feat: add serviceTier parameter to Responses API LLM

[piyush-gambhir]

Summary

Mirrors livekit/agents#5342 for the JavaScript/TypeScript SDK.

The Chat Completions LLM already supports serviceTier for per-request processing tier control. The Responses API LLM is missing this parameter despite the OpenAI API supporting it.

Changes

plugins/openai/src/responses/llm.ts (1 file):

• Add serviceTier?: string to LLMOptions interface
• Pass service_tier through in chat() via modelOptions

Usage

import { responses } from '@livekit/openai-plugin';

const llm = new responses.LLM({
  model: 'gpt-5.4',
  serviceTier: 'priority',  // now supported
});

Backward Compatible

• Optional field, defaults to undefined
• Matches existing Chat Completions LLM pattern

[changeset-bot]

🦋 Changeset detected

Latest commit: bdcd1d4

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

This PR includes changesets to release 22 packages

Name	Type
@livekit/agents-plugin-openai	Patch
@livekit/agents-plugin-anam	Patch
@livekit/agents-plugin-cartesia	Patch
@livekit/agents-plugin-deepgram	Patch
@livekit/agents-plugin-elevenlabs	Patch
@livekit/agents-plugin-google	Patch
@livekit/agents-plugin-inworld	Patch
@livekit/agents-plugin-neuphonic	Patch
@livekit/agents-plugin-resemble	Patch
@livekit/agents-plugin-rime	Patch
@livekit/agents-plugin-sarvam	Patch
@livekit/agents-plugin-xai	Patch
@livekit/agents	Patch
@livekit/agents-plugin-baseten	Patch
@livekit/agents-plugin-bey	Patch
@livekit/agents-plugin-hedra	Patch
@livekit/agents-plugin-lemonslice	Patch
@livekit/agents-plugin-livekit	Patch
@livekit/agents-plugin-phonic	Patch
@livekit/agents-plugin-silero	Patch
@livekit/agents-plugin-trugen	Patch
@livekit/agents-plugins-test	Patch

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