# 5.12 — Chat SSE event types (mock, GREEN)

Phase: 5 — Chat + Rate Limiter (Surface D)
Stage: GREEN

- [x] Chat SSE events: `{"type":"queue"|"reasoning"|"content"|"done"}` implemented; `"error"` not yet emitted (mock never errors)

Done — [app/api/chat/route.ts](../app/api/chat/route.ts). Frontend should render `reasoning` in a collapsible block (this is the demo).