fix(plugin): avoid clearing runtime modules after dependency install

tests/test_plugin_helper.py

@@ -1,4 +1,11 @@
+import sys
+import tempfile
+import threading
+import time
+from pathlib import Path
+from types import ModuleType
 from unittest import TestCase
+from unittest.mock import patch
 
 
 class PluginHelperTest(TestCase):
@@ -21,3 +28,92 @@ class PluginHelperTest(TestCase):
             "local://TestPlugin?version=v2",
             PluginHelper.sanitize_repo_url_for_statistic(repo_url)
         )
+
+    def test_pip_install_keeps_modules_imported_during_install(self):
+        """
+        验证依赖安装窗口内被其他任务导入的运行态模块不会被误删。
+        """
+        try:
+            from app.helper.plugin import PluginHelper
+        except ModuleNotFoundError as exc:
+            self.skipTest(f"missing dependency: {exc}")
+
+        module_names = ["app.plugins.dynamicwechat.helper", "Crypto.Cipher._mode_cbc"]
+        previous_modules = {name: sys.modules.get(name) for name in module_names}
+
+        def fake_execute(_cmd):
+            for module_name in module_names:
+                sys.modules[module_name] = ModuleType(module_name)
+            return True, "ok"
+
+        try:
+            with tempfile.TemporaryDirectory() as temp_dir:
+                requirements_file = Path(temp_dir) / "requirements.txt"
+                requirements_file.write_text("demo-package\n", encoding="utf-8")
+                with patch("app.helper.plugin.SystemUtils.execute_with_subprocess", side_effect=fake_execute):
+                    success, message = PluginHelper.pip_install_with_fallback(requirements_file)
+
+            self.assertTrue(success)
+            self.assertEqual("ok", message)
+            for module_name in module_names:
+                self.assertIn(module_name, sys.modules)
+        finally:
+            for module_name, previous_module in previous_modules.items():
+                if previous_module is None:
+                    sys.modules.pop(module_name, None)
+                else:
+                    sys.modules[module_name] = previous_module
+
+    def test_pip_install_serializes_concurrent_calls(self):
+        """
+        验证多个依赖安装请求会复用同一把锁串行执行 pip。
+        """
+        try:
+            from app.helper.plugin import PluginHelper
+        except ModuleNotFoundError as exc:
+            self.skipTest(f"missing dependency: {exc}")
+
+        thread_count = 2
+        active_installs = 0
+        max_active_installs = 0
+        state_lock = threading.Lock()
+        start_event = threading.Event()
+        errors = []
+
+        def fake_execute(_cmd):
+            nonlocal active_installs, max_active_installs
+            with state_lock:
+                active_installs += 1
+                max_active_installs = max(max_active_installs, active_installs)
+            time.sleep(0.05)
+            with state_lock:
+                active_installs -= 1
+            return True, "ok"
+
+        def worker(requirements_file: Path):
+            try:
+                start_event.wait()
+                PluginHelper.pip_install_with_fallback(requirements_file)
+            except Exception as err:  # pragma: no cover - 仅用于并发测试失败诊断
+                errors.append(err)
+
+        with tempfile.TemporaryDirectory() as temp_dir:
+            requirements_files = []
+            for index in range(thread_count):
+                requirements_file = Path(temp_dir) / f"requirements-{index}.txt"
+                requirements_file.write_text("demo-package\n", encoding="utf-8")
+                requirements_files.append(requirements_file)
+
+            threads = [
+                threading.Thread(target=worker, args=(requirements_file,))
+                for requirements_file in requirements_files
+            ]
+            with patch("app.helper.plugin.SystemUtils.execute_with_subprocess", side_effect=fake_execute):
+                for thread in threads:
+                    thread.start()
+                start_event.set()
+                for thread in threads:
+                    thread.join()
+
+        self.assertEqual([], errors)
+        self.assertEqual(1, max_active_installs)