## Why
Filesystem helpers should not inherit access to system scratch directories beyond the paths granted by their filesystem policy, while ordinary processes still need scratch access for compatibility.
## What changed
- Move the `/tmp` and `/var/tmp` read/write grants, including their `/private` aliases, from the shared platform defaults into the process-only Seatbelt defaults.
- Keep process access to `/Applications` alongside the scratch-directory grants.
## Testing
Add a macOS Seatbelt test that verifies the generated policies and, when nested Seatbelt execution is available, confirms process scratch access, helper denial, and helper access to an approved project path.
GitOrigin-RevId: 26d83f09c131c1f1d000163b2f8929f601749719
dank-openai
7f82397363