Require IconSha256 in schema

Relevant area(s)

WinGet CLI

Relevant command(s)

winget show

Brief description of your issue

winget show <id> will skip showing an icon if IconSha256 is missing, even though it's nullable in the locale schema. Found in https://github.com/pl4nty/winget-extras/issues/879.

I'm happy to send a PR if that's ok.

Steps to reproduce

1. Create a locale manifest with Icons[].IconUrl and Icons[].IconFileType only
2. Build a source and run winget show <id> on it
3. Observe the missing icon
4. Add Icons[].IconSha256 and retry, the icon will be shown

Logs:

2026-08-18 10:55:24.630 <I> [CLI ] Found one app. App id: Purslane.RustDesk App name: RustDesk
2026-08-18 10:55:24.634 <I> [CLI ] Manifest fields: Name [RustDesk], Version [1.4.9]
2026-08-18 10:55:24.649 <E> [FAIL] C:\__w\1\s\external\pkg\src\AppInstallerSharedLib\AppInstallerStrings.cpp(886)\WindowsPackageManager.dll!00007FF9F4FCD9F7: (caller: 00007FF9F5085E64) Exception(1) tid(73e0) 80070057 The parameter is incorrect.
    Msg:[ConvertToHexString: Invalid buffer size] 
2026-08-18 10:55:24.649 <E> [FAIL] C:\__w\1\s\external\pkg\src\AppInstallerCLICore\Workflows\WorkflowBase.cpp(160)\WindowsPackageManager.dll!00007FF9F5361E25: (caller: 00007FF9F5072D0D) LogHr(1) tid(73e0) 80070057 The parameter is incorrect.
    Msg:[C:\__w\1\s\external\pkg\src\AppInstallerSharedLib\AppInstallerStrings.cpp(886)\WindowsPackageManager.dll!00007FF9F4FCD9F7: (caller: 00007FF9F5085E64) Exception(1) tid(73e0) 80070057 The parameter is incorrect.
    Msg:[ConvertToHexString: Invalid buffer size] 
] 
2026-08-18 10:55:24.803 <I> [CLI ] Leaf command succeeded: root:show

Expected behavior

Icon and info is shown

Actual behavior

Icon is missing, other info shown

Environment

~> winget --info
    Windows Package Manager v1.29.280
    © 2026 Microsoft. All rights reserved.

Windows: Windows.Desktop v10.0.26200.9106
System Architecture: X64
Package: Microsoft.DesktopAppInstaller v1.29.280.0

WinGet Directories
-----------------------------------------------------------------------------------------------------------------------
Logs                               %LOCALAPPDATA%\Packages\Microsoft.DesktopAppInstaller_8wekyb3d8bbwe\LocalState\Diag…
User Settings                      %LOCALAPPDATA%\Packages\Microsoft.DesktopAppInstaller_8wekyb3d8bbwe\LocalState\sett…
Portable Links Directory (User)    %LOCALAPPDATA%\Microsoft\WinGet\Links
Portable Links Directory (Machine) C:\Program Files\WinGet\Links
Portable Package Root (User)       %LOCALAPPDATA%\Microsoft\WinGet\Packages
Portable Package Root              C:\Program Files\WinGet\Packages
Portable Package Root (x86)        C:\Program Files (x86)\WinGet\Packages
Installer Downloads                %USERPROFILE%\Downloads
Configuration Modules              %LOCALAPPDATA%\Microsoft\WinGet\Configuration\Modules

Links
---------------------------------------------------------------------------
Privacy Statement   https://aka.ms/winget-privacy
License Agreement   https://aka.ms/winget-license
Third Party Notices https://aka.ms/winget-3rdPartyNotice
Homepage            https://aka.ms/winget
Windows Store Terms https://www.microsoft.com/en-us/storedocs/terms-of-sale


Group Policy                                       State
-----------------------------------------------------------
Enable Windows App Installer Experimental Features Disabled
Enable Windows App Installer Hash Override         Disabled
Enable Additional Windows App Installer Sources    Enabled

Additional source Type                         Argument
---------------------------------------------------------------------------------
winget-extras     Microsoft.PreIndexed.Package https://winget.tplant.com.au/cache

Admin Setting                             State
--------------------------------------------------
LocalManifestFiles                        Disabled
BypassCertificatePinningForMicrosoftStore Disabled
InstallerHashOverride                     Disabled
LocalArchiveMalwareScanOverride           Disabled
ProxyCommandLineOptions                   Disabled
ConfigurationProcessorPath                Disabled
DefaultProxy                              Disabled

Start with the locale schema and the winget show command path, then reproduce the behavior using an Icons entry containing IconUrl and IconFileType without IconSha256. Trace where the missing hash is handled and verify completion by running winget show again and confirming the icon and other information are displayed.