Undo ends every session of the user, including the one that opened the link; saving that deleted session at the end of the request made Django answer 400 although the address had been restored. The view now drops its own session (as sign-out does), also on the unclear-outcome page. Tests for both cases from a signed-in browser.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FocPJ75XPma7TcuYEMy8zm