Three issues fixed:
1. Port mismatch: The sidecar reported the OBS port (8080) in the
ready event but the frontend needs the API port (8081). Now reports
the API port so WebSocket/REST connects to the right place.
2. Broadcast from wrong thread: Engine init fires state_changed from
a background thread, but _broadcast_control used get_event_loop()
which returns the wrong loop. Now captures the uvicorn event loop
at startup via on_event("startup").
3. Missed ready state: If the engine finishes before the WebSocket
client connects, the "ready" state_changed was never received.
Added status polling (GET /api/status) on WebSocket connect that
retries every 2s while appState is "initializing".
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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