The newly announced GPT-5.6 series restructures production economics by introducing a 1.25x surcharge on cache writes coupled with a guaranteed 30-minute minimum cache life and explicit breakpoints. For teams running high-frequency agent loops, this shift guarantees highly predictable latency and a 90% discount on reads, though it increases the cost of initial prompt compilation. Coupled with the mid-tier Terra model priced at $2.50 input and $15 output per million tokens, you can now deploy highly complex agent workflows at exactly half the operational cost of GPT-5.5.