Time Machine - bid history and change tracking

Time Machine answers "what did we change and did it work": historical bid states, side-by-side date comparisons of campaign settings, and the change history trail across manual edits, automation, and AI-staged changes.

Use it before repeating a move on an entity - if the last change made results worse, that is evidence to revert rather than push further. The workforce and automation reviewer consult the same history before staging.