When the login string resolves to an existing user and the password is
wrong, BOTH overrides used to write a failure row:
- _check_credentials wrapper: result=failure, reason=bad_password
- _login wrapper (catching the propagating AccessDenied): result=
failure, reason=unknown_user
Discovered in production smoke on westin-v19 after the deploy: a
single failed login for info@gsafinancialconsulting.com produced two
audit rows (one bad_password, one unknown_user). The unknown_user
label was wrong — the user IS in the system.
Fix: _login now checks whether the login string resolves to any user
BEFORE writing the unknown_user row. If yes, _check_credentials
already logged the attempt and _login skips. If no, the user lookup
in super() failed and _login is the only chance to log.
Regression test test_login_known_user_bad_password_single_row asserts
exactly one row per attempt and that the row carries bad_password
(not unknown_user) when the user exists.
30 tests green locally; production smoke on westin-v19 confirms:
one row per failed login, bad_password, IP 172.18.0.1 captured.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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