GPT-5.6

GPT-5.6 Sol gets a chat-focused retune with 68% fewer factual errors in OpenAI's internal eval, a new effort slider, and GPT-5.6 Luna becomes the default model for Free and Go users with unlimited text chats. What the API did not change and why the split matters.

The "Building abundant intelligence" essay carries real engineering numbers: GPT-5.6 Sol cut serving costs 20%, speculative decoding gained 15%, and two settings moved ARC-AGI-3 from 13.3% to 38.3% with six times fewer tokens.

OpenAI slashes GPT-5.6 Luna by 80% to $0.20/M input tokens, cuts Terra by 20%, adds Sol Fast mode at 2.5x speed, and reveals Sol autonomously optimized its own production kernels.

A practical guide to routing between Claude Opus 5, Sonnet 5, Haiku 4.5, GPT-5.6 Sol/Terra/Luna, and Kimi K3 based on task complexity, cost budget, and latency requirements - with decision frameworks and code examples.

Luna drops from $1/$6 to $0.20/$1.20 per million tokens, Terra from $2.50/$15 to $2/$12, and Sol gets a paid Fast mode. What the new floor means for agent economics, Codex quotas, and the competition.

OpenAI crossed 8 million active users on Codex and ChatGPT Work in one week. Here is what drove the surge, what changed for developers, and what to watch as capacity scales.

OpenAI's GPT-5.6 Sol, Terra, and Luna tiers versus Anthropic's Claude Fable 5 and Mythos 5. Verified pricing, benchmarks, and a practical framework for picking a coding model in July 2026.

OpenAI is consolidating its desktop apps, not merging ChatGPT and Codex into one indistinguishable product. Here is how ChatGPT Work, Codex, and GPT-5.6 fit together.

A practical guide to choosing GPT-5.6 Sol, Terra, and Luna, using programmatic tool calling, caching, and the multi-agent beta in production.

GPT-5.6 Sol dropped on June 26, 2026 as a limited preview with government-imposed access restrictions. Here is what developers need to know about the three-tier Sol/Terra/Luna model family, pricing, availability timeline, and how to prepare your codebase for GA.

Fable 5 is API-only at 2x GPT-5.6 Sol's price with a 15-point SWE-Bench Pro gap. Here is the decision framework for choosing between them in August 2026.