feat: add create_session and run_sse on reverse mcp app

veadk/toolkits/apps/reverse_mcp/client_with_reverse_mcp.py

@@ -23,14 +23,24 @@
 
 
 class ClientWithReverseMCP:
-    def __init__(self, ws_url: str, mcp_server_url: str, client_id: str):
+    def __init__(
+        self,
+        ws_url: str,
+        mcp_server_url: str,
+        client_id: str,
+        filters: list[str] | None = None,
+    ):
         """Start a client with reverse mcp,
 
         Args:
             ws_url: The url of the websocket server (cloud). Like example.com:8000
             mcp_server_url: The url of the mcp server (local).
+            client_id: The client id for the websocket connection.
+            filters: Optional list of tool names to filter (whitelist). If None, all tools are available.
         """
         self.ws_url = f"ws://{ws_url}/ws?id={client_id}"
+        if filters:
+            self.ws_url += f"&filters={','.join(filters)}"
         self.mcp_server_url = mcp_server_url
 
         # set timeout for httpx client

veadk/toolkits/apps/reverse_mcp/server_with_reverse_mcp.py

@@ -15,13 +15,20 @@
 import asyncio
 import json
 import uuid
-from typing import TYPE_CHECKING
-
-from fastapi import FastAPI, Request, Response, WebSocket
+from typing import TYPE_CHECKING, Any, Optional
+
+from fastapi import FastAPI, HTTPException, Request, Response, WebSocket
+from fastapi.responses import StreamingResponse
+from google.adk.agents.run_config import StreamingMode
+from google.adk.artifacts import InMemoryArtifactService
+from google.adk.cli.adk_web_server import RunAgentRequest
+from google.adk.runners import Runner as GoogleRunner, RunConfig
+from google.adk.sessions import InMemorySessionService, Session
 from google.adk.tools.mcp_tool.mcp_session_manager import (
     StreamableHTTPConnectionParams,
 )
 from google.adk.tools.mcp_tool.mcp_toolset import MCPToolset
+from google.adk.utils.context_utils import Aclosing
 from pydantic import BaseModel
 
 from veadk import Runner
@@ -93,11 +100,15 @@ def __init__(
         self.port = port
 
         self.app = FastAPI()
+
+        self.artifact_service = InMemoryArtifactService()
+
         # build routes for self.app
         self.build()
 
         self.ws_session_mgr = WebsocketSessionManager()
         self.ws_agent_mgr: dict[str, "Agent"] = {}
+        self.ws_session_service_mgr: dict[str, "InMemorySessionService"] = {}
 
     def build(self):
         logger.info("Build routes for server with reverse mcp")
@@ -126,19 +137,6 @@ async def invoke(payload: InvokeRequest) -> InvokeResponse:
 
             agent = self.ws_agent_mgr[payload.websocket_id]
 
-            if not agent.tools:
-                logger.debug("Mount fake MCPToolset to agent")
-
-                # we hard code the mcp url with `/mcp` to obey the mcp protocol
-                agent.tools.append(
-                    MCPToolset(
-                        connection_params=StreamableHTTPConnectionParams(
-                            url=f"http://127.0.0.1:{self.port}/mcp",
-                            headers={REVERSE_MCP_HEADER_KEY: payload.websocket_id},
-                        ),
-                    )
-                )
-
             runner = Runner(app_name=payload.app_name, agent=agent)
             response = await runner.run(
                 messages=[prompt],
@@ -152,18 +150,43 @@ async def invoke(payload: InvokeRequest) -> InvokeResponse:
         @self.app.websocket("/ws")
         async def ws_endpoint(ws: WebSocket):
             client_id = ws.query_params.get("id")
+
             if not client_id:
                 await ws.close(
                     code=400,
                     reason="WebSocket `id` is required like `/ws?id=my_id`",
                 )
                 return
 
+            # Parse filters from query params, comma-separated string
+            filters_str = ws.query_params.get("filters")
+            filters = None
+            if filters_str:
+                filters = [t.strip() for t in filters_str.split(",") if t.strip()]
+
             logger.info(f"Register websocket {client_id} to session manager.")
             self.ws_session_mgr.connections[client_id] = ws
 
             logger.info(f"Fork agent for websocket {client_id}")
-            self.ws_agent_mgr[client_id] = self.agent.clone()
+            agent = self.agent.clone()
+
+            # Mount MCPToolset when creating agent
+            mcp_toolset_url = f"http://127.0.0.1:{self.port}/mcp"
+            mcp_toolset_headers = {REVERSE_MCP_HEADER_KEY: client_id}
+            logger.debug(f"Mount MCPToolset to agent for websocket {client_id}")
+            agent.tools.append(
+                MCPToolset(
+                    connection_params=StreamableHTTPConnectionParams(
+                        url=mcp_toolset_url,
+                        headers=mcp_toolset_headers,
+                    ),
+                    tool_filter=filters,
+                )
+            )
+            self.ws_agent_mgr[client_id] = agent
+
+            logger.info(f"Create session service for websocket {client_id}")
+            self.ws_session_service_mgr[client_id] = InMemorySessionService()
 
             await ws.accept()
             logger.info(f"Websocket {client_id} connected")
@@ -172,8 +195,160 @@ async def ws_endpoint(ws: WebSocket):
                 raw = await ws.receive_text()
                 await self.ws_session_mgr.handle_ws_message(client_id, raw)
 
+        class CreateSessionRequest(BaseModel):
+            state: Optional[dict[str, Any]] = None
+            session_id: Optional[str] = None
+            websocket_id: str
+
+        class RunAgentRequestWithWsId(RunAgentRequest):
+            websocket_id: str
+
+        def _get_session_service(websocket_id: str) -> InMemorySessionService:
+            """Get session service for the websocket client."""
+            if websocket_id not in self.ws_session_service_mgr:
+                raise HTTPException(
+                    status_code=404, detail=f"WebSocket client {websocket_id} not found"
+                )
+            return self.ws_session_service_mgr[websocket_id]
+
+        @self.app.post(
+            "/apps/{app_name}/users/{user_id}/sessions",
+            response_model_exclude_none=True,
+        )
+        async def create_session(
+            app_name: str,
+            user_id: str,
+            req: CreateSessionRequest,
+        ) -> Session:
+            """Create a new session."""
+            session_id = req.session_id if req.session_id else str(uuid.uuid4())
+            session = Session(
+                app_name=app_name,
+                user_id=user_id,
+                id=session_id,
+                state=req.state if req.state else {},
+            )
+            session_service = _get_session_service(req.websocket_id)
+            await session_service.create_session(
+                app_name=app_name,
+                user_id=user_id,
+                session_id=session_id,
+                state=req.state if req.state else {},
+            )
+            logger.info(
+                f"Created session: {session_id} for user {user_id} in app {app_name}"
+            )
+            return session
+
+        @self.app.post(
+            "/apps/{app_name}/users/{user_id}/sessions/{session_id}",
+            response_model_exclude_none=True,
+        )
+        async def create_session_with_id(
+            app_name: str,
+            user_id: str,
+            session_id: str,
+            req: CreateSessionRequest,
+        ) -> Session:
+            """Create a session with specific ID."""
+            session_service = _get_session_service(req.websocket_id)
+            await session_service.create_session(
+                app_name=app_name,
+                user_id=user_id,
+                session_id=session_id,
+                state=req.state if req.state else {},
+            )
+            session = Session(
+                app_name=app_name,
+                user_id=user_id,
+                id=session_id,
+                state=req.state if req.state else {},
+            )
+            logger.info(f"Created session with ID: {session_id} for user {user_id}")
+            return session
+
+        @self.app.post("/run_sse")
+        async def run_agent_sse(req: RunAgentRequestWithWsId) -> StreamingResponse:
+            """Run agent with SSE streaming."""
+            session_service = _get_session_service(req.websocket_id)
+
+            # Get session
+            session = await session_service.get_session(
+                app_name=req.app_name,
+                user_id=req.user_id,
+                session_id=req.session_id,
+            )
+            if not session:
+                raise HTTPException(status_code=404, detail="Session not found")
+
+            # Get agent for this websocket
+            if req.websocket_id in self.ws_agent_mgr:
+                agent = self.ws_agent_mgr[req.websocket_id]
+                logger.debug(f"Using agent from websocket {req.websocket_id}")
+            else:
+                raise HTTPException(
+                    status_code=404,
+                    detail=f"WebSocket client {req.websocket_id} not found",
+                )
+
+            # Create runner
+            runner = GoogleRunner(
+                agent=agent,
+                app_name=req.app_name,
+                session_service=session_service,
+                artifact_service=self.artifact_service,
+            )
+
+            # Determine streaming mode from request
+            stream_mode = StreamingMode.SSE if req.streaming else StreamingMode.NONE
+
+            async def event_generator():
+                try:
+                    async with Aclosing(
+                        runner.run_async(
+                            user_id=req.user_id,
+                            session_id=req.session_id,
+                            new_message=req.new_message,
+                            state_delta=req.state_delta,
+                            run_config=RunConfig(streaming_mode=stream_mode),
+                            invocation_id=req.invocation_id,
+                        )
+                    ) as agen:
+                        async for event in agen:
+                            # ADK Web renders artifacts from `actions.artifactDelta`
+                            # during part processing *and* during action processing
+                            # 1) the original event with `artifactDelta` cleared (content)
+                            # 2) a content-less "action-only" event carrying `artifactDelta`
+                            events_to_stream = [event]
+                            if (
+                                event.actions.artifact_delta
+                                and event.content
+                                and event.content.parts
+                            ):
+                                content_event = event.model_copy(deep=True)
+                                content_event.actions.artifact_delta = {}
+                                artifact_event = event.model_copy(deep=True)
+                                artifact_event.content = None
+                                events_to_stream = [content_event, artifact_event]
+
+                            for event_to_stream in events_to_stream:
+                                sse_event = event_to_stream.model_dump_json(
+                                    exclude_none=True, by_alias=True
+                                )
+                                logger.debug(f"SSE event: {sse_event}")
+                                yield f"data: {sse_event}\n\n"
+                except Exception as e:
+                    logger.exception(f"Error in event_generator: {e}")
+                    yield f"data: {json.dumps({'error': str(e)})}\n\n"
+
+            return StreamingResponse(
+                event_generator(),
+                media_type="text/event-stream",
+            )
+
         # build the fake MPC server,
         # and intercept all requests to the client websocket client.
+        # NOTE: This catch-all route must be defined LAST
         @self.app.api_route("/{path:path}", methods=["GET", "POST"])
         async def mcp_proxy(path: str, request: Request):
             client_id = request.headers.get(REVERSE_MCP_HEADER_KEY)
@@ -202,10 +377,27 @@ async def mcp_proxy(path: str, request: Request):
 
             logger.debug(f"[Reverse mcp proxy] Response from local: {resp}")
 
+            # Filter hop-by-hop headers to avoid Content-Length mismatch
+            headers = resp["payload"]["headers"]
+            hop_by_hop_headers = {
+                "content-length",
+                "transfer-encoding",
+                "connection",
+                "keep-alive",
+                "proxy-authenticate",
+                "proxy-authorization",
+                "te",
+                "trailers",
+                "upgrade",
+            }
+            filtered_headers = {
+                k: v for k, v in headers.items() if k.lower() not in hop_by_hop_headers
+            }
+
             return Response(
                 content=resp["payload"]["body"],  # type: ignore
                 status_code=resp["payload"]["status"],  # type: ignore
-                headers=resp["payload"]["headers"],  # type: ignore
+                headers=filtered_headers,  # type: ignore
             )
 
     def run(self):