Magic links open in the device browser, not the OAuth in-app browser,
so the session doesn't carry over. A login code lets mobile users
type a 6-digit code from their email into the login page instead.
- Generate 6-digit numeric code alongside magic link token
- Store code in magic_tokens table
- Add verify-code step to login API endpoint
- Show code input UI after magic link is sent
- Include code in email template
- i18n keys for code UI (en + de)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>