Reconnect and persistence

The SDK keeps voice calls alive across two classes of disruption:

• Transient WebSocket drops — codes 1006, 1011, etc. The SessionClient reconnects automatically with a configurable backoff.
• Page reload mid-call — voice-call state is persisted to sessionStorage for ~20 seconds after disconnect, so a refresh during a call can resume cleanly.

Page-reload resume

On mount, ask the client for any persisted call and resume it:

useEffect(() => {
  const stored = delphi.restorePersistedCall();
  if (stored) {
    delphi.reconnectCall(stored).catch(console.error);
  }
}, [delphi]);

restorePersistedCall() returns the stored call descriptor or null. reconnectCall(descriptor) opens a fresh voice_conversation session bound to the same endpointId, re-attaches WebRTC, and restores the SIP leg.

Twenty-second window

The persisted state is only valid for about 20 seconds after disconnect. Beyond that the user should redial. The window protects against accidental reloads, not against intentional dwell time.

Channel WebSocket auto-reconnect

SessionClient reconnects its channel WebSocket on transient disconnects without exposing the gap to callers (state.connected briefly flips to false and back). Configurable via:

const session = await delphi.openSession({
  endpointId,
  mode: 'audio_playback',
  reconnectDelay: 1000, // ms; default uses a short fixed delay
});

Voice sessions reconnect through the same mechanism and the WebRTC peer connection is re-negotiated as needed.

Idle timeout vs reconnect

Reconnect logic is independent of the idle timeout:

• Non-voice sessions still close after sessionIdleTimeoutMs of true inactivity (no messages in either direction). Reconnects do not extend it; user actions do.
• Voice sessions ignore the idle timeout entirely; only endCall() (or a hard disconnect past the reconnect window) ends them.

What is persisted

The persisted blob is intentionally small:

Field	Purpose
endpointId	Which endpoint to resume on.
sessionId	Server-side session identifier.
webrtcGatewayUrl	Where the gateway lives.
telproDomain	TelPro routing hint.
timestamp	Used to enforce the 20-second window.

No audio, no transcripts, no API key. Token re-issuance happens server-side via sessionTokenUrl on resume.