## What changed
- On session startup, remove exact `allow` entries from `rules/default.rules`
for command prefixes that Codex no longer suggests as policy amendments.
- Record the migration in `.sandbox_migration` so it runs only once, preserving
rules created after the migration.
- Skip the migration when user and project exec policy rules are ignored.
- Expand the protected prefix list across shells, interpreters, package runners,
and destructive or privilege-related commands.
## Testing
- Cover selective removal, case-insensitive matching, one-time behavior, and the
startup path with ignored policy rules.
GitOrigin-RevId: a0c60e3f82b9630e621fd034b40462e3ab775102
