fix(hub): trust only listed Chrome extension origins

[erkamyaman]

What and why

The Express hub (hubDefaultOrigins) and the Vite plugin (isAllowedHubOrigin) accepted any chrome-extension:// origin. The Vite plugin skips the one-time code on loopback, so any installed extension could read live state and call write RPCs.

• Only our extension is trusted: extension-origin.ts accepts an extension origin only if it is our pinned ID or is listed in allowedOrigins. hub.ts and vite.ts use it; the Express hub keeps our origin even next to a user's own allowedOrigins list.
• Stable ID: extension/manifest.json now has a key, so every build gets the ID dcogniffeelebaolkkfbopmjcblhblfk, trusted by default. Our extension needs no config. A self-built extension with another key goes in allowedOrigins, and its 403 message says exactly what to add.
• Store zip: extension:zip (now scripts/extension-zip.mjs) drops key from the manifest, since the Chrome Web Store refuses it, and adds key.pem when PANGULAR_EXTENSION_KEY points at the private key, for the first upload of a new item. The private key is kept by the maintainers, not in the repo.
• Docs: security, Chrome extension (getting started and contributing), configuration, Express, Vite and the Analog guide.

Closes #157

How it was verified

• pnpm commit:check, pnpm format:check, pnpm typecheck, pnpm skills:check
• pnpm test:devtools (1190) and pnpm test:panel
• pnpm docs:build, pnpm test:axe, pnpm extension:build
• Tests on the hub registry, SSE, WebSocket upgrade and the Vite request gate: our ID accepted by default, another extension refused, a user-listed ID accepted. A test checks the manifest key produces the pinned ID.
• extension:zip checked both ways: no key in the zipped manifest, and key.pem included when PANGULAR_EXTENSION_KEY is set.

Notes for reviewers

After merging, reload the unpacked extension: its ID changes to dcogniffeelebaolkkfbopmjcblhblfk. For the first Web Store upload, run PANGULAR_EXTENSION_KEY=/path/to/key.pem pnpm extension:zip.

Summary by CodeRabbit

• New Features
  • The Pangular Inspector extension is trusted by default when connecting to Vite and Express servers.
  • Other extension builds can be granted access through allowedOrigins. When a connection is refused because an extension ID is unlisted, the extension can show the origin to add.
  • Extension packaging can include a private key for a first Chrome Web Store upload, and checks that it matches the manifest.
• Documentation
  • Updated setup, security, and publishing guidance to explain trusted extension IDs, origin configuration, and key handling.

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: 7d0b8c8a-bf1d-484b-b699-14a58eae78bb

📥 Commits

Reviewing files that changed from the base of the PR and between 2d1989c and 1ac3c32.

📒 Files selected for processing (4)

• apps/docs/src/content/contributing/chrome-extension.md
• extension/panel-bridge.js
• packages/devtools/src/__tests__/extension-panel-bridge.test.ts
• scripts/extension-zip.mjs

🚧 Files skipped from review as they are similar to previous changes (4)

• extension/panel-bridge.js
• scripts/extension-zip.mjs
• packages/devtools/src/tests/extension-panel-bridge.test.ts
• apps/docs/src/content/contributing/chrome-extension.md

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📝 Walkthrough

Walkthrough

The change pins the published extension ID and limits default hub and Vite origin checks to that ID. Other extension origins can be configured. Packaging supports an optional private key, and a 403 message identifies an unlisted extension origin.

Changes

Extension Origin Trust

Layer / File(s)	Summary
Pin extension identity and package key extension/manifest.json, scripts/extension-zip.mjs, package.json, packages/devtools/src/__tests__/extension-origin.test.ts, apps/docs/src/content/contributing/chrome-extension.md	The manifest now has a public key. The ZIP script omits it from the packaged manifest and can add a matching private key as key.pem. The contribution guide describes first-upload key use.
Validate and enforce extension origins packages/devtools/src/extension-origin.ts, packages/devtools/src/hub.ts, packages/devtools/src/vite.ts, packages/devtools/src/__tests__/*origin*.test.ts, packages/devtools/src/__tests__/hub.test.ts, packages/devtools/src/__tests__/vite-auth.test.ts, packages/devtools/src/__tests__/vite-upgrade-guard.test.ts, apps/docs/src/content/getting-started/*, apps/docs/src/content/security.md	The hub and Vite plugin accept the published extension ID by default and support explicitly allowed extension origins. Tests and guides describe default and allowlist behavior, including one-time-code handling.
Add custom-origin refusal guidance extension/panel-bridge.js, packages/devtools/src/__tests__/extension-panel-bridge.test.ts, apps/docs/src/content/getting-started/chrome-extension.md	A 403 message includes an allowedOrigins hint when an extension ID differs from the pinned ID. Tests and the FAQ cover the hint.

Priority: ⬆️ High

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix · Severity of issue fixed: High

Merge Risk: ⚪ Minimal · up to 1ac3c

The extension identity and origin guidance are consistent. No actionable merge-blocking risk is established.

Security Architecture Review

Security architecture risk: 🟡 Moderate · up to 2d198

The default policy rejects unrelated extensions, which improves protection. However, Express now admits the pinned extension even when a configured origin list omits it. That identity can also be reproduced by an unpacked extension using the public manifest key. Independent authentication limits the impact, but the explicit-list change broadens a security boundary. Private-key handling during store upload also remains incompletely verified.

Retained concerns

• Medium · security · observed: Express now adds the pinned extension origin to every array-valued allowedOrigins setting, including empty arrays and lists that omit extensions. This broadens admission compared with the base and prevents array-based configuration from excluding that identity. Because an unpacked extension can reproduce the identity using the public manifest key, the added trust is not limited to maintainer-authenticated code. Data or action access remains conditional on independent authentication and enabled capabilities; custom registry objects remain an alternative control.

Security review details

Security Blast Radius

• inferred — The introduced admission expansion affects Express hubs using array-valued origin configuration. Successful access is bounded to the hub's exposed inspectors and enabled actions, including state from connected inspected pages; it does not establish arbitrary operating-system authority. The material new attack path requires an attacker-controlled unpacked extension to be installed and the hub to be reachable, with authentication disabled or otherwise satisfied.

Security Findings and Attack Paths

• inferred — An installed malicious unpacked extension can copy the public manifest key, obtain the pinned origin, and pass the newly augmented Express array policy even when its operator did not list that extension. With auth disabled, inspected test assertions demonstrate SSE admission for that origin. Broader RPC exploitation is conditional, not a demonstrated authentication bypass. Under default broad extension acceptance, and in Vite before this PR, comparable extension admission already existed.

Trust Boundaries and Controls

• observed — Unrelated extension IDs and noncanonical extension origins are rejected by the shared policy. Vite retains loopback checks for HTTP and WebSocket upgrades. Express documentation retains the independent one-time code by default, and custom origin registry objects are not augmented. These controls limit the concern; trusting the pinned origin does not itself authorize access through every other boundary.

Resilience and Maintainability Implications

• observed — When PANGULAR_EXTENSION_KEY is set, the private key is deliberately copied into the upload ZIP. The inspected repository references document manual upload, but do not establish the Web Store's removal, retention, or mismatch-validation behavior. A private-key disclosure through that consumer is therefore unresolved, not an observed finding.

Hardening Proposals

• proposed — Preserve operator control over built-in extension trust: keep explicit Express arrays authoritative or provide a clear opt-out. Describe the pinned identity as origin filtering rather than proof of unpacked-code provenance.
• proposed — Validate that a supplied private key derives the pinned public identity, distinguish key-bearing upload archives from ordinary distribution archives, and document verified store handling. Atomic output publication and explicit cleanup ownership would reduce ambiguity during failed or concurrent packaging.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 26.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 15 functions across 10 files. (1 skipped:…	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the change to restrict Chrome extension origins. It does not mention that the pinned extension ID remains trusted by default, but it still summarizes the main security chan…
Linked Issues check	✅ Passed	Issue #157 requires a fixed default extension ID, support for explicitly allowed extension IDs, updated documentation, and tests that reject unknown IDs in Express and Vite. The current change summary…
Out of Scope Changes check	✅ Passed	The manifest key, ZIP packaging behavior, 403 guidance, tests, and documentation support issue #157. The ZIP script removes the manifest key for store packaging and includes a matching maintainer-prov…

Full details: Docstring Coverage

Explanation

Docstring coverage is 26.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 15 functions across 10 files. (1 skipped: 1 unsupported.)

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Actionable comments posted: 2

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🤖 Prompt to fix review comments

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Inline comments:
Review comments at @extension/panel-bridge.js:
- Around line 103-104: Update the 403 hint in the refusal-message logic to avoid
implying that adding an origin fixes every refusal: show it only when the
response identifies an origin refusal, or clarify that it does not override
Vite’s loopback restriction. Preserve the existing behavior for other statuses
and pinned origins.

Review comments at @scripts/extension-zip.mjs:
- Around line 21-22: Update the packaging flow in the keyPath validation block
to derive the supplied PEM’s public key and compare it with the pinned key in
the manifest before removing manifest.key; fail packaging if they do not match,
and only copy the key to stage/key.pem after validation succeeds.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: 081de285-3e8e-4026-b896-c739ad071121

📥 Commits

Reviewing files that changed from the base of the PR and between 98611a1 and 2d1989c.

📒 Files selected for processing (18)

• apps/docs/src/content/contributing/chrome-extension.md
• apps/docs/src/content/getting-started/chrome-extension.md
• apps/docs/src/content/getting-started/configuration.md
• apps/docs/src/content/getting-started/express.md
• apps/docs/src/content/getting-started/vite.md
• apps/docs/src/content/security.md
• extension/manifest.json
• extension/panel-bridge.js
• package.json
• packages/devtools/src/__tests__/extension-origin.test.ts
• packages/devtools/src/__tests__/extension-panel-bridge.test.ts
• packages/devtools/src/__tests__/hub.test.ts
• packages/devtools/src/__tests__/vite-auth.test.ts
• packages/devtools/src/__tests__/vite-upgrade-guard.test.ts
• packages/devtools/src/extension-origin.ts
• packages/devtools/src/hub.ts
• packages/devtools/src/vite.ts
• scripts/extension-zip.mjs

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