make mcp.handleNotify public

[slimslenderslacks]

mcp: make handleNotify function public

When implementing an MCP proxy use case, the implementations of ResourceListChangedHandler, ToolListChangeHandler, or PromptListChangeHandler are simpler if these handlers can re-use this function from the mcp package. For example, to forward ToolListChangeRequests from a ClientSession to a ServerSession, a simple handler could be written like this:

    ToolListChangedHandler: func(ctx context.Context, req *mcp.ToolListChangedRequest) {
        _ = mcp.HandleNotify(ctx, "notifications/tools/list_changed", newServerRequest(serverSession, req.Params))
    }

Alternatively, since NotifyProgress, Log, Elicit, and ResourceUpdated are on the ServerSession or Session, should an analogous Notify be available on ServerSession?

[jba]

We've never thought about a case where an MCP client is a proxy to an MCP server. I suspect other things would have to be different as well. Also, handleNotify has a low-level API (it requires the name of the JSON-RPC method, for example). We can probably support this use case better.

Please open a proposal; I think we are some distance from accepting PRs on this topic.
I am going to gently close this. We can re-open it if we decide to go this way.