---
id: T01
parent: S02
milestone: M002
provides: []
requires: []
affects: []
key_files: ["app/src/types/canvas.ts", "app/src/hooks/useCanvasState.ts", "app/src/hooks/__tests__/useCanvasState.test.ts", "app/src/utils/artboardShapes.ts", "app/src/utils/__tests__/artboardShapes.test.ts", "app/src/utils/alignment.ts", "app/src/utils/__tests__/alignment.test.ts", "app/src/components/canvas/ArtboardSetup.tsx", "app/src/test-setup.ts", "app/package.json"]
key_decisions: ["Used vitest-canvas-mock instead of jest-canvas-mock (jest globals unavailable in Vitest)", "select/deselect actions excluded from undo stack — selection is UI concern not content mutation", "History capped at 50 entries to bound memory", "useReducer + useRef pattern: reducer for renders, ref for undo/redo stacks"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "Ran `cd app && npx vitest run --reporter=verbose` — 71 tests pass (6 test files, 0 failures). Ran `cd app && npx tsc --noEmit` — zero type errors under strict mode with noUnusedLocals/noUnusedParameters."
completed_at: 2026-03-26T05:31:55.492Z
blocker_discovered: false
---

# T01: Built canvas type system, useCanvasState hook with undo/redo, artboard shapes, alignment utils, ArtboardSetup component, and 48 new tests passing

> Built canvas type system, useCanvasState hook with undo/redo, artboard shapes, alignment utils, ArtboardSetup component, and 48 new tests passing

## What Happened
---
id: T01
parent: S02
milestone: M002
key_files:
  - app/src/types/canvas.ts
  - app/src/hooks/useCanvasState.ts
  - app/src/hooks/__tests__/useCanvasState.test.ts
  - app/src/utils/artboardShapes.ts
  - app/src/utils/__tests__/artboardShapes.test.ts
  - app/src/utils/alignment.ts
  - app/src/utils/__tests__/alignment.test.ts
  - app/src/components/canvas/ArtboardSetup.tsx
  - app/src/test-setup.ts
  - app/package.json
key_decisions:
  - Used vitest-canvas-mock instead of jest-canvas-mock (jest globals unavailable in Vitest)
  - select/deselect actions excluded from undo stack — selection is UI concern not content mutation
  - History capped at 50 entries to bound memory
  - useReducer + useRef pattern: reducer for renders, ref for undo/redo stacks
duration: ""
verification_result: passed
completed_at: 2026-03-26T05:31:55.507Z
blocker_discovered: false
---

# T01: Built canvas type system, useCanvasState hook with undo/redo, artboard shapes, alignment utils, ArtboardSetup component, and 48 new tests passing

**Built canvas type system, useCanvasState hook with undo/redo, artboard shapes, alignment utils, ArtboardSetup component, and 48 new tests passing**

## What Happened

Created the foundational layer for the design canvas (View 2): discriminated union CanvasObject type system with five variants (rect, circle, ellipse, line, image), the central useCanvasState hook using useReducer + useRef pattern for state + history separation, artboard shape path generators (shield, pennant) with dimension presets and unit conversion, 9 pure alignment/distribute functions, and the ArtboardSetup modal component. Installed konva, react-konva, and vitest-canvas-mock (substituted for jest-canvas-mock which crashes in Vitest). Extended test-setup.ts with canvas mock. All 71 tests pass (23 existing + 48 new) and TypeScript compiles clean.

## Verification

Ran `cd app && npx vitest run --reporter=verbose` — 71 tests pass (6 test files, 0 failures). Ran `cd app && npx tsc --noEmit` — zero type errors under strict mode with noUnusedLocals/noUnusedParameters.

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `cd app && npx vitest run --reporter=verbose` | 0 | ✅ pass | 2090ms |
| 2 | `cd app && npx tsc --noEmit` | 0 | ✅ pass | 2100ms |


## Deviations

Used vitest-canvas-mock instead of jest-canvas-mock as specified in plan. jest-canvas-mock internally calls jest.fn() which doesn't exist in Vitest runtime, causing ReferenceError on all test suites.

## Known Issues

None.

## Files Created/Modified

- `app/src/types/canvas.ts`
- `app/src/hooks/useCanvasState.ts`
- `app/src/hooks/__tests__/useCanvasState.test.ts`
- `app/src/utils/artboardShapes.ts`
- `app/src/utils/__tests__/artboardShapes.test.ts`
- `app/src/utils/alignment.ts`
- `app/src/utils/__tests__/alignment.test.ts`
- `app/src/components/canvas/ArtboardSetup.tsx`
- `app/src/test-setup.ts`
- `app/package.json`


## Deviations
Used vitest-canvas-mock instead of jest-canvas-mock as specified in plan. jest-canvas-mock internally calls jest.fn() which doesn't exist in Vitest runtime, causing ReferenceError on all test suites.

## Known Issues
None.
