## Summary
1. Revert https://github.com/openai/codex/pull/17848 so the Bazel and
`BUILD` file changes leave `main`.
2. Prepare for a narrower follow up that restores only `SECURITY.md`.
## Validation
1. Reviewed the revert diff against `main`.
2. Ran a clean diff check before push.
## Summary
1. Add a Security Boundaries section to `SECURITY.md`.
2. Point readers to the Codex Agent approvals and security documentation
for sandboxing, approvals, and network controls.
## Validation
1. Reviewed the `SECURITY.md` diff in a clean worktree.
2. No tests run. Docs only change.