Sandbox policies ignored for certain commands with "allow dev tool access"

[tdryer]

Describe the bug

Sandbox user filesystem policies are ignored for certain commands (eg. python) when "allow dev tool access" is enabled.

Affected version

GitHub Copilot CLI 1.0.83

Steps to reproduce the behavior

1. Enable Copilot CLI's sandbox and "allow dev tool access" (enabled by default).
2. Add a user policy for a read/write filesystem path.
3. Ask Copilot to write to that path using python:

   python -c 'import os; open("/home/tom/.cache/uv/test", "w")'
   

   The command fails with Read-only file system.
4. Ask Copilot to run the same command via a wrapper with a different basename (eg. env):

   env python -c 'import os; open("/home/tom/.cache/uv/test", "w")'
   

   The command succeeds.

Expected behavior

User filesystem policies are honored for all commands, even when "allow dev tool access" is enabled.

Additional context

• Operating System: Linux (Ubuntu 26.04)

[caarlos0]

Hi!

Sandbox user filesystem policies are ignored for certain commands

Not really, they are still followed, but enabling dev tools adds more paths, like in your case, it allows writing to the uv cache, since you're trying to use python.

There's more information in copilot help sandbox.

Let us know if you think we should make this different, and thanks for trying it out :)

---

will close for now, but feel free to continue the discussion.