# Pin Codex development tool paths Pins constrain absolute-path fallback to binaries trusted by each developer. From the development shell's repository root: ```sh mkdir -p ~/.codex/rules python3 scripts/setup_dev_execpolicy.py \ > ~/.codex/rules/codex_dev_tool_paths.rules ``` They constrain absolute executable paths for the repository's [development rules](../../.codex/rules/development.rules). Rules load when a Codex session starts.