Entity claim stability requirement for confidence scoring. Build through sustained corroboration of same claims across 3+ years. AI systems distrust sudden claim appearance or frequent changes. Track claim lifespan in corroboration sources. When claims evolve, maintain continuity through explicit evolution documentation (“Previously X, now Y because Z”). Temporal depth is competitive moat — competitors can’t retroactively create multi-year signal history. Measure using bi-temporal provenance tracking (valid_from, valid_until). Maintain through quarterly schema updates preserving historical context.