Add OAuth 2.1 compliant authorization to the ValTown MCP server following official MCP authorization specifications. The current system has basic token-based auth via headers, but needs to be upgraded to full OAuth 2.1 compliance with metadata endpoints, dynamic client registration, and PKCE flow support.

• Cross-system OAuth Integration: Requires implementing OAuth 2.1 server capabilities or integrating with external OAuth provider
• Multiple New Endpoints: Need /.well-known/oauth-authorization-server, /.well-known/oauth-protected-resource, dynamic client registration endpoint
• Security Protocol Implementation: PKCE flow, token validation, audience validation, secure token exchange
• Architecture Changes: Current simple header-based auth needs to be replaced with full OAuth flow
• Third-party Integration Complexity: ValTown doesn't have OAuth server, so need to bridge API token system with OAuth specs

• Backend Changes: Major - Multiple new endpoints, OAuth flow implementation, metadata generation
• Frontend Changes: None - This is pure backend OAuth server functionality
• Data Model Changes: Yes - Client registration storage, token management, session handling
• API Changes: New - Multiple new OAuth endpoints (.well-known, /oauth/authorize, /oauth/token, etc.)
• Breaking Changes: No - Can maintain backward compatibility with current header-based auth

Execute: /complex-pipeline oauth-authorization

• Comprehensive planning with OAuth 2.1 specification review
• Phased implementation:
  1. OAuth metadata endpoints
  2. Dynamic client registration
  3. PKCE authorization flow
  4. Token validation and audience checks
  5. Integration with existing ValTown API token system
• Multiple validation gates for OAuth compliance testing

• Technical Risk: High - OAuth 2.1 compliance is complex, security-critical
• Business Risk: Medium - Authorization changes could break existing integrations
• Rollback Complexity: Moderate - Can maintain dual auth methods during transition

1. ValTown API Token Bridge: Need to map ValTown's simple API tokens to OAuth token format
2. OAuth Server Implementation: Either implement minimal OAuth server or use library
3. PKCE Flow: Implement secure code challenge/verifier mechanism
4. Metadata Generation: Dynamic generation of OAuth server and protected resource metadata
5. Client Registration: Storage and management of dynamically registered clients

1. Review this assessment
2. Approve the complexity score
3. Execute /complex-pipeline oauth-authorization
4. Backend OAuth implementation MUST be completed and validated before any client-side integration testing