The Four Kinds of Memory Your Agent Actually Needs

Ask someone to describe "agent memory" and you'll usually get some version of "it remembers stuff you told it." True, but a little too simple. Not all memories are built the same, and treating them like they are is exactly how memory quietly breaks.

So let's slow down and actually name the four kinds you're dealing with. Once you see the split, you can't unsee it.

Fact

A fact is something true about your life right now.

• "My dentist appointment is at 2pm on Thursday."
• "I live in Austin now."

Facts have a shelf life. The appointment gets rescheduled, you move again, life happens. A good memory has to expect that a fact will eventually get replaced, and know to let go of the old one when it does. Nothing's worse than being reminded about an appointment you already moved, or having something addressed to a place you left a year ago.

Preference

A preference is a standing choice about how you like things, not a claim about the world.

• "I don't eat cilantro."
• "I always want the window seat."

Here's the twist: preferences don't age out the way facts do. You didn't set them because they were only true on a given date, you set them because that's just how you are. If a memory decays everything by age, a preference from six months ago quietly gets buried under whatever's newest, even though it's just as true today as it was then.

Episodic

An episodic memory is something that happened, once.

• "We went to that new Italian place last Tuesday and the service was slow."
• "Grandma asked about the trip to the coast last time we called."

Episodes are great for context, they're the "wait, haven't we talked about this before?" instinct. But they're a snapshot, not a standing truth. You don't "correct" an episode the way you correct a stale fact. It just sits there as a record of a moment.

Procedural

A procedural memory is a learned "here's how you actually do this," usually earned the hard way.

• "Turn the shower handle past hot, then back a little, or it never warms up."
• "Take the back road after 4pm, the highway backs up."

These are the memories worth their weight in gold, because they usually come from a real mistake or a hundred small trials already worked out so you don't have to redo them. Which is exactly why they deserve to surface loudly instead of getting lost in the pile.

Why any of this matters

Stuff all four into the same bucket and treat them the same way, and you get two very specific, very annoying failure modes:

• Stale facts overstay their welcome. An outdated fact keeps winning because nothing ever marked it dead.
• Preferences and habits get buried. A memory that fades everything with time quietly demotes the exact things that were never supposed to fade in the first place.

Knowing what kind of memory you're holding, right from the moment it's formed, is a small bit of structure that heads off both problems before they start. It also explains why "just remember what was said" was never going to be the whole answer, which is where we're headed next.