mcp-freecad

# FreeCAD AI Addon Crash Fix Summary ## Issue The FreeCAD AI addon was crashing on startup with a segmentation fault in PySide2, especially when switching workbenches. ## Root Causes 1. Incorrect signal definition in `provider_integration_service.py` - Qt signals in PySide2 MUST be defined as class attributes, not instance attributes. 2. QTimer.singleShot causing crashes during workbench activation, possibly due to lambda functions and Qt event loop state. ## Error Messages ``` AttributeError: 'PySide2.QtCore.Signal' object has no attribute 'connect' Program received signal SIGSEGV, Segmentation fault. ``` ## Fixes Applied ### 1. Fixed Signal Definitions Changed the signal definitions in `/home/jango/Git/mcp-freecad/freecad-ai/ai/provider_integration_service.py`: ### Before (INCORRECT): ```python class ProviderIntegrationService(QtCore.QObject): def __init__(self): # This is WRONG - signals cannot be created in __init__ self.provider_added = QtCore.Signal(str, str) self.provider_removed = QtCore.Signal(str) self.provider_status_changed = QtCore.Signal(str, str, str) self.providers_updated = QtCore.Signal() ``` ### After (CORRECT): ```python class ProviderIntegrationService(QtCore.QObject): # Signals MUST be defined as class attributes provider_added = QtCore.Signal(str, str) provider_removed = QtCore.Signal(str) provider_status_changed = QtCore.Signal(str, str, str) providers_updated = QtCore.Signal() def __init__(self): # Initialize other instance attributes here ``` ### 2. Removed QTimer Usage Removed all QTimer.singleShot calls to avoid crashes. All initialization is now done directly: #### In `main_widget.py`: ```python # Before - CRASHES QtCore.QTimer.singleShot(1000, self.provider_service.initialize_providers_from_config) QtCore.QTimer.singleShot(500, self._connect_widgets_to_service_safe) QtCore.QTimer.singleShot(2000, self._final_connection_check) # After - STABLE self.provider_service.initialize_providers_from_config() self._connect_widgets_to_service_safe() self._final_connection_check() ``` #### In `provider_integration_service.py`: ```python # Before - CRASHES QtCore.QTimer.singleShot(500, lambda: self.test_provider_connection(provider_name)) QtCore.QTimer.singleShot(100, lambda: self._perform_connection_test(provider_name)) # After - STABLE self.test_provider_connection(provider_name) self._perform_connection_test(provider_name) ``` #### In `freecad_ai_workbench.py`: ```python # Direct widget creation instead of using timer self._create_dock_widget() ``` ## Additional Actions 1. Disabled the broken `3D_Printing_Tools` addon that was causing import errors 2. Fixed the signal definitions to be class attributes as required by PySide2 3. Removed all QTimer.singleShot calls which were causing segmentation faults ## Note on QTimer Issue The use of QTimer.singleShot with lambda functions during workbench initialization was causing crashes, likely due to: - Qt event loop not being fully initialized when switching workbenches - Lambda functions creating closure issues with Qt's signal/slot mechanism - Timing issues during rapid workbench switching The solution was to remove all timer-based initialization and perform all setup synchronously. ## Result - FreeCAD now starts without crashing - The FreeCAD AI addon loads successfully - The workbench is registered and available - No more segmentation faults when switching to the FreeCAD AI workbench - All provider initialization happens synchronously without timer-related crashes ## Testing To test the fix: ```bash export QT_QPA_PLATFORM=xcb ./FreeCAD_1.0.0-conda-Linux-x86_64-py311.AppImage ``` The addon should now load without errors and the FreeCAD AI workbench should be available in the workbench selector.