> 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.

# Hydra

## Entries

- [Hydra S2S - concurrency limits + per-org rate metering](https://docs.smallest.ai/changelog/hydra/2026/5/20.md): Hydra speech-to-speech sessions are now governed by a per-org concurrency feature with rate metering tied to the billing service.