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fix(windows): handle hwnd==0 gracefully for UAC/secure desktop #118

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Merged
ErikBjare merged 1 commit into from
Feb 27, 2026
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fix(windows): handle hwnd==0 gracefully for UAC/secure desktop #118

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15 changes: 12 additions & 3 deletions aw_watcher_window/lib.py
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Original file line number Diff line number Diff line change
Expand Up @@ -39,11 +39,20 @@ def get_current_window_windows() -> Optional[dict]:
from . import windows

window_handle = windows.get_active_window_handle()

# hwnd 0 means no foreground window (e.g. during UAC prompt, lock screen,
# or secure desktop). Return None so heartbeat_loop skips this poll cycle.
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@ErikBjare ErikBjare Feb 27, 2026

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Should it skip poll cycle or lead to unknown?

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@TimeToBuildBob TimeToBuildBob Feb 27, 2026

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Good question — I'd argue skip the poll cycle is the right behavior here, for the same reason we already do it for non-Windows (the get_current_window functions return None and heartbeat_loop treats it as 'no window, try again').

The distinction:

  • hwnd == 0: There is literally no foreground window (lock screen, UAC prompt, secure desktop). Nothing to record.
  • app = None (from failed OpenProcess / WMI): There is a window, we just can't identify it → falls back to "unknown".

Recording "unknown" during a UAC prompt or lock screen would create misleading activity — the user isn't actually in any app. Skipping the heartbeat leaves a gap (or the previous heartbeat's pulsetime covers it), which is semantically correct.

That said, if you'd prefer "unknown" for continuity, happy to change it — it's a one-liner swap.

if not window_handle:
return None

try:
app = windows.get_app_name(window_handle)
except Exception: # TODO: narrow down the exception
# try with wmi method
app = windows.get_app_name_wmi(window_handle)
except Exception:
# Fall back to WMI for elevated/admin processes where OpenProcess fails
try:
app = windows.get_app_name_wmi(window_handle)
except Exception:
app = None

title = windows.get_window_title(window_handle)

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