route progress notifications to the POST SSE Handler for MCP Servers (#12035)

* route progress notifications to the POST SSE Handler for MCP Servers

* add changeset

* lint

---------

Co-authored-by: gradio-pr-bot <gradio-pr-bot@users.noreply.github.com>
Co-authored-by: Freddy Boulton <41651716+freddyaboulton@users.noreply.github.com>

Author: 3 people

.changeset/spotty-buckets-tickle.md

@@ -0,0 +1,5 @@
+---
+"gradio": patch
+---
+
+fix:route progress notifications to the POST SSE Handler for MCP Servers

gradio/mcp.py

@@ -331,6 +331,9 @@ async def call_tool(
                         progress_token=progress_token,
                         progress=step,
                         message=message,  # type: ignore
+                        related_request_id=str(
+                            self.mcp_server.request_context.request_id
+                        ),
                     )
                     step += 1
                 elif update.type == "output" and update.final: