[BUG] Desktop 1.28929.0 (Windows MSIX): Browser pane kills whole app - CI blocks vk_swiftshader.dll (no CodeIntegrity.cat in package), GPU exit 101457950; regression from 1.26832.0

Environment

• Claude Desktop 1.28929.0 (Microsoft Store MSIX, Claude_1.28929.0.0_x64__pzs8sxrjxfjjc), Claude Code Desktop 2.1.227
• Windows 11 Pro 10.0.26200
• Desktop tower, single discrete GPU: NVIDIA GeForce RTX 4060, driver 32.0.16.1047 (unchanged since 2026-05-31) — not a hybrid-graphics machine
• Windows KBs installed 2026-08-12: KB5120708, KB5121003, KB5123304

Summary

Opening the in-app Browser pane (preview_start / any mcp__Claude_Browser__* flow that creates a browser preview) kills the entire desktop app within ~2 seconds, every time (3/3 since 2026-08-12). The app then needs the Windows "Repair" flow before it will relaunch. Reboots do not help.

This worked fine on 1.26832.0 — browser previews succeeded on 2026-08-10 (07:04, 18:13) and 2026-08-11 (08:35). The app auto-updated to 1.28929.0 before 2026-08-12 07:40, and every Browser-pane launch since then has crashed: 08-12 19:47:28, 08-12 20:17:10, 08-13 03:35:07 (local).

main.log signature (identical all 3 times)

[Preview] Created browser preview { serverId: 'browser-preview-...' }
[PreviewContext] Blocked subresource to private-resolving host { resourceType: 'xhr' }
GPU process gone: {
  type: 'GPU',
  reason: 'crashed',
  exitCode: 101457950,
  serviceName: 'GPU'
}

…then the log stops mid-stream — the Electron main process dies with the GPU process. No claude.exe entry in Windows Error Reporting, no Crashpad report.

Root cause confirmed locally — Code Integrity blocks bundled vk_swiftshader.dll (same mechanism as #80999)

Microsoft-Windows-CodeIntegrity/Operational contains exactly three Claude-related Event 3033 blocks in the retained log, matching the three crashes to the second (e.g. 2026-08-13 03:35:07):

Code Integrity determined that a process (\Device\HarddiskVolume3\Program Files\WindowsApps\Claude_1.28929.0.0_x64__pzs8sxrjxfjjc\app\claude.exe) attempted to load \Device\HarddiskVolume3\Program Files\WindowsApps\Claude_1.28929.0.0_x64__pzs8sxrjxfjjc\app\vk_swiftshader.dll that did not meet the Microsoft signing level requirements.

Each is accompanied by 3× Event 3010:

Code Integrity was unable to load the \Device\HarddiskVolume3\Program Files\WindowsApps\Claude_1.28929.0.0_x64__pzs8sxrjxfjjc\AppxMetadata\CodeIntegrity.cat catalog. Status 0xC000003A.

Verified on disk: the installed 1.28929.0 package root contains only app, assets, AppxBlockMap.xml, AppxManifest.xml, AppxSignature.p7x, priconfig.xml, resources.pri, resources.scale-200.pri — there is no AppxMetadata folder / CodeIntegrity.cat at all. So when the GPU process falls back to SwiftShader during Browser-pane creation, the DLL load is deterministically blocked (embedded signature has no page hashes, no catalog to fall back to), the GPU process is killed with exit 101457950 (0x060C201E), and the whole app dies.

Sequence: Browser pane created → seed page load → Blocked subresource to private-resolving host (new PreviewContext behavior in this build) → SwiftShader fallback attempt → CI block → GPU process killed → app dead. Notably, on this same build a Browser pane whose page load failed (ERR_CERT_AUTHORITY_INVALID, 08-12 14:41) did not crash — the crash requires the page to actually render.

Attribution caveat

Cannot fully separate the 1.26832→1.28929 update from the same-day Windows KBs: the old MSIX was removed on update (can't check whether it shipped a CodeIntegrity.cat) and the CI event log's retention starts 2026-08-12. What is certain: the current package lacks the catalog, and the crash onset coincides with the update.

Related open issues (same exit code / mechanism)

#80999 (root-cause analysis this report confirms on a second, non-managed, single-GPU machine), #81159, #81275, #83744, #85967, #86265 (reports it across 1.26832/1.28929), #86094, #85905.

Ask

Ship the MSIX with page-hashed signatures for the bundled DLLs or include AppxMetadata\CodeIntegrity.cat, so vk_swiftshader.dll survives the GPU process's Microsoft-signed-only mitigation.