14 tests covering /admin/users/<id>/{deactivate,activate,delete}:
- deactivate/activate flips and 404 on unknown user
- deactivate-self refused (409)
- deactivated user cannot log in (same 401 as wrong-password)
- existing sessions stop working after deactivation (load_current_user
returns None for inactive users → @require_login redirects to /login)
- delete-self refused (409)
- delete refuses when user owns Server, Blueprint, or custom Overlay
- delete on orphan succeeds (302 → /admin/users)
- delete nulls out Job.user_id (jobs survive as audit trail)
- delete-other-admin succeeds when more than one admin exists
The "last admin" branch in the delete endpoint is defense-in-depth and
unreachable via normal flow (any path that triggers it is shadowed by
self-delete) — covered by a comment, not a test.
