Protocol messages

Client and server talk over WebSocket with a binary-encoded message protocol defined in core.

• The wire id is the @ProtoId(n) annotation on each ServerMessage / ClientMessage subclass.
• The ServerMessageCodec / ClientMessageCodec registries are generated by :codec-processor (KSP, runs on kspCommonMainKotlinMetadata) — never hand-edit them.
• A new message = add the subclass with the next free @ProtoId. The build fails on a missing, duplicate, or non-contiguous id, and a test asserts every subclass is in the codec registry.

Flow at a glance

1. Client Connect (carries auth token + language) → GameLoop.onConnect() validates.
2. Server Welcome (chunk transport, spawn, config) → client initialises.
3. Client MoveIntent / BlockBreak / BlockPlace / Command → server validates.
4. Server PlayerUpdate / WorldUpdate / ChunkData / Notification → clients apply.

The full HTTP surface is documented in HTTP API routes.