midSessionDeathGap

Tracking URL for why this harness does not prove the mid-session-death obligation — the accountability analog of capabilityGaps for the injectMidSessionDeath hook.

The base default is a non-null umbrella URL (CapabilityGaps.MID_SESSION_DEATH): an un-overridden harness (one that leaves injectMidSessionDeath at its default false) is tracked by default, never silently green. A harness that overrides injectMidSessionDeath to actually drop the transport proves the obligation and MUST override this to return null/blank (no gap). midSessionDeathObligationIsTrackedWhenUnproven enforces the pairing: hook-returns-false ⇒ this must be non-blank.