## Why
Applying session settings rebuilt and compared a legacy filesystem policy even
when the update could not trigger cwd-based policy rebinding.
## What changed
Compute the legacy projection only for cwd changes whose filesystem policy has
a rebindable project-root write entry. Preserve the existing equivalence check
before rederiving the policy.
GitOrigin-RevId: c428a5c54f1b5b1300be406cac374a6fd29bb9a8