//! Authentication flow implementations for Microsoft Entra ID (Azure AD) and Auth0.
//!
//! This module provides the core OAuth2 authentication logic, kept intentionally
//! separate from CLI concerns in [`crate::cli`]. Each submodule implements a
//! specific grant type or shared abstraction.
//!
//!
/// The [`Authenticator`](authenticator::Authenticator) trait and execution helpers.
/// Machine-to-machine flow via the Client Credentials grant.
/// Interactive browser login via the Authorization Code flow with PKCE.
/// OAuth2 endpoint URL builder for supported identity providers.