diff --git a/src/cthulhu/plugin_system_manager.py b/src/cthulhu/plugin_system_manager.py
index 7c314cd..478670b 100644
--- a/src/cthulhu/plugin_system_manager.py
+++ b/src/cthulhu/plugin_system_manager.py
@@ -996,7 +996,9 @@ class PluginSystemManager:
 
             try:
                 logger.info(f"Activating plugin: {module_name}")
-                self.plugin_manager.hook.activate(plugin=plugin_instance)
+                # Lifecycle is per-plugin. Broadcasting through pluggy replays
+                # activate() on every previously-registered plugin.
+                plugin_instance.activate(plugin_instance)
             except Exception as e:
                 logger.error(f"Error activating plugin {module_name}: {e}")
                 import traceback
@@ -1035,7 +1037,9 @@ class PluginSystemManager:
             plugin_instance = pluginInfo.instance
             if plugin_instance:
                 try:
-                    self.plugin_manager.hook.deactivate(plugin=plugin_instance)
+                    # Mirror targeted activation and only deactivate the plugin
+                    # instance being unloaded.
+                    plugin_instance.deactivate(plugin_instance)
                 except Exception as e:
                     logger.error(f"Error deactivating plugin {module_name}: {e}")
 
diff --git a/tests/test_plugin_system_manager_regressions.py b/tests/test_plugin_system_manager_regressions.py
new file mode 100644
index 0000000..f14db33
--- /dev/null
+++ b/tests/test_plugin_system_manager_regressions.py
@@ -0,0 +1,98 @@
+import sys
+import tempfile
+import textwrap
+import types
+import unittest
+from pathlib import Path
+from unittest import mock
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[1] / "src"))
+
+input_event_manager_stub = types.ModuleType("cthulhu.input_event_manager")
+input_event_manager_stub.get_manager = mock.Mock(return_value=mock.Mock())
+sys.modules["cthulhu.input_event_manager"] = input_event_manager_stub
+
+from cthulhu.plugin_system_manager import PluginInfo, PluginSystemManager
+
+
+PLUGIN_TEMPLATE = """
+from cthulhu.plugin import Plugin, cthulhu_hookimpl
+
+
+class {class_name}(Plugin):
+    def __init__(self):
+        super().__init__()
+        self.activation_count = 0
+        self.deactivation_count = 0
+
+    @cthulhu_hookimpl
+    def activate(self, plugin=None):
+        self.activation_count += 1
+
+    @cthulhu_hookimpl
+    def deactivate(self, plugin=None):
+        self.deactivation_count += 1
+"""
+
+
+class PluginSystemManagerRegressionTests(unittest.TestCase):
+    def _create_plugin_info(self, root_dir: str, module_name: str) -> PluginInfo:
+        plugin_dir = Path(root_dir) / module_name
+        plugin_dir.mkdir()
+        (plugin_dir / "plugin.py").write_text(
+            textwrap.dedent(PLUGIN_TEMPLATE.format(class_name=module_name)),
+            encoding="utf-8",
+        )
+        return PluginInfo(
+            module_name,
+            module_name,
+            str(plugin_dir),
+            canonical_name=module_name,
+            source_id="test",
+            origin="test",
+        )
+
+    def _create_manager(self) -> PluginSystemManager:
+        app = mock.Mock()
+        app.getSignalManager.return_value = mock.Mock()
+        return PluginSystemManager(app)
+
+    @mock.patch("cthulhu.plugin_system_manager.dbus_service.get_remote_controller")
+    def test_loading_second_plugin_does_not_reactivate_first_plugin(self, remote_controller):
+        remote_controller.return_value = mock.Mock()
+
+        with tempfile.TemporaryDirectory() as temp_dir:
+            manager = self._create_manager()
+            first_plugin = self._create_plugin_info(temp_dir, "FirstPlugin")
+            second_plugin = self._create_plugin_info(temp_dir, "SecondPlugin")
+
+            self.assertTrue(manager.loadPlugin(first_plugin))
+            self.assertEqual(first_plugin.instance.activation_count, 1)
+
+            self.assertTrue(manager.loadPlugin(second_plugin))
+
+            self.assertEqual(first_plugin.instance.activation_count, 1)
+            self.assertEqual(second_plugin.instance.activation_count, 1)
+
+    @mock.patch("cthulhu.plugin_system_manager.dbus_service.get_remote_controller")
+    def test_unloading_plugin_does_not_deactivate_other_loaded_plugins(self, remote_controller):
+        remote_controller.return_value = mock.Mock()
+
+        with tempfile.TemporaryDirectory() as temp_dir:
+            manager = self._create_manager()
+            first_plugin = self._create_plugin_info(temp_dir, "FirstPlugin")
+            second_plugin = self._create_plugin_info(temp_dir, "SecondPlugin")
+
+            self.assertTrue(manager.loadPlugin(first_plugin))
+            self.assertTrue(manager.loadPlugin(second_plugin))
+
+            second_instance = second_plugin.instance
+
+            self.assertTrue(manager.unloadPlugin(second_plugin))
+
+            self.assertEqual(first_plugin.instance.deactivation_count, 0)
+            self.assertEqual(second_instance.deactivation_count, 1)
+
+
+if __name__ == "__main__":
+    unittest.main()