Progress notifications from inside a running tool.

A client asks for progress by sending a progressToken in the request's _meta. On the modern (2026-07-28) era over Streamable HTTP, such a tools/call is answered as a Server-Sent Events stream, and report/3 sends a notifications/progress carrying that token ahead of the response:

tool "import" do
  handle fn conn, %{"rows" => rows} ->
    total = length(rows)

    rows
    |> Enum.with_index(1)
    |> Enum.each(fn {row, done} ->
      import_row(row)
      ConduitMcp.Progress.report(conn, done, total: total, message: "row #{done}")
    end)

    text("imported #{total} rows")
  end
end

report/3 is a no-op — it returns :ok and sends nothing — whenever there is no stream to send on: the request carried no progressToken, it is a legacy-era request (answered with a single JSON body), the client did not accept text/event-stream, or the call is running through ConduitMcp.Handler.handle_request/3. Tools can therefore call it unconditionally.

Pass the conn the tool received. Notifications are sent asynchronously and arrive before the tool's response.