# Project State: Itinerary Editor

## Project Reference

**Core Value:** Drag-and-drop that operates on semantic positions (day + sortOrder), not row indices - so user intent is preserved across data reloads.

**Current Focus:** Phase 1 - Semantic Position Model (Plan 01 complete)

## Current Position

**Phase:** 1 of 4 (Semantic Position Model)
**Plan:** 1 of 2 complete
**Status:** In progress
**Last activity:** 2026-01-18 - Completed 01-01-PLAN.md

```
Progress: [#---------] 12.5%
Phase 1:  [#####-----] 50% (1/2 plans)
Phase 2:  [----------] Not Started
Phase 3:  [----------] Not Started
Phase 4:  [----------] Not Started
```

## Performance Metrics

| Metric | Value |
|--------|-------|
| Total Requirements | 23 |
| Completed | 3 |
| Current Phase | 1 |
| Plans Executed | 1 |

## Accumulated Context

### Key Decisions

| Decision | Rationale | Phase |
|----------|-----------|-------|
| UITableView over SwiftUI List | SwiftUI drag-drop lacks insertion line precision | Pre-planning |
| (day, sortOrder) position model | Row indices break on reload; semantic position is stable | Pre-planning |
| Insertion lines (not zones) | User wants precise feedback on exact drop location | Pre-planning |
| Invalid drops rejected (snap back) | Cleaner than auto-clamping; user knows what happened | Pre-planning |
| Games get sortOrder from 100 + minutes since midnight | Range 100-1540 leaves room for negative sortOrder items | 01-01 |
| Normalization threshold at 1e-10 | Standard floating-point comparison for precision exhaustion | 01-01 |
| Day 1 = trip.startDate | 1-indexed, games belong to their start date | 01-01 |

### Learned

- Previous attempts failed due to row-based thinking instead of semantic positioning
- Travel was incorrectly treated as structural ("travelBefore") instead of positional
- Hard-coded flatten order ignoring sortOrder caused reload issues
- SortOrderProvider provides static methods for all sortOrder calculations
- Trip extension provides instance methods for day number derivation

### TODOs

- [ ] Create tests for semantic position persistence (Plan 01-02)

### Blockers

None currently.

## Session Continuity

**Last Session:** 2026-01-18T19:52:00Z
**Stopped at:** Completed 01-01-PLAN.md
**Resume file:** .planning/phases/01-semantic-position-model/01-02-PLAN.md

### Context for Next Session

Plan 01-01 complete. SortOrderProvider utility created with 6 static methods. Trip extended with dayNumber(for:) and date(forDay:). Next: Plan 01-02 creates tests verifying semantic position persistence.

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*State initialized: 2026-01-18*
*Last updated: 2026-01-18*