Allow per-session sandbox override for local VM and benchmark

What variant of Codex are you using?

CLI

What feature would you like to see?

I have encountered several issues when using Codex for I/O benchmarking involving QEMU/KVM.

Codex can edit and build code in my local workspace, but in some cases it cannot run the actual benchmark because the session sandbox blocks required host-side operations.

A concrete example is virtio-fs benchmarking with QEMU + virtiofsd. The workflow works from my normal shell, but Codex cannot complete it because the sandbox blocks the local socket/IPC setup needed by virtiofsd.

This makes systems and performance work harder than it needs to be. Codex can prepare the code and scripts, but I still have to run them manually and send the results back.

Requested improvement:

• allow an explicit per-session sandbox override
• make it opt-in and clearly visible
• ideally support local VM/socket/process-heavy workflows without

requiring a separate environment

Thanks for your concern.

Additional information

_No response_