fix(claw-server): allow Electron Fetch metadata

[Serg Baburin (gmist)]

What this changes

Allows Electron-based MCP clients to connect to the Neo /mcp endpoint when they send Sec-Fetch-* headers.
Requests with an Origin header remain blocked.

Why

Electron automatically adds Sec-Fetch-Site, Sec-Fetch-Mode, and Sec-Fetch-Dest headers. BrowserOS Neo previously rejected these requests with 403 unsupported request, preventing clients such as Cherry Studio from connecting. Fixes #2458.

How to check it

The regression test verifies that:

• requests with Origin return 403;
• requests with Electron-style Sec-Fetch-* headers return 200.

Before you request review

• Ran the checks for the path you touched (see CONTRIBUTING.md)
• Added or updated tests where the behaviour changed
• Checked this on the platforms it affects

[greptile-apps]

PR author is not in the allowed authors list.

[github-actions]

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[graphify-labs]

Graphify reviewed this change.

Worth a look — the grounded gate found no coupling regressions or blocking issues, but 1 advisory finding(s) below merit a look before merge.

Not checked: tests were not run; formal verification proved 0 of 1 changed function(s) (1 not verified).

Formal verification. PR-changed functions: 0/1 verified (0 proven, 0 may-equivalent, 0 distinguished) · 1 not verified (1 unsupported).

Not verified on this run: mcp\_request\_hygiene (unsupported).

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Graphify review — findings

Loosens the loopback /mcp guard so mcp_request_hygiene rejects a request only when it carries an Origin header, and no longer treats Sec-Fetch-Site as a browser signal. Electron-based MCP clients such as Cherry Studio send browser-default Sec-Fetch-* metadata and were being rejected with 403 as a result. The trade-off is that an Origin-less request marked cross-site now reaches /mcp, so the Origin check is the only remaining browser-page gate. Updates the route test and the claw-mcp contract case to pin the new behaviour: Origin still returns 403, while initialize with Sec-Fetch-* headers returns 200 and the expected server info.

Worth a look

• Removing the Sec-Fetch-Site check lets Origin-less cross-site GETs reach /mcp — packages/browseros-agent/apps/claw-server/src/api/http/mod.rs:155 · Escalate · medium
  • agreed by 2 of 2 members but NOT verified (no proof, no reproducing execution) — consensus is not a verdict; needs human review

Analysis details — impact, health, verification

Impact & health

Graphify review

Impact — 142 functions depend on the 94 functions this change touches.

Health — grade A; 10 existing hotspot(s) in the area this change touches (pre-existing, not introduced here):

• createApiRoutes() — 3 callers, 20 callees (high)
• createMcpRoutes() — 7 callers, 5 callees (medium)
• registerKlavisTools() — 2 callers, 10 callees (medium)
• initialize_mcp() — 5 callers, 3 callees (medium)
• createHttpServer() — 2 callers, 6 callees (medium)
• ensureRun() — 1 callers, 9 callees (medium)
• canonical_cancel_endpoint_aborts_in_flight_dispatch() — 0 callers, 7 callees (medium)
• mcp_session_naming_appends_five_tips_without_elicitation() — 0 callers, 7 callees (medium)
• …and 2 more

Verification — 142 functions in the blast radius were not formally verified this run (proofs are advisory here).

Gate & verification

graphify gate

PASS — objectively clean (no health regressions, tests not run — proofs not run this pass (advisory)). Grounded, not self-assessed.

Advisory (not blocking):

• verification_scope: 125 function(s) in the blast radius were not formally verified this run

Formal verification

Could not verify: Could not verify mcp\_request\_hygiene.

The verifier did not have enough to check mcp\_request\_hygiene, so it is saying so rather than guessing. No false assurance is the whole point.

Guarantee: No guarantee either way, this is an honest abstention, not a pass.

Note: Reason: unsupported return type: Response

[Serg Baburin (gmist)]

I have read the CLA Document and I hereby sign the CLA