fix(xai): emit one final user transcript per turn

[rosetta-livekit-bot]

Ports livekit/agents#6729 and folds in agents-js#1912.

xAI retranscribes its persistent input item from the beginning at every audio commit. Hold the latest committed transcript until a response produces output, then emit one final transcript for the turn. This also closes silently abandoned response streams, preserves held turns during chat-context reconciliation, handles unknown xAI item anchors, and settles rejected OpenAI chat-context events without waiting for the timeout.

Source diff coverage

• Adapted: livekit-plugins/livekit-plugins-openai/livekit/plugins/openai/realtime/realtime_model.py -> plugins/openai/src/realtime/realtime_model.ts. Ported event-ID-correlated chat-context waiters, nonfatal rejection handling, settled-waiter guards, reconnect reset ordering, generation-close/subclass hooks, and audio debug suppression using TypeScript primitives. The rebased target now provides native toUpdate reconciliation, which supplies the modified-item behavior required by held turns.
• Adapted: livekit-plugins/livekit-plugins-xai/livekit/plugins/xai/realtime/realtime_model.py -> plugins/xai/src/realtime/realtime_model.ts. Added the xAI realtime session subclass with deferred final transcripts, silent-response disposal, held-turn reconciliation, unknown-anchor fallback, reconnect/close flushing, and audio/text response boundaries.
• Adapted: livekit-plugins/livekit-plugins-xai/livekit/plugins/xai/types.py -> plugins/xai/src/realtime/realtime_model.ts, where agents-js defines GrokRealtimeModels. Added grok-voice-think-fast-2.0.
• Ported: tests/test_realtime/test_openai_realtime_model.py -> plugins/openai/src/realtime/realtime_model.test.ts. Ported all five chat-context rejection/waiter scenarios.
• Ported: tests/test_realtime/test_xai_realtime_model.py -> plugins/xai/src/realtime/realtime_model.test.ts. Ported the source turn-state, mirror integrity, reconciliation, anchor, and abandoned-response scenarios; the Python-only speech timestamp assertion is represented by the target contract that repeated same-item speech starts keep the held turn pending because agents-js does not track per-item speech onset timestamps.
• Not applicable: none.

Validation

• pnpm exec turbo run build --filter=@livekit/agents-plugin-openai... --filter=@livekit/agents-plugin-xai...
• env -u OPENAI_API_KEY pnpm test -- plugins/openai (106 passed, 7 credential-gated skipped)
• env -u XAI_API_KEY pnpm test -- plugins/xai (25 passed, 1 credential-gated skipped)
• ESLint on all changed source and test files
• Prettier check on all changed source and test files

Package-wide lint was also run, but current main has unrelated Prettier failures in untouched OpenAI and xAI files. cue-cli runtime validation remains unavailable because the environment has LiveKit credentials but no XAI_API_KEY.

[changeset-bot]

🦋 Changeset detected

Latest commit: 0f0dfee

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 39 packages

Name	Type
@livekit/agents-plugin-openai	Major
@livekit/agents-plugin-xai	Major
@livekit/agents-plugin-anam	Major
@livekit/agents-plugin-cartesia	Major
@livekit/agents-plugin-cerebras	Major
@livekit/agents-plugin-elevenlabs	Major
@livekit/agents-plugin-fishaudio	Major
@livekit/agents-plugin-google	Major
@livekit/agents-plugin-hume	Major
@livekit/agents-plugin-inworld	Major
@livekit/agents-plugin-krisp	Major
@livekit/agents-plugin-neuphonic	Major
@livekit/agents-plugin-perplexity	Major
@livekit/agents-plugin-rime	Major
@livekit/agents-plugin-sarvam	Major
@livekit/agents	Major
@livekit/agents-plugin-anthropic	Major
@livekit/agents-plugin-assemblyai	Major
@livekit/agents-plugin-azure	Major
@livekit/agents-plugin-baseten	Major
@livekit/agents-plugin-bey	Major
@livekit/agents-plugin-deepgram	Major
@livekit/agents-plugin-did	Major
@livekit/agents-plugin-hedra	Major
@livekit/agents-plugin-lemonslice	Major
@livekit/agents-plugin-liveavatar	Major
@livekit/agents-plugin-livekit	Major
@livekit/agents-plugin-minimax	Major
@livekit/agents-plugin-mistral	Major
@livekit/agents-plugin-mistralai	Major
@livekit/agents-plugin-phonic	Major
@livekit/agents-plugin-protoface	Major
@livekit/agents-plugin-resemble	Major
@livekit/agents-plugin-runway	Major
@livekit/agents-plugin-silero	Major
@livekit/agents-plugin-soniox	Major
@livekit/agents-plugin-tavus	Major
@livekit/agents-plugin-trugen	Major
@livekit/agents-plugins-test	Major

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[devin-ai-integration]

Devin Review found 3 potential issues.

View 3 additional findings in Devin Review.

[devin-ai-integration]

🟡 Newly added public class and its overrides ship without API documentation

The new publicly exported xAI realtime session class and its methods are added without any TSDoc comments, which the repository's contribution rules require for every new class/method.
Impact: Generated API documentation for the xAI plugin will have an undocumented public class.

Rule reference

CONTRIBUTING.md: "If writing new methods/interfaces/enums/classes, document them. This project uses TypeDoc for automatic API documentation generation, and every new addition has to be properly documented." The new RealtimeSession class (plugins/xai/src/realtime/realtime_model.ts:64) and its public members (close, interrupt, session() on RealtimeModel at plugins/xai/src/realtime/realtime_model.ts:59) carry no doc comments.

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