The hard part of agent memory is noticing when it's stale

A lot of teams are now giving coding agents a shared memory that follows them from one tool to another. That's the right direction. The hard part, at least in what we measured, is not storing the memory. It's noticing when it is no longer true. In our Big Agentic Brain evals, when the only entries in memory were outdated, Sonnet saw the stale one in 88% of those runs and flagged it in only 4%. Success fell back to the no-memory baseline. So the company brain we built treats upkeep as part of the design: a correction supersedes the old entry, and an optional valid-until date archives it the day after. Memories do not expire by default; the date is for time-bound facts. I wrote up the broader case here: https://nevolin.be/blog/company-brain-shared-board-for-agents The code is here: https://github.com/enhesa/big-agentic-brain I'm involved in building BAB.