Fix MCP server lifecycle issue

In HTTP/SSE mode, a client disconnection triggered a partial agent shutdown
(project deactivation, dashboard manager & GUI viewer shutdown)

CHANGELOG.md

@@ -7,7 +7,8 @@ Status of the `main` branch. Changes prior to the next official version change w
     Instead, they can define `added_modes` to add modes on top of base and default modes.  
     See updated [documentation on modes](https://oraios.github.io/serena/02-usage/050_configuration.html#modes).
   - Serena's default configuration now uses `interactive` and `editing` as `base_modes` instead of as `default_modes`.
-  - Fixed path validation in `search_for_pattern` tool (thanks to [@dodge1218](https://github.com/dodge1218) for the report) 
+  - Fixed path validation in `search_for_pattern` tool (thanks to [@dodge1218](https://github.com/dodge1218) for the report)
+  - Fix: In HTTP/SSE mode, a client disconnection triggered a partial agent shutdown (project deactivation, dashboard manager & GUI viewer shutdown)
   
 * JetBrains:
   - Add new tools:

src/serena/cli.py

@@ -362,7 +362,7 @@ class TopLevelCommands(AutoRegisteringGroup):
         if default_modes or added_modes:
             mode_selection_def = ModeSelectionDefinitionWithAddedModes(default_modes=default_modes or None, added_modes=added_modes or None)
 
-        factory = SerenaMCPFactory(context=context, project=project_file, memory_log_handler=memory_log_handler)
+        factory = SerenaMCPFactory(transport=transport, context=context, project=project_file, memory_log_handler=memory_log_handler)
         server = factory.create_mcp_server(
             host=host,
             port=port,

src/serena/mcp.py

@@ -52,14 +52,22 @@ class SerenaMCPFactory:
     Factory for the creation of the Serena MCP server with an associated SerenaAgent.
     """
 
-    def __init__(self, context: str = DEFAULT_CONTEXT, project: str | None = None, memory_log_handler: MemoryLogHandler | None = None):
+    def __init__(
+        self,
+        transport: Literal["stdio", "sse", "streamable-http"],
+        context: str = DEFAULT_CONTEXT,
+        project: str | None = None,
+        memory_log_handler: MemoryLogHandler | None = None,
+    ):
         """
+        :param transport: The transport to use for the MCP server.
         :param context: The context name or path to context file
         :param project: Either an absolute path to the project directory or a name of an already registered project.
             If the project passed here hasn't been registered yet, it will be registered automatically and can be activated by its name
             afterward.
         :param memory_log_handler: the in-memory log handler to use for the agent's logging
         """
+        self.transport = transport
         self.context = SerenaAgentContext.load(context)
         self.project = project
         self.agent: SerenaAgent | None = None
@@ -342,16 +350,27 @@ class SerenaMCPFactory:
 
     @asynccontextmanager
     async def server_lifespan(self, mcp_server: FastMCP) -> AsyncIterator[None]:
-        """Manage server startup and shutdown lifecycle."""
+        """
+        Manages the lifespan of MCP server instances and performs necessary setup and teardown.
+        For stdio transport, there is a single server instance.
+        For other transports, this is called once per connection!
+
+        :param mcp_server: the MCP server instance to configure
+        """
         openai_tool_compatible = self.context.name in ["chatgpt", "codex", "oaicompat-agent"]
         self._set_mcp_tools(mcp_server, openai_tool_compatible=openai_tool_compatible)
         log.info("MCP server lifetime setup complete")
         try:
             yield
         finally:
-            log.info("MCP server shutting down")
-            if self.agent is not None:
-                self.agent.on_shutdown()
+            # Shut down the server if we are running in stdio mode.
+            # For other transports, we do nothing; the singleton agent instance remains active.
+            if self.transport == "stdio":
+                log.info("MCP server shutting down")
+                if self.agent is not None:
+                    self.agent.on_shutdown()
+            else:
+                log.info("Client disconnected")
 
     def _get_initial_instructions(self) -> str:
         assert self.agent is not None