[Windows] Smart App Control kills desktop app on every launch: vk_swiftshader.dll fails signing verification (MSIX ships without CodeIntegrity.cat)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The desktop app crashes repeatedly (multiple times per day, often within minutes of launch), killing all running sessions. Windows sometimes then refuses to relaunch it with a "Can't open this app" dialog that references Smart App Control. Settings → Apps → Claude → Repair fails ("We couldn't repair this app. Try again in a bit.") even with all Claude processes terminated.

What Should Happen?

claude should not crash

Error Messages/Logs

Environment
Claude Desktop 1.26832.0.0 (MSIX package Claude_1.26832.0.0_x64__pzs8sxrjxfjjc), installed from claude.com/download
Windows 11 Pro 10.0.26200, Smart App Control ON (enforcement state 1)
HP EliteBook 645 G9, AMD Ryzen 5 PRO 5675U with integrated Radeon graphics
AMD driver 31.0.21925.1001 (2026-05-19) — issue reproduced on 31.0.21924.61 (2025-12-10) as well

Root cause evidence
Every crash correlates 1:1 with a Code Integrity enforcement block in Microsoft-Windows-CodeIntegrity/Operational:

Event 3033 (Error) — repeated at 18:51, 18:57, 19:47, 20:48 on 2026-08-07, matching each crash:

Code Integrity determined that a process (\Device\HarddiskVolume3\Program Files\WindowsApps\Claude_1.26832.0.0_x64__pzs8sxrjxfjjc\app\claude.exe) attempted to load \Device\HarddiskVolume3\Program Files\WindowsApps\Claude_1.26832.0.0_x64__pzs8sxrjxfjjc\app\vk_swiftshader.dll that did not meet the Microsoft signing level requirements.

Event 3010 (Warning) — always accompanying, 3–4x per occurrence:

Code Integrity was unable to load the \Device\HarddiskVolume3\Program Files\WindowsApps\Claude_1.26832.0.0_x64__pzs8sxrjxfjjc\AppxMetadata\CodeIntegrity.cat catalog. Status 0xC000003A.

Confirmed on this machine: AppxMetadata\CodeIntegrity.cat does not exist in the installed package — the installer ships without it. vk_swiftshader.dll itself carries a valid Anthropic Authenticode signature (verified via Get-AuthenticodeSignature: Valid, CN="Anthropic, PBC"), but with no package catalog, Code Integrity cannot establish the signing level Smart App Control requires, so the load is blocked and the app dies instead of degrading gracefully.

Steps to Reproduce

1. Windows 11 machine with Smart App Control enabled (default on many new PCs)
2. Install Claude Desktop 1.26832.0.0 from claude.com/download
3. Launch the app and use it normally
4. App crashes within minutes; Event Viewer > Microsoft-Windows-CodeIntegrity/Operational shows Event 3033 blocking vk_swiftshader.dll, plus Event 3010 (CodeIntegrity.cat missing, status 0xC000003A)
5. Repair and reinstall do not help — the fresh package also lacks AppxMetadata\CodeIntegrity.cat

Claude Model

Opus

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

1.26832.0.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_