## What changed
Add `policy::build_request` to `codex-rs/mxc-sandbox` to translate `MxcCommand` permissions into native MXC execution requests. Preserve filesystem denies, read-only carveouts, and protected metadata paths, and resolve overlapping grants using canonical path identities.
Map network permissions to ingress, egress, and loopback policies; quote arguments for Windows process creation; and disable DACL mutation fallback. Reject unsupported symbolic roots and deny globs, empty commands, relative working directories, and non-Unicode request paths.
## Testing
Enable unit tests and add coverage for filesystem grants and carveouts, disabled DACL mutation, deny-glob rejection, relative working directories, and non-Unicode paths.
GitOrigin-RevId: 3e647ed5fa932ab9d528eb44a49dd9283ef50481
## What changed
- Add `codex-mxc-sandbox` with native MXC availability detection and a launcher that inherits standard I/O and waits for the sandboxed process.
- Reject unsupported learning-mode and fallback policies, and verify deny-path support before launch.
- Route the existing Windows MXC availability metric through the new crate and move its Windows linking dependencies alongside the adapter.
GitOrigin-RevId: e2a220b85718e00b0e710c30bbe66b6c56958176
