fix(desktop): report a stock Chrome user agent in the browser tab

[waleedlatif1]

Summary

• The Browser tab sent Electron's default user agent, which carries Sim/<version> and Electron/<version> tokens. Detection libraries sites gate on test for Electron before Chrome (bowser matches /electron/i several descriptors ahead of its Chrome one; ua-parser-js reports Electron as the browser name), so we read as "Electron" — on no site's supported list. Ashby warns "Ashby does not support this browser"; stricter sites refuse to render.
• Rebuild the user agent as the desktop form Chrome's user-agent reduction specifies — same platform token, Chromium major version, rest zeroed, no application or Electron token.
• Apply it on both the browser partition session and each tab's WebContents. Both are load-bearing: session.setUserAgent does not reach an already-created WebContents (and the first tab is what creates the session), and service workers do not inherit a tab's user agent — with only the tab's set, a worker's script request still announced Electron.
• Scoped to the browser partition. app.userAgentFallback is deliberately untouched, so the Sim shell's own user agent is unchanged.

Type of Change

• Bug fix

Testing

Verified against a real Electron 43.1.1 runtime with a local echo server, with the app named Sim so both tokens are present in the input:

• Input ... Sim/43.1.1 Chrome/150.0.7871.114 Electron/43.1.1 Safari/537.36 → output Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0.0.0 Safari/537.36.
• Document request, service-worker script request, and navigator.userAgent all report that string.
• Removing the session-level call reproduced the leak: the document request stayed clean while /sw.js went out as Chrome/150.0.7871.114 Electron/43.1.1.
• navigator.userAgentData.brands is Not;A=Brand + Chromium — Electron was never listed there, so the header and the client hints agree rather than conflict.

Unit tests cover the derivation and a regression test asserts every tab gets a user agent with no Electron token; both were confirmed to fail without the fix. Full desktop suite (1135 tests), type-check, and lint pass.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Aug 14, 2026 6:43am

[cursor]

PR Summary

Low Risk
Scoped to the browser agent partition and tab WebContents; no auth or shell UA changes. Main caveat is sites that intentionally block non-standard clients may now treat the tab as stock Chrome.

Overview
Browser tabs no longer advertise Electron to sites. Electron’s default string includes Sim/ and Electron/ tokens that UA parsers treat as unsupported browsers; the change rebuilds the agent from app.userAgentFallback into Chrome’s user-agent–reduction desktop form (platform + Chromium major, no app/Electron tokens).

Application is layered on the browser partition and each tab: session.setUserAgent on the agent partition covers service workers that don’t inherit a tab’s UA, and contents.setUserAgent on every tab covers the first WebContents created when the session already exists. The Sim shell’s global userAgentFallback is unchanged.

New user-agent helpers plus session and electron-mock tests assert the derived string and that every tab gets a Chrome-like UA with no Electron or Sim/ tokens.

^{Reviewed by Cursor Bugbot for commit 3106c54. Configure here.}

[greptile-apps]

Greptile Summary

The PR normalizes the embedded browser’s Electron user agent into Chrome’s reduced desktop form so compatibility checks recognize it as Chrome.

• Derives the stock Chrome string from Electron’s platform token and Chromium major version.
• Applies the override to both the browser partition session and every tab WebContents.
• Adds parser, tab-level regression, and Electron-mock coverage.

Confidence Score: 5/5

The PR appears safe to merge, with both tab and service-worker request paths receiving the normalized user agent before navigation.

The transformation matches the current Electron user-agent format, and all browser-agent WebContents creation paths synchronously apply both session-level and tab-level overrides before loading content.

Important Files Changed

Filename	Overview
apps/desktop/src/main/browser-agent/user-agent.ts	Adds a focused transformation from Electron’s default user agent to Chrome’s reduced desktop format.
apps/desktop/src/main/browser-agent/session.ts	Applies the normalized user agent to the agent partition and each tab before navigation begins.
apps/desktop/src/main/browser-agent/user-agent.test.ts	Covers token removal, exact reduced output, platform preservation, fallback behavior, and Electron integration.
apps/desktop/src/main/browser-agent/session.test.ts	Verifies that every created browser-agent tab receives a Chrome-form user agent without Electron or Sim tokens.
apps/desktop/src/test/electron-mock.ts	Extends Electron test doubles with the fallback user agent and session/WebContents setters required by the change.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[Electron default user agent] --> B[Extract platform and Chromium major]
  B --> C[Build reduced Chrome user agent]
  C --> D[Browser partition session]
  C --> E[Each tab WebContents]
  D --> F[Service-worker and session requests]
  E --> G[Document requests and navigator.userAgent]

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