You tell a friend why a family gathering has changed. Later, a work colleague asks whether you are available that day. The colleague may need your availability, but not the private family explanation.
A communication assistant with access to both conversations could technically retrieve the detail. That does not make the detail appropriate to include in the work reply.
The useful question is not only ‘Is this information relevant?’ It is also ‘Is it permitted and necessary in this relationship?’ A reply can often answer the practical question with less disclosure: ‘I’m not available that afternoon.’
Memory boundaries should distinguish learning a general preference from sharing specific private content. A preferred level of brevity is different from another person’s personal circumstances. Even a preference may need a limited scope.
Users should be able to understand which sources influence a suggestion and stop information from crossing a boundary they did not intend.
When evaluating a tool, try a fictional example where a private reason and a public availability question coexist. Check whether the draft reveals more than the second conversation needs. Personalization should make a message more appropriate, and appropriate communication includes knowing which available details should remain in their original context.