This describes httpjail, a new Rust sandbox proxy tool: https://github.com/coder/httpjail

It works for any process, not just Claude Code. I got it working with Codex CLI like this:

  httpjail --js "r.host === 'chatgpt.com'" -- codex

After installing it using Cargo (and Homebrew):

  brew upgrade rust
  cargo install httpjail

I wrote more notes about it here: https://simonwillison.net/2025/Sep/19/httpjail/