- monitorEventLoopDelay is lowered from the builtin call dispatch, by module and member, so aliased named imports, namespace members and destructured requires all reach it. Shorthand and possibly undefined resolutions take Node's default.
- The runtime validates the resolution as Node does (an integer of at least 1) and throws a catchable RangeError with ERR_OUT_OF_RANGE.
- `'stack' in err` and Object.prototype's keys are true for every Error. The declared-member fold applies only to keys some program class declares and that built-in errors don't carry in runtime slots; other keys stay fenced.
- Library mode's async_free gate refuses the event-loop metrics, which library links leave out. They join the perf_hooks fence family.