Windows 11 25H2 Settings records the default browser under
UrlAssociations\https\UserChoiceLatest\ProgId and stops updating the legacy
UserChoice key, which UCPD.sys also write-protects. Reading only the legacy
ProgId made real-profile browsing refuse a correctly configured Edge/Chrome
default ("not a supported Chromium browser"), with WinError 2 when the key
exists without a value, or picked a stale browser when it still held one.
Resolve the effective ProgId via AssocQueryStringW(ASSOCSTR_PROGID) first,
then fall back to UserChoiceLatest\ProgId, then the legacy UserChoice value.
Classification (channels fail closed) is unchanged.
Salvages #106971 (Shell API lookup); the UserChoiceLatest fallback follows
#108064 and the reports on #107854.
Co-authored-by: Konstantin Khlopkov <konstantin.khlopkov93@gmail.com>
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