fix(inference): accept numeric STT error codes

[Maples7]

Description

Accept numeric STT error codes in inference server events.

Changes Made

• widen sttErrorEventSchema.code from string-only to string | number
• add a focused regression test covering a numeric STT error code such as 429
• keep the change scoped to STT error event parsing only

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

This fixes the schema mismatch reported in #1230.

The bug is that some STT error payloads use numeric codes such as 429. Today those frames fail sttServerEventSchema.safeParseAsync(...) and are dropped as parse failures instead of surfacing as STT errors.

This PR is intentionally minimal and does not change any retry logic or higher-level error handling.

---

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

[changeset-bot]

🦋 Changeset detected

Latest commit: c90d7db

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

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[CLAassistant]

All committers have signed the CLA.

[devin-ai-integration]

✅ Devin Review: No Issues Found

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

View in Devin Review to see 2 additional findings.

[Maples7]

Additional reproduction evidence from a downstream integration:

1. The current upstream schema on main and @livekit/agents@1.2.6 is still string-only for sttErrorEventSchema.code.
2. A minimal Zod reproduction rejects { type: 'error', message: 'quota exceeded', code: 429 } with Expected string, received number.
3. In agents/src/inference/stt.ts, a failed sttServerEventSchema.safeParseAsync(...) only logs Failed to parse STT server event and then continues, so the STT error frame is dropped.
4. This is separate from a local turn-detector startup failure I debugged in my app: that startup issue prevented the worker from booting at all, while this upstream schema bug affects observability once the worker is otherwise healthy.

That separation matters because both failure modes can look identical from the client side: “I spoke, but no transcript or useful STT error showed up.”

[davidzhao]

great catch. looking at the server side, it doesn't seem possible for code to be a string