T3 Wave 4 (T24). Adds wire protocol + server handler for registering
user-authored custom modifier descriptors on a room's per-engine
custom registry (ADR-4).
Protocol:
- CustomModifierDescriptorSchema (Zod v3 mirror of the chess-side
schema; structural validation only — primitive-kind semantics stay
client-side to avoid duplicating the primitive catalog across the
zod v3/v4 boundary).
- 'custom-modifier.register' client message carrying { roomCode,
descriptor }.
- 'custom-modifier.registered' server broadcast mirroring the same
shape out to every connected client in the room.
- New error codes: CUSTOM_MODIFIER_INVALID, CUSTOM_MODIFIER_LIMIT.
Handler:
- Auth + room-match checks matching the rest of the WS surface.
- Lazy per-room Map<id, CustomModifierDescriptorWire> created on first
register.
- Capacity cap at 10 distinct ids per room (T3 DoS guard). Re-register
with the same id REPLACES without consuming a new slot.
- On success: broadcasts to every connected client (proposer included
— confirms server-authoritative state).
6 integration tests (mock ServerWebSocket harness; same pattern as
ws.modifier-profile-update.test.ts): happy-path accept+broadcast,
same-id replace, 11th-distinct rejection, roomCode mismatch, no-auth
rejection, malformed descriptor (schema layer). All green; 1369 unit
tests pass. Engine-side wire-up (late-joiner mirroring, client client.ts
subscriber) deferred to T25/T26 UI work.
Joey Yakimowich-Payne
109be25be6