* feat(mcp): add ID-JAG egress auth as a v2 outbound-credentials arm
Adds the oauth2_id_jag MCP egress auth mode (draft-ietf-oauth-identity-assertion-authz-grant,
shipped by Okta as "AI agent token exchange") as a first-class arm of the v2
outbound_credentials resolver rather than a standalone v1 handler.
ID-JAG is a two-leg flow: an RFC 8693 token exchange swaps the caller's id_token for an
ID-JAG assertion at the IdP org authorization server, then an RFC 7523 jwt-bearer grant
presents that assertion to the MCP's resource authorization server for the access token
used to call the upstream. The gateway authenticates to both endpoints with a private-key
JWT client_assertion, falling back to client_secret when no key is configured.
The mode is modeled as IdJagConfig in the AuthConfig discriminated union, with client auth
as a ClientAuth tagged union (private_key_jwt or client_secret) so required fields are
enforced at construction and illegal states are unrepresentable. A new token_endpoint
collaborator performs the authenticated OAuth token-endpoint call and caches the result
with per-key single-flight; the resolver's _id_jag arm runs the two legs and returns an
httpx.Auth or a typed CredError. A missing caller identity token fails closed
(precondition_required), so an ID-JAG server never falls back to a static credential. The
v1->v2 adapter maps oauth2_id_jag servers onto IdJagConfig and the existing live v2 path
resolves them, so no standalone handler, has_id_jag_config flag, or resolve_mcp_auth
precedence branch is needed.
The ID-JAG client_private_key is encrypted at rest alongside client_secret.
* fix(mcp): sort token_endpoint imports to satisfy the I001 budget gate
* fix(mcp): give token_endpoint pyright suppressions reasons for the LIT004 budget
The freshly-merged base ratcheted the LIT004 ceiling down, so the six
unexplained pyright suppressions in token_endpoint.py went over budget.
Annotate each with why the boundary is untyped (litellm http handler and
InMemoryCache are untyped; response.json() is validated by
_TokenEndpointResponse in fetch) so the gate counts them as explained.
* fix(mcp): enforce ID-JAG exchange over caller auth overrides and redact token endpoint from client errors
For oauth2_id_jag servers the v2 resolver mints the upstream assertion from the caller's identity token; a caller-supplied x-mcp-auth / x-mcp-<alias>-authorization override or a conflicting injected Authorization must not disable that exchange and forward an arbitrary bearer, so IdJagConfig now joins authorization_code and token_exchange as a resolver-owned mode that keeps the v2 spec and ignores the override.
The token endpoint error branches previously returned the configured endpoint URL in the client-visible 503 detail. The endpoint now stays in server-side logs and clients get a generic token-exchange failure.
* fix(mcp): bind the ID-JAG token cache to the exchange config and map token endpoint network errors to typed CredErrors
* fix(mcp): fail closed when an oauth2_id_jag server is half-configured instead of deferring to v1 static credentials
* fix(mcp): evict the cached ID-JAG bearer on an upstream 401 so the retry re-exchanges
* fix(mcp): map an unsignable client assertion to a typed misconfigured error instead of an unhandled 500
* fix(mcp): redact credential fields from the server-registry debug dump
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