Rationale
A task touches only the paths it claimed; work found elsewhere is not accepted as done.
Required behaviour
Work outside the paths a task claimed is not accepted as that task's work.
Failure behaviour
A violation is a FAIL finding under the category scope, and the command that found it exits 10. Under watch the same violation is reported as drift and the command exits 11.
Verification
mj_validate_scope decides it, dispatched from check, finish, watch. The behavioural case test/cases/04_start_check.sh proves it, and CI runs that case.