# cin90 login

Sign in to coderin90.com from the terminal

Sign in to coderin90.com.

A browser approves the sign-in and the CLI receives a token. You will never
be asked for a password here — cin90 does not handle your password at all.

The token is written to ~/.config/cin90/credentials.json, readable only by
you. Running this again repairs those permissions if something loosened them.

Instructors: `cin90 login --scope mcp` signs in to the teaching tools that
`cin90 teach` uses. That token is stored beside your ordinary sign-in and
leaves it untouched; if credentials.json cannot be read, it refuses and asks
you to run `cin90 login` first. A plain `cin90 login` over an unreadable file
rewrites it, which drops the teaching tools sign-in; it says so when it does.

## Usage

```
cin90 login [flags]
```

## Flags

```
  -h, --help           help for login
      --scope string   what the token is for: cli, or mcp for the teaching tools (default "cli")
```

## See also

- [cin90](/docs/cin90/)