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buzz/mobile/lib/features
Logan Johnson 965fe1dffa fix(mobile): hydrate and refresh relay presence snapshots (#7382)
<!-- Draft PR body for #7382 · fix(mobile): hydrate and refresh relay
presence snapshots · https://github.com/block/buzz/pull/7382 -->

🤖

## Summary

Mobile showed every person in a DM as **Offline** until they happened to
publish a presence update while the app was connected. Presence was
never loaded when the app opened, never refreshed, and a missing or
failed read looked identical to actually being offline. This PR makes
presence load and stay current: on connect or foreground, the app
fetches the relay's presence snapshot for everyone visible, keeps the
live subscription open while it does, and re-checks every 60 seconds
while the app is in the foreground. A missing or failed read shows
**Unknown** (no dot), not Offline.

- Snapshot reads are authenticated like the rest of the session and
batched by exact key (at most 100 per batch), instead of relying on live
events only.
- The live subscription opens before the snapshot, so updates published
during the read are not dropped. Per-key revisions fence stale **query
completions**: a snapshot that finishes after newer live evidence for
that key does not overwrite it.
- Refreshing every 60 foreground seconds observes relay lease expiry and
retry failures; missing or failed evidence simply stays absent — it is
never reported as Offline.
- Disconnects, backgrounding, and account/community changes reset the
cache cleanly. The app's existing subscription/recovery machinery is
reused rather than duplicated.

Mirrors Desktop's presence hydration
(`desktop/src-tauri/src/commands/profile.rs::get_presence`,
`desktop/src/features/presence/hooks.ts`).

### Presence contract: best effort between polls

Presence is a best-effort estimate that the next foreground poll
corrects. This PR does not give strict causal order between snapshots
and live events:

- Snapshots carry relay time. Live kind:20001 events carry the signer's
time. These clocks are not comparable.
- A live event at or below a snapshot's relay second is not applied
directly. The client confirms it with a fresh snapshot. This works
because the relay persists presence before fan-out.
- An empty (all-Offline) snapshot carries no relay second. If the relay
stored an Online event, then its fan-out was delayed past lease expiry
and an empty snapshot, the delayed event can show Online/Away until the
next 60-second poll. Base `main` has the same stale-delivery exposure
with no correction at all.

Strict ordering needs relay-issued ordering metadata on both paths, or a
fresh confirmation for every live event. Both are protocol or latency
tradeoffs and are out of scope here.

### Related issue

- Fixes: N/A. Closest open duplicates: #4417 (larger presence bootstrap
+ UI patch), #5617. Related: #6200, #7295.
- First slice of the mobile remote-agent parity port. This PR includes
the Unknown rendering at all three consumers (DM header, channel tile,
profile sheet). #7383 and #7526 stack on it and add test coverage only.

### Testing

- Rebased on `main` `95b018c87` (2026-09-30). At stack tip `7c8a93081`:
`just mobile-check` clean; full `just mobile-test` **2,593 passed**.
Earlier receipts below apply to the pre-rebase head.

- Regressions cover cold-open hydration, live/snapshot races, lease
expiry, failed reads and retries, disconnect/background/scope changes,
and >100-key batching.
- At the branch head: `just mobile-check` and the full mobile test suite
pass independently, and every broader CI gate has successful evidence
after isolated recovery runs (no monolithic local `just ci` run) —
receipts in the [exact-head evidence
comment](https://github.com/block/buzz/pull/7382#issuecomment-5573112882).
- Verification is automated-test level; no native device or simulator
run is claimed. No layout change in this slice.

### Screenshots

No layout change in this slice — the renders below show the same
existing profile sheet, with the presence status now following hydrated
relay data. Flutter production-widget test renders — not native-device
screenshots or acceptance captures.

| Scenario | Before | After |
|---|---|---|
| Existing profile opened cold, with a signed relay snapshot saying
Online | ![Before: the profile stays Offline — the snapshot is never
fetched](https://github.com/user-attachments/assets/4b4899c8-364c-4621-8d59-949189860eb3)
| ![After: the profile shows Online once the snapshot
hydrates](https://github.com/user-attachments/assets/7b1a9ecd-a7a8-4e04-b007-b86565a39cfc)
|

<details>
<summary>Capture provenance</summary>

Rendered by the Flutter widget engine in a `flutter test` run
(production widgets, production theme; no device or simulator). Before:
this PR's declared base `3c7f288c60d67df78577b237e27c3dfc8831aaa1`.
After: its head `a8e8028bfb9bb67de2db03ed448839e2f3ab2b0d`.

</details>

Signed-off-by: Logan Johnson <loganj@squareup.com>
2026-09-30 20:10:24 -04:00
..
2026-08-19 17:48:09 +01:00