paseo/docs/timeline-sync.md

Timeline sync

Agent chat delivery has two paths:

1. Live stream — agent_stream WebSocket messages for immediacy. These may be delta-shaped lifecycle updates.
2. Authoritative history — fetch_agent_timeline_request for correctness. This always returns full projected timeline items, never lifecycle deltas.

The invariant is:

If the daemon has committed timeline rows for an agent, any connected client that opens or resumes that agent eventually displays every row through the daemon's current tail.

Presence is not delivery

Client heartbeat reports presence:

• device type
• app visibility
• focused agent
• last activity time

Heartbeat is used for notification routing. It must not be used as a correctness gate for agent_stream delivery. A stale mobile focus heartbeat may affect whether the user gets notified; it must not make timeline rows disappear from the live stream.

Catch-up is paged but complete

Large unbounded timeline responses can exceed relay frame limits, so catch-up uses bounded pages. Bounded does not mean partial.

Page limits are projected-item targets. A tool call lifecycle is one projected item even if it spans many source sequence numbers, and assistant/reasoning chunks are merged before counting. The response carries seqStart, seqEnd, sourceSeqRanges, and collapsed so clients can advance sequence cursors without rendering delta rows.

When the app fetches direction: "after" and the daemon responds with hasNewer: true, the app must immediately fetch the next page from endCursor. The catch-up is complete only when hasNewer: false.

The first load of an agent without a local cursor is different: it fetches a bounded latest tail page. Older history remains user-driven by scrolling upward.

Resume behavior

When a client resumes with a known cursor, it catches up after that cursor to completion. It does not replace the view with a latest tail page, because tail pagination can skip the middle of a long background run.

When a client resumes without a cursor, it fetches the latest tail page.

Relevant code

• Server live stream forwarding: packages/server/src/server/session.ts
• App sync planning: packages/app/src/timeline/timeline-sync-plan.ts
• App stream/timeline reducer: packages/app/src/timeline/session-stream-reducers.ts
• Session wiring: packages/app/src/contexts/session-context.tsx