OpenAI AMA: Reddit summary about new ChatGPT and GPT-5.6

OpenAI’s Codex team has disclosed new operating guidance for GPT-5.6 and Codex during a Reddit AMA held on July 10, alongside confirmation that Codex now reaches more than five million weekly users. That figure has doubled in three months, while the team says it shipped 150 features and product changes during the same period.

Summary of Reddit AMA about "GPT-5.6 and Codex in ChatGPT" with OpenAI's Codex team on 2026-07-10

(opened with the stat that more than 5 million people use Codex every week, twice as many as three months ago, with 150 features and improvements shipped in that period)

Model… https://t.co/FfFeVibJpS pic.twitter.com/7bv7fid9hO

— Tibor Blaho (@btibor91) July 10, 2026

For most coding work, OpenAI recommends GPT-5.6Sol at Medium reasoning. Sol Ultra is positioned for migrations, security-sensitive changes, production incidents, and other tasks where mistakes are costly. Terra is intended for faster or usage-conscious work, while Luna is suited to lightweight operations and subagents. There is no automatic model router yet, although the new reasoning slider can fall back to Terra at its lowest setting.

The team said Sol is its strongest option for interface work, especially when reference images are supplied. Sol Medium is also described as faster than GPT-5.5 for many tasks, while Fast mode runs at roughly 1.5 times the normal speed. OpenAI is preparing a Cerebras-backed configuration targeting about 750 tokens per second, but has made no commitment to a one-million-token context window for Sol.

Codex users were also advised to give agents bounded goals, require tests after each attempt , and use the “/goal” command for longer investigations. OpenAI acknowledged that models can abandon patches too quickly when results are imperfect. Greater persistence and lower code complexity are now listed as areas for further work.

Agentic usage is counted by the feature being used rather than the device or interface. Codex in the desktop app, CLI, IDE, web, and mobile draws from the same agentic allowance as ChatGPT Work, while standard ChatGPT conversations use a separate allocation. OpenAI said task cost can vary sharply depending on repository size, reasoning depth, and execution time, and that it is working on clearer usage reporting.

The company also addressed criticism of the merged ChatGPT desktop app. ChatGPT Classic and the new app can run side by side for now, while fixes are being applied to browser control, stuck threads, connection failures, packaging, and resource usage. Windows parity is receiving additional attention, and a Linux desktop app is under development, with no public timeline.

Notes on GPT-5.6, which includes some interesting new additions to the API (programmatic tool calling and multi-agent in particular) - plus 18 pelicans for the 6 reasoning levels and 3 new models:https://t.co/pZOrG6QxTL

— Simon Willison (@simonw) July 9, 2026

Early reactions remain mixed. Simon Willison said Sol Medium may become his default for coding, while also describing the selection of models and reasoning as confusing. Ethan Mollick questioned whether ChatGPT Work has a clear role beside Codex, reflecting continued uncertainty about how OpenAI is separating its general-purpose agent from its developer-focused workspace.

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