Claude.ai never calls /register endpoint to dynamically register the client

[GoooGu]

This causes it that whenever getClient is called, we always returns null and hence we get this error

{"error":"invalid_client","error_description":"Invalid client_id"} when trying to connect to the custom integrations on claude.ai.

The MCP inspector, however, does not have this problem because it calls "/register" each time.

[fixparser]

Also running into the issue with claude.ai and {"error":"invalid_client","error_description":"Invalid client_id"}, but i'm using a completely different OAuth 2.1 implementation. I've tried: custom OAuth 2.1 server, using @modelcontextprotocol/sdk examples code with in memory oauth, and also using a complete auth server setup using Keycloak. NOTHING seems to work properly when adding a custom mcp server publicly. I do get the "Server connected successfully."-message on Claude.ai but the state is still disconnected so it doesn't complete the handshake somehow.