OpenAI’s API changelog lists GPT-6.1 Sol for both the Responses API and Chat Completions API. For prompts up to 272K input tokens, standard pricing is $2 per million input tokens, $0.10 cached input, $2.50 cache write, and $10 output. OpenAI also introduced multi-agent support in beta, allowing a Responses API workflow to delegate independent work to subagents. For Codex and agent developers, the practical impact is access to a lower-cost model for complex coding and professional tasks while gaining a first-party multi-agent delegation path.