# pdftract-2wqir: Keyboard shortcuts verification

## Summary

Implemented comprehensive keyboard shortcuts in the inspector frontend for power user productivity.

## Changes made

### `crates/pdftract-cli/src/inspect/frontend/app.js`

1. **Extended `setupKeyboard()` function** (lines 443-467 → new):
   - Added `ArrowUp`/`ArrowDown` handlers for scrolling within page
   - Added `?` key handler to toggle help overlay
   - Added `Escape` handler to close help overlay (priority over Escape in inputs)
   - Improved input handling: Escape now blurs any input/textarea, clears search if in search input

2. **Added `prevPage()` and `nextPage()` wrapper functions** (after `navigatePage()`):
   - Semantic wrappers for `navigatePage(-1)` and `navigatePage(1)`
   - Matches naming convention suggested in task description

3. **Added `scrollPage(delta)` function**:
   - Scrolls the canvas container by 100px per keypress
   - Supports smooth scrolling within long pages

4. **Added `toggleHelp(show)` function**:
   - Toggles help overlay visibility
   - Focuses close button for accessibility when opening
   - Hides overlay when `show` is false

5. **Added `setupHelp()` function**:
   - Wires up the ? button click handler
   - Wires up close button click handler
   - Adds click-outside-to-close behavior

6. **Updated `init()` function**:
   - Added call to `setupHelp()`

### `crates/pdftract-cli/src/inspect/frontend/index.html`

1. **Added "?" button** in toolbar:
   - Placed between search input and layer toggles
   - `aria-label="Show keyboard shortcuts"` and `title="Keyboard shortcuts (?)"`
   - Class `btn-help` for circular styling

2. **Added help overlay** at end of body:
   - Modal with semi-transparent backdrop
   - Lists all keyboard shortcuts with semantic formatting
   - Close button (×) in top-right corner
   - Click-outside-to-close behavior

### `crates/pdftract-cli/src/inspect/frontend/style.css`

1. **Added `.btn-help` styles**:
   - Circular button (32px × 32px)
   - Centered "?" text, weight 600

2. **Added `.help-overlay` styles**:
   - Fixed full-screen backdrop (rgba(0,0,0,0.5))
   - Flex centering for content
   - z-index 2000 (above all other UI)

3. **Added `.help-content` styles**:
   - White rounded card (8px radius)
   - Max-width 500px, responsive width
   - Box shadow and max-height constraints

4. **Added `.help-shortcuts`, `.help-shortcut`, `.help-key`, `.help-desc` styles**:
   - Tabular layout for key + description pairs
   - Monospace font for keys
   - Visual separator between navigation and layer keys

## Acceptance criteria verification

| Criteria | Status | Notes |
|----------|--------|-------|
| ArrowLeft on page 5 → goes to page 4 | **PASS** | `navigatePage(-1)` called via ArrowLeft handler |
| ArrowRight on last page → no-op | **PASS** | `if(newPage>=0&&newPage<totalPages)` check prevents out-of-bounds |
| / focuses search | **PASS** | Already implemented, confirmed working |
| 1-8 toggle overlays with visual feedback | **PASS** | `toggleLayer()` called; layer button `active` class toggles via `applyLayers()` |
| Esc blurs input + clears focus | **PASS** | `document.activeElement.blur()` on Escape; help overlay closes on Escape |
| ? shows help overlay | **PASS** | `toggleHelp()` shows overlay; lists all shortcuts |

## Retrospective

### What worked
- The existing `setupKeyboard()` function was well-structured and easy to extend
- Using `dataset.layers` for layer state management made toggleLayer() straightforward
- CSS-only layer visibility via `html[data-layers~="layerName"]` selector pattern is clean

### What didn't
- Initial `setupKeyboard()` check `if(e.target.tagName==='INPUT'&&e.target!==searchInput)return` was too broad—it prevented Escape from blurring non-search inputs. Fixed by restructuring to handle Escape separately before the early return.

### Surprise
- The code already had `setupKeyboard()` with most shortcuts implemented (arrows, /, 1-9, Escape). This task was primarily about:
  1. Adding `?` for help
  2. Adding `ArrowUp`/`ArrowDown` for scrolling
  3. Improving Escape handling to close help overlay

### Reusable pattern
- Help overlay pattern: `toggleHelp(show)` with semantic boolean, click-outside-to-close via `e.target===overlay` check, and close button focus for accessibility
- Keyboard shortcut pattern: Check `e.target.tagName` for INPUT/TEXTAREA, special-case Escape for blur, use `e.preventDefault()` on navigation keys to suppress browser defaults