docs(testing): add an RC end-to-end computer-use checklist

Turns the maintainer's informal pre-1.5 manual testing checklist into a
durable doc, extended with everything shipped since that a unit/browser test
can't exercise: native window capture (vs. display-only), stop reliability
with all extras disabled, HUD drag tracking, playhead sync during playback,
auto-zoom cursor-following, Full Camera, and export-audio verification --
each phrased as a regression check against the specific issue it guards
(#60, #115, #100, #111, #72, #108).

Meant to be run top to bottom against a release candidate via the
computer-use workflow already documented in AGENTS.md § Desktop E2E testing
with computer-use, with a results log at the bottom to track what build was
tested and what was found.

Author: EtienneLescot

docs/testing/rc-e2e-checklist.md

@@ -0,0 +1,100 @@
+# RC end-to-end checklist (computer-use)
+
+A manual smoke-test checklist for validating a release candidate on a real desktop,
+via the computer-use workflow described in `AGENTS.md` § Desktop E2E testing with
+computer-use. Originates from the maintainer's pre-1.5 testing checklist; extended
+with everything added since that a unit/browser test can't exercise (native capture,
+tray, real audio/webcam devices, real window management).
+
+Use this top to bottom for an RC. Check off each item as you verify it; note the
+build/commit tested and any findings (with a linked issue) at the bottom.
+
+## How to run this
+
+1. Launch the build under test (`npm run dev` for a branch/worktree, or the packaged
+   RC installer for a full release candidate).
+2. Grant computer-use access to the app's process (`electron.exe` for a dev build,
+   `Openscreen.exe`/`Openscreen.app` for a packaged build).
+3. Work through the sections in order — later sections (Editor, Persistence) depend
+   on having a real recording from the Capture section.
+4. A finding is a bug only if it reproduces twice. Note the repro steps.
+
+---
+
+## Capture + Launch
+
+- [ ] Pre-commit / build sanity: app launches, HUD appears, no console errors on startup
+- [ ] Source selector opens and lists screens/windows with live thumbnails
+- [ ] Selecting a source works for **full screen**
+- [ ] Selecting a source works for a **single app window** (not just full screen — regression check for #60: confirm the recorded video is NOT a black screen, including a window with an odd-pixel client size if you can arrange one)
+- [ ] Record start/stop works from the HUD
+- [ ] **Stop reliably completes** with system audio/mic/webcam/cursor all *disabled* (regression check for #115: this combination used to hang indefinitely on Windows) — confirm the editor opens within a few seconds of clicking stop
+- [ ] Stop reliably completes with system audio + mic + webcam + cursor all *enabled* (no regression to the normal path)
+- [ ] Tray icon "Stop Recording" works while recording (right-click → Stop, or left/double-click to refocus the HUD if it's minimized)
+- [ ] Opening an existing video file works from the launch window
+- [ ] Opening an existing project works from the launch window
+- [ ] **HUD drag tracks the cursor** with no drift, including a long drag across most of the screen (regression check for #100) — drag it, release, and confirm it doesn't jump afterward
+- [ ] Countdown overlay (if enabled) shows before recording starts and doesn't block the source
+
+## Audio
+
+- [ ] Mic toggle on/off works before recording
+- [ ] Mic device selection (if multiple mics available) works
+- [ ] System audio toggle works — verify across **two separate recordings** (toggle state isn't sticky/stale between them)
+- [ ] Mic-only recording produces audible mic audio on playback
+- [ ] System-audio-only recording produces audible system audio on playback
+- [ ] Mic + system audio together: both are audible and levels are reasonably balanced (not one drowning out the other)
+- [ ] **Exported video has audio** matching what was audible in the editor preview (regression check for #108: mic/system audio used to be silently dropped on export) — check this for at least one mic+system-audio recording
+
+## Editor Load + Playback
+
+- [ ] Recording stop opens the editor automatically with the correct video (and webcam PiP, if recorded) loaded
+- [ ] Playback, pause, seek all work from the transport controls
+- [ ] **Playhead tracks actual video position with no visible lag**, including while dragging the playhead during playback (regression check for #111)
+- [ ] Cursor telemetry overlay (highlight/spotlight, if enabled during capture) renders correctly and stays aligned with the actual cursor position throughout playback
+
+## Webcam / Full Camera
+
+- [ ] Webcam PiP renders during playback in the position/size/shape configured (rectangle vs. other mask shapes)
+- [ ] Webcam mirroring toggle works
+- [ ] Webcam reactive zoom (PiP grows on cursor activity, if enabled) behaves reasonably
+- [ ] **Full Camera segment**: press `C` (or the equivalent UI action) to add a Full Camera segment on the timeline; scrubbing through it grows the webcam to fullscreen with an ease-in, and eases back out at the segment's end
+
+## Timeline
+
+- [ ] Add / edit / remove each element type: **zoom region**, **annotation**, **trim region**, **speed region** — confirm each behaves correctly in preview playback
+- [ ] **Auto-zoom regions follow the cursor for their whole span**, not just a static frozen point at the start (regression check for #72) — record a clip with the cursor moving/typing across the screen, let auto-zoom place a region, confirm the pan tracks the movement
+- [ ] Region drag/resize snaps and persists correctly (re-open the project or scrub away and back to confirm the change stuck)
+- [ ] No overlap/ordering bugs on timeline items (annotations are the one type allowed to overlap by design — everything else should not silently collide)
+- [ ] Undo/redo (Ctrl+Z / Ctrl+Shift+Z) works for at least one add/edit/remove action per element type
+- [ ] **Exported video matches the editor preview 1:1** for whatever combination of zoom/annotation/trim/speed/Full-Camera was added — this is the one item worth actually exporting and watching back, not just eyeballing the preview
+
+## Project Persistence
+
+- [ ] Save works (explicit save action, if present, or auto-save)
+- [ ] Load works: close and reopen the project, confirm every timeline element, webcam settings, and style setting (wallpaper/padding/shadow/etc.) survived exactly as left
+
+## Style / Other
+
+- [ ] Wallpaper, padding, shadow intensity, border radius, aspect ratio, motion blur sliders all visibly affect the preview when tweaked
+- [ ] Blur / background-disable-adjacent settings (see #84 — if a dedicated "disable background" control exists by the time you're testing, verify it; otherwise skip)
+- [ ] Language switcher changes UI strings correctly (spot-check one non-English locale)
+- [ ] Export completes for at least one full project combining several of the above (audio + zoom + Full Camera + trim), and the resulting file plays back correctly outside the app (e.g. in a system video player)
+
+## Windows-native specifics (if testing on Windows)
+
+- [ ] Software-encoder fallback notice (if the machine can't use hardware H.264) appears appropriately and doesn't block recording
+- [ ] Diagnostic bundle export (Settings → diagnostics, if present) completes without error
+
+## macOS-native specifics (if testing on macOS)
+
+- [ ] No crash immediately after stopping a recording (regression check for #21 — a known unresolved shutdown-path crash; if it reproduces, note the crash reporter output)
+- [ ] Recording survives an macOS Spaces switch while the HUD is visible
+
+---
+
+## Results log
+
+| Date | Build / commit tested | Tester | Findings |
+|------|------------------------|--------|----------|
+|      |                        |        |          |