Adds full support for directed, bidirectional, and undirected relationships
between actors with visual arrow markers and intuitive controls.
**Type System:**
- Add EdgeDirectionality type (directed | bidirectional | undirected)
- Add directionality field to RelationData
- Add defaultDirectionality field to EdgeTypeConfig
**Visual Representation:**
- Directed edges: single arrow marker at target (→)
- Bidirectional edges: arrow markers at both ends (↔)
- Undirected edges: no arrow markers (—)
- Separate marker definitions for start/end to ensure correct orientation
**Property Panel Controls:**
- MUI ToggleButtonGroup for selecting directionality
- Visual connection indicator with directional symbols
- Reverse direction button (swaps source/target, only for directed edges)
- Live updates with 500ms debounce
**Edge Type Configuration:**
- Default directionality selector in edge type form
- Dropdown with helpful descriptions (→, ↔, —)
- Applied to both create and edit workflows
**Edge Creation:**
- New edges inherit defaultDirectionality from edge type config
- Falls back to 'directed' for backwards compatibility
**Reverse Direction:**
- Swaps source/target and sourceHandle/targetHandle
- Maintains edge ID and selection state
- Tracked in undo/redo history
Includes comprehensive UX specification document with wireframes,
interaction patterns, accessibility guidelines, and implementation phases.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
