Connect and resume
Upgrade the same URL with the bearer header and readacked_through from the ready frame. Relay replays every event after that checkpoint, oldest first, with its original ID; deduplicate, commit in order, and ACK the highest committed sequence.
Read the full_sync frame
When pending events fall outside the 30-day window, Relay sends afull_sync frame with reason checkpoint_outside_retention and the boundary sequence. Delivery and ACKs pause until you complete recovery.
1
Pause normal ACKs
Send no
ack frames until recovery has committed and its completion frame is sent.2
Read authoritative state
Page through
GET /v1/chats, then read visible history with GET /v1/chats/{chatId}/messages.3
Rebuild durably
Commit the recovered chat, message, membership, reaction, and receipt state as one snapshot.
4
Complete the boundary
Send the exact
through_sequence from the full_sync frame.Send full_sync_complete
Commit the snapshot only after every chat page and every message page has been read, then send the completion frame with the exact boundary. Relay marks pending events through that boundary as superseded and resumes with events after it. Completion acknowledges transport only; it does not advance Delivered or Read:Use the SDK callback
The SDK callsonFullSync with the boundary and sends full_sync_complete only after the callback resolves. If the callback throws, the SDK reconnects without completing recovery, so a partial snapshot never becomes the checkpoint:
TypeScript SDK callback
Handle events during sync
Relay keeps assigning sequences while recovery runs; newer pending events resume after the boundary. When a thing appears both in the REST reads and in a later event, prefer the event.When it fails
Afull_sync_mismatch error means the boundary you sent differs from the frame’s; send the exact value. If a REST read fails, do not complete the sync: fix the read, reconnect, and start again from the new frame. An ACK sent during recovery is answered with full_sync_required.