Read-Point Planning: Your Backlog Is a Cache of Beliefs
Cache invalidation is famously one of the two hard things in computer science. The joke survives because the pain is real: keep a copy of something, and the moment the original changes, your copy starts lying to you. It lies silently, with a straight face, and it lies hardest to the people who trust it most.
Here is the uncomfortable part. You are operating a large cache right now, and you are not invalidating it at all. It is called your backlog.
What a ticket actually is
A cache is a sticky note about something you checked once, kept because checking again is expensive. That is the whole concept. The note is cheap to read, and that is its value. The note does not know when the thing it describes changes, and that is its danger.
