Echo Protocol

## Echo Protocol 0.5.0-beta.2 — Minecraft 1.21.11

Compatibility port of **Echo Protocol 0.5.0-beta.2 — The House Remembers** to Minecraft 1.21.11.

Gameplay content remains equivalent to the original 0.5.0-beta.2 release.

### Changes

- Added full compatibility with Minecraft 1.21.11.
- Updated Yarn mappings and Fabric dependencies.
- Migrated command permission handling to the Minecraft 1.21.11 API.
- Updated Echo rendering to use the current translucent entity render layer.
- Fixed player skin caching so temporary fallback skins are not permanently cached.
- Preserved the render-state based Echo renderer.
- Preserved classic and slim player skin models.
- Preserved the stable UUID tracked-data codec.
- Preserved multiplayer privacy and server-side entity tracking.
- Preserved the existing persistent memory schema and configuration format.
- No gameplay systems were removed or simplified.

### Verified gameplay systems

- Memory Echo
- Corrupted Echo
- Mimic Echo
- False Memories
- Contradictory Memories
- Panic Imprints
- Peripheral Echo
- Audio Residue
- Borrowed Habits
- Familiar Locations
- Room Memory Graph
- Memory Threads
- Memory Contamination
- Observation Profile
- The Original
- Intensity presets
- Persistent memory

### Verification

- 50 automated tests: Passed
- Clean production build: Passed
- Dedicated Fabric server: Verified
- Real Fabric client: Verified
- Full representative gameplay pipeline: Verified
- Echo renderer and player skins: Verified
- Restart persistence: Verified
- Two-client multiplayer privacy: Verified
- shared_echoes=false: private Echoes remained private
- shared_echoes=true: intended shared Echo visibility verified
- No critical runtime errors detected
- No Echo entity leaks detected
- No packet spam detected
- No "Can't keep up" issues detected during verification

### Requirements

- Minecraft Java Edition 1.21.11
- Fabric Loader 0.19.3+
- Fabric API
- Java 21
- Install on both client and server for multiplayer