[ide-mode] Wire up env variables to sandbox (#5804)

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

@@ -324,7 +324,7 @@ export class IdeClient {
         version: '1.0.0',
       });
       transport = new StreamableHTTPClientTransport(
-        new URL(`http://localhost:${port}/mcp`),
+        new URL(`http://${getIdeServerHost()}:${port}/mcp`),
       );
       await this.client.connect(transport);
       this.registerClientHandlers();
@@ -345,3 +345,12 @@ export class IdeClient {
     }
   }
 }
+
+function getIdeServerHost() {
+  const isInContainer =
+    fs.existsSync('/.dockerenv') ||
+    fs.existsSync('/run/.containerenv') ||
+    !!process.env.SANDBOX ||
+    !!process.env.container;
+  return isInContainer ? 'host.docker.internal' : 'localhost';
+}