Capture oversized screenshots instead of dropping them.

Retina clipboard images over the RGBA size cap were silently skipped; downscale and store a thumbnail so they still appear in history, with regression tests.

docs/TESTING.md

@@ -16,14 +16,14 @@ maCopy has an automated suite. There is no separate “live” Storybook/UI docs
 | `npm run lint` | TypeScript `tsc --noEmit` |
 | `npm run check` | Lint + all tests (CI-style gate) |
 
-Current counts (approx.): **~60 frontend** + **~52 Rust** unit tests.
+Current counts (approx.): **~60 frontend** + **~65 Rust** unit tests.
 
 ## What is covered
 
 ### Frontend (`src/**/*.test.tsx`, `transforms.test.ts`)
 
 - App: load entries, paste invoke, delete via keyboard
-- ClipboardList: selection, multi-select modifiers, image stubs/thumbs, Alt=plain paste
+- ClipboardList: selection, multi-select modifiers, image stubs/thumbs (including truncated thumb previews), Alt=plain paste
 - ContextMenu: Paste / Paste plain / transforms / Pin / Delete
 - SettingsPanel: toggles, history limit, hotkey recorder, **Launch at login → autostart enable**
 - SearchBar basics
@@ -34,18 +34,23 @@ Tauri APIs are mocked in `src/test/setup.ts` (invoke, window, events, clipboard,
 ### Backend (`src-tauri/src/**` `#[cfg(test)]`)
 
 - SQLite CRUD, FTS5, trim + pin preservation, settings
-- List previews: truncate text, omit image blobs, return thumbnails
+- List previews: truncate text, omit image blobs, return thumbnails (including stub `[image WxH]` rows)
+- Search excludes image rows (text-only FTS)
 - Sensitive redaction (card / password / banking) while `get_entry` stays full
 - Hotkey parser (`cmd+\`` etc.)
-- Image thumbnail / PNG helpers
+- Image thumbnail / PNG helpers + `fit_rgba_under_bytes` against production `MAX_IMAGE_BYTES`
+- **Oversized / Retina screenshot prepare** — never skip; downscale + thumb + DB list preview
 - Clipboard content hashing fingerprints
 
 ## What is *not* covered (yet)
 
 - End-to-end UI on a real Mac (no Playwright against the Tauri window)
+- Live pasteboard polling (requires macOS Accessibility / real `NSPasteboard`)
 - Accessibility permission / AppleScript paste in CI
 - Notarized release smoke tests
 - Performance benchmarks in CI
+- Prefer-image-when-text-also-present (poller text-wins path)
+- Exclude-apps / pause-monitoring integration
 
 ## Recommended workflow