Model analysis · Simon Willison · Intermediate to advanced
You want a concise independent read of GPT-6 Astra's launch claims, benchmark caveats, long-context results, pricing, and early comparison with Claude Fable 5.1 and GPT-5.6 Sol.
gpt-6 astra, model selection, benchmarks, coding agents, long context
Release notes · OpenAI · Intermediate
You want the primary-source August 13, 2026 OpenAI changelog entry for Ultrafast mode before teaching or adopting the new GPT-5.6 Sol latency tradeoff.
openai, ultrafast mode, gpt-5.6 sol, latency, release notes
Model docs · OpenAI · Beginner to advanced
You need to choose between current GPT-5.6 variants, smaller GPT-5.4 variants, reasoning levels, tool support, and cost-sensitive API paths, including the current default starting points of GPT-5.6 Sol, Terra, and Luna.
openai, gpt, gpt-5, reasoning models, model selection
Release notes · OpenAI · Intermediate to advanced
You want OpenAI's June 26, 2026 preview page for GPT-5.6 Sol, Terra, and Luna, including the first public details on `max` reasoning effort and `ultra` subagent mode.
openai, gpt-5.6 sol, reasoning, subagents, coding