Passwordless login (emailed one-time code) as an opt-in for self-hosted

[RaphaelFakhri]

I run a self-hosted CE instance (v3.2.1) and the only way in is an email plus a password. TOTP exists, but it's a second factor on top of the password, so it makes signing in longer rather than simpler. I'd like an option to sign in with a one-time code emailed to the account address, with no password at all.

Why it comes up

My instance has a handful of sites and I've started adding people who only ever look at one of them: a client who wants to see traffic for the site I built them. They log in roughly once a month. A password they use once a month is a password they lose, and then it's on me to reset it for them, because a self-hosted instance has no "forgot password" flow unless the operator wired up SMTP and told everyone about it.

Shared links solve the read-only case nicely, and I'm using them. They're not a substitute for an account when someone needs their own login, and they're a secret-URL model that I'd rather not hand out more of than I have to.

Why I assume it doesn't exist

I'm guessing the reason is that CE ships without SMTP configured, and login-by-email would brick any instance whose mailer was never set up. That seems like the right default to protect. What I'm asking for is the opt-in version, not a change to how CE behaves out of the box.

What I think would work

• An env flag, off by default, along the lines of PASSWORDLESS_LOGIN=true, that only takes effect when a mailer is actually configured.
• With it on, the login form offers "email me a code" next to the password field. Short-lived, single-use code, rate limited per address.
• Passwords keep working for every existing account, so nobody can lock themselves out by flipping the flag, and the operator account can always get in the normal way.
• Ideally it's per-account rather than instance-wide, so an operator can keep a password on their own account and let occasional viewers use codes.

If a full passwordless flow is more than you want to carry, a plain "email me a reset link" on the login page would cover most of the pain for self-hosters, since right now a forgotten password on CE means someone has to go and run code against the database.

Happy to hear if this has been considered and rejected, or if the feedback board is the better place for it. I know that's where feature requests are routed, but it's for the hosted product, and this is specifically a self-hosted problem.