## Summary
- normalize effective readable, writable, and unreadable sandbox roots
after resolving special paths so symlinked roots use canonical runtime
paths
- add a protocol regression test for a symlinked writable root with a
denied child and update protocol expectations to canonicalized effective
paths
- update macOS seatbelt tests to assert against effective normalized
roots produced by the shared policy helpers
## Testing
- just fmt
- cargo test -p codex-protocol
- cargo test -p codex-core explicit_unreadable_paths_are_excluded_
- cargo clippy -p codex-protocol -p codex-core --tests -- -D warnings
## Notes
- This is intended to fix the symlinked TMPDIR bind failure in
bubblewrap described in #14672.
Fixes#14672
9060dc7557