You could also increase compaction.reserveTokens in ~/.pi/agent/settings.json to make pi compact more often. Also you can use /compact <instructions> to specify what facts should be included in the summary.

One hard part is that from a handoff file you only have information for 1 session, so you have to manually determine next week which facts are still true. At Substrate we solve this problem using our memory: we have 1 memory outside of an agent and track the source of every fact. https://trysubstrate.co/l/a2hn