ADR-002: Google OAuth Only

Status: Accepted

Obsolete. Email/password (User.PasswordHash, PasswordResetToken), Apple sign-in (User.AppleSubject) and anonymous guest users (ADR-014) all shipped after this. Google is one of four ways in, not the only one. Date: 2024-12

Context

User authentication needed for:

• Reading progress sync
• Bookmarks and notes
• My Library

Options:

1. Email/password
2. Multiple OAuth providers
3. Google OAuth only

Decision

Use Google Sign-In only for user authentication.

• No email/password forms
• No other social providers (initially)
• Single “Continue with Google” button

Implementation

• ASP.NET Core external auth
• JWT access token (short-lived) + refresh token
• User record created on first login
• Email trusted from Google

Consequences

Pros

• No password storage/management
• Trusted email verification
• Simpler auth flow
• Reduced attack surface

Cons

• Excludes non-Google users
• Dependency on Google services
• May need to add providers later

Notes

• Admin panel uses separate email/password auth
• User table stores GoogleSubject for identity linking