Archilas keeps the earlier note and marks it replaced when a later one contradicts it. The date stays on both. The context an agent receives prefers the current note.
The failure I kept hitting was not “no memory.” It was the wrong memory. A note from last quarter was still worded like policy. The Slack message that changed it was sitting in another tool.
The rule I shipped
A newer decision marks the older one. I do not delete the older one, because I want to see what changed and when. The 1 October Notion note stays, struck as replaced. The 2 October Slack note is current. A Linear ticket on 6 October can sit beside it without erasing either date.
Agent actions follow the same rule. If I told the agent to leave custom SAML out of the first release, that instruction is a note, with the date. A later instruction can replace it.