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|
/**
* @license
* Copyright 2025 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import * as vscode from 'vscode';
import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
import express, { Request, Response } from 'express';
import { randomUUID } from 'node:crypto';
import {
isInitializeRequest,
type JSONRPCNotification,
} from '@modelcontextprotocol/sdk/types.js';
import { Server as HTTPServer } from 'node:http';
const MCP_SESSION_ID_HEADER = 'mcp-session-id';
const IDE_SERVER_PORT_ENV_VAR = 'GEMINI_CLI_IDE_SERVER_PORT';
function sendActiveFileChangedNotification(
transport: StreamableHTTPServerTransport,
logger: vscode.OutputChannel,
) {
const editor = vscode.window.activeTextEditor;
const filePath = editor ? editor.document.uri.fsPath : '';
logger.appendLine(`Sending active file changed notification: ${filePath}`);
const notification: JSONRPCNotification = {
jsonrpc: '2.0',
method: 'ide/activeFileChanged',
params: { filePath },
};
transport.send(notification);
}
export class IDEServer {
private server: HTTPServer | undefined;
private context: vscode.ExtensionContext | undefined;
private logger: vscode.OutputChannel;
constructor(logger: vscode.OutputChannel) {
this.logger = logger;
}
async start(context: vscode.ExtensionContext) {
this.context = context;
const transports: { [sessionId: string]: StreamableHTTPServerTransport } =
{};
const sessionsWithInitialNotification = new Set<string>();
const app = express();
app.use(express.json());
const mcpServer = createMcpServer();
const disposable = vscode.window.onDidChangeActiveTextEditor((_editor) => {
for (const transport of Object.values(transports)) {
sendActiveFileChangedNotification(transport, this.logger);
}
});
context.subscriptions.push(disposable);
app.post('/mcp', async (req: Request, res: Response) => {
const sessionId = req.headers[MCP_SESSION_ID_HEADER] as
| string
| undefined;
let transport: StreamableHTTPServerTransport;
if (sessionId && transports[sessionId]) {
transport = transports[sessionId];
} else if (!sessionId && isInitializeRequest(req.body)) {
transport = new StreamableHTTPServerTransport({
sessionIdGenerator: () => randomUUID(),
onsessioninitialized: (newSessionId) => {
this.logger.appendLine(`New session initialized: ${newSessionId}`);
transports[newSessionId] = transport;
},
});
transport.onclose = () => {
if (transport.sessionId) {
this.logger.appendLine(`Session closed: ${transport.sessionId}`);
sessionsWithInitialNotification.delete(transport.sessionId);
delete transports[transport.sessionId];
}
};
mcpServer.connect(transport);
} else {
this.logger.appendLine(
'Bad Request: No valid session ID provided for non-initialize request.',
);
res.status(400).json({
jsonrpc: '2.0',
error: {
code: -32000,
message:
'Bad Request: No valid session ID provided for non-initialize request.',
},
id: null,
});
return;
}
try {
await transport.handleRequest(req, res, req.body);
} catch (error) {
const errorMessage =
error instanceof Error ? error.message : 'Unknown error';
this.logger.appendLine(`Error handling MCP request: ${errorMessage}`);
if (!res.headersSent) {
res.status(500).json({
jsonrpc: '2.0' as const,
error: {
code: -32603,
message: 'Internal server error',
},
id: null,
});
}
}
});
const handleSessionRequest = async (req: Request, res: Response) => {
const sessionId = req.headers[MCP_SESSION_ID_HEADER] as
| string
| undefined;
if (!sessionId || !transports[sessionId]) {
this.logger.appendLine('Invalid or missing session ID');
res.status(400).send('Invalid or missing session ID');
return;
}
const transport = transports[sessionId];
try {
await transport.handleRequest(req, res);
} catch (error) {
const errorMessage =
error instanceof Error ? error.message : 'Unknown error';
this.logger.appendLine(
`Error handling session request: ${errorMessage}`,
);
if (!res.headersSent) {
res.status(400).send('Bad Request');
}
}
if (!sessionsWithInitialNotification.has(sessionId)) {
sendActiveFileChangedNotification(transport, this.logger);
sessionsWithInitialNotification.add(sessionId);
}
};
app.get('/mcp', handleSessionRequest);
this.server = app.listen(0, () => {
const address = (this.server as HTTPServer).address();
if (address && typeof address !== 'string') {
const port = address.port;
context.environmentVariableCollection.replace(
IDE_SERVER_PORT_ENV_VAR,
port.toString(),
);
this.logger.appendLine(`IDE server listening on port ${port}`);
}
});
}
async stop(): Promise<void> {
if (this.server) {
await new Promise<void>((resolve, reject) => {
this.server!.close((err?: Error) => {
if (err) {
this.logger.appendLine(
`Error shutting down IDE server: ${err.message}`,
);
return reject(err);
}
this.logger.appendLine(`IDE server shut down`);
resolve();
});
});
this.server = undefined;
}
if (this.context) {
this.context.environmentVariableCollection.clear();
}
}
}
const createMcpServer = () => {
const server = new McpServer(
{
name: 'gemini-cli-companion-mcp-server',
version: '1.0.0',
},
{ capabilities: { logging: {} } },
);
server.registerTool(
'getActiveFile',
{
description:
'(IDE Tool) Get the path of the file currently active in VS Code.',
inputSchema: {},
},
async () => {
const activeEditor = vscode.window.activeTextEditor;
const filePath = activeEditor ? activeEditor.document.uri.fsPath : '';
if (filePath) {
return {
content: [{ type: 'text', text: `Active file: ${filePath}` }],
};
} else {
return {
content: [
{
type: 'text',
text: 'No file is currently active in the editor.',
},
],
};
}
},
);
return server;
};
|
