## Why
Resolving attacker-mutable path components while preparing a Seatbelt profile can let a writable root be rebound to a different location before the sandbox is applied. File roots also need to remain confined to the file itself rather than granting access to descendants after replacement.
## What changed
- Preserve mutable components of writable-root paths until Seatbelt binds them, while still normalizing trusted top-level aliases such as `/tmp`.
- Use literal grants for existing file and device roots, and subpath grants for directories and missing roots.
- Exclude both logical and resolved forms of protected subpaths so symlinked metadata directories remain read-only.
## Testing
Add coverage for ancestor rebinding, file-root symlink and directory replacement, missing directory roots, top-level aliases, and symlinked metadata carveouts.
GitOrigin-RevId: 63c00e44dd30766e873b8acdad09d6657657fad9
jif
02de49f718