Phase 01: Semantic Position Model - 2 plans in 2 waves - Wave 1: SortOrderProvider + Trip day derivation (parallel-ready) - Wave 2: Tests verifying persistence behavior Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Phases: 1. Semantic Position Model: DATA-*, PERS-* (foundation) 2. Constraint Validation: CONS-* (rules engine) 3. Visual Flattening: FLAT-* (display bridge) 4. Drag Interaction: DRAG-* (UI layer) All 23 v1 requirements mapped to phases.