[QA] ✅ VERIFIED - All validation working correctly **Testing Completed:** - ✅ Client-side validation prevents empty/whitespace titles - ✅ Server-side validation enforces data integrity (web.py:940-945) - ✅ Error toasts display correctly - ✅ Title input remains visible and focused after validation errors - ✅ Users can immediately correct and save valid titles - ✅ Database integrity maintained (no empty titles stored) **Manual Browser Testing:** All 3 test scenarios passed **Code Review:** Implementation follows best practices **Security:** Defense in depth with both client and server validation See full QA report: /tmp/qa-TRCKR-362.md Screenshots: /tmp/trckr-362-*.png

## Implementation Complete ### Changes Made 1. **Client-side validation** (server/templates/modals/issue_detail.html): - Added empty/whitespace title validation in saveIssueChanges() - Shows 'Title cannot be empty' error toast when validation fails - Added handleTitleBlur() function to prevent blur from hiding input when clicking save button - After validation error, title input stays visible and focused for easy correction 2. **Server-side validation** (server/routes/web.py:938-944): - Added validation in PATCH /web/issues/{issue_id} endpoint - Returns 400 error with toast message if title is empty or whitespace-only 3. **E2E Tests** (tests/e2e/test_issue_empty_title_error.py): - Added TestIssueUpdateEmptyTitleError class with 4 tests ### Test Results All 4 E2E tests pass (7.15s runtime).