Presence Awareness

Presence is a real-time, best-effort notification layer that someone else is viewing or actively editing a record. It is informational only — and should never be the mechanism that decides whether a write is accepted.

What it Carries#

• “Alice is currently viewing this application” (session indicator)
• “Alice is editing the risk rating field” (field-level touch indicator)
• “This application changed 2 minutes ago — you may want to refresh” (stale data warning)

What it does NOT do#

• Does not persist anything to the database
• Does not carry a version number or get checked against one
• Is not retried if dropped, is not guaranteed to arrive in order, and is not acknowledged
• Is never the gate that decides accept/reject on a save

Why it's safe to be unreliable#

Nothing breaks if a presence message is late, lost, or out of order. In the worst-case scenario, Bob's "Alice is editing" indicator is a few seconds stale. This is purely cosmetic and has no data integrity consequences.

Key Principle#

Presence is a courtesy layer sitting on top of correctness, not a part of it. The actual safety mechanism is the server-side version check on the PATCH endpoint (synchronous, HTTP request/response, version-gated). If you ever find yourself needing the WebSocket or SSE message to arrive in order to prevent a bad write, that is a clear signal that correctness logic has leaked into the wrong transport.

“Presence is helpful. OCC is still required.”
Sockets tell you something happened; the version check on save is what actually stops a stale write from landing.