Expand description
Gateway-to-auth bridge: translates soma-auth’s upstream OAuth runtime
(Soma’s product OAuth storage, refresh, and credential cache) into
soma-gateway’s generic UpstreamOAuthProvider/UpstreamOAuthManager
traits, so the standalone gateway engine can authenticate to upstream MCP
servers without knowing about Soma’s auth types (plan section 3.20).
Moved out of apps/soma (formerly gateway_auth.rs), where it was kept
as a temporary bridge for mergeability — this crate is its permanent home
per PR 11’s acceptance criterion that apps/soma constructs adapters but
contains none of their implementation logic.