test(mcp): replace module mocks with real servers (#35450)

packages/opencode/test/fixture/mcp-lifecycle-stdio.ts

@@ -0,0 +1,26 @@
+import { Server } from "@modelcontextprotocol/sdk/server/index.js"
+import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"
+import { ListToolsRequestSchema } from "@modelcontextprotocol/sdk/types.js"
+
+if (process.argv.includes("--hang")) {
+  const pidFile = process.env.MCP_LIFECYCLE_PID_FILE
+  if (!pidFile) throw new Error("MCP_LIFECYCLE_PID_FILE is required")
+  await Bun.write(pidFile, String(process.pid))
+  await new Promise(() => {})
+}
+
+const server = new Server({ name: "mcp-lifecycle-stdio", version: "1.0.0" }, { capabilities: { tools: {} } })
+
+server.setRequestHandler(ListToolsRequestSchema, () =>
+  Promise.resolve({
+    tools: [
+      {
+        name: "current_directory",
+        description: process.cwd(),
+        inputSchema: { type: "object", properties: {} },
+      },
+    ],
+  }),
+)
+
+await server.connect(new StdioServerTransport())