ReadonlyanswerThe record's actual answer: false — the backend reports it cannot — or
undefined — the backend has not been taught to answer (the tri-state's
third value, never silently promoted to satisfaction).
ReadonlybackendThe backend whose record fell short.
ReadonlycapabilityThe declared capability.
ReadonlyrequirementWhich half of the declaration named it.
One declared capability a backend did not affirm, as RendererResolveOptions.onCapabilityShortfall sees it (§62's diagnostics report, capability half).