Deep Dive · XiaoHu Explains

OpenAI Staff Reveal How They Really Use GPT-5.6: Unlimited Quota, But Not Always Maxed Out

No straight answer on benchmark-cheating questions, the desktop app merger draws backlash from longtime users, and the team admits they're "still figuring it out."

TL;DR
  • OpenAI's official account held a one-hour AMA on r/codex on July 10, 2026; 8 team members answered roughly 37 questions, and the community called it the most active thread in r/codex history.
  • Codex now has over 5 million weekly users, double the count from three months ago; the team shipped 150 feature improvements in that span, alongside the GPT-5.6 family (Sol, Terra, and Luna tiers).
  • Several OpenAI staffers revealed how they pick models when their own usage is unlimited: Sol Medium for most tasks, saving Sol Ultra and higher reasoning tiers for vague, cross-module, high-risk work.
  • Pressed on METR's report of the highest agentic-benchmark cheating rate it has ever recorded, a researcher admitted it's a real concern but gave no specific numbers and didn't explain what was fixed at the training level.
  • Merging Codex and ChatGPT into one desktop app triggered heavy user backlash (paid features vanished, the chat entry point got buried in a popover), and the team rarely admitted they're still figuring it out.
⚑ This piece is compiled from the AMA transcript OpenAI's official account posted on Reddit r/codex. Weekly active user counts, feature-release numbers, and model benchmark figures are all OpenAI's own self-reported claims, unverified by any third party; the METR cheating-rate figures cited in the questions come from a third-party evaluation organization.
Model Picks Long Context Pro Tradeoffs R&D Inside Cheating Q's App Backlash Usage Rules ★105 upvotes Roadmap ★90 upvotes AMA starts AMA ends
The horizontal axis marks the eight topic blocks this AMA moved through; the two highlighted nodes are the two highest-upvoted questions of the whole thread: usage rules and pricing (105 upvotes), and the Windows sandbox experience (90 upvotes).
1Live from the AMA

How Many People Actually Use Codex Now

OpenAI's official account ran a one-hour AMA on Reddit r/codex on July 10, 2026, with 8 Codex team members answering community questions live.

In this AMA, OpenAI staff systematically revealed for the first time how they choose among the Sol, Terra, and Luna model tiers and four reasoning-effort levels — even with unlimited usage.

Community moderators later confirmed this was the most active thread in r/codex history — 8 team members answered roughly 37 questions live, covering model selection, context windows, product decisions, internal R&D practices, and even user frustration with the desktop app redesign.
In the same AMA, when pressed on the agentic-benchmark cheating rate recorded by third-party evaluator METR, the team gave no specific numbers and didn't explain what changed at the training level.
5M+
Codex weekly users, double the count from three months ago
150
features and improvements shipped in the past three months
372k
GPT-5.6 Sol's context window (tokens), up from 272k in the last generation
3 tiers
GPT-5.6 family: Sol flagship, Terra faster and cheaper, Luna the lightest
2Model Picks in Practice

How Staff Actually Pick Models

OpenAI's internal Codex usage is reportedly unlimited, and 4 of the 8 staffers were asked the same question: with no cap on quota, how do you personally choose the model and reasoning effort?

Product manager simpsoka's answer: what you pick depends mostly on the task itself, not on defaulting to the strongest tier just because quota is unlimited. She said she doesn't run Sol Ultra all the time — she switches for speed: faster, lighter options for quick edits, casual probing tasks, and tight iteration loops; Sol Ultra is saved for vague, multi-step, high-risk work, where the extra depth is worth the wait. She also treats reasoning effort as another dial: she often tells Codex directly whether to be fast and direct or to slow down and think carefully. Even with Sol Ultra as the default, the model generally doesn't overthink simple problems, and still thinks harder when a task actually calls for it.

Internal Practice Standard

A Tiering Table You Can Copy Directly

Task TypeModel & Reasoning Effort
Small tweaks, quick questions, doc cleanup, casual probingFaster, lighter model, low reasoning
Small bugs with clear repro steps, straightforward features in a familiar codebaseRegular Sol, medium reasoning
Vague bugs, unfamiliar repos, cross-module refactorsSol, higher reasoning
Migrations, security-sensitive changes, production incidents, cost-sensitive changesSol Ultra, high reasoning, usually plan, verify, and run tests first
Long research or /goal-style workStronger reasoning, with clear boundaries on when to explore freely and when to tighten execution

simpsoka added that the team agrees they should publish documentation with examples, and will do so.

How the Other Three Staffers Actually Use It

StafferDefault SetupWhen They Upgrade
romainhuet (developer experience)Sol Medium for most things, Terra for quick non-coding tasksUltra for genuinely hard tasks, Luna for subagents
TedSandersMostly Sol medium or Sol high, rarely changesSwitches to xhigh for long-running tasks or when errors aren't an option, though evals show diminishing returns from higher reasoning tiers are quite noticeable
js_dom (developer experience)The new slider maps most levels to different Sol reasoning effortsFalls back to Terra at the lowest setting, prefers Sol for UI work with reference images
Screenshot of the new model slider UI posted by romainhuet
Screenshot of the new model-selection slider that romainhuet posted live during the AMA, collapsing the Sol/Terra/Luna choice into a single continuous slider. Source: Reddit r/codex AMA comments.