isHarnessSilence function
Whether a failure is a fast NON-RESULT rather than failed work.
Both facts stay engine-owned: the reported kind and the wall-clock floor. Only CapabilityFailureKind.noResult can be silence — a fast INVALID result is a real invalid result, not an environment refusal.
Implementation
bool isHarnessSilence({
required CapabilityFailureKind kind,
required Duration? ranFor,
}) =>
kind == CapabilityFailureKind.noResult &&
ranFor != null &&
ranFor < kHarnessSilenceFloor;