This commit addresses three recurring issues with the update system:
1. **Checksum mismatches (v4.27.0, v4.28.0):**
- Root cause: Release process uploads checksums.txt first, but if artifacts
are rebuilt after that upload, checksums become stale
- Fix: Update RELEASE_CHECKLIST.md to REQUIRE running validate-release.sh
before publishing (step 9, non-negotiable)
- The validation script exists and catches these errors, but wasn't being
enforced in the release process
2. **Duplicate error modals:**
- Root cause: UpdateProgressModal rendered in both App.tsx
(GlobalUpdateProgressWatcher) and UpdateBanner.tsx
- Fix: Remove UpdateProgressModal from UpdateBanner.tsx
- GlobalUpdateProgressWatcher automatically shows the modal when updates
start, so the banner's modal is redundant
3. **Rate limiting too strict:**
- Root cause: UpdateProgressModal polls /api/updates/status every 2 seconds
(30 req/min), but rate limit was 20/min
- Fix: Increase UpdateEndpoints rate limit from 20/min to 60/min
- Allows modal to poll without hitting rate limits during updates
These were all manual process errors and configuration issues, not code bugs.
The validation script enforcement prevents future checksum mismatches.