Claude Desktop auth uses ASWebAuthenticationSession (Safari/WebKit) instead of default browser, blocking Firefox passkey users

Summary

Claude Desktop on macOS launches authentication via ASWebAuthenticationSession, which always uses the Safari/WebKit cookie jar and credential store regardless of the system default browser. This blocks users whose passkeys, password manager, and saved sessions live in Firefox (or any non-Safari browser).

Environment

• macOS (Darwin 25.4.0)
• Claude Desktop (current)
• Default web browser: Firefox
• Passkeys + credentials stored in Firefox / password manager Firefox extension

Steps to reproduce

1. Set Firefox as default browser (System Settings → Desktop & Dock → Default web browser → Firefox).
2. Open Claude Desktop.
3. Trigger any auth/login flow.

Expected

Auth flow opens in the system default browser (Firefox), so existing passkeys and saved credentials are usable.

Actual

Auth flow opens in an in-app ASWebAuthenticationSession web view backed by WebKit / Safari. Firefox passkeys and credentials are not accessible. User must either re-create passkeys in Safari/iCloud Keychain or manually copy the auth URL into Firefox.

Workarounds (none ideal)

• Copy auth URL out of the in-app session and paste into Firefox.
• Migrate passkeys to iCloud Keychain / install password manager Safari extension.
• Use the web app at claude.ai in Firefox instead of the Desktop app.

Request

Add an opt-out or setting to use the system default browser (NSWorkspace open:) for the OAuth/login flow instead of ASWebAuthenticationSession, or document a supported workaround for non-Safari users.

Note

I realize this repo is for the Claude Code CLI rather than Claude Desktop — filing here because Desktop has no public issue tracker. Happy to be redirected if there is a better channel.