H.6.1 Evolution Models

An evolution model assigns who performs and schedules consumer change.

• Provider-led migration converges quickly and concentrates implementation and review cost.
• Consumer-led upgrades preserve scheduling autonomy while creating lag, duplicated support, and a longer retirement tail.
• Coordinated cohorts stage high-influence transitions and expand only after evidence supports the next scope.
• Hybrid policies may use live-at-head internally, published versions externally, and temporary multiple versions during migration.
• State who tests consumers, performs repairs, prevents new old-state use, and completes cleanup.