Avatar interruptions no longer stall; realtime STT model param fixed

Patch Changes

• Fix DataStream avatars (Anam, Bey, D-ID, LemonSlice, Runway, Tavus, Trugen) stalling the - #1795 (@smorimoto) conversation on user interruption when paired with the OpenAI Realtime API.

  DataStreamAudioOutput parsed the lk.playback_finished RPC payload with a compile-time-only as PlaybackFinishedEvent cast. The LiveKit avatar protocol serializes that payload with snake_case keys (playback_position, synchronized_transcript) — confirmed against Anam's live engine, which emits {"playback_position": 2.0, "interrupted": true, "synchronized_transcript": null} — so the camelCase playbackPosition read back undefined. That became Math.floor(undefined * 1000) === NaN, which JSON.stringify serializes as null in conversation.item.truncate; the OpenAI Realtime API then rejected the truncate with an invalid_type error and the interrupted turn could not recover.

  DataStreamAudioOutput now normalizes the wire payload (snake_case primary, camelCase fallback), which also restores the previously-dropped synchronizedTranscript on interrupted turns. As defense-in-depth, the realtime truncate path now clamps a non-finite audioEndMs to a valid non-negative integer in both AgentActivity and the OpenAI plugin so a malformed or absent playback position can never again serialize as null.

• Fix openai realtime STT (transcription session) failing on every model - #1767 (@tsushanth) with invalid_request_error.invalid_model when connecting directly to wss://api.openai.com/.../realtime.

  OpenAI's native endpoint now treats a ?model= query param on the WebSocket upgrade URL as selecting a conversation session, so the subsequent transcription-mode session.update is rejected — surfacing as invalid_model and a 4000 close. Drop the ?model= parameter when the host is api.openai.com (the model is conveyed via session.update → audio.input.transcription.model instead).

  OpenAI-compatible proxies (LiteLLM, Cloudflare AI Gateway, etc.) still receive the model on the upgrade URL so they can route by model before the first frame, preserving the original intent of #1467.

• Updated dependencies [27a6e829350c13fcdca533d68f864bebda70de89, 9cc7215bc08c34f24b5d9f7f8fbe754d7e67c267, ed2364ad105d7fde9baccc463a7bdbffa6a1699c, ed2364ad105d7fde9baccc463a7bdbffa6a1699c, 27a6e829350c13fcdca533d68f864bebda70de89, e64698c2e67048ff577d5024488929193d0b60e4, ec4a2a48d7ba1f6c20a86303b264188fa47fae0d, e1acca813568869fd345b5eee16be211e8595d9b, bb8e6251354062714e39ae5a44244e1ef65b385b, ed2364ad105d7fde9baccc463a7bdbffa6a1699c]:

  • @livekit/agents@1.4.7