{"id":"gof-changemanager-mediator-singleton","text":"A ChangeManager (especially DAGChangeManager) prevents redundant updates when an observer depends on multiple subjects; it acts as both a Mediator between subjects and observers and is typically a Singleton.","truth_value":"IN","source":"entries/2026/06/17/gof-oo-chunk-19.md","source_url":"","source_hash":"","justifications":[],"dependents":["changemanager-mediator-observer-composition","changemanager-resolves-observer-liability-via-pattern-composition","changemanager-validates-singleton-as-composition-mediating-infrastructure","singleton-as-cross-category-enabling-infrastructure","singleton-pervasive-instance-governance-across-categories"],"metadata":{"last_premise_reviewed":"2026-06-17T18:19:22","premise_review_result":"pass"},"created_at":"2026-06-17T21:30:27+00:00","updated_at":"2026-06-17T21:30:27+00:00","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"gof-changemanager-mediator-singleton","truth_value":"IN","reason":"premise"}]}}