feat: Native Messaging Host — Bypass CSP restrictions in authenticated sessions

[Delqhi]

Problem

CVE-2026-0628 demonstrated that malicious extensions could hijack authenticated sessions. In response, Chrome tightened CSP restrictions on extensions operating in authenticated contexts. This blocks our content script injection on sites like Prolific.

Evidence

• BlindAccessJournal: CVE-2026-0628 — "A critical vulnerability discovered in 2026, catalogued as CVE-2026-0628"
• AstraSync: The Authenticated Session Problem
• Chrome Native Messaging docs: chrome.runtime.connectNative() keeps SW alive indefinitely

Solution (Implemented)

Created native-host/ directory with:

1. opensin_host.py — Python stdio-based native messaging host
2. install_host.sh — Registers the host manifest with Chrome on macOS

The host communicates via stdin/stdout (32-bit length-prefixed JSON), bypassing all browser sandbox and CSP restrictions.

Bonus: connectNative() keeps the MV3 service worker alive indefinitely (bypasses the 30-second termination rule).

Files Changed

• native-host/opensin_host.py (NEW)
• native-host/install_host.sh (NEW)

Acceptance Criteria

• Host installs correctly on macOS via install_host.sh
• Extension can send/receive JSON messages via native port
• Service worker stays alive as long as native port is open
• CSP-blocked pages can still be automated via native host relay

[Delqhi]

Implementation note from cloud execution lane:

• Reported outcome: native messaging host support was turned from a stub into an integrated feature with service-worker side native-port lifecycle handling, deterministic host manifest generation, installer flow, and authenticated-session fallback path.
• Reported validation: targeted native-host tests and broader test suite passed in the execution lane.
• Important repo-state note: unrelated local modifications in the default checkout still require selective staging / worktree hygiene before merge.