♻️ refactor: On-demand MCP connections: remove proactive reconnect, default to available (#11839)

* feat: Implement reconnection staggering and backoff jitter for MCP connections

- Enhanced the reconnection logic in OAuthReconnectionManager to stagger reconnection attempts for multiple servers, reducing the risk of connection storms.
- Introduced a backoff delay with random jitter in MCPConnection to improve reconnection behavior during network issues.
- Updated the ConnectionsRepository to handle multiple server connections concurrently with a defined concurrency limit.

Added tests to ensure the new reconnection strategy works as intended.

* refactor: Update MCP server query configuration for improved data freshness

- Reduced stale time from 5 minutes to 30 seconds to ensure quicker updates on server initialization.
- Enabled refetching on window focus and mount to enhance data accuracy during user interactions.

* ♻️  refactor: On-demand MCP connections; remove proactive reconnection, default to available

  - Remove reconnectServers() from refresh controller (connection storm root cause)
  - Stop gating server selection on connection status; add to selection immediately
  - Render agent panel tools from DB cache, not live connection status
  - Proceed to cached tools on init failure (only gate on OAuth)
  - Remove unused batchToggleServers()
  - Reduce useMCPServersQuery staleTime from 5min to 30s, enable refetchOnMount/WindowFocus

* refactor: Optimize MCP tool initialization and server connection logic

- Adjusted tool initialization to only occur if no cached tools are available, improving efficiency.
- Updated comments for clarity on server connection and tool fetching processes.
- Removed unnecessary connection status checks during server selection to streamline the user experience.

client/src/components/SidePanel/Agents/MCPTools.tsx

@@ -46,7 +46,7 @@ export default function MCPTools({
               return null;
             }
 
-            if (serverInfo.isConnected) {
+            if (serverInfo?.tools?.length && serverInfo.tools.length > 0) {
               return (
                 <MCPTool key={`${serverInfo.serverName}-${agentId}`} serverInfo={serverInfo} />
               );

client/src/components/Tools/MCPToolSelectDialog.tsx

@@ -96,17 +96,17 @@ function MCPToolSelectDialog({
         await new Promise((resolve) => setTimeout(resolve, 500));
       }
 
-      // Then initialize server if needed
+      // Only initialize if no cached tools exist; skip if tools are already available from DB
       const serverInfo = mcpServersMap.get(serverName);
-      if (!serverInfo?.isConnected) {
+      if (!serverInfo?.tools?.length) {
         const result = await initializeServer(serverName);
-        if (result?.success && result.oauthRequired && result.oauthUrl) {
+        if (result?.oauthRequired && result.oauthUrl) {
           setIsInitializing(null);
-          return;
+          return; // OAuth flow must complete first
         }
       }
 
-      // Finally, add tools to form
+      // Add tools to form (refetches from backend's persisted cache)
       await addToolsToForm(serverName);
       setIsInitializing(null);
     } catch (error) {

client/src/data-provider/MCP/queries.ts

@@ -12,10 +12,10 @@ export const useMCPServersQuery = <TData = t.MCPServersListResponse>(
     [QueryKeys.mcpServers],
     () => dataService.getMCPServers(),
     {
-      staleTime: 1000 * 60 * 5, // 5 minutes - data stays fresh longer
-      refetchOnWindowFocus: false,
+      staleTime: 30 * 1000, // 30 seconds — short enough to pick up servers that finish initializing after first load
+      refetchOnWindowFocus: true,
       refetchOnReconnect: false,
-      refetchOnMount: false,
+      refetchOnMount: true,
       retry: false,
       ...config,
     },

client/src/hooks/MCP/useMCPServerManager.ts

@@ -433,33 +433,6 @@ export function useMCPServerManager({
     [startupConfig?.interface?.mcpServers?.placeholder, localize],
   );
 
-  const batchToggleServers = useCallback(
-    (serverNames: string[]) => {
-      const connectedServers: string[] = [];
-      const disconnectedServers: string[] = [];
-
-      serverNames.forEach((serverName) => {
-        if (isInitializing(serverName)) {
-          return;
-        }
-
-        const serverStatus = connectionStatus?.[serverName];
-        if (serverStatus?.connectionState === 'connected') {
-          connectedServers.push(serverName);
-        } else {
-          disconnectedServers.push(serverName);
-        }
-      });
-
-      setMCPValues(connectedServers);
-
-      disconnectedServers.forEach((serverName) => {
-        initializeServer(serverName);
-      });
-    },
-    [connectionStatus, setMCPValues, initializeServer, isInitializing],
-  );
-
   const toggleServerSelection = useCallback(
     (serverName: string) => {
       if (isInitializing(serverName)) {
@@ -473,15 +446,10 @@ export function useMCPServerManager({
         const filteredValues = currentValues.filter((name) => name !== serverName);
         setMCPValues(filteredValues);
       } else {
-        const serverStatus = connectionStatus?.[serverName];
-        if (serverStatus?.connectionState === 'connected') {
-          setMCPValues([...currentValues, serverName]);
-        } else {
-          initializeServer(serverName);
-        }
+        setMCPValues([...currentValues, serverName]);
       }
     },
-    [mcpValues, setMCPValues, connectionStatus, initializeServer, isInitializing],
+    [mcpValues, setMCPValues, isInitializing],
   );
 
   const handleConfigSave = useCallback(
@@ -677,7 +645,6 @@ export function useMCPServerManager({
     isPinned,
     setIsPinned,
     placeholderText,
-    batchToggleServers,
     toggleServerSelection,
     localize,