Implement request deduplication to prevent multiple duplicate calls to GET
/api/setup when multiple components mount simultaneously. The fix introduces:
1. New 'useSharedSetupStatus' hook with module-level caching
- Shares a single in-flight request across all consumers
- Implements 30-second cache TTL with cache invalidation
- Notifies all subscribers when cache is invalidated
2. Refactored 'useSetup' hook to use shared cache
- Internally uses useSharedSetupStatus for status checks
- Calls invalidateSetupStatus() after successful setup submission
- Maintains backward-compatible API
3. Updated components using setup status
- SetupGuard and SetupPage automatically benefit from deduplication
- No changes needed to consumer code
4. Updated tests
- Mocked useSharedSetupStatus in component tests
- Added comprehensive tests for cache behavior
- All existing tests pass
5. Documentation updates
- Added 'Request Deduplication & Shared Caching' section to Web-Development.md
- Explains when and how to use shared hooks
- Provides complete implementation example
This eliminates wasted resources from duplicate API calls and potential
race conditions where different requests return slightly different states.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Add abortable API signals for setup status and server health/log fetches, document hook cancellation patterns, and cover stale refresh cancellation with tests.
Logs a warning when the initial setup status request fails, allowing
operators to diagnose issues during the setup phase. The form remains
visible while the error is logged for debugging purposes.
