A model has no memory. It has a context window, which is re-sent in full on every request and forgotten completely between them. Everything marketed as agent memory is a decision about what to put in that window and where the rest is kept.
The metaphor is doing damage
Borrowing “short-term” and “long-term” from cognitive psychology implies a consolidation process that does not exist. Nothing moves from one store to the other on its own. There is no forgetting curve, no rehearsal, no sleep. There is a string you assemble before each API call.
Ask three engineering questions instead, and the categories fall out on their own: when is it written, when is it read back into context, and what makes it go away. Anything called memory that cannot answer all three is a vector database with ambitions.
Three patterns
