Port dry Cave Ages and safe landing to 26.3 beta

ports/mc263/README.md

@@ -3,7 +3,7 @@
 This is an **experimental beta port** for issues #97–#104, not gameplay parity
 with the Minecraft 1.21.1 release. The 26.3 backend persists separate Ages and
 their seeds. Books, the Book Binder, and the Ink Mixer work, and the Binder can
-author Standard, Amplified, Island, Flat, or Void terrain with supported
+author Standard, Amplified, Island, Flat, Void, or Cave terrain with supported
 biome-distribution pages. Other terrain families, feature/material effects,
 portals, and much of
 the 1.21.1 gameplay remain unported. Use a test world and keep a backup; do not
@@ -177,6 +177,23 @@ surface decoration in Flat. Void continues to generate no floor or biome
 decoration. The operator-only `age create_multi` probe creates two-biome test
 Ages for the dedicated-server smoke test.
 
+The local `1.0.1.37-beta.1` slice adds the Cave terrain page to Binder
+authoring. It uses Minecraft's caves noise settings, accepts Cave and Nether
+biome pages (including multi-biome distribution), and searches below Y=64 for
+a safe arrival instead of landing on the roof. The 26.3 vanilla Cave preset
+defaults to water below Y=32, so this port derives a dry Cave setting with
+air as its default fluid and the sea level below the world floor. This applies
+to newly generated Cave chunks; it does not drain existing chunks. Cave-specific Nether surface
+materials from 1.21.1 are not ported yet. The dedicated-server smoke now
+creates and reloads Cave Ages alongside the other terrain families.
+
+The dry-Cave follow-up is packaged as `1.0.1.38-beta.1`; no 26.3 release is
+published until the in-game check passes and publication is explicitly requested.
+
+The local `1.0.1.39-beta.1` follow-up rejects fluid at both feet and head
+height during safe-landing searches. It also refuses to carve the fallback
+platform into submerged space if no dry footing can be found.
+
 From the repository root:
 
 ```sh

ports/mc263/RELEASE_NOTES_1.0.1.39-beta.1.md

@@ -0,0 +1,14 @@
+# Rivencraft 26.3 beta 1.0.1.39-beta.1
+
+This beta adds Cave terrain to authored Ages on Minecraft 26.3.
+
+- Bind Descriptive Books with the Cave terrain page and Cave or Nether biome pages, including supported multi-biome distributions.
+- Cave Ages use the cave noise shape but remain dry by default. Newly generated chunks no longer flood below the vanilla cave sea level.
+- Cave travel searches from Y=64 downward for dry, properly footed space instead of landing on the cave roof or underwater.
+- Expanded dedicated-server checks for Cave creation, biome distribution, and persistence after restart.
+
+The player verified the Cave and safe-landing changes in game. Existing generated chunks are not drained or regenerated. A future Flooded page will provide an authored water level; see [issue #107](https://git.paddedcell.org/dnorberg/rivencraft/issues/107).
+
+This 26.3 port is still experimental and does not yet include all features of the separate Minecraft 1.21.1 version. Use a test world and keep a backup. Minecraft 1.21.1 saves are not supported by this beta.
+
+Requires Minecraft 26.3, NeoForge 26.3.0.99 or a compatible 26.3 build, and Java 25.

ports/mc263/gradle.properties

@@ -7,4 +7,4 @@ neo_version=26.3.0.99
 mod_id=rivencraft
 mod_name=Rivencraft
 mod_license=LGPL-3.0-or-later
-mod_version=1.0.1.36-beta.1
+mod_version=1.0.1.39-beta.1

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

@@ -78,7 +78,7 @@ public final class PortAgeCommands {
                                                                         context, "terrain").toUpperCase(Locale.ROOT));
                                                             } catch (IllegalArgumentException exception) {
                                                                 context.getSource().sendFailure(Component.literal(
-                                                                        "Unknown terrain; use standard, amplified, island, flat, or void"));
+                                                                        "Unknown terrain; use standard, amplified, island, cave, flat, or void"));
                                                                 return 0;
                                                             }
                                                             return createAge(context, terrain);
@@ -94,18 +94,23 @@ public final class PortAgeCommands {
                                                                         context, "terrain").toUpperCase(Locale.ROOT));
                                                             } catch (IllegalArgumentException exception) {
                                                                 context.getSource().sendFailure(Component.literal(
-                                                                        "Unknown terrain; use flat or void"));
+                                                                        "Unknown terrain; use cave, flat, or void"));
                                                                 return 0;
                                                             }
-                                                            if (terrain != PortAgeTerrain.FLAT && terrain != PortAgeTerrain.VOID) {
+                                                            if (terrain != PortAgeTerrain.CAVE
+                                                                    && terrain != PortAgeTerrain.FLAT
+                                                                    && terrain != PortAgeTerrain.VOID) {
                                                                 context.getSource().sendFailure(Component.literal(
-                                                                        "Multi-biome probe supports flat or void only"));
+                                                                        "Multi-biome probe supports cave, flat, or void only"));
                                                                 return 0;
                                                             }
                                                             return createAge(context, terrain, new PortBiomePlan(
-                                                                    PortBiomePlan.Distribution.TILED, java.util.List.of(
-                                                                            Identifier.withDefaultNamespace("plains"),
-                                                                            Identifier.withDefaultNamespace("forest"))));
+                                                                    PortBiomePlan.Distribution.TILED,
+                                                                    terrain == PortAgeTerrain.CAVE
+                                                                            ? java.util.List.of(Identifier.withDefaultNamespace("lush_caves"),
+                                                                                    Identifier.withDefaultNamespace("dripstone_caves"))
+                                                                            : java.util.List.of(Identifier.withDefaultNamespace("plains"),
+                                                                                    Identifier.withDefaultNamespace("forest"))));
                                                         })))))
                         .then(Commands.literal("list")
                                 .executes(context -> {

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

@@ -5,6 +5,7 @@ public enum PortAgeTerrain {
     STANDARD,
     AMPLIFIED,
     ISLAND,
+    CAVE,
     FLAT,
     VOID
 }

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

@@ -33,6 +33,27 @@ public final class PortAgeTravel {
     }
 
     private static BlockPos findLanding(ServerLevel target) {
+        if (target.getChunkSource().getGenerator() instanceof net.minecraft.world.level.levelgen.NoiseBasedChunkGenerator noise
+                && noise.generatorSettings().value().noiseSettings().equals(target.registryAccess()
+                .lookupOrThrow(Registries.NOISE_SETTINGS)
+                .getOrThrow(net.minecraft.world.level.levelgen.NoiseGeneratorSettings.CAVES)
+                .value().noiseSettings())) {
+            // The cave roof is not a valid arrival surface. Search down from
+            // Legacy's Y=64 start, then construct the normal safety platform
+            // at that height only when no footed opening can be found.
+            for (int radius = 0; radius <= 16; radius++) {
+                for (int x = -radius; x <= radius; x++) {
+                    for (int z = -radius; z <= radius; z++) {
+                        if (Math.max(Math.abs(x), Math.abs(z)) != radius) continue;
+                        for (int y = Math.min(64, target.getMaxY() - 2); y > target.getMinY(); y--) {
+                            BlockPos foot = new BlockPos(x, y, z);
+                            if (hasFooting(target, foot)) return foot;
+                        }
+                    }
+                }
+            }
+            return makePlatform(target, new BlockPos(0, 64, 0));
+        }
         // A Flat Age has a known surface. Use it directly before a heightmap
         // fallback can place a platform in the air above a low superflat world.
         FlatLevelGeneratorSettings flatSettings = switch (target.getChunkSource().getGenerator()) {
@@ -62,10 +83,21 @@ public final class PortAgeTravel {
         // origin is ocean or foliage. Final book landing rules are ported later.
         int y = Math.max(64, target.getHeight(Heightmap.Types.MOTION_BLOCKING, 0, 0) + 2);
         if (y + 2 >= target.getMaxY()) return null;
-        BlockPos foot = new BlockPos(0, y, 0);
+        return makePlatform(target, new BlockPos(0, y, 0));
+    }
+
+    private static BlockPos makePlatform(ServerLevel target, BlockPos foot) {
+        if (foot.getY() <= target.getMinY() || foot.getY() + 2 >= target.getMaxY()) return null;
+        // A carved pocket inside a flooded cave immediately refills. Refuse
+        // that landing instead of placing the player in submerged spawn space.
+        if (!target.getFluidState(foot).isEmpty() || !target.getFluidState(foot.above()).isEmpty()) return null;
+        for (Direction direction : Direction.Plane.HORIZONTAL) {
+            if (!target.getFluidState(foot.relative(direction)).isEmpty()
+                    || !target.getFluidState(foot.above().relative(direction)).isEmpty()) return null;
+        }
         for (int x = -1; x <= 1; x++) {
             for (int z = -1; z <= 1; z++) {
-                target.setBlock(new BlockPos(x, y - 1, z), Rivencraft.CRYSTAL_BLOCK.get().defaultBlockState(), 3);
+                target.setBlock(foot.offset(x, -1, z), Rivencraft.CRYSTAL_BLOCK.get().defaultBlockState(), 3);
             }
         }
         target.setBlock(foot, Blocks.AIR.defaultBlockState(), 3);
@@ -76,6 +108,8 @@ public final class PortAgeTravel {
     private static boolean hasFooting(ServerLevel target, BlockPos foot) {
         BlockPos floor = foot.below();
         return target.getBlockState(floor).isFaceSturdy(target, floor, Direction.UP)
+                && target.getFluidState(foot).isEmpty()
+                && target.getFluidState(foot.above()).isEmpty()
                 && target.getBlockState(foot).getCollisionShape(target, foot).isEmpty()
                 && target.getBlockState(foot.above()).getCollisionShape(target, foot.above()).isEmpty();
     }

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

@@ -11,6 +11,7 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.OptionalLong;
 import net.dnorberg.rivencraft.Rivencraft;
+import net.dnorberg.rivencraft.writing.PortRegistryPages;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.core.Holder;
 import net.minecraft.core.HolderSet;
@@ -325,7 +326,19 @@ public final class RuntimeAgeBackend {
                 || terrain != PortAgeTerrain.STANDARD) {
             if (!(generator instanceof NoiseBasedChunkGenerator noise))
                 throw new IllegalStateException("Overworld generator cannot accept authored noise settings");
-            var source = generator.getBiomeSource();
+            var source = terrain == PortAgeTerrain.CAVE
+                    ? new FixedBiomeSource(server.registryAccess().lookupOrThrow(Registries.BIOME)
+                            .getOrThrow(Biomes.LUSH_CAVES))
+                    : generator.getBiomeSource();
+            if (terrain == PortAgeTerrain.CAVE && biomePlan != null) {
+                var biomes = server.registryAccess().lookupOrThrow(Registries.BIOME);
+                for (Identifier biomeId : biomePlan.biomes()) {
+                    var holder = biomes.get(ResourceKey.create(Registries.BIOME, biomeId))
+                            .orElseThrow(() -> new IllegalArgumentException("Unknown authored biome: " + biomeId));
+                    if (!PortRegistryPages.isCaveBiome(holder))
+                        throw new IllegalArgumentException("Cave terrain requires a Cave or Nether biome: " + biomeId);
+                }
+            }
             if (biomePlan != null && biomePlan.distribution() != PortBiomePlan.Distribution.NATIVE) {
                 source = authoredBiomeSource(server, biomePlan, seed);
             }
@@ -335,6 +348,7 @@ public final class RuntimeAgeBackend {
                         .getOrThrow(NoiseGeneratorSettings.AMPLIFIED);
                 case ISLAND -> server.registryAccess().lookupOrThrow(Registries.NOISE_SETTINGS)
                         .getOrThrow(NoiseGeneratorSettings.FLOATING_ISLANDS);
+                case CAVE -> dryCaveSettings(server);
                 case FLAT, VOID -> throw new IllegalStateException("Flat terrain should use FlatLevelSource");
             };
             generator = new NoiseBasedChunkGenerator(source, settings);
@@ -369,4 +383,14 @@ public final class RuntimeAgeBackend {
             throw exception;
         }
     }
+
+    private static Holder<NoiseGeneratorSettings> dryCaveSettings(MinecraftServer server) {
+        NoiseGeneratorSettings caves = server.registryAccess().lookupOrThrow(Registries.NOISE_SETTINGS)
+                .getOrThrow(NoiseGeneratorSettings.CAVES).value();
+        return Holder.direct(new NoiseGeneratorSettings(
+                caves.noiseSettings(), caves.defaultBlock(), Blocks.AIR.defaultBlockState(),
+                caves.noiseRouter(), caves.materialRule(), caves.spawnTarget(),
+                caves.noiseSettings().minY() - 1, caves.disableMobGeneration(), Optional.empty(),
+                caves.useLegacyRandomSource(), caves.debugFunctions()));
+    }
 }

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

@@ -23,6 +23,8 @@ public final class PortAuthoredWriting {
             Rivencraft.MOD_ID, "terrain/flat");
     private static final Identifier VOID_TERRAIN = Identifier.fromNamespaceAndPath(
             Rivencraft.MOD_ID, "terrain/void");
+    private static final Identifier CAVE_TERRAIN = Identifier.fromNamespaceAndPath(
+            Rivencraft.MOD_ID, "terrain/cave");
 
     private PortAuthoredWriting() {}
 
@@ -60,7 +62,7 @@ public final class PortAuthoredWriting {
     private static boolean isTerrain(Identifier page) {
         return page.equals(STANDARD_TERRAIN) || page.equals(AMPLIFIED_TERRAIN)
                 || page.equals(ISLAND_TERRAIN) || page.equals(FLAT_TERRAIN)
-                || page.equals(VOID_TERRAIN);
+                || page.equals(VOID_TERRAIN) || page.equals(CAVE_TERRAIN);
     }
 
     private static PortBiomePlan.Distribution controller(Identifier page) {
@@ -85,6 +87,7 @@ public final class PortAuthoredWriting {
         if (pages.contains(ISLAND_TERRAIN)) return PortAgeTerrain.ISLAND;
         if (pages.contains(FLAT_TERRAIN)) return PortAgeTerrain.FLAT;
         if (pages.contains(VOID_TERRAIN)) return PortAgeTerrain.VOID;
+        if (pages.contains(CAVE_TERRAIN)) return PortAgeTerrain.CAVE;
         return PortAgeTerrain.STANDARD;
     }
 
@@ -94,14 +97,17 @@ public final class PortAuthoredWriting {
                 "Unsupported terrain or biome-page combination in this port slice");
         List<Identifier> biomes = new ArrayList<>();
         PortBiomePlan.Distribution distribution = null;
+        boolean caveTerrain = pages.contains(CAVE_TERRAIN);
         for (Identifier page : pages) {
             if (isTerrain(page)) continue;
             PortBiomePlan.Distribution selected = controller(page);
             if (selected != null) { distribution = selected; continue; }
             Identifier biome = PortRegistryPages.biomeId(page);
             var registry = registries.lookupOrThrow(Registries.BIOME);
-            if (registry.get(ResourceKey.create(Registries.BIOME, biome)).isEmpty())
-                throw new IllegalArgumentException("Unknown authored biome: " + biome);
+            var holder = registry.get(ResourceKey.create(Registries.BIOME, biome))
+                    .orElseThrow(() -> new IllegalArgumentException("Unknown authored biome: " + biome));
+            if (caveTerrain && !PortRegistryPages.isCaveBiome(holder))
+                throw new IllegalArgumentException("Cave terrain requires a Cave or Nether biome: " + biome);
             biomes.add(biome);
         }
         if (distribution == PortBiomePlan.Distribution.NATIVE)

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

@@ -67,7 +67,7 @@ public final class PortRegistryPages {
     public static List<ItemStack> biomePages(HolderLookup.Provider registries, boolean caves) {
         return registries.lookupOrThrow(Registries.BIOME).listElements()
                 .filter(holder -> !holder.key().identifier().equals(DEFERRED_PLACEHOLDER))
-                .filter(holder -> isCave(holder) == caves)
+                .filter(holder -> isCaveBiome(holder) == caves)
                 .map(holder -> PageItem.createSymbolPage(biomePageId(holder.key().identifier())))
                 .sorted((left, right) -> left.get(Rivencraft.SYMBOL_PAGE_ID.get()).toString()
                         .compareTo(right.get(Rivencraft.SYMBOL_PAGE_ID.get()).toString()))
@@ -81,7 +81,7 @@ public final class PortRegistryPages {
                 .map(id -> PageItem.createSymbolPage(blockPageId(id))).toList();
     }
 
-    private static boolean isCave(net.minecraft.core.Holder.Reference<net.minecraft.world.level.biome.Biome> holder) {
+    public static boolean isCaveBiome(net.minecraft.core.Holder.Reference<net.minecraft.world.level.biome.Biome> holder) {
         String path = holder.key().identifier().getPath();
         return holder.is(CAVE_BIOMES) || holder.is(BiomeTags.IS_NETHER)
                 || path.equals("deep_dark") || path.endsWith("_caves");

ports/mc263/src/main/resources/data/rivencraft/tags/worldgen/biome/cave_biomes.json

@@ -0,0 +1,8 @@
+{
+  "replace": false,
+  "values": [
+    "minecraft:lush_caves",
+    "minecraft:dripstone_caves",
+    "minecraft:deep_dark"
+  ]
+}