When creating or updating files that persist user-controlled commands/state for later execution (hooks, observer/session forwarding, etc.), treat the contents as sensitive and enforce least-privilege permissions at install/write time. Verify the permissions in an automated install/integration test so regressions are caught early.
Implementation checklist:
Example (shell + test concept):
# Ensure the persisted hook/observer command file is owner-only
umask 077
# when creating/updating the file:
# e.g., printf '%s' "$command" > "$hook_file"
# then verify
mode=$(stat -c '%a' "$hook_file")
[ "$mode" = '600' ] || { echo "Expected 0600, got $mode" >&2; exit 1; }
This prevents unintended disclosure or tampering of sensitive execution instructions via overly-permissive files (e.g., 0644/0666), aligning with security best practices for stored secrets/state.