Fix Snapshot crash from comtypes VARIANT marshaling on non-ASCII UI elements#148
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Jeomon merged 2 commits intoCursorTouch:mainfrom Mar 26, 2026
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March 25, 2026 18:44
…lements When the UI Automation tree traversal encounters a UI element whose COM property triggers a TypeError in comtypes VARIANT marshaling (e.g. non-ASCII window titles or accessibility properties), the Snapshot tool crashes instead of returning a partial result. Add a defensive TypeError guard at both the per-child and per-node levels in tree_traversal so problematic elements are logged and skipped, allowing the rest of the desktop state capture to complete. Fixes CursorTouch#147 Made-with: Cursor
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Description
Adds a defensive guard in
tree_traversalso Snapshot skips the knowncomtypesord()VARIANT marshaling failure instead of aborting the entire traversal.Motivation
On some desktops, a UI Automation property can cause
comtypesto raiseTypeError: ord() expected a character, but string of length 5 foundwhile Snapshot is walking the tree. The problematic element or subtree can be skipped safely; crashing the entire Snapshot call is unnecessary.Changes
File:
src/windows_mcp/tree/service.pyTypeErrorguard in the per-child iteration loop to skip a single problematic child and continue with remaining siblingsTypeErrorguard at the outer node level to skip the current subtree when the current node itself triggers the same failurecomtypes/automation.pyord()TypeError; unrelatedTypeErrors still follow the existing error pathWARNINGlevel for diagnosticsFile:
tests/test_tree_service.pycomtypes/automation.pytracebackTesting
uv run --with pytest pytest tests/test_tree_service.pypython -m py_compile src/windows_mcp/tree/service.py tests/test_tree_service.pyuv run --with ruff ruff check src/windows_mcp/tree/service.py tests/test_tree_service.pysrc/windows_mcp/tree/service.py; the change adds no new lint findingsUpstream Context
Related Issues
Fixes #147