Login and logout verifiedimportant
Turns the www-auth credentials into a session cookie — the same cookie that opens the REST API.
In detail
The form posts to /login; success sets a cookie and reloads. GET /loggedon reports who is signed in, and the engine keeps sessions in a table of their own. Two properties are worth recording. The credentials themselves are refused as HTTP Basic on the data endpoints — only the session works. And the session works on /v1 as well, so signing into the console grants the full API, which makes this screen the real perimeter of a MailerQ node.