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.
23 requirements across 5 categories (Data Model, Constraints, Flattening, Drag, Persistence) 5 requirements deferred to v2 (Accessibility, External Drops)