Plan-04-04 debug session-2 root cause: the offscreen-console capture
in tests/uat/lib/launch.ts:registerOffscreenConsoleAttach matched zero
offscreen targets across 4 spike runs, creating a critical observability
gap that prevented disambiguation of Plan 04-04 Wave 0 spike failure
mode.
Empirical investigation (tests/uat/spike-diagnose-offscreen-target.ts,
NEW): when chrome.offscreen.createDocument fires, Puppeteer's
`targetcreated` event fires with `type='other'` and `url=''` BEFORE the
CDP target metadata stabilizes. The previous filter (whether
`background_page` or `page`) never matched at event time. By the time
the metadata stabilizes (visible via `browser.targets()`), the
target's type is `'background_page'` (not `'page'` — MV2's
background_page type IS still used by Chrome's CDP for invisible
extension documents, despite MV3 abolishing classic background pages).
Fix:
- Match the offscreen target by URL pattern (load-bearing criterion;
type field is intentionally unchecked because it's unreliable at
targetcreated time).
- Bind to BOTH `targetcreated` AND `targetchanged` events (the latter
fires when the URL stabilizes after navigation).
- Add a `browser.targets()` enumeration race-free safety net for
cases where the offscreen target exists at registration time.
Verification: tests/uat/spike-diagnose-offscreen-target.ts now emits
`(launch: offscreen console attached — url=chrome-extension://.../src/offscreen/index.html)`
followed by `[off:log] [OS:Recorder] Recording started ...` (zero such
lines in any prior spike run).
Test-infra correctness fix; ZERO production source changes. FORBIDDEN_HOOK_STRINGS
inventory unchanged at 12 entries. No new test-only `__MOKOSH_UAT__` symbols.
References:
- .planning/debug/sw-offscreen-persistence-investigation-session-2.md
(session-2 debug note documenting empirical root cause)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Mark
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