docs(pdftract-2wqir): add verification note

notes/pdftract-2wqir.md

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+# 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