[Bug]: Microsoft Teams web still redirects to /error/eoa in the preview browser (#16616 reproduces on 0.1.8 nightly) #31458

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/desktop

Steps to reproduce

1. open the preview browser in the desktop app (default profile)
2. go to https://teams.cloud.microsoft/ (or https://teams.microsoft.com/v2/)

curl shows the Electron/ token alone decides it:

UA='Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/152.0.7977.169 Electron/44.10.1 Safari/537.36'
curl -s -o /dev/null -w '%{http_code} %{redirect_url}\n' -A "$UA" https://teams.cloud.microsoft/

Expected behavior

Teams loads its sign-in or the chat list, like in Chrome

Actual behavior

302 to https://teams.cloud.microsoft/error/eoa, then https://teams.microsoft.com/statics/evergreen-assets/tabs/error/eoa answers 404 and the page stays blank

the preview sends:

Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) T3CodeNightly/0.1.8-nightly.20261104.4179 Chrome/152.0.7977.169 Electron/44.10.1 Safari/537.36

#16616 was closed as completed on 2026-10-22 but i still get it, and #16617 (per-profile user agent) was deferred. same root cause as #30014 (Entra passkeys) and #22444 (WhatsApp Web)

i understand the native identity is kept on purpose because of Turnstile. could the Electron/ token be dropped only for Microsoft hosts (*.cloud.microsoft, teams.microsoft.com, login.microsoftonline.com), or only from the request header like the A/B in #30014? that would fix this and #30014 without touching Turnstile sites

Impact

Major degradation or frequent failure

Version or commit

0.1.8-nightly.20261104.4179 (Electron 44.10.1, Chromium 152.0.7977.169)

Environment

macOS 26 (Darwin 25.6), desktop app, preview browser, default profile

Logs or stack traces

Screenshots, recordings, or supporting files

No response

Workaround

none in T3; the Claude desktop app's built-in browser loads Teams and signs in to a work tenant without the Microsoft Single Sign On extension, so only the user agent seems to be in the way