External sign-in

What can you do with it?

To avoid another password, to show GitHub or 42 on the public profile, or to access the plans of a 42 school.

When the provider returns the authorised account, ArduMaker decides which profile it belongs to, in this order:

The profile with the open session in the browser: it is linking from its account.
The profile that already has that provider account: it is signing in.
The profile with the same email: it is the same person registered another way.
None: a new account is created with a random password the person does not use.

Link result	What happened
`creada`	Linked for the first time.
`actualizada`	It already belonged to this profile; its data was refreshed.
`movida`	It was on another profile and moved to this one.
`reemplazada`	This profile had another account from the same provider; the new one stays.

After returning from the provider, the front end turns the short session into a normal session and applies «remember me» if chosen.

The provider integration on the profile is created or updated.
If the 42 account moves to another profile, the 42 school membership moves with it.
A new session opens for that device.

Sign-in with a provider

The person signs in with their provider and sees in their settings which accounts are linked.

Code	Cause
409 `ultima_integracion`	It is the last linked account and confirmation is missing. Without it, an account created through a provider may be left with no way to sign in.
404 `no_vinculada`	That account is not linked to the profile.
400 `proveedor_desconocido`	The provider is not `github`, `google` or `42`.

There are no MCP tools to sign in or link accounts. See /mcp/docs.