Audit runs backwards from the state
The instinct is to reach for logs, but logs are organised by time and audit questions are organised by record. You start from a piece of state that looks wrong and need to walk back to its origin. That only works if the origin is attached to the record itself, which means it has to be written at the same moment the record is.
Contradictions are the early warning
The most useful audit signal is not a query anyone runs — it is a write that disagrees with something already stored. A system that silently overwrites loses that signal. A system that surfaces the conflict as an inspectable state change turns the moment of corruption into the moment of detection.
What to require from a memory layer
Before trusting a memory layer with state your agents act on, confirm you can answer all five audit questions without writing custom instrumentation: origin, timing, verification, contradiction, and reversibility. Any of those you have to build yourself is a component you will also have to maintain and test.
