Knowledge
Knowledge is what the persona searches when it answers. You choose the collections of documents it may read, and when it needs something it searches them and quotes an excerpt. It never gets a whole document back, only the parts that match.
Every search runs two ways at once: a keyword search, which is good at exact words, and a search by meaning, which is good at paraphrase. The results are merged, with the matches by meaning first.
The search reaches only what the persona has been given: its own document collections, and the documents it has access to within them. If any of that is missing, the search finds nothing rather than something it should not.
Searching by meaning depends on each document being prepared in advance. Each piece of a document records whether that preparation still matches its text, and pieces that are not yet prepared wait in a queue until they are.