bug: Streamable HTTP Sampling doesnt work

[Scutc]

Description

Newly merged feature of sampling for StreamableHttp doesn't work. Examples from sampling_http_server and sampling_http_client are now working. Client send request, but on step of waiting client response process stuck until timeout exceed.

select { case response := <-responseChan: if response.err != nil { return nil, response.err } return response.result, nil case <-ctx.Done(): return nil, ctx.Err() }

Server SSE sampling event doesn't catched and proceed by client.

[andig]

Seems e2e test is working with InProcess client

[andig]

@Scutc could you please try PR?

[Scutc]

@andig same behavior. On step of sending sending sample request server hangs and failed by ctx deadline, but client doesn't get sampling SSE event in its handler.

[andig]

Unfortunately no idea. I'm not an expert on streamable HTTP, hence tried to create an e2e Test in https://github.com/mark3labs/mcp-go/pull/531/files#diff-f4a154ef0240959d903c5f3e9c0591c2734a3a3117a3d84943d909fcf4e3caba that validates the full communication (and seems to pass). Could you check if there's anything in that test that you're doing differently? I would specifically suggest to check around here: https://github.com/mark3labs/mcp-go/pull/531/files#diff-f4a154ef0240959d903c5f3e9c0591c2734a3a3117a3d84943d909fcf4e3cabaR178-R184.

[Scutc]

@andig Great, e2e was really helpful. The problem of sampling_http_client is that transport created without option transport.WithContinuousListening()

And also it make sense to correct url from http://localhost:8080 to http://localhost:8080/mcp , otherwise connection failed

[dgreene-r7]

On top of this issue it doesn't seem as though there's a way to actually disable sampling which leads to some interesting issues with stateless servers that are horizontally scaled.

[dakolli]

Can we please merge #531 or did the maintainer die?