Include segment index in travel anchor IDs ("travel:INDEX:from->to")
so Follow Team trips visiting the same city pair multiple times get
unique, independently addressable travel segments. Prevents override
dictionary collisions and incorrect validDayRange lookups.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Extract all itinerary reordering logic from ItineraryTableViewController into
ItineraryReorderingLogic.swift for testability. Key changes:
- Add flattenDays, dayNumber, travelRow, simulateMove pure functions
- Add calculateSortOrder with proper region classification (before/after games)
- Add computeValidDestinationRowsProposed with simulation+validation pattern
- Add coordinate space conversion helpers (proposedToOriginal, originalToProposed)
- Fix DragZones coordinate space mismatch (was mixing proposed/original indices)
- Add comprehensive documentation of coordinate space conventions
Test coverage includes:
- Row flattening order and semantic travel model
- Sort order calculation for before/after games regions
- Travel constraints validation
- DragZones coordinate space correctness
- Coordinate conversion helpers
- Edge cases (empty days, multi-day trips)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
