[tinalenguyen]

Port of livekit/agents#7425.

• Gemini TTS: add gemini-3.8-flash-tts and gemini-3.8-flash-lite-tts. On these models the expression marker rides per-part speech_metadata.style (one request part per style change), instructions move into the style instead of a spoken preamble, headerless PCM is requested explicitly, and a two-speaker config (speakers + speaker) is supported.
• provider_format: add the gemini expr dialect (instructions, sound vocabulary and aliases, steering table). Sounds, breaks and emphasis lower to inline tags; the expression marker is left for the plugin.
• tts.StreamAdapter: normalize and convert markup when expressive is on, snapshot the expressive flag per stream, pass the dialect and _setExpressive through to the wrapped TTS.
• Expressive gate: allow any TTS with a dialect that the framework lowers for (inference.TTS, or non-streaming / StreamAdapter), not only the gateway.
• Transcript stripping: a marker heading a line takes the space after it, and a marker ending the text takes the space before it.

Description

Changes Made

Pre-Review Checklist

• Build passes: All builds (lint, typecheck, tests) pass locally
• AI-generated code reviewed: Removed unnecessary comments and ensured code quality
• Changes explained: All changes are properly documented and justified above
• Scope appropriate: All changes relate to the PR title, or explanations provided for why they're included
• Video demo: A small video demo showing changes works as expected and did not break any existing functionality using Agent Playground (if applicable)

Testing

• Automated tests added/updated (if applicable)
• All tests pass
• Make sure both restaurant_agent.ts and realtime_agent.ts work properly (for major changes)

Additional Notes

---

Note to reviewers: Please ensure the pre-review checklist is completed before starting your review.

[changeset-bot]

🦋 Changeset detected

Latest commit: 0b77057

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

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[chenghao-mou]

similar python issue and one nit. It works well in my testing.

[chenghao-mou]

Codex:

js gotcha:

const speakers = { Sienna: 'Kore', Comanchero: 'Puck' };

'Sienna' in speakers;   // true — configured speaker
'Nobody' in speakers;   // false
'toString' in speakers; // true — inherited method