Initial commit - Phase 3/4

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/plugins/hello_world/main.py

@@ -1,13 +1,30 @@
-"""Hello World example plugin for Dangerous Pi."""
+"""Hello World example plugin for Dangerous Pi.
+
+This plugin demonstrates the plugin framework capabilities including:
+- Lifecycle methods (on_load, on_enable, on_disable, on_unload)
+- Hook registration
+- Header widget display
+"""
 import sys
-from pathlib import Path
 
-# Add app directory to path for imports
-app_path = Path(__file__).parent.parent.parent
-if str(app_path) not in sys.path:
-    sys.path.insert(0, str(app_path))
-
-from backend.managers.plugin_manager import PluginBase, PluginMetadata
+# Import PluginBase from the already-loaded module to ensure class identity matches
+# This is necessary because the plugin manager uses issubclass() check
+# Try both module name variants (depends on how the app is started)
+_plugin_manager_module = (
+    sys.modules.get('app.backend.managers.plugin_manager') or
+    sys.modules.get('backend.managers.plugin_manager')
+)
+if _plugin_manager_module:
+    PluginBase = _plugin_manager_module.PluginBase
+    PluginMetadata = _plugin_manager_module.PluginMetadata
+    WidgetSeverity = _plugin_manager_module.WidgetSeverity
+else:
+    # Fallback for standalone testing
+    from pathlib import Path
+    app_path = Path(__file__).parent.parent.parent
+    if str(app_path) not in sys.path:
+        sys.path.insert(0, str(app_path))
+    from backend.managers.plugin_manager import PluginBase, PluginMetadata, WidgetSeverity
 
 
 class HelloWorldPlugin(PluginBase):
@@ -26,6 +43,17 @@ class HelloWorldPlugin(PluginBase):
         """Called when the plugin is enabled."""
         print("Hello World Plugin: Enabled!")
 
+        # Register a header widget to show plugin is active
+        self.register_widget(
+            widget_id="status",
+            severity=WidgetSeverity.SUCCESS,
+            message="Hello World plugin active",
+            icon="👋",
+            dismissible=True,
+            action_label="Settings",
+            action_url="/settings"
+        )
+
         # Register a hook for PM3 commands
         async def pm3_command_hook(command: str):
             """Hook that logs PM3 commands."""
@@ -47,6 +75,9 @@ class HelloWorldPlugin(PluginBase):
         """Called when the plugin is disabled."""
         print(f"Hello World Plugin: Disabled! (processed {self.counter} commands)")
 
+        # Remove the header widget
+        self.unregister_widget("status")
+
     async def on_unload(self):
         """Called when the plugin is unloaded."""
         print("Hello World Plugin: Unloaded! Goodbye!")