> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Agent versioning and post-call metrics

> Every agent now has immutable published versions.

Every agent now has immutable published versions. Configuration changes flow through drafts; publishing a draft creates a new version that can be activated or rolled back. The prior in-place config mutation via `PATCH /agent/{id}` returns 400 on config-level fields.

Post-call disposition metrics are now a first-class field on the agent draft config. The backend extracts structured metric values from each call transcript and surfaces them on the call log.

* [Agent Versioning guide](/voice-agents/build/versioning)
* [Post-Call Metrics guide](/voice-agents/build/post-call-metrics)

> Every agent now has immutable published versions.