Initial commit: claude derived solution

README.md

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+# Gravestone × Sable Compatibility Patch
+
+A minimal patch mod for Minecraft **1.21.1 / NeoForge** that fixes gravestone
+placement when a player dies on a Sable sub-level (e.g. a **Create Aeronautics**
+airship). Without this mod, dying mid-flight makes gravestone place its block
+(and a dirt support block) in the parent world at the player's visible position.
+The blocks then clip into the airship's collision shape and stall its physics.
+
+With this mod installed, the grave is placed inside the airship's plot area, so
+it lands on the deck and travels with the airship like any other block on it.
+
+## How it works (one paragraph)
+
+Sable stores each sub-level's blocks in a far-away "plot" region of the same
+`Level`. The visible airship position is a logical pose that's applied at render
+and collision time only. Gravestone's `DeathEvents.playerDeath` calls
+`GraveUtils.getGraveStoneLocation(level, deathPos)` with the player's world
+position — but that position is empty space, so the search either fails or
+places the grave clipping into the airship. This mod uses Mixin Extras'
+`@WrapOperation` to intercept that single call and substitute the player's
+position transformed into the sub-level's plot-local frame
+(`subLevel.logicalPose().transformPositionInverse(playerPos)`). Gravestone's
+existing search routine then finds the deck above the player's feet and places
+the grave correctly inside the contraption. If the player isn't on a sub-level
+when they die, the mod is a no-op.
+
+The mod uses **Sable Companion** rather than depending on Sable directly, so
+it's safe to ship in packs without Sable (the companion's default
+implementation just returns null for all sub-level queries → graves behave
+exactly like vanilla gravestone).
+
+## Build
+
+Requires **JDK 21**.
+
+If you don't already have a Gradle wrapper jar in `gradle/wrapper/`, bootstrap
+one first (one-time, needs any system Gradle ≥ 8.10 — `sdk install gradle 8.10`,
+`brew install gradle`, `apt install gradle`, etc.):
+
+```bash
+gradle wrapper --gradle-version 8.10
+```
+
+Alternatively, copy `gradlew`, `gradlew.bat`, and `gradle/wrapper/` from any
+recent NeoForge 1.21.1 mod template (e.g. the official
+[NeoForge MDK](https://github.com/neoforged/MDK)).
+
+Then build the mod:
+
+```bash
+./gradlew build
+```
+
+The output jar is at `build/libs/gravestone_sable_compat-1.0.0.jar`.
+
+If the Modrinth maven can't resolve `gravestone-mod` for your machine, drop
+`gravestone-1.21.1-1.0.19.jar` (or any 1.21.1 build of gravestone) into a
+`libs/` folder at the project root, comment out the `compileOnly
+"maven.modrinth:gravestone-mod:..."` line in `build.gradle`, and uncomment the
+`compileOnly fileTree(dir: 'libs', ...)` line.
+
+## Runtime requirements
+
+Drop the built jar into your modpack alongside:
+
+| Mod | Version |
+|---|---|
+| NeoForge | 21.1.x (1.21.1) |
+| [Gravestone (henkelmax)](https://modrinth.com/mod/gravestone-mod) | 1.21.1-1.0.19 or later |
+| [Sable](https://modrinth.com/mod/sable) | 1.0+ |
+| [Sable Companion](https://github.com/ryanhcode/sable-companion) | 1.6+ (bundled inside this jar via JarInJar; no separate install needed) |
+| Create Aeronautics | any version that uses Sable |
+
+The mixin only attaches to `de.maxhenkel.gravestone.events.DeathEvents.playerDeath`'s
+single call to `GraveUtils.getGraveStoneLocation(Level, BlockPos)`. The signature
+of that call has been stable across gravestone 1.21.1-1.0.19 → 1.0.37, so the
+mod should work with any of them. If a future build refactors that method, the
+mixin will fail loudly at load time (`defaultRequire: 1`) rather than silently
+no-op.
+
+## File layout
+
+```
+gravestone-sable-compat/
+├─ build.gradle
+├─ gradle.properties
+├─ settings.gradle
+├─ src/main/java/com/example/gravestonesablecompat/
+│  ├─ GravestoneSableCompat.java          # tiny @Mod entry point
+│  └─ mixin/DeathEventsMixin.java         # the actual fix (one @WrapOperation)
+└─ src/main/resources/
+   ├─ META-INF/neoforge.mods.toml
+   ├─ gravestone_sable_compat.mixins.json
+   └─ pack.mcmeta
+```
+
+## License
+
+MIT — go wild.