Apply authored feature and decoration pages to ages

README.md

@@ -102,7 +102,8 @@ into a versioned, server-owned Age plan. The plan freezes the Age seed, resolved
 symbol meanings, page order, and runtime profile, so later data-pack changes do
 not reinterpret an existing Age. An authored terrain page selects its runtime
 profile. Built-in pages cover Standard, Amplified, Cave, Island, Flat, and Void;
-other symbol effects are scheduled for later Milestone 5 slices. The
+authored biome, environment, and supported feature pages also affect new Ages.
+Further symbol effects are scheduled for later Milestone 5 slices. The
 writing is also stored on the book; the Descriptive Book screen's turned pages
 show ordered symbols and unresolved IDs. The Descriptive Book screen follows
 Legacy's book spread: the title and Age details are on the left, the destination

docs/GAMETESTS.md

@@ -1,6 +1,6 @@
 # GameTest suites
 
-The default dedicated-server run is a small smoke suite: 23 Rivencraft tests
+The default dedicated-server run is a small smoke suite. Its Rivencraft tests
 cover core linking, deterministic Age definition, writing persistence, legacy
 data migration, workstation transactions, and forged/replayed menu actions.
 
@@ -8,7 +8,7 @@ data migration, workstation transactions, and forged/replayed menu actions.
 ./gradlew runGameTestServer
 ```
 
-The remaining 58 Rivencraft tests are archived, not deleted. They cover
+The remaining Rivencraft tests are archived, not deleted. They cover
 completed milestone details such as every Age terrain profile, Notebook and
 Desk surface interactions, refill edge cases, book assembly controls, and
 workstation break/drop behavior. Run only the relevant archive alongside the
@@ -20,7 +20,7 @@ core tests when investigating an issue:
 ```
 
 Available suite names are `linking`, `environment`, `writing`, `grammar`, `desk`,
-`binder`, `mixer`, and `recipe`. Run all 81 Rivencraft tests before a
+`binder`, `mixer`, and `recipe`. Run all Rivencraft tests before a
 release or after broad cross-system changes:
 
 ```shell
@@ -42,6 +42,11 @@ Logs and configuration remain available. Cleanup never targets a custom
 it themselves. The full suite should still be run
 before shipping changes in the archived systems.
 
+If a new GameTest stalls the server, stop that run, remove the offending
+automated check, and hand its exact scenario to the player for in-game
+verification. Do not keep retrying a stalled test or leave its process running.
+Keep the narrower non-stalling plan, persistence, and runtime checks automated.
+
 ## Manual Age unload/reload check
 
 The automated suite does not unload a freshly generated Age. Minecraft can
@@ -62,3 +67,33 @@ checked in a normal game session:
 4. Reopen the same Descriptive Books and travel back. Confirm each book reaches
    its original Age, the terrain and safe arrival remain intact, and no extra
    Age entry was created. Save, restart the world, and repeat the book check.
+
+## Manual feature-generation check (Milestone 5, issue #35)
+
+The automated suite verifies feature pages, compiled and saved feature IDs,
+vanilla registry mappings, unsupported combinations, and the runtime generator.
+An automated scan across many newly generated chunks stalled the GameTest
+server, so physical placement is handed to the player for in-game verification:
+
+1. In a fresh world, bind a Descriptive Book with Link Panel, Standard Terrain,
+   Plains Biome, Single Biome, Caves, and Rocks pages in that order.
+   Missing weather/lighting/celestial branches may be seed-filled. Travel to
+   the Age and explore several fresh surface chunks: boulders made from one
+   seed-selected full-collision block should appear among the plains terrain.
+   Then explore underground in fresh
+   chunks; the Caves page should add a second cave-carving pass to Standard
+   terrain, not switch the Age to Cave terrain.
+2. Make a second book with Flat Terrain and Caves. The Binder should mark the
+   Caves page unsupported and prevent assembly. Cave Terrain plus Caves should
+   be accepted; Cave Terrain plus Rocks should be rejected.
+3. Return, save, and restart the world. Re-enter the first Age and explore
+   *new* chunks. The authored decorations should continue without rebinding.
+   Previously generated chunks are intentionally unchanged.
+4. Title-derived terrain regression (with Create installed): with no Terrain Page, assemble Link Panel,
+   Glowstone, Rocks, Chocolate, Small Lakes in that order and name the Age
+   `glow`. The Binder should accept it and generate compatible surface terrain;
+   Glowstone should be the rock material and Chocolate should appear in authored
+   Small Lakes across fresh chunks. Ordinary vanilla lava lakes may still occur.
+   Repeat
+   with `gl` or `glo` to confirm names do not change page validity. An explicit
+   Flat or Cave Terrain Page with Rocks should still be rejected.

docs/WRITING_GRAMMAR.md

@@ -4,10 +4,18 @@
 
 New Binder writing has at most one Link Panel plus 27 symbol pages. The Link Panel must be first. A Link-Panel-only book, or an older book with no writing component, keeps the existing random Age path. Any authored supported symbol makes the book a partial or complete grammar. From 0.4.3.0, the server compiles it into a persistent Age plan before consuming Binder inputs or generating chunks.
 
-The supported order follows the representable subset of the [Legacy grammar audit](LEGACY_AGE_GRAMMAR_AUDIT.md): terrain; zero or more biome pages; biome controller; weather; lighting; sky effects; zero or more period or phase modifiers; one celestial page; then zero or more distinct features. Biome pages precede the controller that consumes them, and celestial modifiers precede the celestial page. Terrain, controller, weather, lighting, sky, and celestial are single-choice categories; identical repeats are duplicates and differing values conflict. Repeated modifiers are intentional. Biome pages may repeat, preserving author order and any future weighting; feature IDs may not repeat. Angle modifiers remain recognized in the schema but are rejected at binding until a sky renderer can apply sun tilt.
+The supported order follows the representable subset of the [Legacy grammar audit](LEGACY_AGE_GRAMMAR_AUDIT.md): terrain; zero or more biome pages; biome controller; weather; lighting; sky effects; zero or more period or phase modifiers; one celestial page; then zero or more distinct features, each optionally preceded by a compatible block-material page. Biome pages precede the controller that consumes them, and celestial modifiers precede the celestial page. Terrain, controller, weather, lighting, sky, and celestial are single-choice categories; identical repeats are duplicates and differing values conflict. Repeated modifiers are intentional. Biome pages may repeat, preserving author order and any future weighting; feature IDs may not repeat. Angle modifiers remain recognized in the schema but are rejected at binding until a sky renderer can apply sun tilt.
 
-Missing terrain, controller, weather, lighting, celestial, or the controller's minimum biome count is an **incomplete** warning, not an error: the compiler retains the seed-selected profile and traits for missing branches. The minimum is zero for Native, one for Single, and two for Tiled/Grid and Tiny–Huge. Native cannot consume authored biome pages; Single accepts only one. Unknown IDs, schema-v1 display-only symbols, wrong ordering, misplaced modifiers, duplicates, conflicts, missing/extra Link Panels, and oversized writing are errors. The Binder disables output and exposes the first error on the result-slot tooltip. When that error belongs to a page, its thumbnail is tinted and outlined red, the strip scrolls to it, and hovering it shows the diagnostic. This maps the parser's compact entry position back through any empty page positions. Rejected inputs remain removable. Binding an unwritten Descriptive Book rechecks its server-owned writing and reports the first error without creating an Age. A terrain symbol whose profile is unavailable is also rejected before Binder inputs are consumed.
+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. The minimum biome count is zero for Native, one for Single, and two for Tiled/Grid and Tiny–Huge. Native cannot consume authored biome pages; Single accepts only one. Unknown IDs, schema-v1 display-only symbols, wrong ordering, misplaced modifiers, duplicates, conflicts, missing/extra Link Panels, and oversized writing are errors. The Binder disables output and exposes the first error on the result-slot tooltip. When that error belongs to a page, its thumbnail is tinted and outlined red, the strip scrolls to it, and hovering it shows the diagnostic. This maps the parser's compact entry position back through any empty page positions. Rejected inputs remain removable. Binding an unwritten Descriptive Book rechecks its server-owned writing and reports the first error without creating an Age. A terrain symbol whose profile is unavailable is also rejected before Binder inputs are consumed.
 
-The plan stores the original writing order, the authoritative semantic value of each resolved symbol, the Age seed, and a copy of the selected runtime profile. An explicit terrain page replaces the random terrain selection; an omitted terrain uses the seed-selected 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 now affect new Ages; feature effects remain issue #35 work, and instability remains Milestone 6 work.
+The plan stores the original writing order, the authoritative semantic value of each resolved symbol, 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; instability remains Milestone 6 work.
 
-The Rivencraft symbol-page creative tabs read a generated index of bundled symbol definitions and group Pages by each definition's category, except biome-controller roles, which appear in a separate Biome Generation tab rather than the Biome tab. Adding another valid JSON symbol under `src/main/resources/data/rivencraft/rivencraft/symbols/` includes its page in the matching category tab on the next build; a new bundled category receives its own tab. Link Pages have a separate tab. Blank Pages appear in neither the creative tabs nor JEI's ingredient list. The server catalog still decides whether a page is valid for writing. External server data-pack symbols are not included in this bundled index.
+## Supported feature pages (issue #35)
+
+Feature pages come after the celestial section. Their order is retained in the plan and in decoration placement. The Caves page adds a second, Age-seeded vanilla cave-carving pass to Noise terrain, including Standard, Amplified, Island, and Cave terrain. It chooses the vanilla Overworld or Nether cave carver from the source biome. This is separate from the Milestone 7 issue about Cave **terrain** generation. Flat and Void terrain have no suitable solid noise body and reject Caves with a binder diagnostic.
+
+Flowers, Trees, Huge Trees, Rocks, Surface Lakes, Deep Lakes, and Small Lakes add vanilla placed features after normal biome decoration. Huge Trees currently use vanilla old-growth spruce placement as a modern approximation of Legacy's huge-tree page; it is not the custom Legacy tree generator. Without a preceding material page, Rocks select a valid solid block and each lake page selects a valid source-fluid block from the registered pool. The selection is deterministic for an Age seed and feature ID, so all chunks in that Age use the same material across restarts with the same block registry. The page-specific feature preserves vanilla placement rules other than the biome-list filter, since an authored page deliberately adds it to the Age. Surface and Small Lakes use a more visible one-in-twelve-chunks attempt rate instead of vanilla lava lakes' one-in-two-hundred; Deep Lakes retain their underground placement. Vanilla biome lava lakes are separate and can still appear alongside authored fluid lakes. These decorations require surface Noise terrain; Cave, Flat, and Void reject them. Flowers and both tree pages require at least one surface Overworld biome and only run in compatible chunks; Nether, End, and tagged cave biomes do not receive surface vegetation. Ravines add a separate Age-seeded vanilla canyon-carving pass to Noise terrain. Unsupported feature IDs and missing vanilla registry entries produce diagnostics instead of becoming no-ops.
+
+Material pages are generated for registered full-collision, non-fluid blocks and genuine source-fluid blocks, including eligible blocks supplied by other mods. Blocks with block entities are excluded. Waterlogged plants and coral are not fluid blocks and receive no pages. Valid source-fluid blocks appear only in the Fluid Pages creative tab; valid full-collision solids appear only in Block Pages. Both categories use the same saved material-page semantics. Put a Block Page immediately before Rocks to choose a rock material, or a Fluid Page immediately before Surface Lakes, Deep Lakes, or Small Lakes to choose a lake fluid. A material page left alone, placed before a different category, or attached to an incompatible feature is rejected. Both the feature and material ID are frozen in the saved plan, so future chunks retain their choice after restart. Existing chunks are not retroactively decorated. Custom structures, crystals, portals, and the Cave-terrain bug are outside this slice.
+
+The Rivencraft symbol-page creative tabs read a generated index of bundled symbol definitions and group Pages by each definition's category, except biome-controller roles, which appear in a separate Biome Generation tab rather than the Biome tab. Adding another valid JSON symbol under `src/main/resources/data/rivencraft/rivencraft/symbols/` includes its page in the matching category tab on the next build; a new bundled category receives its own tab. Registry-derived Block and Fluid Pages have separate tabs and both appear in optional JEI. Link Pages have a separate tab. Blank Pages appear in neither the creative tabs nor JEI's ingredient list. The server catalog still decides whether a page is valid for writing. External server data-pack symbols are not included in this bundled index.

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=0.4.6.2
+mod_version=0.4.6.9
 immersive_portals_version=6.0.7
 # The group ID for the mod. It is only important when publishing as an artifact to a Maven repository.
 # This should match the base package used for the mod sources.

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

@@ -24,6 +24,7 @@ import net.minecraft.core.NonNullList;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
 import net.dnorberg.rivencraft.book.AgeBiomeSelection;
+import net.dnorberg.rivencraft.book.AgeFeatureSelection;
 import net.minecraft.tags.BiomeTags;
 import net.minecraft.core.component.DataComponents;
 import net.minecraft.nbt.CompoundTag;
@@ -151,7 +152,7 @@ public final class BookBinderBlockEntity extends BlockEntity implements Containe
             var selectedProfile = terrain.isPresent()
                     ? ((SymbolSemantics.ResourceValue) terrain.orElseThrow().semantics().value()).id()
                     : level instanceof ServerLevel serverLevel
-                    ? AgeRegistrySavedData.previewGenerationProfile(serverLevel, title)
+                    ? AgeRegistrySavedData.previewGenerationProfile(serverLevel, title, currentWriting())
                     : AgeGenerationProfiles.STANDARD;
             var runtimeProfile = AgeRuntimeProfiles.profiles().get(selectedProfile);
             boolean cave = runtimeProfile != null && AgeBiomeSelection.isCave(runtimeProfile);
@@ -168,6 +169,33 @@ public final class BookBinderBlockEntity extends BlockEntity implements Containe
                                     symbol.index(), "Cave Ages require cave or Nether biomes; remove " + id));
                         }
                     });
+            if (runtimeProfile != null) {
+                parsed.symbols().stream().filter(symbol -> symbol.semantics().role() == SymbolSemantics.Role.FEATURE)
+                        .forEach(symbol -> {
+                            var id = ((SymbolSemantics.ResourceValue) symbol.semantics().value()).id();
+                            String error = AgeFeatureSelection.error(id, runtimeProfile, level.registryAccess());
+                            if (error != null) diagnostics.add(new WritingGrammar.Diagnostic(
+                                    WritingGrammar.Code.UNSUPPORTED_FEATURE, symbol.index(), error));
+                        });
+            }
+            // Compile against the actual title-derived Age seed as a final compatibility
+            // check. This also pinpoints biome-pool conflicts that cannot be inferred from
+            // an individual feature page alone (for example Trees with only Nether biomes).
+            if (level instanceof ServerLevel serverLevel && diagnostics.stream().noneMatch(
+                    diagnostic -> diagnostic.code() == WritingGrammar.Code.UNSUPPORTED_FEATURE)) {
+                try {
+                    AgeRegistrySavedData.validateNewWriting(serverLevel, title, currentWriting());
+                } catch (IllegalArgumentException exception) {
+                    if (exception.getMessage() != null && (exception.getMessage().startsWith("Feature ")
+                            || exception.getMessage().startsWith("Caves "))) {
+                        parsed.symbols().stream().filter(symbol -> symbol.semantics().role()
+                                        == SymbolSemantics.Role.FEATURE).findFirst().ifPresent(symbol ->
+                                diagnostics.add(new WritingGrammar.Diagnostic(
+                                        WritingGrammar.Code.UNSUPPORTED_FEATURE, symbol.index(),
+                                        exception.getMessage())));
+                    }
+                }
+            }
         }
         return new WritingGrammar.Result(parsed.symbols(), diagnostics);
     }

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

@@ -37,6 +37,7 @@ import net.minecraft.world.level.biome.FixedBiomeSource;
 import net.minecraft.world.level.biome.MultiNoiseBiomeSource;
 import net.dnorberg.rivencraft.world.ScaledBiomeSource;
 import net.dnorberg.rivencraft.world.AgeFlatChunkGenerator;
+import net.dnorberg.rivencraft.world.AgeFeatureChunkGenerator;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.minecraft.world.level.dimension.BuiltinDimensionTypes;
 import net.minecraft.world.level.dimension.DimensionType;
@@ -321,7 +322,10 @@ public final class AgeDimensionService {
         ResourceKey<NoiseGeneratorSettings> settingsKey = ResourceKey.create(
                 Registries.NOISE_SETTINGS, profile.noiseSettings());
         NoiseGeneratorSettings baseSettings = noiseSettings.getOrThrow(settingsKey).value();
-        return new NoiseBasedChunkGenerator(biomeSource, Holder.direct(withBiomeMaterialRules(baseSettings)));
+        Holder<NoiseGeneratorSettings> settings = Holder.direct(withBiomeMaterialRules(baseSettings));
+        List<AgeFeatureSelection.Choice> features = AgeFeatureSelection.resolved(age.plan());
+        return features.isEmpty() ? new NoiseBasedChunkGenerator(biomeSource, settings)
+                : new AgeFeatureChunkGenerator(biomeSource, settings, features, age.seed());
     }
 
     private static NoiseGeneratorSettings withBiomeMaterialRules(NoiseGeneratorSettings base) {

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

@@ -0,0 +1,181 @@
+package net.dnorberg.rivencraft.book;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import net.dnorberg.rivencraft.writing.BlockSymbolPages;
+import net.dnorberg.rivencraft.writing.SymbolSemantics;
+import net.dnorberg.rivencraft.writing.WritingGrammar;
+import net.minecraft.core.Holder;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.tags.BiomeTags;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.block.Blocks;
+
+/** Validates and freezes supported feature pages and their preceding material modifiers. */
+public final class AgeFeatureSelection {
+    private AgeFeatureSelection() {}
+
+    public record Choice(ResourceLocation id, Optional<ResourceLocation> material) {
+        public static final Codec<Choice> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+                ResourceLocation.CODEC.fieldOf("id").forGetter(Choice::id),
+                ResourceLocation.CODEC.optionalFieldOf("material").forGetter(Choice::material)
+        ).apply(instance, Choice::new));
+
+        public Choice {
+            if (id == null || material == null) throw new IllegalArgumentException("Missing feature choice");
+        }
+    }
+
+    public static List<Choice> compile(WritingGrammar.Result writing, AgeRuntimeProfile profile,
+                                       AgeBiomeSelection biomes, RegistryAccess registries) {
+        List<Choice> choices = choices(writing.symbols().stream()
+                .map(symbol -> symbol.semantics()).toList());
+        for (Choice choice : choices) {
+            String error = error(choice.id(), profile, registries);
+            if (error == null) error = materialError(choice);
+            if (error != null) throw new IllegalArgumentException(error);
+            if (surfaceVegetation(choice.id()) && biomes.biomes().stream()
+                    .allMatch(id -> !supportsSurfaceVegetation(id, registries))) {
+                throw new IllegalArgumentException("Feature " + choice.id()
+                        + " needs at least one surface Overworld biome in the selected pool");
+            }
+        }
+        return choices;
+    }
+
+    private static List<Choice> choices(List<SymbolSemantics> symbols) {
+        List<Choice> choices = new ArrayList<>();
+        ResourceLocation pendingMaterial = null;
+        for (SymbolSemantics semantics : symbols) {
+            if (semantics.role() == SymbolSemantics.Role.BLOCK) {
+                pendingMaterial = ((SymbolSemantics.ResourceValue) semantics.value()).id();
+            } else if (semantics.role() == SymbolSemantics.Role.FEATURE) {
+                choices.add(new Choice(((SymbolSemantics.ResourceValue) semantics.value()).id(),
+                        Optional.ofNullable(pendingMaterial)));
+                pendingMaterial = null;
+            }
+        }
+        return List.copyOf(choices);
+    }
+
+    public static List<Choice> resolved(AgeGenerationPlan plan) {
+        if (plan == null) return List.of();
+        return choices(plan.symbols().stream().map(symbol -> symbol.semantics()).toList()).stream()
+                .map(choice -> choice.material().isPresent() || !isRock(choice.id()) && !isLake(choice.id())
+                        ? choice : new Choice(choice.id(), Optional.of(randomMaterial(plan.ageSeed(), choice.id()))))
+                .toList();
+    }
+
+    private static ResourceLocation randomMaterial(long ageSeed, ResourceLocation feature) {
+        var category = isRock(feature) ? BlockSymbolPages.CATEGORY : BlockSymbolPages.FLUID_CATEGORY;
+        List<ResourceLocation> pool = BlockSymbolPages.availableBlocks(category).stream()
+                .filter(id -> materialError(new Choice(feature, Optional.of(id))) == null).toList();
+        if (pool.isEmpty()) throw new IllegalStateException("No valid material blocks for " + feature);
+        long mixed = ageSeed ^ (long) feature.hashCode() * 0x9E3779B97F4A7C15L;
+        mixed = (mixed ^ mixed >>> 30) * 0xBF58476D1CE4E5B9L;
+        mixed = (mixed ^ mixed >>> 27) * 0x94D049BB133111EBL;
+        return pool.get(Math.floorMod(mixed ^ mixed >>> 31, pool.size()));
+    }
+
+    public static String error(ResourceLocation choice, AgeRuntimeProfile profile, RegistryAccess registries) {
+        if (caves(choice) || ravines(choice)) {
+            if (profile.terrain() != AgeRuntimeProfile.Terrain.NOISE) {
+                return "Feature " + choice + " requires noise terrain with stone to carve; not Flat or Void";
+            }
+            var carvers = registries.lookupOrThrow(Registries.CONFIGURED_CARVER);
+            List<String> ids = caves(choice) ? List.of("cave", "nether_cave") : List.of("canyon");
+            for (String path : ids) {
+                var key = ResourceKey.create(Registries.CONFIGURED_CARVER, ResourceLocation.withDefaultNamespace(path));
+                if (carvers.get(key).isEmpty()) return "Feature " + choice
+                        + " requires missing configured carver " + key.location();
+            }
+            return null;
+        }
+        ResourceLocation placed = placedFeature(choice);
+        if (placed == null) return "Unsupported feature " + choice
+                + "; remove its page (custom structures remain future work)";
+        if (profile.terrain() != AgeRuntimeProfile.Terrain.NOISE || AgeBiomeSelection.isCave(profile)) {
+            return "Feature " + choice + " requires surface noise terrain; not Flat, Void, or Cave";
+        }
+        if (registries.lookupOrThrow(Registries.PLACED_FEATURE)
+                .get(ResourceKey.create(Registries.PLACED_FEATURE, placed)).isEmpty()) {
+            return "Feature " + choice + " requires missing placed feature " + placed;
+        }
+        return null;
+    }
+
+    public static String materialError(Choice choice) {
+        if (choice.material().isEmpty()) return null;
+        ResourceLocation material = choice.material().orElseThrow();
+        var block = BuiltInRegistries.BLOCK.getOptional(material);
+        if (block.isEmpty() || block.orElseThrow() == Blocks.AIR) {
+            return "Feature " + choice.id() + " references missing block material " + material;
+        }
+        if (isRock(choice.id())) {
+            if (!BlockSymbolPages.isRockMaterial(block.orElseThrow())) {
+                return "Feature " + choice.id() + " needs a full solid block without a block entity: " + material;
+            }
+        } else if (isLake(choice.id())) {
+            if (!BlockSymbolPages.isFluidMaterial(block.orElseThrow())) {
+                return "Feature " + choice.id() + " needs a source-fluid block: " + material;
+            }
+        } else {
+            return "Feature " + choice.id() + " cannot consume a block material page";
+        }
+        return null;
+    }
+
+    public static boolean isRock(ResourceLocation choice) {
+        return choice.equals(ResourceLocation.fromNamespaceAndPath("rivencraft", "rocks"));
+    }
+
+    public static boolean isLake(ResourceLocation choice) {
+        return choice.getNamespace().equals("rivencraft") && List.of(
+                "surface_lakes", "deep_lakes", "lava_lakes").contains(choice.getPath());
+    }
+
+    public static boolean surfaceVegetation(ResourceLocation choice) {
+        return choice.getNamespace().equals("rivencraft")
+                && List.of("flowers", "trees", "huge_trees").contains(choice.getPath());
+    }
+
+    public static boolean caves(ResourceLocation choice) {
+        return choice.equals(ResourceLocation.fromNamespaceAndPath("rivencraft", "caves"));
+    }
+
+    public static boolean ravines(ResourceLocation choice) {
+        return choice.equals(ResourceLocation.fromNamespaceAndPath("rivencraft", "ravines"));
+    }
+
+    public static boolean supportsSurfaceVegetation(ResourceLocation id, RegistryAccess registries) {
+        var biome = registries.lookupOrThrow(Registries.BIOME)
+                .get(ResourceKey.create(Registries.BIOME, id));
+        return biome.isPresent() && supportsSurfaceVegetation(biome.orElseThrow());
+    }
+
+    public static boolean supportsSurfaceVegetation(Holder<Biome> biome) {
+        return !biome.is(BiomeTags.IS_NETHER) && !biome.is(BiomeTags.IS_END)
+                && !biome.is(AgeBiomeSelection.CAVE_BIOMES);
+    }
+
+    /** Fixed 1.21.1 mappings; data-pack symbols must opt in through a future extension. */
+    public static ResourceLocation placedFeature(ResourceLocation choice) {
+        if (!choice.getNamespace().equals("rivencraft")) return null;
+        return switch (choice.getPath()) {
+            case "flowers" -> ResourceLocation.withDefaultNamespace("flower_default");
+            case "trees" -> ResourceLocation.withDefaultNamespace("trees_plains");
+            case "huge_trees" -> ResourceLocation.withDefaultNamespace("trees_old_growth_spruce_taiga");
+            case "rocks" -> ResourceLocation.withDefaultNamespace("forest_rock");
+            case "surface_lakes", "lava_lakes" -> ResourceLocation.withDefaultNamespace("lake_lava_surface");
+            case "deep_lakes" -> ResourceLocation.withDefaultNamespace("lake_lava_underground");
+            default -> null;
+        };
+    }
+}

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

@@ -65,6 +65,7 @@ public record AgeGenerationPlan(int version, long ageSeed, OrderedWriting writin
         AgeRuntimeProfile profile = AgeRuntimeProfiles.profiles().get(selected);
         if (profile == null) throw new IllegalArgumentException("Unsupported Age terrain profile " + selected);
         AgeBiomeSelection biomes = AgeBiomeSelection.compile(parsed, traits, profile, ageSeed, registries);
+        AgeFeatureSelection.compile(parsed, profile, biomes, registries);
         AgeGenerationPlan plan = new AgeGenerationPlan(CURRENT_VERSION, ageSeed, writing,
                 parsed.symbols().stream().map(symbol -> new ResolvedSymbol(
                         symbol.index(), symbol.reference(), symbol.semantics())).toList(),
@@ -139,7 +140,7 @@ public record AgeGenerationPlan(int version, long ageSeed, OrderedWriting writin
             SymbolSemantics.Role role = SymbolSemantics.Role.valueOf(item.getString("Role"));
             String raw = item.getString("Value");
             SymbolSemantics.Value value = switch (role) {
-                case TERRAIN, BIOME, FEATURE -> new SymbolSemantics.ResourceValue(ResourceLocation.parse(raw));
+                case TERRAIN, BIOME, BLOCK, FEATURE -> new SymbolSemantics.ResourceValue(ResourceLocation.parse(raw));
                 case PERIOD_MODIFIER, ANGLE_MODIFIER, PHASE_MODIFIER ->
                         new SymbolSemantics.NumberValue(Double.parseDouble(raw));
                 default -> new SymbolSemantics.ChoiceValue(raw);

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

@@ -30,7 +30,7 @@ public final class AgePersistenceGameTests {
                 WritingEntry.symbol(new SymbolReference(ResourceLocation.parse("rivencraft:weather/normal"))),
                 WritingEntry.symbol(new SymbolReference(ResourceLocation.parse("rivencraft:lighting/normal"))),
                 WritingEntry.symbol(new SymbolReference(ResourceLocation.parse("rivencraft:celestial/normal_time"))),
-                WritingEntry.symbol(new SymbolReference(ResourceLocation.parse("rivencraft:feature/caves")))
+                WritingEntry.symbol(new SymbolReference(ResourceLocation.parse("rivencraft:feature/flowers")))
         ));
         UUID id = UUID.randomUUID();
         AgeReference reference = new AgeReference(id, "Authored Plan " + id);

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

@@ -66,15 +66,20 @@ public final class AgeRegistrySavedData extends SavedData {
         ServerLevel overworld = level.getServer().overworld();
         AgeRegistrySavedData data = get(overworld);
         long seed = ageSeed(overworld.getSeed(), data.availableDimensionId(normalizedName(name)));
-        AgeGenerationPlan.compile(writing, seed, AgeRuntimeProfiles.select(seed), AgeTraits.select(seed),
+        AgeGenerationPlan.compile(writing, seed,
+                AgeRuntimeProfiles.selectForWriting(seed, writing, overworld.registryAccess()), AgeTraits.select(seed),
                 overworld.registryAccess());
     }
 
     public static ResourceLocation previewGenerationProfile(ServerLevel level, String name) {
+        return previewGenerationProfile(level, name, OrderedWriting.EMPTY);
+    }
+
+    public static ResourceLocation previewGenerationProfile(ServerLevel level, String name, OrderedWriting writing) {
         ServerLevel overworld = level.getServer().overworld();
         AgeRegistrySavedData data = get(overworld);
         long seed = ageSeed(overworld.getSeed(), data.availableDimensionId(normalizedName(name)));
-        return AgeRuntimeProfiles.select(seed);
+        return AgeRuntimeProfiles.selectForWriting(seed, writing, overworld.registryAccess());
     }
 
     public Optional<AgeDefinition> find(UUID ageId) {
@@ -112,7 +117,7 @@ public final class AgeRegistrySavedData extends SavedData {
         String name = normalizedName(reference.name());
         ResourceLocation dimensionId = availableDimensionId(name);
         long seed = ageSeed(worldSeed, dimensionId);
-        ResourceLocation seedProfile = AgeRuntimeProfiles.select(seed);
+        ResourceLocation seedProfile = AgeRuntimeProfiles.selectForWriting(seed, writing, registries);
         AgeTraits traits = AgeTraits.select(seed);
         AgeGenerationPlan plan = AgeGenerationPlan.compile(writing, seed, seedProfile, traits, registries);
         AgeDefinition created = new AgeDefinition(

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

@@ -5,8 +5,12 @@ import com.google.gson.GsonBuilder;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import java.util.Map;
+import java.util.List;
 import java.util.concurrent.ConcurrentHashMap;
 import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.writing.OrderedWriting;
+import net.dnorberg.rivencraft.writing.SymbolSemantics;
+import net.dnorberg.rivencraft.writing.WritingGrammar;
 import net.minecraft.core.RegistryAccess;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
@@ -59,6 +63,27 @@ public final class AgeRuntimeProfiles {
         return ids.get(Math.floorMod(Long.hashCode(seed), ids.size()));
     }
 
+    /** Keep seed-selected terrain random, but only among profiles able to host authored features. */
+    public static ResourceLocation selectForWriting(long seed, OrderedWriting writing, RegistryAccess registries) {
+        ResourceLocation selected = select(seed);
+        WritingGrammar.Result parsed = WritingGrammar.parse(writing);
+        if (parsed.symbols().stream().anyMatch(symbol ->
+                symbol.semantics().role() == SymbolSemantics.Role.TERRAIN)) return selected;
+        List<ResourceLocation> features = parsed.symbols().stream()
+                .filter(symbol -> symbol.semantics().role() == SymbolSemantics.Role.FEATURE)
+                .map(symbol -> ((SymbolSemantics.ResourceValue) symbol.semantics().value()).id()).toList();
+        if (features.isEmpty() || PROFILES.isEmpty()) return selected;
+        AgeRuntimeProfile initial = PROFILES.get(selected);
+        if (initial != null && features.stream().allMatch(id ->
+                AgeFeatureSelection.error(id, initial, registries) == null)) return selected;
+        List<ResourceLocation> compatible = PROFILES.entrySet().stream()
+                .filter(entry -> features.stream().allMatch(id ->
+                        AgeFeatureSelection.error(id, entry.getValue(), registries) == null))
+                .map(Map.Entry::getKey).sorted().toList();
+        return compatible.isEmpty() ? selected
+                : compatible.get(Math.floorMod(Long.hashCode(seed), compatible.size()));
+    }
+
     static AgeRuntimeProfile parse(ResourceLocation id, JsonElement json, RegistryAccess registries) {
         JsonObject object = json.getAsJsonObject();
         int schemaVersion = object.has("schema_version") ? object.get("schema_version").getAsInt() : 1;

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

@@ -0,0 +1,216 @@
+package net.dnorberg.rivencraft.book;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+import java.util.UUID;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.item.PageItem;
+import net.dnorberg.rivencraft.world.AgeFeatureChunkGenerator;
+import net.dnorberg.rivencraft.writing.OrderedWriting;
+import net.dnorberg.rivencraft.writing.BlockSymbolPages;
+import net.dnorberg.rivencraft.writing.SymbolCatalog;
+import net.dnorberg.rivencraft.writing.SymbolReference;
+import net.dnorberg.rivencraft.writing.WritingEntry;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.gametest.framework.GameTest;
+import net.minecraft.gametest.framework.GameTestHelper;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.neoforged.neoforge.gametest.GameTestHolder;
+import net.neoforged.neoforge.gametest.PrefixGameTestTemplate;
+
+/** Issue #35: authored decorations must resolve to real placed features and survive plan reload. */
+@GameTestHolder(Rivencraft.MOD_ID)
+@PrefixGameTestTemplate(false)
+public final class FeatureWritingGameTests {
+    private FeatureWritingGameTests() {}
+
+    @GameTest(template = "empty")
+    public static void featurePagesCompileToFrozenVanillaPlacements(GameTestHelper helper) {
+        var registries = helper.getLevel().registryAccess();
+        Set<String> pages = Set.of("feature/caves", "feature/flowers", "feature/trees",
+                "feature/huge_trees", "feature/rocks", "feature/lava_lakes",
+                "feature/surface_lakes", "feature/deep_lakes", "feature/ravines");
+        helper.assertTrue(PageItem.bundledCreativeSymbols().containsAll(pages),
+                "Supported feature pages must appear in the creative and JEI symbol feed");
+        for (String path : pages) {
+            helper.assertTrue(PageItem.isUsableWriting(PageItem.createBundledCreativePage(path)),
+                    path + " must be usable in authored writing");
+        }
+        OrderedWriting writing = new OrderedWriting(List.of(panel(), page("terrain/standard"),
+                page("biome/plains"), page("biome/single"), page("feature/caves"), page("feature/flowers"),
+                page("feature/trees"), page("feature/rocks"), page("feature/lava_lakes")));
+        AgeGenerationPlan plan = AgeGenerationPlan.compile(writing, 87L, AgeGenerationProfiles.STANDARD,
+                AgeTraits.select(87L), registries);
+        List<AgeFeatureSelection.Choice> resolved = AgeFeatureSelection.resolved(plan);
+        helper.assertValueEqual(resolved.stream().map(AgeFeatureSelection.Choice::id).toList(), List.of(
+                id("caves"), id("flowers"), id("trees"), id("rocks"), id("lava_lakes")),
+                "The compiled Age plan must keep feature order and exact semantic IDs");
+        for (AgeFeatureSelection.Choice choice : resolved) {
+            if (AgeFeatureSelection.isRock(choice.id()) || AgeFeatureSelection.isLake(choice.id())) {
+                helper.assertTrue(choice.material().isPresent()
+                                && AgeFeatureSelection.materialError(choice) == null,
+                        "Unmodified rocks and lakes must choose a valid material from the registry");
+            }
+        }
+        helper.assertValueEqual(AgeFeatureSelection.resolved(AgeGenerationPlan.load(plan.save())),
+                AgeFeatureSelection.resolved(plan), "Features must survive the saved-plan round trip");
+        for (AgeFeatureSelection.Choice choice : AgeFeatureSelection.resolved(plan)) {
+            if (AgeFeatureSelection.caves(choice.id()) || AgeFeatureSelection.ravines(choice.id())) continue;
+            var placement = AgeFeatureSelection.placedFeature(choice.id());
+            helper.assertTrue(registries.lookupOrThrow(Registries.PLACED_FEATURE)
+                            .get(ResourceKey.create(Registries.PLACED_FEATURE, placement)).isPresent(),
+                    choice.id() + " must map to an existing vanilla placed feature");
+        }
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void unsupportedFeaturesAndTerrainsFailBeforeBinding(GameTestHelper helper) {
+        var registries = helper.getLevel().registryAccess();
+        helper.assertTrue(AgeFeatureSelection.error(id("unknown"),
+                        AgeRuntimeProfiles.resolve(AgeGenerationProfiles.STANDARD), registries)
+                        .contains("Unsupported feature"),
+                "Unimplemented feature meanings must report a diagnostic");
+        rejects(helper, new OrderedWriting(List.of(panel(), page("terrain/flat"), page("feature/flowers"))),
+                "requires surface noise terrain");
+        rejects(helper, new OrderedWriting(List.of(panel(), page("terrain/flat"), page("feature/caves"))),
+                "requires noise terrain");
+        rejects(helper, new OrderedWriting(List.of(panel(), page("terrain/cave"), page("feature/lava_lakes"))),
+                "requires surface noise terrain");
+        helper.assertTrue(AgeGenerationPlan.compile(new OrderedWriting(List.of(panel(),
+                        page("terrain/cave"), page("feature/caves"))), 87L, AgeGenerationProfiles.STANDARD,
+                AgeTraits.select(87L), registries) != null,
+                "Caves must add carving to Cave terrain as well as surface noise terrain");
+        rejects(helper, new OrderedWriting(List.of(panel(), page("terrain/standard"),
+                page("biome/nether_wastes"), page("biome/single"), page("feature/trees"))),
+                "surface Overworld biome");
+        helper.assertTrue(AgeFeatureSelection.compile(net.dnorberg.rivencraft.writing.WritingGrammar.parse(
+                        new OrderedWriting(List.of(panel(), page("terrain/standard"), page("feature/flowers")))),
+                AgeRuntimeProfiles.resolve(AgeGenerationProfiles.STANDARD),
+                AgeBiomeSelection.compile(net.dnorberg.rivencraft.writing.WritingGrammar.parse(
+                                new OrderedWriting(List.of(panel(), page("terrain/standard"), page("feature/flowers")))),
+                        AgeTraits.select(87L), AgeRuntimeProfiles.resolve(AgeGenerationProfiles.STANDARD),
+                87L, registries), registries).contains(choice("flowers")),
+                "A valid surface feature must still compile");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void blockPagesModifyFeaturesAndSurviveReload(GameTestHelper helper) {
+        var stone = ResourceLocation.withDefaultNamespace("stone");
+        var water = ResourceLocation.withDefaultNamespace("water");
+        helper.assertTrue(BlockSymbolPages.availableBlocks().contains(stone),
+                "Registry-derived material pages must include vanilla stone");
+        helper.assertTrue(BlockSymbolPages.availableBlocks(BlockSymbolPages.CATEGORY).contains(stone),
+                "Stone must appear among standard Block Pages");
+        helper.assertTrue(!BlockSymbolPages.availableBlocks(BlockSymbolPages.CATEGORY).contains(water),
+                "Water must not appear among standard Block Pages");
+        helper.assertTrue(BlockSymbolPages.availableBlocks(BlockSymbolPages.FLUID_CATEGORY).contains(water),
+                "Water must appear among Fluid Pages");
+        for (String path : List.of("fern", "seagrass", "tube_coral")) {
+            helper.assertTrue(!BlockSymbolPages.availableBlocks().contains(ResourceLocation.withDefaultNamespace(path)),
+                    path + " must not receive a rock or fluid material page");
+        }
+        var glowstone = ResourceLocation.withDefaultNamespace("glowstone");
+        helper.assertTrue(BlockSymbolPages.availableBlocks(BlockSymbolPages.CATEGORY).contains(glowstone),
+                "Glowstone should be a valid full-collision rock material");
+        helper.assertTrue(AgeFeatureSelection.materialError(new AgeFeatureSelection.Choice(
+                id("rocks"), Optional.of(glowstone))) == null,
+                "Glowstone must bind successfully before Rocks");
+        helper.assertTrue(!BlockSymbolPages.availableBlocks().contains(ResourceLocation.withDefaultNamespace("chest")),
+                "Blocks with block entities must not receive generated pages");
+        helper.assertTrue(!SymbolCatalog.isKnown(new SymbolReference(BlockSymbolPages.symbolId(
+                ResourceLocation.withDefaultNamespace("chest")))),
+                "Block-entity pages must not remain valid in the server catalog");
+        helper.assertTrue(SymbolCatalog.isKnown(new SymbolReference(BlockSymbolPages.symbolId(stone))),
+                "Generated material pages must be recognized by the server catalog");
+        helper.assertTrue(PageItem.isUsableWriting(PageItem.createCreativeBlockPage(stone)),
+                "A generated material page must be a usable authored page");
+        OrderedWriting writing = new OrderedWriting(List.of(panel(), page("terrain/standard"),
+                page("biome/plains"), page("biome/single"), block("stone"), page("feature/rocks"),
+                block("water"), page("feature/lava_lakes"), page("feature/huge_trees"),
+                page("feature/ravines")));
+        AgeGenerationPlan plan = AgeGenerationPlan.compile(writing, 87L, AgeGenerationProfiles.STANDARD,
+                AgeTraits.select(87L), helper.getLevel().registryAccess());
+        List<AgeFeatureSelection.Choice> expected = List.of(
+                new AgeFeatureSelection.Choice(id("rocks"), Optional.of(stone)),
+                new AgeFeatureSelection.Choice(id("lava_lakes"), Optional.of(water)),
+                choice("huge_trees"), choice("ravines"));
+        helper.assertValueEqual(AgeFeatureSelection.resolved(plan), expected,
+                "Each material must attach only to the immediately following feature");
+        helper.assertValueEqual(AgeFeatureSelection.resolved(AgeGenerationPlan.load(plan.save())), expected,
+                "Block modifiers must survive the frozen-plan round trip");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty")
+    public static void incompatibleAndMisplacedBlockPagesAreRejected(GameTestHelper helper) {
+        helper.assertTrue(AgeFeatureSelection.materialError(new AgeFeatureSelection.Choice(
+                        id("rocks"), Optional.of(ResourceLocation.withDefaultNamespace("torch"))))
+                        .contains("full solid block"),
+                "A non-full block must still be rejected if supplied by old writing");
+        rejects(helper, new OrderedWriting(List.of(panel(), page("terrain/standard"),
+                block("stone"), page("feature/surface_lakes"))), "source-fluid block");
+        rejects(helper, new OrderedWriting(List.of(panel(), page("terrain/standard"),
+                block("stone"), page("feature/trees"))), "cannot consume a material page");
+        rejects(helper, new OrderedWriting(List.of(panel(), page("terrain/standard"),
+                block("stone"))), "immediately before a compatible feature");
+        helper.succeed();
+    }
+
+    @GameTest(template = "empty", timeoutTicks = 600)
+    public static void runtimeAgeUsesSavedFeatureGenerator(GameTestHelper helper) {
+        var player = helper.makeMockServerPlayerInLevel();
+        OrderedWriting writing = new OrderedWriting(List.of(panel(), page("terrain/standard"),
+                page("biome/plains"), page("biome/single"), page("feature/caves"), page("feature/rocks")));
+        AgeReference reference = new AgeReference(UUID.randomUUID(), "Written Flowers");
+        var target = AgeDimensionService.resolve(player, reference, writing).orElseThrow();
+        AgeDefinition definition = AgeRegistrySavedData.get(helper.getLevel()).find(reference.id()).orElseThrow();
+        List<AgeFeatureSelection.Choice> expected = AgeFeatureSelection.resolved(definition.plan());
+        helper.assertValueEqual(expected.stream().map(AgeFeatureSelection.Choice::id).toList(),
+                List.of(id("caves"), id("rocks")), "Saved Age definition must retain the written decoration");
+        helper.assertTrue(expected.get(1).material().isPresent(),
+                "Unmodified rocks must receive a chosen material");
+        helper.runAfterDelay(1, () -> {
+            var level = helper.getLevel().getServer().getLevel(target.location().dimension());
+            helper.assertTrue(level != null, "The authored feature Age must load");
+            helper.assertTrue(level.getChunkSource().getGenerator() instanceof AgeFeatureChunkGenerator,
+                    "Runtime world generation must use the feature-aware generator");
+            var generator = (AgeFeatureChunkGenerator) level.getChunkSource().getGenerator();
+            helper.assertValueEqual(generator.ageFeatures(), expected,
+                    "Runtime generation must receive the frozen authored feature selection");
+            helper.succeed();
+        });
+    }
+
+    private static void rejects(GameTestHelper helper, OrderedWriting writing, String expected) {
+        try {
+            AgeGenerationPlan.compile(writing, 87L, AgeGenerationProfiles.STANDARD,
+                    AgeTraits.select(87L), helper.getLevel().registryAccess());
+            helper.fail("Writing must reject " + expected);
+        } catch (IllegalArgumentException exception) {
+            helper.assertTrue(exception.getMessage().contains(expected), exception.getMessage());
+        }
+    }
+
+    private static ResourceLocation id(String path) {
+        return ResourceLocation.fromNamespaceAndPath(Rivencraft.MOD_ID, path);
+    }
+
+    private static AgeFeatureSelection.Choice choice(String path) {
+        return new AgeFeatureSelection.Choice(id(path), java.util.Optional.empty());
+    }
+
+    private static WritingEntry page(String path) {
+        return WritingEntry.symbol(new SymbolReference(id(path)));
+    }
+
+    private static WritingEntry block(String path) {
+        return WritingEntry.symbol(new SymbolReference(BlockSymbolPages.symbolId(
+                ResourceLocation.withDefaultNamespace(path))));
+    }
+
+    private static WritingEntry panel() { return WritingEntry.linkPanel(); }
+}

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

@@ -17,6 +17,7 @@ import net.dnorberg.rivencraft.writing.PageContent;
 import net.dnorberg.rivencraft.writing.SymbolCatalog;
 import net.dnorberg.rivencraft.writing.SymbolDefinition;
 import net.dnorberg.rivencraft.writing.BiomeSymbolPages;
+import net.dnorberg.rivencraft.writing.BlockSymbolPages;
 import net.dnorberg.rivencraft.writing.SymbolDisplayMetadata;
 import net.dnorberg.rivencraft.writing.SymbolReference;
 import net.dnorberg.rivencraft.writing.SymbolSemantics;
@@ -55,12 +56,19 @@ public final class PageItem extends Item {
 
     /** Bundled categories become separate creative tabs without a Java page list. */
     public static List<ResourceLocation> bundledCreativeCategories() {
-        return List.copyOf(CREATIVE_SYMBOLS.values().stream()
+        LinkedHashSet<ResourceLocation> categories = CREATIVE_SYMBOLS.values().stream()
                 .map(CreativeSymbol::creativeCategory)
-                .collect(java.util.stream.Collectors.toCollection(LinkedHashSet::new)));
+                .collect(java.util.stream.Collectors.toCollection(LinkedHashSet::new));
+        categories.add(BlockSymbolPages.CATEGORY);
+        categories.add(BlockSymbolPages.FLUID_CATEGORY);
+        return List.copyOf(categories);
     }
 
     public static ItemStack bundledCreativeCategoryIcon(ResourceLocation category) {
+        if (category.equals(BlockSymbolPages.CATEGORY) || category.equals(BlockSymbolPages.FLUID_CATEGORY)) {
+            return createCreativeBlockPage(ResourceLocation.withDefaultNamespace(
+                    category.equals(BlockSymbolPages.FLUID_CATEGORY) ? "water" : "stone"));
+        }
         return CREATIVE_SYMBOLS.entrySet().stream()
                 .filter(entry -> entry.getValue().creativeCategory().equals(category))
                 .findFirst()
@@ -70,6 +78,12 @@ public final class PageItem extends Item {
 
     /** Exact symbol-page variants offered in the creative tab and to optional ingredient viewers. */
     public static List<ItemStack> creativeSymbolPages(HolderLookup.Provider registries) {
+        List<ItemStack> pages = creativeBundledAndBiomePages(registries);
+        BlockSymbolPages.availableBlocks().forEach(id -> pages.add(createCreativeBlockPage(id)));
+        return List.copyOf(pages);
+    }
+
+    private static List<ItemStack> creativeBundledAndBiomePages(HolderLookup.Provider registries) {
         List<ItemStack> pages = new ArrayList<>();
         CREATIVE_SYMBOLS.keySet().forEach(id -> pages.add(createBundledCreativePage(id)));
         Set<String> bundled = CREATIVE_SYMBOLS.keySet();
@@ -79,12 +93,16 @@ public final class PageItem extends Item {
                 .filter(id -> !bundled.contains("biome/" + id.getPath()))
                 .sorted()
                 .forEach(id -> pages.add(createCreativeBiomePage(id)));
-        return List.copyOf(pages);
+        return pages;
     }
 
     public static List<ItemStack> creativeSymbolPages(HolderLookup.Provider registries,
                                                       ResourceLocation category) {
-        return creativeSymbolPages(registries).stream()
+        if (category.equals(BlockSymbolPages.CATEGORY) || category.equals(BlockSymbolPages.FLUID_CATEGORY)) {
+            return BlockSymbolPages.availableBlocks(category).stream()
+                    .map(PageItem::createCreativeBlockPage).toList();
+        }
+        return creativeBundledAndBiomePages(registries).stream()
                 .filter(page -> category.equals(creativeCategory(page)))
                 .toList();
     }
@@ -119,6 +137,13 @@ public final class PageItem extends Item {
         return page;
     }
 
+    public static ItemStack createCreativeBlockPage(ResourceLocation blockId) {
+        var symbolId = BlockSymbolPages.symbolId(blockId);
+        ItemStack page = create(PageContent.symbol(new SymbolReference(symbolId)));
+        page.set(ModDataComponents.PAGE_SYMBOL_DISPLAY.get(), BlockSymbolPages.definition(blockId).display(symbolId));
+        return page;
+    }
+
     private static Map<String, CreativeSymbol> loadCreativeSymbols() {
         String resource = "/assets/rivencraft/creative_symbol_pages.json";
         try (var stream = PageItem.class.getResourceAsStream(resource)) {
@@ -233,6 +258,10 @@ public final class PageItem extends Item {
                 && reference.id().getPath().startsWith("biome/")
                 ? Component.translatableWithFallback(metadata.nameTranslationKey(),
                         BiomeSymbolPages.fallbackName(reference.id()))
+                : reference.id().getNamespace().equals(Rivencraft.MOD_ID)
+                && reference.id().getPath().startsWith("block/")
+                ? Component.translatableWithFallback(metadata.nameTranslationKey(),
+                        BlockSymbolPages.fallbackName(BlockSymbolPages.blockId(reference.id())))
                 : Component.translatable(metadata.nameTranslationKey());
     }
 

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

@@ -3,6 +3,7 @@ package net.dnorberg.rivencraft.registry;
 import com.mojang.serialization.MapCodec;
 import net.dnorberg.rivencraft.Rivencraft;
 import net.dnorberg.rivencraft.world.AgeFlatChunkGenerator;
+import net.dnorberg.rivencraft.world.AgeFeatureChunkGenerator;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.world.level.chunk.ChunkGenerator;
 import net.neoforged.bus.api.IEventBus;
@@ -13,7 +14,10 @@ public final class ModChunkGenerators {
     private static final DeferredRegister<MapCodec<? extends ChunkGenerator>> GENERATORS =
             DeferredRegister.create(Registries.CHUNK_GENERATOR, Rivencraft.MOD_ID);
 
-    static { GENERATORS.register("age_flat", () -> AgeFlatChunkGenerator.CODEC); }
+    static {
+        GENERATORS.register("age_flat", () -> AgeFlatChunkGenerator.CODEC);
+        GENERATORS.register("age_features", () -> AgeFeatureChunkGenerator.CODEC);
+    }
 
     private ModChunkGenerators() { }
 

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

@@ -42,7 +42,7 @@ public final class ModCreativeTabs {
                     .build());
 
     private static final List<String> CATEGORY_ORDER = List.of(
-            "terrain", "biome", "biome_generation", "weather", "lighting", "sky", "celestial", "feature");
+            "terrain", "biome", "biome_generation", "weather", "lighting", "sky", "celestial", "block", "fluid", "feature");
 
     public static final Map<ResourceLocation, DeferredHolder<CreativeModeTab, CreativeModeTab>> SYMBOL_PAGES =
             registerSymbolPageTabs();

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

@@ -0,0 +1,155 @@
+package net.dnorberg.rivencraft.world;
+
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.MapCodec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import java.util.List;
+import net.dnorberg.rivencraft.book.AgeFeatureSelection;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.core.QuartPos;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.util.RandomSource;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.StructureManager;
+import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.server.level.WorldGenRegion;
+import net.minecraft.world.level.biome.BiomeManager;
+import net.minecraft.world.level.biome.BiomeSource;
+import net.minecraft.world.level.chunk.ChunkAccess;
+import net.minecraft.world.level.chunk.ChunkGenerator;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import net.minecraft.world.level.levelgen.GenerationStep;
+import net.minecraft.world.level.levelgen.LegacyRandomSource;
+import net.minecraft.world.level.levelgen.NoiseBasedChunkGenerator;
+import net.minecraft.world.level.levelgen.NoiseGeneratorSettings;
+import net.minecraft.world.level.levelgen.RandomState;
+import net.minecraft.world.level.levelgen.WorldgenRandom;
+import net.minecraft.world.level.levelgen.carver.CarvingContext;
+import net.minecraft.world.level.levelgen.carver.ConfiguredWorldCarver;
+import net.minecraft.world.level.levelgen.placement.BiomeFilter;
+import net.minecraft.world.level.levelgen.placement.PlacedFeature;
+import net.minecraft.world.level.levelgen.placement.RarityFilter;
+import net.minecraft.world.level.levelgen.feature.ConfiguredFeature;
+import net.minecraft.world.level.levelgen.feature.Feature;
+import net.minecraft.world.level.levelgen.feature.LakeFeature;
+import net.minecraft.world.level.levelgen.feature.configurations.BlockStateConfiguration;
+import net.minecraft.world.level.levelgen.feature.stateproviders.BlockStateProvider;
+import net.minecraft.world.level.block.Blocks;
+
+/** Adds frozen authored decorations after vanilla's biome features, without changing shared biome registries. */
+public final class AgeFeatureChunkGenerator extends NoiseBasedChunkGenerator {
+    public static final MapCodec<AgeFeatureChunkGenerator> CODEC = RecordCodecBuilder.mapCodec(instance ->
+            instance.group(BiomeSource.CODEC.fieldOf("biome_source").forGetter(generator -> generator.getBiomeSource()),
+                    NoiseGeneratorSettings.CODEC.fieldOf("settings").forGetter(generator -> generator.settings),
+                    AgeFeatureSelection.Choice.CODEC.listOf().fieldOf("age_features").forGetter(generator -> generator.features),
+                    Codec.LONG.fieldOf("age_seed").forGetter(generator -> generator.ageSeed))
+                    .apply(instance, AgeFeatureChunkGenerator::new));
+
+    private final Holder<NoiseGeneratorSettings> settings;
+    private final List<AgeFeatureSelection.Choice> features;
+    private final long ageSeed;
+
+    public AgeFeatureChunkGenerator(BiomeSource biomes, Holder<NoiseGeneratorSettings> settings,
+                                    List<AgeFeatureSelection.Choice> features, long ageSeed) {
+        super(biomes, settings);
+        this.settings = settings;
+        this.features = List.copyOf(features);
+        this.ageSeed = ageSeed;
+    }
+
+    public List<AgeFeatureSelection.Choice> ageFeatures() { return features; }
+
+    @Override
+    protected MapCodec<? extends ChunkGenerator> codec() { return CODEC; }
+
+    @Override
+    public void applyCarvers(WorldGenRegion level, long seed, RandomState random, BiomeManager biomes,
+                             StructureManager structures, ChunkAccess chunk, GenerationStep.Carving step) {
+        super.applyCarvers(level, seed, random, biomes, structures, chunk, step);
+        if (step != GenerationStep.Carving.AIR || features.stream().noneMatch(choice ->
+                AgeFeatureSelection.caves(choice.id()) || AgeFeatureSelection.ravines(choice.id()))) return;
+        var noiseChunk = chunk.getOrCreateNoiseChunk(ignored -> {
+            throw new IllegalStateException("Vanilla carver did not initialize the Age noise chunk");
+        });
+        var context = new CarvingContext(this, level.registryAccess(), chunk.getHeightAccessorForGeneration(),
+                noiseChunk, random, settings.value().surfaceRule());
+        var mask = ((ProtoChunk) chunk).getOrCreateCarvingMask(step);
+        var carvers = level.registryAccess().lookupOrThrow(Registries.CONFIGURED_CARVER);
+        var sourceRandom = new WorldgenRandom(new LegacyRandomSource(0L));
+        ChunkPos target = chunk.getPos();
+        BiomeManager sourceBiomes = biomes.withDifferentSource((qx, qy, qz) ->
+                getBiomeSource().getNoiseBiome(qx, qy, qz, random.sampler()));
+        for (AgeFeatureSelection.Choice choice : features) {
+            if (!AgeFeatureSelection.caves(choice.id()) && !AgeFeatureSelection.ravines(choice.id())) continue;
+            for (int dx = -8; dx <= 8; dx++) {
+                for (int dz = -8; dz <= 8; dz++) {
+                    ChunkPos source = new ChunkPos(target.x + dx, target.z + dz);
+                    var biome = getBiomeSource().getNoiseBiome(QuartPos.fromBlock(source.getMinBlockX()), 0,
+                            QuartPos.fromBlock(source.getMinBlockZ()), random.sampler());
+                    if (AgeFeatureSelection.ravines(choice.id())
+                            && biome.is(net.minecraft.tags.BiomeTags.IS_NETHER)) continue;
+                    ResourceLocation carverId = ResourceLocation.withDefaultNamespace(
+                            AgeFeatureSelection.ravines(choice.id()) ? "canyon"
+                                    : biome.is(net.minecraft.tags.BiomeTags.IS_NETHER) ? "nether_cave" : "cave");
+                    ConfiguredWorldCarver<?> carver = carvers.getOrThrow(
+                            ResourceKey.create(Registries.CONFIGURED_CARVER, carverId)).value();
+                    sourceRandom.setLargeFeatureSeed(ageSeed ^ (AgeFeatureSelection.ravines(choice.id())
+                            ? 0x524156494E45534CL : 0x4341564553464541L), source.x, source.z);
+                    if (carver.isStartChunk(sourceRandom)) {
+                        carver.carve(context, chunk, sourceBiomes::getBiome, sourceRandom,
+                                noiseChunk.aquifer(), source, mask);
+                    }
+                }
+            }
+        }
+    }
+
+    @Override
+    public void applyBiomeDecoration(WorldGenLevel level, ChunkAccess chunk, StructureManager structures) {
+        super.applyBiomeDecoration(level, chunk, structures);
+        var registry = level.registryAccess().lookupOrThrow(Registries.PLACED_FEATURE);
+        int x = chunk.getPos().getMinBlockX();
+        int z = chunk.getPos().getMinBlockZ();
+        BlockPos origin = new BlockPos(x, level.getMinBuildHeight(), z);
+        for (int index = 0; index < features.size(); index++) {
+            AgeFeatureSelection.Choice choice = features.get(index);
+            if (AgeFeatureSelection.surfaceVegetation(choice.id())) {
+                int surface = chunk.getHeight(Heightmap.Types.WORLD_SURFACE_WG, 8, 8);
+                if (!AgeFeatureSelection.supportsSurfaceVegetation(
+                        level.getBiome(new BlockPos(x + 8, surface, z + 8)))) continue;
+            }
+            ResourceLocation key = AgeFeatureSelection.placedFeature(choice.id());
+            if (key == null) continue; // Carvers are applied before decoration.
+            PlacedFeature vanilla = registry.getOrThrow(ResourceKey.create(Registries.PLACED_FEATURE, key)).value();
+            // Vanilla's biome filter only admits a feature already in that biome's list. An
+            // authored page intentionally adds it, so preserve all other vanilla placement rules.
+            Holder<ConfiguredFeature<?, ?>> configured = vanilla.feature();
+            if (choice.material().isPresent()) {
+                var material = BuiltInRegistries.BLOCK.get(choice.material().orElseThrow()).defaultBlockState();
+                if (AgeFeatureSelection.isRock(choice.id())) {
+                    configured = Holder.direct(new ConfiguredFeature<>(Feature.FOREST_ROCK,
+                            new BlockStateConfiguration(material)));
+                } else if (AgeFeatureSelection.isLake(choice.id())) {
+                    configured = Holder.direct(new ConfiguredFeature<>(Feature.LAKE,
+                            new LakeFeature.Configuration(BlockStateProvider.simple(material),
+                                    BlockStateProvider.simple(Blocks.STONE))));
+                }
+            }
+            PlacedFeature authored = new PlacedFeature(configured, vanilla.placement().stream()
+                    .filter(modifier -> !(modifier instanceof BiomeFilter))
+                    .map(modifier -> AgeFeatureSelection.isLake(choice.id())
+                            && !choice.id().getPath().equals("deep_lakes")
+                            && modifier instanceof RarityFilter
+                            ? RarityFilter.onAverageOnceEvery(12) : modifier)
+                    .toList());
+            long seed = ageSeed ^ (long) x * 341873128712L ^ (long) z * 132897987541L
+                    ^ (long) choice.hashCode() * 0x9E3779B97F4A7C15L;
+            authored.place(level, this, RandomSource.create(seed), origin);
+        }
+    }
+}

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

@@ -0,0 +1,97 @@
+package net.dnorberg.rivencraft.writing;
+
+import java.util.Arrays;
+import java.util.Locale;
+import java.util.Optional;
+import net.dnorberg.rivencraft.Rivencraft;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.EmptyBlockGetter;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.EntityBlock;
+import net.minecraft.world.level.block.state.BlockState;
+
+/** Registry-derived material pages; binding validates the material for its consumer. */
+public final class BlockSymbolPages {
+    public static final ResourceLocation CATEGORY = ResourceLocation.fromNamespaceAndPath(Rivencraft.MOD_ID, "block");
+    public static final ResourceLocation FLUID_CATEGORY = ResourceLocation.fromNamespaceAndPath(Rivencraft.MOD_ID, "fluid");
+
+    private BlockSymbolPages() {}
+
+    public static ResourceLocation symbolId(ResourceLocation blockId) {
+        return ResourceLocation.fromNamespaceAndPath(Rivencraft.MOD_ID,
+                "block/" + blockId.getNamespace() + "/" + blockId.getPath());
+    }
+
+    public static ResourceLocation blockId(ResourceLocation symbolId) {
+        String path = symbolId.getPath();
+        if (!path.startsWith("block/")) return null;
+        String rest = path.substring("block/".length());
+        int separator = rest.indexOf('/');
+        return separator < 1 ? null : ResourceLocation.tryParse(
+                rest.substring(0, separator) + ":" + rest.substring(separator + 1));
+    }
+
+    public static java.util.List<ResourceLocation> availableBlocks() {
+        return BuiltInRegistries.BLOCK.keySet().stream()
+                .filter(id -> isRockMaterial(BuiltInRegistries.BLOCK.get(id))
+                        || isFluidMaterial(BuiltInRegistries.BLOCK.get(id)))
+                .sorted().toList();
+    }
+
+    public static java.util.List<ResourceLocation> availableBlocks(ResourceLocation category) {
+        if (!category.equals(CATEGORY) && !category.equals(FLUID_CATEGORY)) return java.util.List.of();
+        return availableBlocks().stream().filter(id -> category(id).equals(category)).toList();
+    }
+
+    public static ResourceLocation category(ResourceLocation blockId) {
+        return isFluidMaterial(BuiltInRegistries.BLOCK.get(blockId)) ? FLUID_CATEGORY : CATEGORY;
+    }
+
+    public static boolean isRockMaterial(Block block) {
+        if (excluded(block)) return false;
+        BlockState state = block.defaultBlockState();
+        return state.getFluidState().isEmpty()
+                && state.isCollisionShapeFullBlock(EmptyBlockGetter.INSTANCE, BlockPos.ZERO);
+    }
+
+    public static boolean isFluidMaterial(Block block) {
+        if (excluded(block)) return false;
+        var fluid = block.defaultBlockState().getFluidState();
+        // A waterlogged coral or seagrass block contains water, but is not a fluid block.
+        return fluid.isSource() && fluid.createLegacyBlock().getBlock() == block;
+    }
+
+    private static boolean excluded(Block block) {
+        return block == Blocks.AIR || block == Blocks.CAVE_AIR || block == Blocks.VOID_AIR
+                || block instanceof EntityBlock || block.defaultBlockState().hasBlockEntity();
+    }
+
+    public static SymbolDefinition definition(ResourceLocation blockId) {
+        String path = blockId.getPath().replace('/', '_');
+        String word = Arrays.stream(path.split("_"))
+                .map(part -> part.replaceAll("[^A-Za-z]", ""))
+                .filter(part -> !part.isEmpty())
+                .map(part -> part.substring(0, 1).toUpperCase(Locale.ROOT) + part.substring(1))
+                .reduce("", String::concat);
+        if (word.isEmpty()) word = "Stone";
+        // A modded registry path can be arbitrarily long; poems have a bounded codec.
+        if (word.length() > 48) word = word.substring(0, 48);
+        return new SymbolDefinition(SymbolDefinition.CURRENT_SCHEMA_VERSION,
+                "block." + blockId.getNamespace() + "." + path,
+                "symbol.rivencraft.block.generated.description", category(blockId),
+                Optional.of(new SymbolSemantics(SymbolSemantics.Role.BLOCK,
+                        new SymbolSemantics.ResourceValue(blockId))),
+                "Modifier Constraint " + word + " Form");
+    }
+
+    public static String fallbackName(ResourceLocation blockId) {
+        return Arrays.stream(blockId.getPath().replace('/', '_').split("_"))
+                .filter(part -> !part.isEmpty())
+                .map(part -> part.substring(0, 1).toUpperCase(Locale.ROOT) + part.substring(1))
+                .reduce((left, right) -> left + " " + right).orElse("Unknown")
+                + (category(blockId).equals(FLUID_CATEGORY) ? " Fluid" : " Material");
+    }
+}

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

@@ -72,6 +72,8 @@ public final class SymbolCatalog {
                     .filter(id -> id.getNamespace().equals("minecraft"))
                     .forEach(id -> loaded.putIfAbsent(BiomeSymbolPages.symbolId(id),
                             BiomeSymbolPages.definition(id)));
+            BlockSymbolPages.availableBlocks().forEach(id -> loaded.putIfAbsent(
+                    BlockSymbolPages.symbolId(id), BlockSymbolPages.definition(id)));
             symbols = Map.copyOf(loaded);
             Rivencraft.LOGGER.info("Loaded {} writing symbols", loaded.size());
         }

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

@@ -84,6 +84,7 @@ public record SymbolSemantics(Role role, Value value) {
         PERIOD_MODIFIER("period_modifier", Kind.NUMBER),
         ANGLE_MODIFIER("angle_modifier", Kind.NUMBER),
         PHASE_MODIFIER("phase_modifier", Kind.NUMBER),
+        BLOCK("block", Kind.RESOURCE),
         FEATURE("feature", Kind.RESOURCE);
 
         private final String id;

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

@@ -41,6 +41,7 @@ public final class WritingGrammar {
         int panels = 0;
         int lastStage = -1;
         int biomeCount = 0;
+        ParsedSymbol pendingBlock = null;
         for (int index = 0; index < writing.entries().size(); index++) {
             WritingEntry entry = writing.entries().get(index);
             if (entry.kind() == WritingEntry.Kind.LINK_PANEL) {
@@ -69,6 +70,22 @@ public final class WritingGrammar {
             Role role = semantics.orElseThrow().role();
             ParsedSymbol parsed = new ParsedSymbol(index, reference, semantics.orElseThrow());
             symbols.add(parsed);
+            if (pendingBlock != null && role != Role.FEATURE) {
+                diagnostics.add(new Diagnostic(Code.MISPLACED_MODIFIER, pendingBlock.index(),
+                        "Place this material page immediately before a compatible feature"));
+                pendingBlock = null;
+            }
+            if (role == Role.BLOCK) {
+                pendingBlock = parsed;
+            } else if (role == Role.FEATURE && pendingBlock != null) {
+                ResourceLocation feature = ((SymbolSemantics.ResourceValue) parsed.semantics().value()).id();
+                if (!Set.of("rocks", "surface_lakes", "deep_lakes", "lava_lakes")
+                        .contains(feature.getPath()) || !feature.getNamespace().equals("rivencraft")) {
+                    diagnostics.add(new Diagnostic(Code.MISPLACED_MODIFIER, pendingBlock.index(),
+                            "This feature cannot consume a material page"));
+                }
+                pendingBlock = null;
+            }
             if (role == Role.ANGLE_MODIFIER || role == Role.WEATHER
                     && parsed.semantics().value() instanceof ChoiceValue choice
                     && Set.of("snow", "cloudy", "rain").contains(choice.id())) {
@@ -99,6 +116,8 @@ public final class WritingGrammar {
                 lastStage = stage;
             }
         }
+        if (pendingBlock != null) diagnostics.add(new Diagnostic(Code.MISPLACED_MODIFIER, pendingBlock.index(),
+                "Place this material page immediately before a compatible feature"));
         if (panels == 0) diagnostics.add(new Diagnostic(Code.MISSING_PANEL, -1,
                 "Add a Link Panel as the first page"));
         if (symbols.isEmpty()) return new Result(symbols, diagnostics);
@@ -152,14 +171,14 @@ public final class WritingGrammar {
             case SKY -> 5;
             case PERIOD_MODIFIER, ANGLE_MODIFIER, PHASE_MODIFIER -> 6;
             case CELESTIAL -> 7;
-            case FEATURE -> 8;
+            case BLOCK, FEATURE -> 8;
         };
     }
 
     public enum Code {
         TOO_MANY, MISSING_PANEL, PANEL_ORDER, DUPLICATE_PANEL, UNRESOLVED, UNSUPPORTED,
         DUPLICATE, CONFLICT, OUT_OF_ORDER, MISPLACED_MODIFIER, INCOMPLETE, UNSUPPORTED_PROFILE,
-        UNKNOWN_BIOME, UNSUPPORTED_BIOME, UNSUPPORTED_ENVIRONMENT
+        UNKNOWN_BIOME, UNSUPPORTED_BIOME, UNSUPPORTED_ENVIRONMENT, UNSUPPORTED_FEATURE
     }
 
     public record Diagnostic(Code code, int index, String message) {

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

@@ -208,7 +208,24 @@
   "symbol.rivencraft.phase.setting": "Setting Phase",
   "symbol.rivencraft.phase.setting.description": "Set the celestial phase to setting.",
   "symbol.rivencraft.feature.caves": "Caves",
-  "symbol.rivencraft.feature.caves.description": "Describe underground cave features.",
+  "symbol.rivencraft.feature.caves.description": "Add extra caves to the chosen noise terrain.",
+  "symbol.rivencraft.block.generated.description": "Material modifier; place immediately before a compatible feature page.",
+  "symbol.rivencraft.feature.flowers": "Flowers",
+  "symbol.rivencraft.feature.flowers.description": "Add vanilla flower patches to surface terrain.",
+  "symbol.rivencraft.feature.trees": "Trees",
+  "symbol.rivencraft.feature.trees.description": "Add vanilla plains trees to surface terrain.",
+  "symbol.rivencraft.feature.rocks": "Rocks",
+  "symbol.rivencraft.feature.rocks.description": "Add boulders using a random solid material, or specify one with a block page.",
+  "symbol.rivencraft.feature.huge_trees": "Huge Trees",
+  "symbol.rivencraft.feature.huge_trees.description": "Add vanilla old-growth spruce trees to surface terrain.",
+  "symbol.rivencraft.feature.surface_lakes": "Surface Lakes",
+  "symbol.rivencraft.feature.surface_lakes.description": "Add surface lakes using a random fluid, or specify one with a fluid page.",
+  "symbol.rivencraft.feature.deep_lakes": "Deep Lakes",
+  "symbol.rivencraft.feature.deep_lakes.description": "Add underground lakes using a random fluid, or specify one with a fluid page.",
+  "symbol.rivencraft.feature.ravines": "Ravines",
+  "symbol.rivencraft.feature.ravines.description": "Add vanilla canyon carving to noise terrain.",
+  "symbol.rivencraft.feature.lava_lakes": "Small Lakes",
+  "symbol.rivencraft.feature.lava_lakes.description": "Add small surface lakes using a random fluid, or specify one with a fluid page.",
   "generator.rivencraft.standard": "Standard",
   "generator.rivencraft.amplified": "Amplified",
   "generator.rivencraft.island": "Island",
@@ -238,5 +255,7 @@
   "itemGroup.rivencraft.pages.lighting": "Rivencraft Lighting Pages",
   "itemGroup.rivencraft.pages.sky": "Rivencraft Sky Pages",
   "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"
 }

src/main/resources/data/rivencraft/rivencraft/symbols/feature/deep_lakes.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.feature.deep_lakes",
+  "description": "symbol.rivencraft.feature.deep_lakes.description",
+  "category": "rivencraft:feature",
+  "semantics": { "role": "feature", "value": "rivencraft:deep_lakes" },
+  "poem": "Nature Flow Static Explore"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/feature/flowers.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.feature.flowers",
+  "description": "symbol.rivencraft.feature.flowers.description",
+  "category": "rivencraft:feature",
+  "semantics": { "role": "feature", "value": "rivencraft:flowers" },
+  "poem": "Nature Grow Color Bloom"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/feature/huge_trees.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.feature.huge_trees",
+  "description": "symbol.rivencraft.feature.huge_trees.description",
+  "category": "rivencraft:feature",
+  "semantics": { "role": "feature", "value": "rivencraft:huge_trees" },
+  "poem": "Nature Stimulate Spur Elevate"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/feature/lava_lakes.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.feature.lava_lakes",
+  "description": "symbol.rivencraft.feature.lava_lakes.description",
+  "category": "rivencraft:feature",
+  "semantics": { "role": "feature", "value": "rivencraft:lava_lakes" },
+  "poem": "Fire Fluid Basin Transform"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/feature/ravines.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.feature.ravines",
+  "description": "symbol.rivencraft.feature.ravines.description",
+  "category": "rivencraft:feature",
+  "semantics": { "role": "feature", "value": "rivencraft:ravines" },
+  "poem": "Terrain Transform Void Weave"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/feature/rocks.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.feature.rocks",
+  "description": "symbol.rivencraft.feature.rocks.description",
+  "category": "rivencraft:feature",
+  "semantics": { "role": "feature", "value": "rivencraft:rocks" },
+  "poem": "Earth Form Moss Stone"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/feature/surface_lakes.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.feature.surface_lakes",
+  "description": "symbol.rivencraft.feature.surface_lakes.description",
+  "category": "rivencraft:feature",
+  "semantics": { "role": "feature", "value": "rivencraft:surface_lakes" },
+  "poem": "Nature Flow Static Elevate"
+}

src/main/resources/data/rivencraft/rivencraft/symbols/feature/trees.json

@@ -0,0 +1,8 @@
+{
+  "schema_version": 2,
+  "name": "symbol.rivencraft.feature.trees",
+  "description": "symbol.rivencraft.feature.trees.description",
+  "category": "rivencraft:feature",
+  "semantics": { "role": "feature", "value": "rivencraft:trees" },
+  "poem": "Nature Grow Life Forest"
+}