Is there a publicly supported macOS API, entitlement, or framework capable of enforcing a hard 64 MiB aggregate memory ceiling across a process tree, including its supervisor, observer, and descendants? Enforcement must be established before workload execution, survive fork/exec, and remain effective if the controlling process crashes. We have examined per-process resource limits and process-memory reporting, but these do not establish the required aggregate guarantee. If supported, which API and enforcement mechanism should we use? If not, is there a documented platform limitation?