[Bug]: Cannot downgrade nightly to stable; channel switch does nothing and manual downgrade hides existing chats #4374

Area

apps/desktop

Steps to reproduce

1. Running nightly 0.0.29-nightly.20260722.875 (stable is 0.0.28).
2. Switch update channel from nightly to stable, restart.
3. Manually replace the AppImage with the staged 0.0.28 build, relaunch.

Actual behavior

Step 2: 0.0.28 gets downloaded to ~/.cache/t3code-updater/pending/ but is never installed. The app stays on the nightly. 0.0.29-nightly is a higher semver than 0.0.28, so the updater won't apply it.

Step 3, on 0.0.28: projects and chat threads show up missing/wrong in the UI.

state.sqlite is intact throughout (checked read-only): orchestration_events = 64148 rows through the current session, projection_threads all present with correct titles, projection_thread_messages = 5808 rows, effect_sql_migrations = 15, all projectors in projection_state caught up to the max sequence.

Restoring the nightly 0.0.29 AppImage and relaunching brings all projects and chats back. No data was lost; the threads are just not surfaced by 0.0.28.

Looks like the same class as #4261 (OrchestrationGetSnapshotError: Thread <id> was not found after a version change with events still present). Possibly related: #961, #2181.

Version or commit

0.0.29-nightly.20260722.875 downgraded to 0.0.28.

Environment

Ubuntu 22.04.5 LTS, x86_64, Desktop AppImage, nightly channel, Claude provider, local.