feat: add MCP server start/stop controls

Add ability to start and stop Claude Code as an MCP server from the GUI.

Backend changes:
- Add mcp_serve() command to spawn 'claude mcp serve' process
- Add mcp_stop() command to terminate running MCP serve process
- Add ProcessType::McpServe to process registry with singleton pattern
- Add register_mcp_serve_process() and get_running_mcp_serve() methods
- Update mcp_get_server_status() to check registry for running process

Frontend changes:
- Add Start/Stop MCP Server buttons to MCPImportExport component
- Add status polling (2s interval) to show running state
- Wire onSuccess callback in MCPManager for status refresh
- Fix duplicate toast notification bug

The MCP server allows external tools to communicate with Claude Code
via the Model Context Protocol over stdio transport.

Author: fardeenxyz

src-tauri/src/commands/mcp.rs

@@ -1,4 +1,5 @@
 use anyhow::{Context, Result};
+use chrono::Utc;
 use dirs;
 use log::{error, info};
 use serde::{Deserialize, Serialize};
@@ -612,7 +613,10 @@ pub async fn mcp_add_from_claude_desktop(
 
 /// Starts Claude Code as an MCP server
 #[tauri::command]
-pub async fn mcp_serve(app: AppHandle) -> Result<String, String> {
+pub async fn mcp_serve(
+    app: AppHandle,
+    registry: tauri::State<'_, crate::process::ProcessRegistryState>,
+) -> Result<String, String> {
     info!("Starting Claude Code as MCP server");
 
     // Start the server in a separate process
@@ -624,13 +628,32 @@ pub async fn mcp_serve(app: AppHandle) -> Result<String, String> {
         }
     };
 
+    // If already running, don't start another one
+    if let Ok(Some(existing)) = registry.0.get_running_mcp_serve() {
+        return Ok(format!(
+            "Claude Code MCP server already running (PID: {})",
+            existing.pid
+        ));
+    }
+
     let mut cmd = create_command_with_env(&claude_path);
     cmd.arg("mcp").arg("serve");
 
     match cmd.spawn() {
-        Ok(_) => {
-            info!("Successfully started Claude Code MCP server");
-            Ok("Claude Code MCP server started".to_string())
+        Ok(child) => {
+            let pid = child.id();
+            if pid == 0 {
+                error!("MCP server started but PID is unavailable");
+                return Err("MCP server started but PID is unavailable".to_string());
+            }
+
+            if let Err(e) = registry.0.register_mcp_serve_process(pid) {
+                error!("Failed to register MCP server process: {}", e);
+                return Err(e);
+            }
+
+            info!("Successfully started Claude Code MCP server (PID: {})", pid);
+            Ok(format!("Claude Code MCP server started (PID: {})", pid))
         }
         Err(e) => {
             error!("Failed to start MCP server: {}", e);
@@ -639,6 +662,25 @@ pub async fn mcp_serve(app: AppHandle) -> Result<String, String> {
     }
 }
 
+/// Stops Claude Code MCP server if running
+#[tauri::command]
+pub async fn mcp_stop(
+    registry: tauri::State<'_, crate::process::ProcessRegistryState>,
+) -> Result<String, String> {
+    if let Ok(Some(proc_info)) = registry.0.get_running_mcp_serve() {
+        let run_id = proc_info.run_id;
+        let pid = proc_info.pid;
+        registry
+            .0
+            .kill_process(run_id)
+            .await
+            .map_err(|e| format!("Failed to stop MCP server (PID: {}): {}", pid, e))?;
+        Ok(format!("Claude Code MCP server stopped (PID: {})", pid))
+    } else {
+        Ok("Claude Code MCP server is not running".to_string())
+    }
+}
+
 /// Tests connection to an MCP server
 #[tauri::command]
 pub async fn mcp_test_connection(app: AppHandle, name: String) -> Result<String, String> {
@@ -670,12 +712,28 @@ pub async fn mcp_reset_project_choices(app: AppHandle) -> Result<String, String>
 
 /// Gets the status of MCP servers
 #[tauri::command]
-pub async fn mcp_get_server_status() -> Result<HashMap<String, ServerStatus>, String> {
+pub async fn mcp_get_server_status(
+    registry: tauri::State<'_, crate::process::ProcessRegistryState>,
+) -> Result<HashMap<String, ServerStatus>, String> {
     info!("Getting MCP server status");
 
-    // TODO: Implement actual status checking
-    // For now, return empty status
-    Ok(HashMap::new())
+    let mut status_map = HashMap::new();
+
+    if let Ok(Some(proc_info)) = registry.0.get_running_mcp_serve() {
+        status_map.insert(
+            "claude-code".to_string(),
+            ServerStatus {
+                running: true,
+                error: None,
+                last_checked: Some(Utc::now().timestamp() as u64),
+            },
+        );
+
+        // Also include PID in the log for debugging
+        info!("MCP serve running with PID: {}", proc_info.pid);
+    }
+
+    Ok(status_map)
 }
 
 /// Reads .mcp.json from the current project

src-tauri/src/main.rs

@@ -33,7 +33,7 @@ use commands::claude::{
 use commands::mcp::{
     mcp_add, mcp_add_from_claude_desktop, mcp_add_json, mcp_get, mcp_get_server_status, mcp_list,
     mcp_read_project_config, mcp_remove, mcp_reset_project_choices, mcp_save_project_config,
-    mcp_serve, mcp_test_connection,
+    mcp_serve, mcp_stop, mcp_test_connection,
 };
 
 use commands::proxy::{apply_proxy_settings, get_proxy_settings, save_proxy_settings};
@@ -268,6 +268,7 @@ fn main() {
             mcp_add_json,
             mcp_add_from_claude_desktop,
             mcp_serve,
+            mcp_stop,
             mcp_test_connection,
             mcp_reset_project_choices,
             mcp_get_server_status,

src-tauri/src/process/registry.rs

@@ -9,6 +9,7 @@ use tokio::process::Child;
 pub enum ProcessType {
     AgentRun { agent_id: i64, agent_name: String },
     ClaudeSession { session_id: String },
+    McpServe,
 }
 
 /// Information about a running agent process
@@ -82,6 +83,7 @@ impl ProcessRegistry {
     }
 
     /// Register a new running agent process using sidecar (similar to register_process but for sidecar children)
+    #[allow(dead_code)]
     pub fn register_sidecar_process(
         &self,
         run_id: i64,
@@ -152,6 +154,46 @@ impl ProcessRegistry {
         Ok(run_id)
     }
 
+    /// Register a long-running MCP serve process (stores PID only, no child handle)
+    ///
+    /// NOTE: Only ONE MCP serve process should run at a time (singleton pattern).
+    /// The caller (mcp_serve command) is responsible for checking if a process
+    /// already exists via get_running_mcp_serve() before calling this method.
+    pub fn register_mcp_serve_process(&self, pid: u32) -> Result<i64, String> {
+        let run_id = self.generate_id()?;
+
+        let process_info = ProcessInfo {
+            run_id,
+            process_type: ProcessType::McpServe,
+            pid,
+            started_at: Utc::now(),
+            project_path: "".to_string(),
+            task: "claude mcp serve".to_string(),
+            model: "".to_string(),
+        };
+
+        // Register without child handle (like sidecar)
+        let mut processes = self.processes.lock().map_err(|e| e.to_string())?;
+
+        let process_handle = ProcessHandle {
+            info: process_info,
+            child: Arc::new(Mutex::new(None)),
+            live_output: Arc::new(Mutex::new(String::new())),
+        };
+
+        processes.insert(run_id, process_handle);
+        Ok(run_id)
+    }
+
+    /// Get the currently running MCP serve process if any
+    pub fn get_running_mcp_serve(&self) -> Result<Option<ProcessInfo>, String> {
+        let processes = self.processes.lock().map_err(|e| e.to_string())?;
+        Ok(processes
+            .values()
+            .find(|handle| matches!(handle.info.process_type, ProcessType::McpServe))
+            .map(|handle| handle.info.clone()))
+    }
+
     /// Internal method to register any process
     fn register_process_internal(
         &self,

src/components/MCPImportExport.tsx

@@ -1,4 +1,4 @@
-import React, { useState } from "react";
+import React, { useEffect, useState } from "react";
 import { Download, Upload, FileText, Loader2, Info, Network, Settings2 } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { Card } from "@/components/ui/card";
@@ -15,6 +15,10 @@ interface MCPImportExportProps {
    * Callback for error messages
    */
   onError: (message: string) => void;
+  /**
+   * Callback for success/info messages
+   */
+  onSuccess: (message: string) => void;
 }
 
 /**
@@ -23,11 +27,31 @@ interface MCPImportExportProps {
 export const MCPImportExport: React.FC<MCPImportExportProps> = ({
   onImportCompleted,
   onError,
+  onSuccess,
 }) => {
   const [importingDesktop, setImportingDesktop] = useState(false);
   const [importingJson, setImportingJson] = useState(false);
   const [importScope, setImportScope] = useState("local");
 
+  const [mcpServeRunning, setMcpServeRunning] = useState(false);
+  const [mcpServeChecking, setMcpServeChecking] = useState(false);
+
+  const refreshMcpServeStatus = async () => {
+    try {
+      const statuses = await api.mcpGetServerStatus();
+      setMcpServeRunning(Boolean(statuses["claude-code"]?.running));
+    } catch {
+      // If status fails, don't block UX; just assume stopped
+      setMcpServeRunning(false);
+    }
+  };
+
+  useEffect(() => {
+    refreshMcpServeStatus();
+    const handle = window.setInterval(refreshMcpServeStatus, 2000);
+    return () => window.clearInterval(handle);
+  }, []);
+
   /**
    * Imports servers from Claude Desktop
    */
@@ -39,23 +63,18 @@ export const MCPImportExport: React.FC<MCPImportExportProps> = ({
 
       // Show detailed results if available
       if (result.servers && result.servers.length > 0) {
-        const successfulServers = result.servers.filter(s => s.success);
         const failedServers = result.servers.filter(s => !s.success);
 
-        if (successfulServers.length > 0) {
-          const successMessage = `Successfully imported: ${successfulServers.map(s => s.name).join(", ")}`;
-          onImportCompleted(result.imported_count, result.failed_count);
-          // Show success details
-          if (failedServers.length === 0) {
-            onError(successMessage);
-          }
-        }
+        // Always call onImportCompleted for server list refresh and count-based toast
+        onImportCompleted(result.imported_count, result.failed_count);
 
+        // Only show detailed error messages for failed servers (onImportCompleted already shows success)
         if (failedServers.length > 0) {
           const failureDetails = failedServers
             .map(s => `${s.name}: ${s.error || "Unknown error"}`)
             .join("\n");
-          onError(`Failed to import some servers:\n${failureDetails}`);
+          console.warn("Failed to import some servers:", failureDetails);
+          // Don't call onError here - onImportCompleted already handles the toast
         }
       } else {
         onImportCompleted(result.imported_count, result.failed_count);
@@ -152,11 +171,29 @@ export const MCPImportExport: React.FC<MCPImportExportProps> = ({
    */
   const handleStartMCPServer = async () => {
     try {
-      await api.mcpServe();
-      onError("Claude Code MCP server started. You can now connect to it from other applications.");
+      setMcpServeChecking(true);
+      const message = await api.mcpServe();
+      await refreshMcpServeStatus();
+      onSuccess(message);
     } catch (error) {
       console.error("Failed to start MCP server:", error);
       onError("Failed to start Claude Code as MCP server");
+    } finally {
+      setMcpServeChecking(false);
+    }
+  };
+
+  const handleStopMCPServer = async () => {
+    try {
+      setMcpServeChecking(true);
+      const message = await api.mcpStop();
+      await refreshMcpServeStatus();
+      onSuccess(message);
+    } catch (error) {
+      console.error("Failed to stop MCP server:", error);
+      onError("Failed to stop Claude Code MCP server");
+    } finally {
+      setMcpServeChecking(false);
     }
   };
 
@@ -305,20 +342,39 @@ export const MCPImportExport: React.FC<MCPImportExportProps> = ({
                 <Network className="h-5 w-5 text-green-500" />
               </div>
               <div className="flex-1">
-                <h4 className="text-sm font-medium">Use Claude Code as MCP Server</h4>
+                <div className="flex items-center justify-between gap-3">
+                  <h4 className="text-sm font-medium">Use Claude Code as MCP Server</h4>
+                  <div className="text-xs text-muted-foreground">
+                    {mcpServeChecking ? "Checking…" : mcpServeRunning ? "Running" : "Stopped"}
+                  </div>
+                </div>
                 <p className="text-xs text-muted-foreground mt-1">
                   Start Claude Code as an MCP server that other applications can connect to
                 </p>
               </div>
             </div>
-            <Button
-              onClick={handleStartMCPServer}
-              variant="outline"
-              className="w-full gap-2 border-green-500/20 hover:bg-green-500/10 hover:text-green-600 hover:border-green-500/50"
-            >
-              <Network className="h-4 w-4" />
-              Start MCP Server
-            </Button>
+
+            {mcpServeRunning ? (
+              <Button
+                onClick={handleStopMCPServer}
+                variant="outline"
+                className="w-full gap-2 border-red-500/20 hover:bg-red-500/10 hover:text-red-600 hover:border-red-500/50"
+                disabled={mcpServeChecking}
+              >
+                <Network className="h-4 w-4" />
+                Stop MCP Server
+              </Button>
+            ) : (
+              <Button
+                onClick={handleStartMCPServer}
+                variant="outline"
+                className="w-full gap-2 border-green-500/20 hover:bg-green-500/10 hover:text-green-600 hover:border-green-500/50"
+                disabled={mcpServeChecking}
+              >
+                <Network className="h-4 w-4" />
+                Start MCP Server
+              </Button>
+            )}
           </div>
         </Card>
       </div>

src/components/MCPManager.tsx

@@ -169,9 +169,10 @@ export const MCPManager: React.FC<MCPManagerProps> = ({
               {/* Import/Export Tab */}
               <TabsContent value="import" className="space-y-6 mt-6">
                 <Card className="overflow-hidden">
-                  <MCPImportExport
+                    <MCPImportExport
                     onImportCompleted={handleImportCompleted}
                     onError={(message: string) => setToast({ message, type: "error" })}
+                    onSuccess={(message: string) => setToast({ message, type: "success" })}
                   />
                 </Card>
               </TabsContent>

src/lib/api.ts

@@ -1496,6 +1496,18 @@ export const api = {
     }
   },
 
+  /**
+   * Stops Claude Code MCP server
+   */
+  async mcpStop(): Promise<string> {
+    try {
+      return await apiCall<string>("mcp_stop");
+    } catch (error) {
+      console.error("Failed to stop MCP server:", error);
+      throw error;
+    }
+  },
+
   /**
    * Tests connection to an MCP server
    */