Module callbacks 

Typed callback registry for Live session events.

Fast lane callbacks (sync, < 1ms): audio, text, transcripts, VAD. Control lane callbacks (async, can block): tool calls, lifecycle, interruptions. Outbound interceptors: transform tool responses, inject context at turn boundaries.

Callback Modes

Each control-lane callback has an associated ExecutionMode:

• Blocking — awaited inline. The event loop waits for completion before processing the next event. Guarantees ordering and state consistency.
• Concurrent — spawned as a detached tokio task. The event loop continues immediately. Use for fire-and-forget work (logging, background agent dispatch, analytics).

Fast-lane callbacks (audio, text, VAD) are always sync and inline. Interceptors (before_tool_response, on_turn_boundary) are always blocking.

on_interrupted, on_turn_boundary, and the on_teardown hooks default to blocking for a reason — audio forwarding resumes only after on_interrupted returns, the next turn proceeds only after on_turn_boundary, and disconnect completes only after teardown — but each can be made concurrent when the body is pure bookkeeping (see the _mode fields and on_teardown_concurrent). on_tool_call and before_tool_response are always blocking: their return value is the tool response.

Structs

EventCallbacks

Typed callback registry for Live session events.

Type Aliases

AsyncCallback

Control-lane async callback with no payload.

AsyncCallbackWith

Control-lane async callback over one payload value.

AsyncCallbackWith2

Control-lane async callback over two payload values.

AudioCallback

Fast-lane sync callback over a raw audio chunk.

BeforeToolResponseCallback

Middleware over outgoing tool responses (inspect/rewrite before send).

InstructionFn

Sync state-reactive instruction generator (None = leave unchanged).

SessionPhaseCallback

Fast-lane sync callback over a wire-level SessionPhase change (connecting → active → disconnecting …). Not the PhaseMachine.

SignalCallback

Fast-lane sync callback with no payload (VAD start/end).

TextCallback

Fast-lane sync callback over a text payload (delta, accumulated text, thought).

ToolCallCallback

Tool-call override: return Some(responses) to reply, None to defer to auto-dispatch via the registered ToolDispatcher.

TranscriptCallback

Fast-lane sync callback over a transcript chunk with its is_final flag.

UsageCallback

Fast-lane sync callback over usage metadata.