fix(amd): resolve transcript-only greetings at eot

[rosetta-livekit-bot]

Ports livekit/agents#7026.

Summary

• resolve transcript-only human and machine greetings at the endpointing backstop when VAD does not provide a valid speech end
• allow explicit null AMD models to reuse session LLM/STT while omitted options retain cloud auto-selection
• preserve accumulated transcripts in timeout verdicts and add the source regression/configuration coverage
• update the public API report and add a minor changeset for the new null option API

Testing

• pnpm test agents (142 files, 2,330 passed, 5 skipped)
• pnpm build:agents
• pnpm --filter @livekit/agents lint
• pnpm --filter @livekit/agents typecheck
• Prettier check on all changed source, test, and changeset files
• cue-cli voice-mode run asserting one AMD_HUMAN framework event with a non-empty final transcript while using llm: null and stt: null

Source diff coverage

• livekit-agents/livekit/agents/voice/amd/classifier.py: adapted to agents/src/voice/amd.ts because JS consolidates classifier and detector logic. Ported the EOT fallback that satisfies the silence gate only when VAD has no valid speech end. Transcript preservation was already implemented in JS and is retained and covered.
• livekit-agents/livekit/agents/voice/amd/detector.py: adapted to agents/src/voice/amd.ts, with the public signature reflected in agents/etc/agents.api.md. Python explicit None maps to TypeScript null; Python NOT_GIVEN maps to omitted/undefined, preserving cloud auto-selection. Python-specific NotGivenOr and is_given infrastructure is not applicable in TypeScript.
• tests/test_amd_classifier.py: adapted to agents/src/voice/amd.test.ts, the consolidated JS AMD suite. Ported timeout transcript preservation, transcript-only human and machine EOT resolution, and latest-transcript-chunk behavior. Existing equivalent timer and lifecycle coverage remains in place.
• tests/test_amd_detector.py: adapted to agents/src/voice/amd.test.ts because JS has no separate detector class or detector test module. Ported the new omitted/null/explicit model-resolution matrix; tests moved unchanged into the new Python file already had equivalents in the existing JS suite, so the Python-only file split is not applicable.

No source behavior or target counterpart was omitted, and no infrastructure gap remains.

---

Ported from livekit/agents#7026

Original PR description

Problem: AMD can receive final transcripts without VAD boundaries. Its LLM verdict then remains behind the silence gate until the detection timeout.

Behavior: The existing transcript EOT backstop now supplies the missing silence signal only when no valid VAD end exists. None reuses session STT or LLM models, while omitted values keep cloud defaults. Timeout verdicts retain the transcript.

Fixes #6996
Addresses AGT-3382

Initial prompt and agent context

Model: GPT-5.6

Can you investigate livekit/agents#6996?

Yeah, EOT sounds good.

we could have None means session STT or LLM, so NOT_GIVEN -> default, None -> Inherit, explicit -> explicit.

Yeah, we should preserve the transcript and add tests against the regression cases.

but eot requires VAD too, right?

yes please.

[changeset-bot]

🦋 Changeset detected

Latest commit: e499f32

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

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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.