eng-pad/PROJECT_PLAN.md

# PROJECT_PLAN.md — eng-pad Implementation Steps

This file tracks all implementation steps. Check off steps as they are
completed and log them in PROGRESS.md.

## Phase 0: Project Documents

- [x] 0.1: Create DESIGN.md
- [x] 0.2: Create PROJECT_PLAN.md (this file)
- [x] 0.3: Create PROGRESS.md
- [x] 0.4: Update CLAUDE.md with build commands and source tree

## Phase 1: Project Skeleton + Data Layer

- [x] 1.1: Generate Android project with Gradle
  - `build.gradle.kts` (root), `app/build.gradle.kts`, `settings.gradle.kts`
  - Kotlin, Compose, Room KSP, minSdk 30, compileSdk/targetSdk 36
- [x] 1.2: Configure `gradle/libs.versions.toml` version catalog
  - Compose BOM, Room, Navigation, Lifecycle, Coroutines
- [x] 1.3: Configure linting (`app/build.gradle.kts` Android Lint config)
- [x] 1.4: Define Room entities
  - `data/model/Notebook.kt`, `Page.kt`, `Stroke.kt`, `PageSize.kt`
- [x] 1.5: Implement type converters
  - `data/db/Converters.kt` — `FloatArray` ↔ `ByteArray`
- [x] 1.6: Define DAOs
  - `data/db/NotebookDao.kt`, `PageDao.kt`, `StrokeDao.kt`
- [x] 1.7: Define Room database
  - `data/db/EngPadDatabase.kt`
- [x] 1.8: Implement repositories
  - `data/repository/NotebookRepository.kt`, `PageRepository.kt`
- [x] 1.9: Unit tests
  - `test/.../data/StrokeBlobTest.kt` — blob roundtrip
  - `test/.../data/PageSizeTest.kt` — page size enum
- **Verify:** `./gradlew build` — PASSED (build + test + lint)

## Phase 2: Notebook List Screen

- [x] 2.1: Set up `MainActivity` with Compose and `NavHost`
  - `MainActivity.kt`, `ui/navigation/NavGraph.kt`, `ui/theme/Theme.kt`
- [x] 2.2: Implement `NotebookListViewModel`
  - `ui/notebooks/NotebookListViewModel.kt`
- [x] 2.3: Implement `NotebookListScreen`
  - `ui/notebooks/NotebookListScreen.kt` — list, create dialog, delete confirmation
- [x] 2.4: Auto-create page 1 on notebook creation
  - In `NotebookRepository.create()`
- [x] 2.5: Navigation: tap notebook → page list (stub screen)
- **Verify:** `./gradlew build` — PASSED (build + test + lint)

## Phase 3: Canvas — Basic Drawing

- [x] 3.1: Implement `PadCanvasView` — stylus event handling
  - `ui/editor/PadCanvasView.kt` — `onTouchEvent`, `getHistoricalX/Y`
- [x] 3.2: Stroke rendering — `Path`/`Paint`, backing bitmap (1/4 resolution)
- [x] 3.3: Grid drawing — 60pt spacing, drawn on screen only
- [x] 3.4: Coordinate transform — canonical ↔ screen via `Matrix`
- [x] 3.5: Implement `CanvasState`
  - `ui/editor/CanvasState.kt` — zoom, pan, active tool, pen widths
- [x] 3.6: Implement `EditorViewModel`
  - `ui/editor/EditorViewModel.kt` — load/save strokes from Room
- [x] 3.7: Implement `EditorScreen` + toolbar
  - `ui/editor/EditorScreen.kt`, `ui/editor/Toolbar.kt`
- [x] 3.8: Wire navigation — notebook list → pages → editor (pages auto-navigates to first page)
- **Verify:** `./gradlew build` — PASSED (build + test + lint). Manual on-device test pending.

## Phase 4: Zoom and Pan

- [x] 4.1: `ScaleGestureDetector` for pinch-to-zoom (0.5×–4×) with focal-point zoom
- [x] 4.2: Finger drag for pan with pointer tracking
- [x] 4.3: Input routing — `TOOL_TYPE_STYLUS` → draw, `TOOL_TYPE_FINGER` → zoom/pan
- **Verify:** `./gradlew build` — PASSED. Manual on-device test pending.

## Phase 5: Eraser

- [x] 5.1: Eraser mode in `CanvasState` (already defined in Phase 3)
- [x] 5.2: Hit testing — bounding box pre-filter (expanded by 42pt radius)
- [x] 5.3: Stroke deletion + backing bitmap rebuild + DB sync
- **Verify:** `./gradlew build` — PASSED. Manual test pending.

## Phase 6: Undo/Redo

- [x] 6.1: `UndoableAction` interface + `AddStrokeAction`, `DeleteStrokeAction`
  - `undo/UndoableAction.kt`, `undo/StrokeActions.kt`
- [x] 6.2: `UndoManager` — undo/redo stacks, depth 50
  - `undo/UndoManager.kt`
- [x] 6.3: Integrated with `EditorViewModel` + toolbar (undo/redo buttons)
- [x] 6.4: Unit tests — 9 tests in `UndoManagerTest.kt`
- **Verify:** `./gradlew build` — PASSED (19 tests total)

## Phase 7: Selection — Move, Copy, Delete

- [x] 7.1: Selection mode — rectangle selection via stylus drag
- [x] 7.2: Visual feedback — blue highlight on selected strokes, dashed selection rect
- [x] 7.3: Operations — delete, drag-to-move, copy (toolbar buttons appear on selection)
- [x] 7.4: Undo integration — DeleteMultipleStrokesAction, MoveStrokesAction, CopyStrokesAction
- **Verify:** `./gradlew build` — PASSED

## Phase 8: Multi-Page Navigation

- [x] 8.1: `PageListScreen` with page grid (aspect-ratio cards)
  - `ui/pages/PageListScreen.kt`, `PageListViewModel.kt`
- [x] 8.2: Add new page FAB
- [x] 8.3: NavGraph updated — pages route shows PageListScreen, tap page → editor
- **Verify:** `./gradlew build` — PASSED

## Phase 9: PDF Export

- [ ] 9.1: `PdfExporter` — Android `PdfDocument` API
  - `ui/export/PdfExporter.kt`
- [ ] 9.2: Share via `Intent.ACTION_SEND` + `FileProvider`
  - `res/xml/file_provider_paths.xml`, `AndroidManifest.xml` updates
- [ ] 9.3: Export button in toolbar (per-page + whole notebook)
- [ ] 9.4: Unit test — verify PDF generation
- **Verify:** `./gradlew test` + open exported PDF, confirm no grid

## Phase 10: Polish

- [ ] 10.1: E-ink optimizations — minimize animations, high contrast
- [ ] 10.2: Auto-save zoom/pan state per page
- [ ] 10.3: Empty states, error handling, delete confirmations
- [ ] 10.4: Performance profiling on target devices