Real-time
Race Platform's real-time pipeline keeps every connected client synchronised when a teammate edits a run sheet, drags a board card, or saves a plan change.
The components
| Component | Role |
|---|---|
Realtime service (apps/realtime/) | WebSocket fan-out. Locally on ws + Node (port 6162), production on Cloudflare Durable Objects. |
| One room per session | Each Durable Object instance corresponds to a sessionId. |
| API → Realtime broadcast | After a successful write, the API POSTs the event to the matching room. |
| Automerge CRDT | Conflict-free merging of concurrent edits on the same document. |
| Client subscription | The Flutter client opens a WebSocket per active session and applies events to local state. |
What you can do today
- The realtime service is up and tested —
10/10tests pass inapps/realtime/. - Clients can subscribe to a session room.
- The API broadcast wire-up exists but client-side subscription isn't wired into Flutter yet — today the client refreshes by polling.
What's coming
This is one of the largest unfinished work items:
- Wire the WebSocket subscription into the Flutter client and
apply
lap.updated,runSheet.updated,boardCard.movedevents to local Riverpod state - Automerge wire-up — replace REST-PATCH editing of run sheets, the board, and run plans with CRDT operations
- Drag-and-drop on the board with optimistic update + server-pushed reconciliation
- Latency budget: target ≤ 500 ms for an edit on machine A to appear on machine B over LAN; ≤ 1 s over WAN
- Reconnection / replay when the WebSocket drops
- Presence indicator — show which other engineers are viewing the same run sheet
Acceptance test progress
From .context/progress.md:
- Realtime service spins up and accepts connections
- Editing a lap on desktop appears in web within 500 ms
- Drag a card on web; desktop reflects within 100 ms
- Edge ingester feeds → run sheets auto-populate within 1 s
The boxes above are the live-race MVP acceptance test for real-time.