NIF_GUID binds the tray icon to the EXE's full path. Once a GUID is
registered for one path, Shell_NotifyIcon(NIM_ADD) silently fails for any
other path using the same GUID. This caused Debug-vs-Release builds and
service+agent dual-process scenarios to fight over the same GUID slot.
Drop NIF_GUID and the static NOTIFY_ICON_GUID; revert to the traditional
(hWnd, uID) identification. The icon is freshly registered per process
launch, no path binding, no cross-instance interference.
The NIF_GUID was leftover from the AUMID/Toast experiment that was later
reverted; only the tray-icon side of that change wasn't cleaned up.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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