Trying out one-shotting With OpenAI Codex

I have been using Claude Code as a daily driver a lot. Today I tried out OpenAI’s Codex. My first impressions are that the ease of installation, instructions and documentation all around are getting better all the time. A lot of stuff can be found to get up and running fast. For example the consolidation (standardisation?) of AGENTS.md is nice to see.

These coding agents are getting more impressive features with each release. For example, you can resume a very specific coding session with codex using the right GUID. Also, invoking the coding tool from a command line using interactive or non-interactive mode allows the tool really to be used in a lot of places such as shell scripts. Very nice to see all these innovations.

I have to experiment more with Codex before I can evaluate how good it is, but the result of one of the first things I tried is still telling. I was reading the Getting started guide of OpenAI self and it recommended this invocation to one-shot a todo list app:

codex --full-auto "create the fanciest todo-list app"

So I tried this. A todo list app is kind of the hello world for coding agents, but still I was curious to see what it would end up with!

After starting the python server, as it suggested, I navigated to http://127.0.0.1:8000/ to see this:

Nice, I can just see all these cool features in the background! But this weird popup dialog just could not be closed. Clicking the button and the cross did not do anything.

So one-shot failed. But maybe two-shots? I asked Codex to fix it, and it tried to by inspecting code and running headless versions of firefox, but in the end it failed and just could not get the app working.

So, even though this exact prompt is stated in the Codex Getting Started guide, it does not work reliably. One-shotting and vibe coding is awesome to watch. But the agent will get stuck and then us meaty creatures still have to step in to fix it. And by that I mean a software developer, because there is no way a total coding novice will be able to fix these kind of issues.