On July 9, OpenAI pushed all three GPT-5.6 tiers — Sol/Terra/Luna — to GA together. Compared with the half-year-old preview, what really landed are two engineering choices that compress the "capability-cost curve" by another tier. Ultra mode — 4-agent parallel orchestration. Traditional scaling does addition on thinking time; GPT-5.6 takes a different path: 4 agents each handle a segment, and a main agent consolidates. BrowseComp single-agent is 90.4%, Ultra reaches 92.2%; Terminal-Bench 2.1 climbs from 88.8% to 91.9%. OpenAI writes this into the Responses API's multi-agent beta, so developers can call it directly, no need to build their own scheduler. Programmatic Tool Calling (PTC) — tool calls from "passthrough" to "programmable". In the past, every tool response had to be stuffed back into the model for the next turn; PTC lets the model write a small program, internally filter and aggregate, and only return the next action to the main loop. Early-customer numbers: PlayCo scenario-construction tokens cut 63.5%, turns cut 50%; Clio legal-document prompt tokens cut 38%, quality flat; Rogo financial-research output tokens cut 24%, completion 28% faster. Longer context isn't news (1M was previewed long ago), but GA's MRCR v2 8-needle 256K-512K segment runs at 91.5%, GraphWalks 1M BFS at 77.1% — the first flagship to take 1M context from benchmark slogan to engineering reality. Paired with PTC, the cost model of long-context Agents has a support point for the first time. Stepping back, Sol/Terra/Luna are positioned as "durable capability tiers" and will iterate at their own cadence, no longer tied to a particular release. With three-tier pricing, OpenAI is no longer selling "the strongest model", but "a budget-schedulable compute gradient" — turning "capability" into composable runtime options. For teams building Agent platforms, the direct signal is: multi-agent orchestration moves from experimental feature to one API tier; tool calls from passthrough to programmable. These two capabilities have a first-tier vendor's stable interface for the first time.