Concepts
Concepts
The realtime model behind every SDK — how a session works, what flows through it, and what happens when something goes wrong.
These pages explain the model; they don't walk you through using it. If you haven't run a session yet, do a quickstart first — the concepts land better with one behind you.
The session model
What a session is and what it runs on.
- Sessions — the HTTP handshake, the LiveKit room, and the control plane.
- Clients, agents, and sessions — the three-tier model: credential, reusable persona, one live run.
- Lifecycle — the event sequence from start to end, in six phases.
- Transport — how audio, control messages, and the handshake flow between client and server.
The conversation
What moves through a live session.
- Realtime events — every message on the data channel, grouped by direction and family.
- Audio — mic capture, agent playback, echo cancellation, and gating modes.
- Turn-taking — voice activity detection, barge-in, and silence handling.
- Transcripts — what was spoken vs what the model emitted, and which to subscribe to.
When things change or break
- Errors — the full error-code table and how to recover from each.
- Protocol version — how wire-protocol breaking changes are signaled.