Changelog

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All notable changes to this project are documented here. The format is based on Keep a Changelog and this project adheres to Semantic Versioning.

[Unreleased]

[0.6.0] - 2026-06-14

Added

  • Origin pinning for protected-resource metadata behind a proxy. A host can now pin the advertised resource/challenge origin and authorization_servers instead of always deriving them from the live request connection, which behind a TLS-terminating proxy is both fragile (http/internal host) and an X-Forwarded-Host spoofing vector into the metadata document a client trusts to find its authorization server.
    • AttestoMCP.Metadata.resolve_origin/2 resolves the resource server origin: an explicit :base_url/:origin (a String.t() or (conn -> url)) wins over the request connection. It drives the resource identifier and the protected_resource_url/3 challenge URL.
    • AttestoMCP.Metadata.protected_resource/3 now defaults authorization_servers to the :config issuer (or an explicit :issuer string) when one is given, rather than the resource origin — the issuer is the authorization server the host already trusts. The resource identifier is not derived from the issuer (RFC 9728 keeps the two distinct).
    • The router macro attesto_mcp_protected_resource_metadata, AttestoMCP.MetadataController, AttestoMCP.Plug.Authenticate, and AttestoMCP.Plug.ProtectResource all accept and thread :base_url/:origin (and :issuer/:config), so the served metadata and the WWW-Authenticate resource_metadata challenge stay aligned when pinned. :base_url/:origin accept a string, a (conn -> url) callback, or a {module, fun} / {module, fun, args} tuple (so a dynamic origin works in a compiled router macro, where an anonymous fn cannot).
    • The generated resource_metadata challenge is now emitted consistently on every rejection the MCP plugs render - token failure, principal-callback rejection (a 401 from AttestoMCP.Plug.Authenticate), and insufficient-scope rejection (a 403 from AttestoMCP.Plug.RequireScopes via ProtectResource)
      • so a client is pointed at metadata on all of them, not just token failures.
    • New guides/proxy_origin.md documents the pinned-origin recipe so consumers do not reinvent a canonical-host guard plug.

Fixed

  • authorization_servers advertises the issuer verbatim: it is no longer trailing-slash-trimmed, since an issuer identifier is compared by exact string match (a trimmed path-based issuer would break discovery). The resource origin is still trimmed (it is joined with a path). A blank explicit :issuer is ignored rather than publishing [""] or overriding a configured issuer.
  • A blank, relative, or non-binary :base_url/:origin pin ("", "/", "/prefix", "mcp.example.com", …) is treated as "not configured" and falls back (:base_url → :origin → request origin) instead of producing relative or empty security metadata (no more resource: "/mcp" or authorization_servers: [""]). A pin must be an absolute scheme://… origin.
  • An explicit :resource / :authorization_servers now short-circuits the derivation, so a lower-precedence origin/issuer callback is never invoked (and cannot fail) for a value the host supplied outright. The resource origin is also resolved at most once per document and shared with the authorization_servers fallback, so a stateful origin callback cannot make the resource and authorization_servers disagree.

Changed

  • AttestoMCP.Metadata.protected_resource/3 now sets resource with put_new (was put), so an explicit :resource opt overrides the derived identifier — matching how :authorization_servers already behaved.
  • With no pinning options supplied, behavior is unchanged: both origins derive from the request connection.

[0.5.2] - 2026-05-31

Fixed

  • Correct the README installation snippet now that the package is published on Hex.

[0.5.1] - 2026-05-31

Changed

  • Reuse Attesto.Test.DPoP for MCP DPoP proof fixtures so downstream MCP tests stay aligned with Attesto's published DPoP helper API.

[0.5.0] - 2026-05-31

Added

  • AttestoMCP.Plug.ProtectResource: a single plug composing AttestoMCP.Plug.Authenticate then AttestoMCP.Plug.RequireScopes into a correctly ordered, halt-respecting pipeline, with the RFC 9728 resource_metadata WWW-Authenticate challenge auto-wired from the resource path.
  • AttestoMCP.Router with the attesto_mcp_protected_resource_metadata/2 Phoenix router macro, and AttestoMCP.MetadataController, serving per-resource /.well-known/oauth-protected-resource/<path> metadata plus a backwards-compatible root /.well-known/oauth-protected-resource route. The served resource identifier matches the ProtectResource challenge.
  • AttestoMCP.Test.DPoPAssertions: shipped ExUnit assertions for host apps proving a DPoP-bound token presented as a plain Bearer is rejected and is accepted with a valid DPoP proof.
  • guides/mcp_wiring.md: copy-pasteable end-to-end wiring guide.
  • phoenix as an optional dependency (only needed by AttestoMCP.Router and AttestoMCP.MetadataController).
  • Initial Plug/Phoenix authentication wrapper for protecting HTTP MCP endpoints with Attesto access-token verification, DPoP proof checks, and mTLS certificate-bound token checks.
  • MCP scope convention helpers.
  • OAuth protected-resource metadata builder and authorization-server metadata delegation.
  • Focused tests for Bearer, DPoP, mTLS, scope enforcement, principal mapping, custom error rendering, and public assign names.