I run Claude Desktop inside a Hyper-V VM. My VM doesn't have the "Virtual Machine Platform" feature installed at all. The app accepts this and simply disables the Cowork tab. I wonder if there's some other way to block the creation of the VM to force Claude Desktop onto this code path without having to uninstall Hyper-V.

That said, Claude (both Desktop and CLI) ships on Windows without any sandboxing support for Code. They only have sandboxing for Linux and macOS. If you need to run it on Windows, I really recommend running it in an isolated VM, which then allows you to omit the "Virtual Machine Platform" feature in the VM and solves this issue. The "Windows Sandbox" OS feature provides such a VM without needing another Windows license.

The VM causes observability problems, which corporate platform stakeholders are sensitive to. They will eventually figure out a way to provide an ESR/logging interface to the sandboxed code that is distinct from the user level telemetry, then Defender/Crowdstrike etc will just support that.