GPT-5.6 Sol list pricing drops to $4 and $20 per million tokens

Vercel's 21 August 2026 changelog records a lower list price for OpenAI's GPT-5.6 Sol — $4 per million input tokens and $20 per million output — and notes that its standing 50% AI Gateway discount still applies on top, so requests routed through the gateway cost less again.

What it means Frontier-tier pricing is now moving down between releases rather than only at them, which is worth re-running the unit-cost maths for on anything built against the previous number.