Wire A24 into the Plan 01-13 Approach B UAT harness as the binding empirical gate for D-P2-01. A24 verifies end-to-end that SAVE_ARCHIVE → chrome.downloads. download receives a `blob:` URL prefix (NOT `data:application/zip;base64,`), closing audit P0-6 functionally. The Plan 02-02 unit tests pin the wire-format at the SW↔offscreen boundary; A24 pins it at the chrome.downloads platform boundary through a real Chrome instance. Strategy: chrome.downloads.onCreated listener captures the URL cross-realm. The plan's <action> block proposed a chrome.downloads.download monkey-patch installed in the harness page realm — but that intercepts only same-realm calls, missing the SW's call. The canonical cross-realm capture pattern is chrome.downloads.onCreated (fires for any download initiated by any extension realm, with the full DownloadItem including .url). Documented as a deviation from the plan's pseudo-code in SUMMARY.md (Rule 1 — bug fix vs the pseudo-code strategy; same A24 contract verified, correct mechanism). Files modified: - tests/uat/extension-page-harness.ts (+~150 lines): assertA24 + A24_* constants - tests/uat/lib/harness-page-driver.ts (+~30 lines): driveA24 page.evaluate wrapper - tests/uat/harness.test.ts (+~10 lines): import driveA24, append to drivers list Verification: - HEADLESS=1 npm run test:uat → 25/25 GREEN (24 baseline + A24) - capturedUrl observed: blob:chrome-extension://lpgnfoop.../... - npx vitest run → 171/171 GREEN (no regression) - Tier-1 FORBIDDEN_HOOK_STRINGS gate → 13/13 GREEN (12 strings preserved) - npx tsc --noEmit → clean Plan 02-04 scope: 1/3 tasks landed (A24); Tasks 2-3 add A25+A26+A27+A28 (latency, meta.json shape, multi-tab strict, REQ-archive-layout strict).
Mokosh UAT harness (Plan 01-11)
Puppeteer-driven Node script that runs 14 assertions end-to-end against a real Chrome instance loaded with the Mokosh extension. Replaces Plan 01-09 Task 5's operator-empirical functional verification (the operator retains only step 1 — build — and step 14 — brand/design acceptance).
Quick start
npm run test:uat
This builds dist-test/ (the hook-enabled bundle) and runs the harness.
Exit 0 means all 14 assertions passed. Final line: UAT harness: 14/14 assertions passed.
Local-debug mode
HEADLESS=0 npm run test:uat
Opens a real Chrome window so you can watch the picker auto-accept, the badge transitions, the popup appear, etc.
Developer iteration tricks
# Skip the production build inside assertion 0 (uses existing dist/):
SKIP_PROD_REBUILD=1 npm run test:uat
# Run the harness against an existing dist-test/ (skip npm run build:test):
npx tsx tests/uat/harness.test.ts
Assertion catalog
| # | Title | Bug class | Hook used |
|---|---|---|---|
| 0 | Production bundle has no test-hook leaks | T-1-11-01 | filesystem grep |
| 1 | SW bootstrap → setIdleMode | — | sw.evaluate |
| 2 | Toolbar onClicked-idle → REC + popup | — | triggerExtensionAction |
| 3 | Offscreen displaySurface === monitor | D-15 | __mokoshTest.getCurrentStream |
| 4 | Toolbar onClicked-recording → popup, no new offscreen | — | targets count |
| 5 | SAVE_ARCHIVE → download fires | — | downloads polling |
| 6 | BUG B: simulateUserStop → badge OFF + no recovery notif | b9eeeeb |
dispatchEvent('ended') |
| 7 | RECORDING_ERROR codec-unsupported → ERR + recovery notif | — | sendMessage |
| 8 | BUG A: onStartup → mokosh-startup- notification creates | a881bf0 |
__mokoshTest.handlers.onStartup |
| 9 | Icon file sizes meet floors | Bug A precondition | sw.evaluate(fetch) |
| 10 | Manifest has notifications + 3 icons | Bug A precondition | chrome.runtime.getManifest |
| 11 | 35s recording → segments.length >= 3 | D-13 | __mokoshTest.getSegmentCount |
| 12 | ffprobe on extracted webm exits 0 | Plan 01-08 | jszip + execFile |
| 13 | Archive shape — video + meta.json version match | Plan 01-07 | jszip |
Failure isolation
Single browser, serial assertions, bail on first failure for setup- dependent assertions (assertion 0 abort means refusing to launch a potentially-leaky bundle). Per-assertion bail keeps the diagnostic output unambiguous — see RESEARCH §5 + Plan 01-11 open-question resolution 4.
On failure, the harness dumps the last 30 lines of SW console + last 30 lines of offscreen console (captured live during the run) to stderr BEFORE rethrowing — gives you contextual triage without needing to re- run with debug logging.
Known gotchas
Locale-specific picker auto-accept
The --auto-select-desktop-capture-source=Entire screen Chrome flag
auto-accepts the screen-share picker. The string "Entire screen" is
en_US-specific. If your Chrome is set to a non-English locale, the
picker option label will differ and the auto-accept will silently fail
(picker stays open; assertion 2 times out).
Fallback: switch your Chrome user-data-dir's locale to en_US for
harness runs, OR adjust the launch arg in tests/uat/lib/launch.ts to
match your locale's equivalent string.
dev-dep Chromium binary size
puppeteer pulls a ~150 MB Chromium binary at npm install time. CI
must accept this. Production npm install --omit=dev skips it cleanly.
Xvfb is NOT required
Per Plan 01-11 RESEARCH §3 empirical probes against Chrome 148, the
--headless=new mode handles screen capture without Xvfb on Linux CI
runners. If a future Chrome regresses this, Xvfb :99 & DISPLAY=:99 npm run test:uat is the fallback.
CI runner screen-capture concern
The 35s recording assertion (A11) captures whatever is on screen during that window. CI MUST run the harness in an isolated container with no concurrent workload — see T-1-11-02 in Plan 01-11's threat model.
Real Chrome download (assertion 5 → A12)
The harness configures per-page download behavior via CDP to a fresh
os.tmpdir()/mokosh-uat-downloads-* directory; downloads are NOT
written to your real ~/Downloads. The temp directory is deleted by OS
tmpdir GC.