## Summary
- send desktop presence heartbeats every 60 seconds instead of every 30
seconds
- extend presence TTL from 90 to 180 seconds to preserve the existing
three-heartbeat expiry window
- add mutation-sensitive tests that pin the one-minute / three-window
timing contract
- update presence documentation to match
This halves steady-state **desktop** presence `SET` + `PUBLISH` traffic
while retaining tolerance for two missed heartbeats. Mobile already uses
a 60-second heartbeat, so the fleet-wide reduction depends on desktop's
share of connected clients.
## Rollout order
Deploy the relay TTL increase before shipping the desktop heartbeat
change. Old desktop + new relay is safe; new desktop + old relay leaves
only a 90-second TTL on a 60-second cadence and can flap after one
missed heartbeat.
## Verification
At initial live-test commit `00816e233b187bc5ba12c667d675ed050a8cc1c9`:
- isolated clean-room relay built from the exact SHA against fresh
Postgres, Redis, and MinIO
- live Redis `MONITOR` observed kind-20001 writes as `SET ... EX 180`,
global `PUBLISH`, and clean-disconnect / explicit-offline `DEL`
- normal workflows passed: channel create/update/archive/unarchive;
message send/get/reply/thread/search; archived-channel write rejection
and resumed write after unarchive
At follow-up commit `bf38a8c5c96f196ff8ee46e48d4141ee7811f186`:
- `pnpm -C desktop test` — 3829 passed
- `pnpm -C desktop typecheck`
- `cargo test -p buzz-pubsub` — 24 passed, 11 Redis-dependent tests
ignored
- mutation probes fail when the server TTL changes to `999999` or the
desktop heartbeat changes back to 30 seconds
- `git diff --check`
The pre-push suite's relevant checks passed, but its unrelated Tauri
clippy step fails on current `origin/main`:
`desktop/src-tauri/src/linux_media.rs` has three dead-code warnings on
macOS. This PR does not modify that file, so the branch was pushed after
independently running the suites above.
## Buzz context
Originating channel: `buzz-redis-cluster-mode`
(`f4e36d32-afdb-447f-8c87-ab003e069d18`)
---------
Signed-off-by: npub1t2tgm7d8f995uqvmnm8h88sg3wnpp9a5xysjf6dg3tjmgt3ltulqdp8ehr <5a968df9a7494b4e019b9ecf739e088ba61097b4312124e9a88ae5b42e3f5f3e@buzz.block.builderlab.xyz>
Co-authored-by: npub1t2tgm7d8f995uqvmnm8h88sg3wnpp9a5xysjf6dg3tjmgt3ltulqdp8ehr <5a968df9a7494b4e019b9ecf739e088ba61097b4312124e9a88ae5b42e3f5f3e@buzz.block.builderlab.xyz>
