Module errors 

OAuth2 errors for gate::oauth2.

These error types model failures that can occur while configuring or executing the OAuth2 Authorization Code + PKCE flow within OAuth2Gate.

Design goals:

• Provide a small, expressive enum for all OAuth2-related failures
• Keep messages safe for end users; avoid leaking sensitive details
• Include deterministic support codes per variant for service/support workflows
• Avoid hard dependencies on specific HTTP clients; store messages instead of foreign errors

Integration:

• The enum implements crate::errors::UserFriendlyError for consistent messaging
• A local Result<T> alias is provided for gate-internal use
• The crate-level integration (e.g., adding a new top-level variant in crate::errors::Error) can be done separately if/when you want to surface OAuth2 errors consistently across the crate.

Enums

OAuth2CookieKind

OAuth2 cookie kinds used in validation errors.

OAuth2Error

OAuth2-specific error type for OAuth2Gate.

Type Aliases

Result

Local Result alias for OAuth2 flows.