fix(core): Use 127.0.0.1 for IDE client connection (#10658)

Author: skeshive

packages/core/src/ide/ide-client.test.ts

@@ -113,7 +113,7 @@ describe('IdeClient', () => {
         'utf8',
       );
       expect(StreamableHTTPClientTransport).toHaveBeenCalledWith(
-        new URL('http://localhost:8080/mcp'),
+        new URL('http://127.0.0.1:8080/mcp'),
         expect.any(Object),
       );
       expect(mockClient.connect).toHaveBeenCalledWith(mockHttpTransport);
@@ -181,7 +181,7 @@ describe('IdeClient', () => {
       await ideClient.connect();
 
       expect(StreamableHTTPClientTransport).toHaveBeenCalledWith(
-        new URL('http://localhost:9090/mcp'),
+        new URL('http://127.0.0.1:9090/mcp'),
         expect.any(Object),
       );
       expect(mockClient.connect).toHaveBeenCalledWith(mockHttpTransport);
@@ -229,7 +229,7 @@ describe('IdeClient', () => {
       await ideClient.connect();
 
       expect(StreamableHTTPClientTransport).toHaveBeenCalledWith(
-        new URL('http://localhost:8080/mcp'),
+        new URL('http://127.0.0.1:8080/mcp'),
         expect.any(Object),
       );
       expect(ideClient.getConnectionStatus().status).toBe(
@@ -662,7 +662,7 @@ describe('IdeClient', () => {
       await ideClient.connect();
 
       expect(StreamableHTTPClientTransport).toHaveBeenCalledWith(
-        new URL('http://localhost:8080/mcp'),
+        new URL('http://127.0.0.1:8080/mcp'),
         expect.objectContaining({
           requestInit: {
             headers: {

packages/core/src/ide/ide-client.ts

@@ -667,10 +667,10 @@ export class IdeClient {
   }
 
   private createProxyAwareFetch() {
-    // ignore proxy for 'localhost' by deafult to allow connecting to the ide mcp server
+    // ignore proxy for '127.0.0.1' by deafult to allow connecting to the ide mcp server
     const existingNoProxy = process.env['NO_PROXY'] || '';
     const agent = new EnvHttpProxyAgent({
-      noProxy: [existingNoProxy, 'localhost'].filter(Boolean).join(','),
+      noProxy: [existingNoProxy, '127.0.0.1'].filter(Boolean).join(','),
     });
     const undiciPromise = import('undici');
     return async (url: string | URL, init?: RequestInit): Promise<Response> => {
@@ -841,5 +841,5 @@ export class IdeClient {
 function getIdeServerHost() {
   const isInContainer =
     fs.existsSync('/.dockerenv') || fs.existsSync('/run/.containerenv');
-  return isInContainer ? 'host.docker.internal' : 'localhost';
+  return isInContainer ? 'host.docker.internal' : '127.0.0.1';
 }