Linux sandbox (bubblewrap) uses non-unique temp registry path, breaking multi-user /tmp

What version of the IDE extension are you using?

v26.429.30905

What subscription do you have?

Plus

Which IDE are you using?

VS Code

What platform is your computer?

Linux 5.14.0-427.42.1.el9_4.x86_64 x86_64 x86_64

What issue are you seeing?

By default, Codex Linux sandbox creates a bubblewrap folder at:

/tmp/codex-bwrap-synthetic-mount-targets

The relevant line of code is: https://github.com/openai/codex/blob/70807730f5a8e093d5182089ad5a4b1b4355f9fa/codex-rs/linux-sandbox/src/linux_run_main.rs#L1238

Because the folder is not user or session-specific, the folder can be already created by another user working with Codex, so trying to create it again results in an error:

failed to open synthetic bubblewrap mount registry lock
/tmp/codex-bwrap-synthetic-mount-targets/lock: Permission denied

What steps can reproduce the bug?

Create a /tmp/codex-bwrap-synthetic-mount-targets folder and make it not accessible by the current user. Try using Codex and observe failures to use the sandbox.

What is the expected behavior?

Codex creates a registry path unique to the user, so that sandboxing always works. The folder should probably use a per-user or per-session path, e.g. include UID or username.

Additional information

_No response_