I Did the Math on GPT-5.6. The $2.50 Terra Tier Is the One I'd Ship First.

OpenAI Releases GPT-5.6 (Sol, Terra, Luna): A Three-Tier Model Family With Programmatic Tool Calling in the…

OpenAI shipped GPT-5.6 tiers (Sol $5/$30, Terra $2.50/$15, Luna $1/$6 per 1M tokens)—leading Coding Index (80 vs Fable 5's 77.2) but trailing SWE-Bench (64.6% vs 80.3%). Tiered gaps require workload choice: coding → Sol, cost-sensitive → Terra/Luna.