feat(endpointing): expose dynamic endpointing alpha parameter

[toubatbrian]

Summary

Port of livekit/agents#5491 (Python) — exposes the alpha EMA (exponential moving average) coefficient for dynamic endpointing on the public EndpointingOptions config surface.

This is an automated Claude Code routine port created by @toubatbrian. Currently in experimentation stage.

What changed in Python (upstream)

The upstream PR adds a new alpha field to EndpointingOptions:

• Field added to the EndpointingOptions TypedDict and _ENDPOINTING_DEFAULTS (default 0.9).
• DynamicEndpointing.__init__ accepts alpha and forwards it to both internal EMA filters (_utterance_pause, _turn_pause).
• DynamicEndpointing.update_options(...) accepts alpha and updates the EMA filters in place without resetting their learned state.
• create_endpointing(options) reads options["alpha"] when constructing a DynamicEndpointing.
• AgentSession.update_options(...) and agent_activity.endpointing_opts plumb alpha through from session-level → agent-level overrides.

The alpha controls how much weight is given to historical end-of-utterance pauses versus the latest sample (higher → more inertia, more smoothing).

What this JS PR does

• Adds an alpha: number field to the EndpointingOptions interface in agents/src/voice/turn_config/endpointing.ts.
• Adds the matching default alpha: 0.9 to defaultEndpointingOptions.

Implementation nuances / parity gap

agents-js does not currently ship a DynamicEndpointing runtime — only the fixed-delay path is wired through AudioRecognition via minEndpointingDelay / maxEndpointingDelay. There is no JS counterpart yet for:

• DynamicEndpointing class with EMA filters (_utterance_pause, _turn_pause)
• create_endpointing(options) factory selecting between fixed and dynamic modes
• AgentSession.update_options(...) / AgentActivity.endpointing_opts runtime plumbing for endpointing fields

Because of that, this port stops at the config-surface level: it makes alpha a first-class option on EndpointingOptions so:

1. Users who set turnHandling.endpointing.alpha today will not get a TypeScript error and the value is plumbed through mergeWithDefaults like the other endpointing fields.
2. When the dynamic endpointing runtime is eventually ported to agents-js, the public config field is already in place — no breaking change to the option shape will be needed at that point.

The Python update_options(alpha=...) runtime path and the DynamicEndpointing test coverage (test_endpointing.py additions) are intentionally not ported here — they would be dead code without the underlying class, and porting the full dynamic endpointing implementation is out of scope for this small config-parity PR.

Files touched

• agents/src/voice/turn_config/endpointing.ts — added alpha to interface + default.

Test plan

• pnpm -w build succeeds (type-only addition, optional field with default).
• turnHandling: { endpointing: { alpha: 0.7 } } accepted by AgentSessionOptions without TS errors.
• No behavior change for existing fixed-mode users (alpha is unused at runtime today).

Reviewers

cc @toubatbrian @livekit/agent-devs

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Linked Python PR: livekit/agents#5491

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Generated by Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: 74bae29

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

This PR includes changesets to release 26 packages

Name	Type
@livekit/agents	Patch
@livekit/agents-plugin-anam	Patch
@livekit/agents-plugin-assemblyai	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-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-mistral	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-runway	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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[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.

[lukasIO]

should this be based on top of #1316?