The compression threshold is threshold × context_length where context_length
is the MAIN agent model's window, not the auxiliary/summary model's. On a
262,144-token model at the default 0.50 the threshold is 131,072 — close to a
common 128K figure by coincidence of the percentage, which has led to confusion
that the auxiliary model's context limit is the trigger. Add a note preempting
that misreading and pointing to the separate summary-model-context constraint.
