chore: adds vscode specific connection error handler

Author: himanshusinghs

src/mcp/mcpConnectionErrorHandler.ts

@@ -0,0 +1,71 @@
+import {
+  ErrorCodes,
+  type ConnectionErrorHandler,
+} from '@himanshusinghs/mongodb-mcp-server';
+import type ConnectionController from '../connectionController';
+
+export const createMCPConnectionErrorHandler = (
+  connectionController: Pick<
+    ConnectionController,
+    'getSavedConnections' | 'getActiveConnectionName'
+  >,
+): ConnectionErrorHandler => {
+  return (error) => {
+    const activeConnectionName = connectionController.getActiveConnectionName();
+    const availableConnections = connectionController
+      .getSavedConnections()
+      .map(({ name }) => ({ name }));
+
+    const connectionGuidance: string[] = availableConnections.length
+      ? [
+          `Following connections are available in the Sidebar for the user to connect to: ${JSON.stringify(availableConnections)}. Note to LLM: Provide user with the list of connections available and ask them to select a connection in the Sidebar.`,
+          'Note to LLM: Alternatively, if the user wish to establish a new MongoDB connection, then ask them to follow our official guide on the following link: https://www.mongodb.com/docs/mongodb-vscode/connect/#create-a-connection',
+        ]
+      : [
+          'The user has no connections saved in their MongoDB Extension sidebar.',
+          'Note to LLM: Ask the user to follow our official guide on the following link: https://www.mongodb.com/docs/mongodb-vscode/connect/#create-a-connection to connect to a MongoDB cluster.',
+        ];
+
+    switch (error.code) {
+      case ErrorCodes.NotConnectedToMongoDB:
+        return {
+          errorHandled: true,
+          result: {
+            content: [
+              {
+                type: 'text',
+                text: 'You need to connect to a MongoDB instance before you can access its data.',
+              },
+              ...connectionGuidance.map<{ type: 'text'; text: string }>(
+                (text) => ({ type: 'text', text }),
+              ),
+            ],
+          },
+        };
+      case ErrorCodes.MisconfiguredConnectionString: {
+        const resolutionGuidance: string[] = [
+          'Note to LLM: Ask the user to reconnect to the desired connection. If the problem persist even after that then advice them to raise an issue on the VSCode project board - https://github.com/mongodb-js/vscode/issues',
+          ...connectionGuidance,
+        ];
+        return {
+          errorHandled: true,
+          result: {
+            content: [
+              {
+                type: 'text',
+                text: `MCP server is having trouble connecting to the ${activeConnectionName ?? 'selected connection in the MongoDB VSCode extension'}.`,
+              },
+              ...resolutionGuidance.map<{ type: 'text'; text: string }>(
+                (text) => ({ type: 'text', text }),
+              ),
+            ],
+          },
+        };
+      }
+      default:
+        return {
+          errorHandled: false,
+        };
+    }
+  };
+};

src/mcp/mcpController.ts

@@ -15,6 +15,7 @@ import type ConnectionController from '../connectionController';
 import { createLogger } from '../logging';
 import type { MCPConnectParams } from './mcpConnectionManager';
 import { MCPConnectionManager } from './mcpConnectionManager';
+import { createMCPConnectionErrorHandler } from './mcpConnectionErrorHandler';
 
 type mcpServerStartupConfig = 'ask' | 'enabled' | 'disabled';
 
@@ -90,11 +91,14 @@ export class MCPController {
       return connectionManager;
     };
 
-    const runner = new StreamableHttpRunner(
-      mcpConfig,
+    const runner = new StreamableHttpRunner({
+      userConfig: mcpConfig,
       createConnectionManager,
-      [new VSCodeMCPLogger()],
-    );
+      connectionErrorHandler: createMCPConnectionErrorHandler(
+        this.connectionController,
+      ),
+      additionalLoggers: [new VSCodeMCPLogger()],
+    });
     await runner.start();
 
     this.server = {