fix: strip trailing slash from issuer URL in OAuth metadata serialization #2019
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…tion Fixes modelcontextprotocol#1919 RFC 8414 examples show issuer URLs without trailing slashes (e.g., `https://example.com` rather than `https://example.com/`). Some OAuth clients (Google ADK, IBM MCP Context Forge) require exact match between the discovery URL and the returned issuer per RFC 8414 Section 3.3. Pydantic's AnyHttpUrl automatically adds a trailing slash when serializing URLs without a path component. This breaks clients that perform exact URL matching during the OAuth discovery flow. This fix adds field_serializer decorators to: - OAuthMetadata.issuer - ProtectedResourceMetadata.resource - ProtectedResourceMetadata.authorization_servers These serializers strip the trailing slash only during JSON serialization, preserving the internal AnyHttpUrl type while ensuring spec-compliant output. Co-Authored-By: Claude Opus 4.5 <[email protected]>
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Summary
Fixes #1919
This PR fixes the OAuth trailing slash issue where Pydantic's
AnyHttpUrlautomatically adds a trailing slash to URLs without path components, breaking OAuth discovery for clients like Google ADK and IBM MCP Context Forge that require exact URL matching per RFC 8414 Section 3.3.Changes
@field_serializer("issuer")toOAuthMetadatato strip trailing slashes during JSON serialization@field_serializer("resource")toProtectedResourceMetadatafor the same reason@field_serializer("authorization_servers")to strip trailing slashes from all auth server URLsTechnical Details
https://example.com/authstays as-is)https://example.com/→https://example.com)Test plan
tests/shared/test_auth.pyforOAuthMetadata.issuerserializationProtectedResourceMetadata.resourceandauthorization_serverstests/server/auth/test_protected_resource.py🤖 Generated with Claude Code