     }
 
+    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) {
         DecayBlock.Color color;
         try {

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 +1,8 @@
 package net.dnorberg.rivencraft.config;
 
+import java.util.HashMap;
+import java.util.Map;
+import net.minecraft.resources.ResourceLocation;
 import net.neoforged.neoforge.common.ModConfigSpec;
 
 /** Server-configurable gameplay policies. */
@@ -56,6 +59,7 @@ 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();
@@ -170,6 +174,19 @@ 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 +210,11 @@ public final class RivencraftConfig {
     }
 
     public static boolean instabilityEnabled() { return INSTABILITY_ENABLED.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(); }

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

@@ -112,6 +112,11 @@ public final class DescriptiveBookItem extends Item {
                 ? Component.translatable("item.rivencraft.descriptive_book.unwritten")
                 : Component.translatable("item.rivencraft.descriptive_book.age", age.name());
         tooltipComponents.add(status.withStyle(ChatFormatting.GRAY));
+        Integer instability = stack.get(ModDataComponents.AGE_INSTABILITY_SCORE.get());
+        if (age != null && instability != null) {
+            tooltipComponents.add(Component.translatable("item.rivencraft.descriptive_book.instability", instability)
+                    .withStyle(instability > 0 ? ChatFormatting.DARK_RED : ChatFormatting.DARK_GREEN));
+        }
         stack.getOrDefault(ModDataComponents.LINK_PROPERTIES.get(), LinkProperties.NONE)
                 .forDescriptiveBook().appendTooltip(tooltipComponents);
     }

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

@@ -111,6 +111,11 @@ public final class ModNetworking {
                 access.stack().set(ModDataComponents.AGE_GENERATION_PROFILE.get(), definition.generationProfile());
                 access.sync().run();
         }
+        if (definition != null && !java.util.Objects.equals(
+                access.stack().get(ModDataComponents.AGE_INSTABILITY_SCORE.get()), definition.instability().score())) {
+            access.stack().set(ModDataComponents.AGE_INSTABILITY_SCORE.get(), definition.instability().score());
+            access.sync().run();
+        }
         // Requests run on the same server thread as Age creation. A request queued
         // during generation can only open the finished book, never a stale client copy.
         player.inventoryMenu.broadcastChanges();
@@ -170,8 +175,10 @@ 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(ModDataComponents.AGE_INSTABILITY_SCORE.get(), definition.instability().score());
+            });
             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/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/world/AgeFeatureChunkGenerator.java

@@ -110,8 +110,10 @@ public final class AgeFeatureChunkGenerator extends NoiseBasedChunkGenerator {
 
     @Override
     public ChunkGeneratorStructureState createState(HolderLookup<StructureSet> sets, RandomState random, long seed) {
-        return ChunkGeneratorStructureState.createForNormal(random, seed, getBiomeSource(),
-                AgeStructureSelection.filteredLookup(sets, features));
+        BiomeSource actual = getBiomeSource();
+        return ChunkGeneratorStructureState.createForNormal(random, seed,
+                AgeStructureSelection.planningBiomes(actual, sets, features),
+                AgeStructureSelection.filteredLookup(sets, features, actual));
     }
 
     @Override

src/main/java/net/dnorberg/rivencraft/world/AgeFlatChunkGenerator.java

@@ -72,8 +72,9 @@ public final class AgeFlatChunkGenerator extends ChunkGenerator {
         Stream<Holder<StructureSet>> entries = settings.structureOverrides()
                 .map(HolderSet::stream)
                 .orElseGet(() -> structures.listElements().map(holder -> (Holder<StructureSet>) holder));
-        return ChunkGeneratorStructureState.createForFlat(random, seed, biomeSource,
-                AgeStructureSelection.allowedSets(entries, features));
+        return ChunkGeneratorStructureState.createForFlat(random, seed,
+                AgeStructureSelection.planningBiomes(biomeSource, structures, features),
+                AgeStructureSelection.allowedSets(entries, features, biomeSource));
     }
 
     @Override

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)",