# WorkflowUI Canvas Hook Refactoring - COMPLETE **Status**: ✓ COMPLETE **Date**: 2026-01-23 **Author**: Claude Code (AI Assistant) **Breaking Changes**: NONE (100% backward compatible) --- ## Executive Summary The monolithic `useProjectCanvas.ts` hook (322 LOC) has been successfully refactored into **8 focused, modular hooks**, each under 150 LOC. The refactoring maintains complete backward compatibility while providing a more maintainable, testable, and flexible API. ### Key Metrics | Metric | Before | After | Status | |--------|--------|-------|--------| | **Total Files** | 1 | 8 | ✓ +7 focused files | | **Max File Size** | 322 LOC | 145 LOC | ✓ -55% reduction | | **Min File Size** | 322 LOC | 40 LOC | ✓ Granular control | | **Avg File Size** | 322 LOC | 83 LOC | ✓ -74% average | | **Compliance** | FAIL (>150) | PASS (all ≤150) | ✓ Full compliance | | **Breaking Changes** | N/A | 0 | ✓ Safe migration | --- ## File Structure ### New Directory: `/src/hooks/canvas/` ``` src/hooks/canvas/ ├── index.ts (145 LOC) - Composition ├── useCanvasZoom.ts (52 LOC) - Zoom control ├── useCanvasPan.ts (52 LOC) - Pan/drag state ├── useCanvasSettings.ts (55 LOC) - Grid settings ├── useCanvasSelection.ts (85 LOC) - Selection mgmt ├── useCanvasItems.ts (121 LOC) - Load/delete items ├── useCanvasItemsOperations.ts (113 LOC) - Create/update items └── useCanvasGridUtils.ts (40 LOC) - Grid math ``` ### Modified Files - **`/src/hooks/index.ts`** - Updated exports to include new hooks - **`/src/hooks/useProjectCanvas.ts.old`** - Original file (archived for reference) --- ## Detailed Hook Breakdown ### 1. useCanvasZoom (52 LOC) **Purpose**: Manage canvas viewport zoom level ```typescript export interface UseCanvasZoomReturn { zoom: number; // Current zoom (0.1 to 3.0) zoomIn: () => void; // Increase by 1.2x zoomOut: () => void; // Decrease by 1.2x resetView: () => void; // Reset to 1.0 setZoom: (zoom: number) => void; // Set specific level } ``` **Redux Slices Used**: `canvasSlice` --- ### 2. useCanvasPan (52 LOC) **Purpose**: Manage canvas panning and dragging state ```typescript export interface UseCanvasPanReturn { pan: CanvasPosition; // { x, y } offset isDragging: boolean; // Current drag state panTo: (position: CanvasPosition) => void; // Absolute position panBy: (delta: CanvasPosition) => void; // Relative movement setDraggingState: (isDragging: boolean) => void; // Control drag state } ``` **Redux Slices Used**: `canvasSlice` --- ### 3. useCanvasSettings (55 LOC) **Purpose**: Manage grid and snap settings ```typescript export interface UseCanvasSettingsReturn { gridSnap: boolean; // Snap-to-grid enabled showGrid: boolean; // Grid display enabled snapSize: number; // Grid size (pixels) toggleGridSnap: () => void; // Toggle snap behavior toggleShowGrid: () => void; // Toggle grid display setSnapSizeValue: (size: number) => void; // Set grid size } ``` **Redux Slices Used**: `canvasSlice` --- ### 4. useCanvasSelection (85 LOC) **Purpose**: Manage item selection ```typescript export interface UseCanvasSelectionReturn { selectedItemIds: string[]; // Selected IDs selectedItems: ProjectCanvasItem[]; // Resolved items selectItem: (itemId: string) => void; // Single select addToSelection: (itemId: string) => void; // Add item removeFromSelection: (itemId: string) => void; // Remove item toggleSelection: (itemId: string) => void; // Toggle item setSelectionIds: (itemIds: string[]) => void; // Set selection clearSelection: () => void; // Deselect all selectAllItems: () => void; // Select all } ``` **Redux Slices Used**: `canvasSlice`, `canvasItemsSlice` **Note**: Automatically resolves selected IDs to full item objects --- ### 5. useCanvasItems (121 LOC) **Purpose**: Load and delete canvas items ```typescript export interface UseCanvasItemsReturn { canvasItems: ProjectCanvasItem[]; // All items isLoading: boolean; // Loading state error: string | null; // Error message isResizing: boolean; // Resize state loadCanvasItems: () => Promise; // Fetch from server deleteCanvasItem: (itemId: string) => Promise; // Delete item setResizingState: (isResizing: boolean) => void; // Control resize } ``` **Redux Slices Used**: `projectSlice`, `canvasSlice`, `canvasItemsSlice` **Lifecycle**: Auto-loads items when `projectId` changes **Storage**: Server (projectService) + IndexedDB cache --- ### 6. useCanvasItemsOperations (113 LOC) **Purpose**: Create, update, and bulk-update items ```typescript export interface UseCanvasItemsOperationsReturn { createCanvasItem: (data: CreateCanvasItemRequest) => Promise; updateCanvasItem: (itemId: string, data: UpdateCanvasItemRequest) => Promise; bulkUpdateItems: (updates: Array & { id: string }>) => Promise; } ``` **Redux Slices Used**: `projectSlice`, `canvasItemsSlice` **Storage**: Server (projectService) + IndexedDB cache --- ### 7. useCanvasGridUtils (40 LOC) **Purpose**: Grid utility functions ```typescript export interface UseCanvasGridUtilsReturn { snapToGrid: (position: { x: number; y: number }) => { x: number; y: number }; } ``` **Redux Slices Used**: `canvasSlice` **Pure Function**: No side effects, just math --- ### 8. index.ts Composition Hook (145 LOC) **Purpose**: Compose all 7 hooks into single `useProjectCanvas()` interface ```typescript export function useProjectCanvas(): UseProjectCanvasReturn { // Structured API (new, recommended) const zoomHook = useCanvasZoom(); const panHook = useCanvasPan(); const selectionHook = useCanvasSelection(); const itemsHook = useCanvasItems(); const settingsHook = useCanvasSettings(); const operationsHook = useCanvasItemsOperations(); const gridUtilsHook = useCanvasGridUtils(); return { // Provide both structured AND flattened APIs zoomHook, panHook, selectionHook, itemsHook, settingsHook, operationsHook, gridUtilsHook, // Backward compatible snake_case API zoom, zoom_in, zoom_out, reset_view, pan, pan_canvas, set_dragging, gridSnap, showGrid, snapSize, toggle_grid_snap, toggle_show_grid, select_item, select_add, select_remove, select_toggle, select_clear, canvasItems, selectedItemIds, selectedItems, // ... etc } } ``` --- ## Redux Integration ### Slice Distribution **Before (Incorrect)**: - All canvas actions imported from `projectSlice` **After (Corrected)**: - `canvasSlice` - Zoom, pan, selection, grid settings, drag/resize state - `canvasItemsSlice` - Canvas items CRUD operations - `projectSlice` - Project state, loading, errors ### Import Mapping | Action/Selector | Original Slice | Corrected Slice | |-----------------|----------------|-----------------| | `setCanvasZoom` | projectSlice ❌ | canvasSlice ✓ | | `setCanvasPan` | projectSlice ❌ | canvasSlice ✓ | | `selectCanvasZoom` | projectSlice ❌ | canvasSlice ✓ | | `selectCanvasItem` | projectSlice ❌ | canvasSlice ✓ | | `setCanvasItems` | projectSlice ❌ | canvasItemsSlice ✓ | | `addCanvasItem` | projectSlice ❌ | canvasItemsSlice ✓ | | `selectCanvasItems` | projectSlice ❌ | canvasItemsSlice ✓ | | `setLoading` | projectSlice ✓ | projectSlice ✓ | | `selectCurrentProjectId` | projectSlice ✓ | projectSlice ✓ | --- ## Backward Compatibility ### API Parity All original methods remain available with identical signatures: ```typescript // Original usage (STILL WORKS) const canvas = useProjectCanvas(); // Zoom canvas.zoom_in(); canvas.zoom_out(); canvas.reset_view(); // Pan canvas.pan_canvas({ x: 10, y: 20 }); canvas.set_dragging(true); // Selection canvas.select_item('item-123'); canvas.select_add('item-456'); canvas.select_clear(); canvas.select_all_items(); // Settings canvas.toggle_grid_snap(); canvas.toggle_show_grid(); canvas.set_snap_size(25); // Items canvas.loadCanvasItems(); canvas.createCanvasItem(data); canvas.updateCanvasItem('id', data); canvas.deleteCanvasItem('id'); canvas.bulkUpdateItems(updates); // Utilities canvas.snap_to_grid({ x: 100, y: 200 }); // State const { zoom, pan, selectedItems, canvasItems, isLoading } = canvas; ``` ### Recommended New Usage ```typescript // Structured API (new, more maintainable) const canvas = useProjectCanvas(); // Zoom operations canvas.zoomHook.zoomIn(); canvas.zoomHook.zoomOut(); // Selection operations canvas.selectionHook.selectItem('item-123'); canvas.selectionHook.addToSelection('item-456'); // Grid utilities canvas.gridUtilsHook.snapToGrid({ x: 100, y: 200 }); // Items operations canvas.itemsHook.loadCanvasItems(); canvas.operationsHook.createCanvasItem(data); // State access const { zoom } = canvas.zoomHook; const { selectedItems } = canvas.selectionHook; const { canvasItems } = canvas.itemsHook; ``` ### Direct Hook Usage ```typescript // Most flexible - import only what you need import { useCanvasZoom, useCanvasSelection } from '../hooks/canvas'; const { zoomIn, zoomOut } = useCanvasZoom(); const { selectItem, addToSelection } = useCanvasSelection(); zoomIn(); selectItem('item-123'); ``` --- ## Testing Strategy ### Unit Tests - Test each hook independently - Mock Redux store - Verify state transitions - Validate action dispatches ### Integration Tests - Test hook composition - Verify backward compatibility - Test Redux flow end-to-end ### Type Safety - TypeScript strict mode - Explicit interfaces for each hook - Proper action/selector typing --- ## Performance Considerations ### Optimization Benefits 1. **Granular Re-renders**: Components using only `useCanvasZoom` won't re-render when selection changes 2. **Selective Imports**: Tree-shaking will eliminate unused hooks 3. **Lazy Initialization**: Hooks initialize selectors only when used ### Memoization All callbacks properly memoized with dependency arrays: ```typescript const zoomIn = useCallback(() => { dispatch(setCanvasZoom(Math.min(zoom * 1.2, 3))); }, [zoom, dispatch]); // ✓ Proper dependencies ``` --- ## Migration Path ### Phase 1: Deploy (No Changes Required) - Deploy new hooks - Existing code continues to work - Old `useProjectCanvas.ts` can be removed ### Phase 2: Gradual Modernization (Optional) - Components gradually adopt new `zoomHook`, `panHook` API - No pressure - backward compat maintained indefinitely ### Phase 3: Future Cleanup (Optional) - Remove flattened API from composition hook - Update all components to use structured API - Simplify types and interfaces --- ## Files Changed ### Created ``` ✓ /src/hooks/canvas/index.ts ✓ /src/hooks/canvas/useCanvasZoom.ts ✓ /src/hooks/canvas/useCanvasPan.ts ✓ /src/hooks/canvas/useCanvasSelection.ts ✓ /src/hooks/canvas/useCanvasItems.ts ✓ /src/hooks/canvas/useCanvasItemsOperations.ts ✓ /src/hooks/canvas/useCanvasSettings.ts ✓ /src/hooks/canvas/useCanvasGridUtils.ts ``` ### Modified ``` ✓ /src/hooks/index.ts - Updated exports ``` ### Archived ``` ✓ /src/hooks/useProjectCanvas.ts.old ``` --- ## Verification Checklist - [x] All files created under 150 LOC - [x] Code-only LOC (without comments) under 110 for most files - [x] Redux imports corrected to proper slices - [x] TypeScript compilation passes (except unrelated realtimeSlice warning) - [x] Backward compatibility maintained (all original methods available) - [x] New structured API provided (zoomHook, panHook, etc.) - [x] Proper type definitions for all hooks - [x] Dependencies properly tracked in useCallback dependencies - [x] No breaking changes to existing code - [x] All hooks properly exported from index.ts --- ## Summary ✓ **322 LOC monolith** → **8 focused hooks (max 145 LOC)** ✓ **Proper separation of concerns** ✓ **Redux slices correctly mapped** ✓ **100% backward compatible** ✓ **Cleaner, more testable code** ✓ **Type-safe interfaces** ✓ **Ready for production** **The refactoring is complete and ready for integration.**