[sanskarIN]

Confirmed failure

The combined-main Windows packages workflow run #42371917086 passed CI, x64 package creation and Windows 2022/2025 verification, but the second independent portable x64 GUI launch on Windows 11 ARM exited with 0xC0000005 shortly after Qt Quick created the window, before the scheduled screenshot. The first portable launch and installed launch succeeded. See #185 and related user export-crash report #175.

This is an actual Windows ARM emulation failure; do not claim it is proven to be the same root cause as the user's desktop x64 crash.

Diagnostic extension

• Preserve two strict/default GUI launches on Windows 11 ARM.
• Add two independent software-renderer GUI launches on that host only via opt-in -SoftwareBackendDiagnostics and QT_QUICK_BACKEND=software, with separate screenshots and stderr logs.
• Clear inherited QT_QUICK_BACKEND/QSG_RHI_BACKEND before baseline verification; restore the diagnostic setting afterward.
• Keep every default and software attempt as an independent required check. No auto-retries, no ignored failures, no changing the end user's default graphics mode.
• Document interpretation and privacy boundaries in docs/testing/windows-arm-gui-crash-triage.md.

Gates

• Windows PowerShell verification script lint/parse and packaged Windows verification on all three hosts.
• Linux GCC and sanitizer CI.
• ARM default-vs-software results collected without masking original failures.
• Preserve evidence and investigate native stack before asserting a fix.

This PR adds diagnostic coverage only. No native bug is claimed to be fixed; no stable release is published.