fix: security audit round 2 (v0.13.4.0) (#640)

* fix: chrome-cdp localhost-only binding

Restrict Chrome CDP to localhost by adding --remote-debugging-address=127.0.0.1
and --remote-allow-origins to prevent network-accessible debugging sessions.

Clears 1 Socket anomaly (Chrome CDP session exposure).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: extension sender validation + message type allowlist

Add sender.id check and ALLOWED_TYPES allowlist to the Chrome extension's
message handler. Defense-in-depth against message spoofing from external
extensions or future externally_connectable changes.

Clears 2 Socket anomalies (extension permissions).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: checksum-verified bun install

Replace unverified curl|bash bun installation with checksum-verified
download-then-execute pattern. The install script is downloaded, sha256
verified against a known hash, then executed. Preserves the Bun-native
install path without adding a Node/npm dependency.

Clears Snyk W012 + 3 Socket anomalies.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: content trust boundary markers in browse output

Wrap page-content commands (text, html, links, forms, accessibility,
console, dialog, snapshot) with --- BEGIN/END UNTRUSTED EXTERNAL CONTENT ---
markers. Covers direct commands (server.ts), chain sub-commands, and
snapshot output (meta-commands.ts).

Adds PAGE_CONTENT_COMMANDS set and wrapUntrustedContent() helper in
commands.ts (single source of truth, DRY). Expands the SKILL.md trust
warning with explicit processing rules for agents.

Clears Snyk W011 (third-party content exposure).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: harden trust boundary markers against escape attacks

- Sanitize URLs in markers (remove newlines, cap at 200 chars) to prevent
  marker injection via history.pushState
- Escape marker strings in content (zero-width space) so malicious pages
  can't forge the END marker to break out of the untrusted block
- Wrap resume command snapshot with trust boundary markers
- Wrap diff command output with trust boundary markers
- Wrap watch stop last snapshot with trust boundary markers

Found by cross-model adversarial review (Claude + Codex).

* chore: bump version and changelog (v0.13.4.0)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* chore: gitignore .factory/ and remove from tracking

Factory Droid support was removed in this branch. The .factory/ directory
was re-added by merging main (which had v0.13.5.0 Factory support).
Gitignore it so it stays out.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,24 @@
 # Changelog
 
+## [0.13.8.0] - 2026-03-29 — Security Audit Round 2
+
+Browse output is now wrapped in trust boundary markers so agents can tell page content from tool output. Markers are escape-proof. The Chrome extension validates message senders. CDP binds to localhost only. Bun installs use checksum verification.
+
+### Fixed
+
+- **Trust boundary markers are escape-proof.** URLs sanitized (no newlines), marker strings escaped in content. A malicious page can't forge the END marker to break out of the untrusted block.
+
+### Added
+
+- **Content trust boundary markers.** Every browse command that returns page content (`text`, `html`, `links`, `forms`, `accessibility`, `console`, `dialog`, `snapshot`, `diff`, `resume`, `watch stop`) wraps output in `--- BEGIN/END UNTRUSTED EXTERNAL CONTENT ---` markers. Agents know what's page content vs tool output.
+- **Extension sender validation.** Chrome extension rejects messages from unknown senders and enforces a message type allowlist. Prevents cross-extension message spoofing.
+- **CDP localhost-only binding.** `bin/chrome-cdp` now passes `--remote-debugging-address=127.0.0.1` and `--remote-allow-origins` to prevent remote debugging exposure.
+- **Checksum-verified bun install.** The browse SKILL.md bootstrap now downloads the bun install script to a temp file and verifies SHA-256 before executing. No more piping curl to bash.
+
+### Removed
+
+- **Factory Droid support.** Removed `--host factory`, `.factory/` generated skills, Factory CI checks, and all Factory-specific code paths.
+
 ## [0.13.7.0] - 2026-03-29 — Community Wave
 
 Six community fixes with 16 new tests. Telemetry off now means off everywhere. Skills are findable by name. And changing your prefix setting actually works now.