refactor: extract isHostConfig into shared plugin-detection utility

Address code review feedback: move host config detection logic into
a dedicated, dependency-free utility module so serve.ts and tests
share the same implementation.

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

packages/cli/src/commands/serve.ts

@@ -7,6 +7,7 @@ import net from 'net';
 import chalk from 'chalk';
 import { bundleRequire } from 'bundle-require';
 import { loadConfig } from '../utils/config.js';
+import { isHostConfig } from '../utils/plugin-detection.js';
 import {
   printHeader,
   printKV,
@@ -193,10 +194,7 @@ export default class Serve extends Command {
       // Skip if config is a host/aggregator config that already contains
       // instantiated plugins — wrapping it would cause duplicate registration
       // and startup failures (e.g. plugin.app.dev-workspace).
-      const isHostConfig = Array.isArray(config.plugins) &&
-        config.plugins.some((p: any) => typeof p?.init === 'function');
-
-      if (!isHostConfig && (config.objects || config.manifest || config.apps)) {
+      if (!isHostConfig(config) && (config.objects || config.manifest || config.apps)) {
         try {
            const { AppPlugin } = await import('@objectstack/runtime');
            await kernel.use(new AppPlugin(config));

packages/cli/src/utils/plugin-detection.ts

@@ -0,0 +1,16 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * Detect whether a loaded config is a host/aggregator configuration.
+ *
+ * A host config already contains a `plugins` array with instantiated Plugin
+ * objects (i.e. objects that have an `init` method). Such configs must NOT
+ * be wrapped again by AppPlugin in the CLI, as that would cause duplicate
+ * plugin registration and startup failures.
+ */
+export function isHostConfig(config: any): boolean {
+  return (
+    Array.isArray(config.plugins) &&
+    config.plugins.some((p: any) => typeof p?.init === 'function')
+  );
+}

packages/cli/test/serve-host-config.test.ts

@@ -1,4 +1,5 @@
 import { describe, it, expect } from 'vitest';
+import { isHostConfig } from '../src/utils/plugin-detection';
 
 /**
  * Tests for the host config detection logic used in serve.ts
@@ -9,13 +10,6 @@ import { describe, it, expect } from 'vitest';
  * and a `plugin.app.<id> failed to start` error.
  */
 describe('Host config detection', () => {
-  // Mirrors the detection logic in serve.ts L196-197
-  function isHostConfig(config: any): boolean {
-    return (
-      Array.isArray(config.plugins) &&
-      config.plugins.some((p: any) => typeof p?.init === 'function')
-    );
-  }
 
   it('should detect host config with instantiated plugins', () => {
     const config = {