Salience

How much a memory matters, as a score that moves. Not how well it matches a query — that is relevance, it is a property of the question, and it is computed fresh every time.

Why it matters in a memory layer

Without it every memory is equally important, so nothing can be ranked down and nothing can be aged out: the store only grows and every query pays for the whole history. Salience is what makes forgetting possible at all.

It is also the signal most often misapplied. Salience is importance, and adding it to a relevance score does not produce a better ranking — measured on this course's corpus, weighting a plain cosine ranker by salience moves the correct answer down, from rank 20 to 22, and promotes a taught procedure to first place for a question about diet. The procedure genuinely is one of the most important things in the store. It is not what was asked.

Distinct from the durability gate, which is a boolean decision made once at write time with no usage history. Salience accumulates evidence — explicit instruction, corroboration, and use — and keeps moving.