## What changed
- Add “System proxy” to `/experimental` for opting into macOS or Windows system proxy settings. Keep `respect_system_proxy` disabled by default.
- Update doctor’s macOS proxy guidance to point to `/experimental` and `codex features enable respect_system_proxy`, and tell users to restart Codex after changing the setting.
## Testing
Add snapshots for the experimental setting and doctor guidance, plus a Responses test verifying that `x-codex-beta-features` includes `respect_system_proxy` only when enabled.
GitOrigin-RevId: caa3e1a7cbe222069f35022b06c59da578b8a4dd