fix(voice): dont abort tool call when preamble forwarding stops

[jjsquillante]

Description

Ensure tool calls are not aborted when preamble text forwarding stops. It refines the execution flow so that cleanup of preamble forwarders does not propagate an abort to in-flight tool executions. It also introduces tests around tool execution behavior.

Changes Made

agents/src/voice/agent_activity.ts

• Adjust logic to decouple preamble forwarding cleanup from tool execution abort signals, ensuring tool calls continue and complete as expected.

agents/src/voice/generation_tools.test.ts

• Add tests

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

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: a82ef4e

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

This PR includes changesets to release 12 packages

Name	Type
@livekit/agents	Patch
@livekit/agents-plugin-cartesia	Patch
@livekit/agents-plugin-deepgram	Patch
@livekit/agents-plugin-elevenlabs	Patch
@livekit/agents-plugin-google	Patch
@livekit/agents-plugin-livekit	Patch
@livekit/agents-plugin-neuphonic	Patch
@livekit/agents-plugin-openai	Patch
@livekit/agents-plugin-resemble	Patch
@livekit/agents-plugin-rime	Patch
@livekit/agents-plugin-silero	Patch
@livekit/agents-plugins-test	Patch

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[CLAassistant]

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[toubatbrian]

Nice finding! Suggest a small improvement (no need to manually create abortController as Task itself will auto spawn a new one if we do not specify inside Task.from:

    const messageOutputs: Array<[string, _TextOut | null, _AudioOut | null]> = [];
    const tasks = [
      Task.from(
        (controller) => readMessages(controller, messageOutputs),
        undefined,
        'AgentActivity.realtime_generation.read_messages',
      ),
    ];

[toubatbrian]

Add some comments

[toubatbrian]

One final request: could you double-check the use case you're aiming to implement with this fix? Once you're happy with it, I’ll go ahead and merge. Thanks again for helping dig into and spot this super tricky bug!

Also, please add a changeset to patch update the agent-js package. Let me know if you need any help!

[jjsquillante]

absolutely -- i've been testing this morning and all is working well. (now that i updated the controller in the forwarders 🤦 ).

i'll add a changeset -- also, would you mind if i open a separate PR to update the contributing.md file? It was confusing because it asked that I commit to the next branch but when i looked at the branch it hadn't been used in over 6 months.

[jjsquillante]

@toubatbrian added changeset to patch -- thank you for the quick review and help on this!

As an aside, the code is very readable and well documented -- it's been a great experience and I very much appreciate the work yall are doing at LiveKit!

[toubatbrian]

i'll add a changeset -- also, would you mind if i open a separate PR to update the contributing.md file? It was confusing because it asked that I commit to the next branch but when i looked at the branch it hadn't been used in over 6 months.

@jjsquillante Yes, please feel free to open a separate PR for that. I got the same ask once and updated the contributing section in the README, but totally forgot to update contributing.md.

[Shubhrakanti]

Reason as to why this wasn't an issue in python https://live-kit.slack.com/archives/C07TWVC0W4A/p1759946906812589?thread_ts=1759897659.483869&cid=C07TWVC0W4A