✅ All 9 tasks completed successfully:
- Backend API with SQL transactions and validation
- Frontend drag-and-drop with @dnd-kit and touch support
- Admin-only reordering in ModerationGroupImagesPage
- Public users cannot reorder (PublicGroupImagesPage)
- Slideshow integration via upload_order
- Optimistic updates with error rollback
- Comprehensive testing and error handling
- Performance: 10 images reordered in 0.148s
Feature ready for production deployment.
- Created comprehensive FEATURE_PLAN-reordering.md with 9 tasks in 3 phases
- Must-Have: Touch-Support for mobile drag-and-drop
- Admin-only: Reordering restricted to ModerationGroupImagesPage
- Public users cannot reorder images (security restriction)
- Technical approach: @dnd-kit/core + PUT /api/groups/:groupId/reorder
- Estimated: 10-12 hours over 2-3 days
