Simplified layout system based on user feedback:
**1. Global Layout Config (Simpler)**
- Moved layoutConfig from per-workspace to global state
- One configuration applies to all workspaces (easier to understand)
- Updated state migration v8→v9 to move config to global level
- Updated WorkspaceSettings UI to edit global config
- Renamed updateWorkspaceLayoutConfig → updateLayoutConfig
**2. Preserve Extra Windows (Fixed Bug)**
- Fixed applyPresetToLayout to keep windows beyond preset slots
- When applying 4-window grid to 6 windows, windows 5-6 are preserved
- Extra windows stacked vertically on right side (70/30 split)
- No more window loss when applying presets
**3. Layout Dropdown in TabBar (Better UX)**
- Added dropdown menu next to workspace tabs
- Shows all available presets with icons (Grid2X2, Columns2, Split)
- Displays window requirements and availability
- Disables presets that need more windows than available
- One-click preset application with toast feedback
- More accessible than /layout command
All tests passing (457 passed). State migration handles v6→v7→v8→v9 correctly.
Generated with [Claude Code](https://claude.com/claude-code)
Add per-workspace layout configuration with smart auto-balancing:
**Core Changes:**
- Add LayoutConfig interface to Workspace type with insertionMode, splitPercentage, insertionPosition
- Create layout-utils.ts with smart direction algorithm that auto-balances horizontal/vertical splits
- Update addWindow() to use workspace layoutConfig instead of hardcoded values
- Migrate state from v7→v8, adding layoutConfig to all workspaces with smart defaults
**Smart Direction Algorithm:**
- Analyzes layout tree to count horizontal vs vertical splits
- Automatically balances by favoring the less-common direction
- Defaults to horizontal (row) for first split
- Provides foundation for "Balanced (auto)" insertion mode
**Testing:**
- Add 30 comprehensive tests for layout-utils.ts (tree analysis, smart direction, window insertion)
- Add 30 tests for logic.ts addWindow() with different layout configs (row/column/smart modes)
- Update migration tests to verify v6→v7→v8 and v7→v8 paths
**Migration:**
- v7→v8 adds layoutConfig with defaults: smart mode, 50% split, second position
- All existing workspaces automatically get smart auto-balancing behavior
Implements orthogonal design: layout behavior = workspace settings (not command flags)
