phase: 06_realtime_websocket_protocol

All green. Final verification complete — writing the report.

**Final pass report — phase 06 `realtime_websocket_protocol`**

- Verified: all 6 task files present in `complete/`; this was the final verification pass (no implementation work outstanding)
- `uv run ruff check .` → all checks passed; `uv run pyright` → 0 errors
- `uv run undercooked-levels validate` → content OK; `uv run pytest` (full suite) → **1751 passed, 0 failed, coverage 97.30% (>90% floor)**; slow sim stage (`-m slow tests/sim --no-cov`) → 2 passed; repo hygiene clean
- App launches: `/healthz` 200, `/` 200, `/api/levels`, `/api/config`, `POST /api/rooms` (201), `/api/stats` all verified live on an ephemeral port (server cleaned up)
- Criteria: scripted client room→hello→ready→start→countdown→≥20 snaps→round — PASS (`test_ws_round_two_clients.py`); identical `round` payloads both clients — PASS (`round_a == round_b`); version mismatch → `err protocol_mismatch` + close `4400` — PASS; 64 KB refused / 4 KB boundary, 500-burst → `rate_limited` → `4404` with bounded queue, 2000 malformed + 200 handshakes within memory bound — PASS; snap ≤ 1.5 KB (4p/4o/3h) and 64×64 ≤ 4 KB, downlink ≤ 60 KB/s over 100 ticks — PASS; `docs/PROTOCOL.md` model-sync test-enforced in both directions + full-round sequence diagram present — PASS
- Docs: README.md had 3 stale spots — status section (claimed 01–05 complete, 06 pending → now 01–06 complete, 07 pending), "until phases 06/07 wire the transport" wording, and the `PROTOCOL.md` layout note ("phase 06 completes it"). All fixed. AGENTS.md verified consistent — no changes needed
- No defects found in completed phases; no live infrastructure touched

Next pending phase: `07_canvas_client_and_hud`.

tests/integration/test_room_fsm.py

@@ -669,15 +669,19 @@ def test_queue_input_rejects_an_unknown_player_with_an_err_event() -> None:
         "player_id": "tok-stranger",
         "seq": 0,
     }
-    # A known seat is queued, stamped with the sim's tick, and the queue is
-    # per-tick: the next `tick_once` consumes and clears it.
+    # A known seat is queued, stamped with the sim's tick, and the queue
+    # is per-tick: the next `tick_once` that advances a substep consumes
+    # and clears it (the task-03 substep guard: a wall-clock tick too
+    # short to fill a `STEP_DT` keeps the queue, so a frame is never
+    # dropped without being applied — hence the 0.05 s frame off the
+    # countdown's final `now`).
     frame = PlayerInput(player_id="tok-a", seq=7)
     assert room.queue_input("tok-a", frame) is True
     state = room.sim_state
     assert state is not None
     assert room._queued_inputs[-1].received_at_tick == state.tick
     assert room._queued_inputs[-1].seq == 7
-    room.tick_once()
+    room.tick_once(now=3.0 + 0.05)
     assert room._queued_inputs == []