feat(metrics): broadcast llm tps + ttfs

[rosetta-livekit-bot]

Ports livekit/agents#6373 to expose per-turn LLM throughput and time-to-first-sentence metrics on assistant messages and preserve them across remote-session and telemetry serialization.

Adds a minor changeset for the new public MetricsReport fields.

Source diff coverage

7 source files classified

• Ported: livekit-agents/livekit/agents/llm/chat_context.py -> agents/src/llm/chat_context.ts. Added public llmNodeTps and llmNodeTtfs assistant-message metrics with equivalent semantics.
• Ported: livekit-agents/livekit/agents/voice/agent_activity.py -> agents/src/voice/agent_activity.ts. Attaches TPS and TTFS to the committed assistant message.
• Ported: livekit-agents/livekit/agents/voice/generation.py -> agents/src/voice/generation.ts. Records inference start, calculates TPS over the first-to-last content window using provider usage, captures only the explicit LiveKit TTS synthesis stamp for TTFS, and retains the existing fallback anchor for TTFB.
• Adapted: livekit-agents/livekit/agents/voice/remote_session.py -> agents/src/voice/remote_session.ts, agents/src/telemetry/traces.ts, and agents/src/telemetry/otel_http_exporter.ts. JS has explicit protobuf and cloud-log serialization boundaries rather than Python's allowed-key tuple, so both fields are mapped at each boundary and encoded as doubles.
• Adapted: tests/test_agent_session.py -> agents/src/voice/agent_session_metrics.test.ts. Uses the JS session/TTS harness to verify TTFS anchors on provider synthesis start and remains distinct from TTFB.
• Ported: tests/test_llm_node_metrics.py -> agents/src/voice/generation_metrics.test.ts. Covers the same usage-present, zero-usage, no-usage, single-chunk, TTFT-exclusion, start-time, and TTFS omission cases.
• Adapted: tests/test_session_host.py -> agents/src/voice/remote_session.test.ts. Drives the JS SessionHost event boundary and verifies both values reach protocol MetricsReport.
• Not applicable: none.

Validation

• pnpm test agents (1591 passed, 5 skipped)
• pnpm build:agents
• pnpm --filter @livekit/agents lint (passes with existing repository warnings)
• pnpm --filter @livekit/agents typecheck
• pnpm --filter @livekit/agents throws:check
• Prettier check for all changed source/test files
• cue-cli voice-mode runtime validation: assistant framework event included llm_node_tps and llm_node_ttfs

api:check was also attempted but is currently blocked before API comparison by API Extractor rejecting the repository's existing generated export * as syntax.

---

Ported from livekit/agents#6373

Original PR description

• llm_node_tps — output tokens/sec, from the provider's usage chunk
• llm_node_ttfs — inference start until the first sentence is handed off for synthesis (reuses livekit.agents.types.USERDATA_TTS_STARTED_TIME)
• agent_false_interruption — the event, forwarded over the session host
  was implemented in #6691

Needs: livekit/protocol#1661 (released, already used)

[changeset-bot]

🦋 Changeset detected

Latest commit: 91f89f9

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	Major
@livekit/agents-plugin-anam	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-cartesia	Major
@livekit/agents-plugin-cerebras	Major
@livekit/agents-plugin-deepgram	Major
@livekit/agents-plugin-did	Major
@livekit/agents-plugin-elevenlabs	Major
@livekit/agents-plugin-fishaudio	Major
@livekit/agents-plugin-google	Major
@livekit/agents-plugin-hedra	Major
@livekit/agents-plugin-hume	Major
@livekit/agents-plugin-inworld	Major
@livekit/agents-plugin-krisp	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-neuphonic	Major
@livekit/agents-plugin-openai	Major
@livekit/agents-plugin-perplexity	Major
@livekit/agents-plugin-phonic	Major
@livekit/agents-plugin-protoface	Major
@livekit/agents-plugin-resemble	Major
@livekit/agents-plugin-rime	Major
@livekit/agents-plugin-runway	Major
@livekit/agents-plugin-sarvam	Major
@livekit/agents-plugin-silero	Major
@livekit/agents-plugin-soniox	Major
@livekit/agents-plugin-tavus	Major
@livekit/agents-plugins-test	Major
@livekit/agents-plugin-trugen	Major
@livekit/agents-plugin-xai	Major

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.