I think many people in this community will recognize this scenario.
A large AGENTS.md.
Maximum context.
A detailed prompt.
One big /goal.
Codex starts working confidently: it explores the repository, builds a plan, and changes the code. Then the scope expands, unnecessary files are read, one fix creates another problem, and in the end we get an expensive result that still needs to be partially rewritten.
For a long time, I thought the solution was to give the model even more information and explain the task in even greater detail.
It seems I was wrong.
On July 18, I saw the email about the Codex Hackathon, just three days before it ended. I currently live in Ukraine, and because of the war, I unfortunately did not have the ability to monitor my inbox and respond in time.
I could have tried to rush something together during the remaining days. But after carefully reading the email and studying the approach behind the new model, I realized that it would be far more useful to rebuild my own way of working before rushing into a project.
I created a separate Codex Workflow Lab and started testing:
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how much context a single task actually needs;
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when
AGENTS.mdhelps and when it becomes a tax on every run; -
how narrow the scope should be;
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how to define checks and completion criteria in advance;
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how to reduce token usage without sacrificing quality;
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where autonomy accelerates the work and where it turns into an expensive cycle of rework.
The first conclusion was uncomfortably simple:
You cannot use a new model effectively inside an old workflow.
/goal does not replace decomposition.
More context does not replace relevant context.
A detailed prompt does not fix an undefined scope.
Autonomy without constraints does not always save time.
I am still running these experiments, and I am definitely not claiming to have figured everything out. That is exactly why I am interested in hearing from developers in this community — people who test Codex on real repositories, not only in ideal demos.
How do you design tasks for Codex today?
Do you use one large /goal, or split the work into short, verifiable cycles?
What has reduced token usage the most in your experience: smaller context, stricter scope, separate instructions, or better validation?
And the question I find most interesting:
Which habit from working with older models did you have to consciously abandon after switching to the new one?
