membershipDrainGap

Tracking URL for why this harness does not prove the membership-drain obligation — the accountability analog of midSessionDeathGap for the injectMembershipDrain hook.

The base default is a non-null umbrella URL (CapabilityGaps.MEMBERSHIP_DRAIN): an un-overridden harness (one that leaves injectMembershipDrain at its default false) is tracked by default, never silently green. A harness that overrides injectMembershipDrain to actually drain a peer proves the obligation and MUST override this to return null/blank. membershipDrainObligationIsTrackedWhenUnproven enforces the pairing.