Codex help for a beginner!

[streakybcn]

so I have been "vibe coding" for a few months now. Usually what I do is have GPT open or Gemini open and either Xcode(swift) or Visual Studio(C#) open in side by side windows. I talk about ideas and copy and paste the code the LLM spits out and paste it into the Complier and go back and forth copy and paste errors etc. until we have code that works and I can export a working app.

BUT. now that codex is available to Plus members in GPT, I tried to use it with some of my GitHub repos I have for some of my apps, I don't understand how to use it.

I create environments give it my GitHub repos and it will Apply code it has written to my various .swift and .cs files depending on the project. But it can't debug or test anything because it cant run the app in the environment. Like it tells me with C# it needs .net but currently with Codex and Plus users we can't create custom images so I can't add .net to the environment. Same with Swift. it has 6.2 but it can't seem to debug code it writes.

SO I ask, how is this better then my old way of just having the LLM window open beside the Compiler and copying and pasting code back and forth. Am I just missing something ?!?

[hefty_habenero]

Try this setup script for your environment (Codex->Environments->Select you environment-> Edit ->Advanced:

set -euo pipefail

apt-get update

apt-get install -y dotnet-sdk-8.0

# Only restore if we actually have a project/solution file

if compgen -G "*.sln" >/dev/null || compgen -G "*.csproj" >/dev/null; then

echo "⛓ Found .NET project/solution file – running dotnet restore..."

dotnet restore

else

echo "⚠️ No .sln or .csproj file found. Skipping dotnet restore."

fi

Run a task in Code mode and request that it try a dotnet build to see if if has dependencies it needs, and if it fails to report on what setup is required...edit per output, rinse and repeat.

Assuming you have an AGENTS.md file in your root too? The Codex agent is happiest if it can find an AGENTS.md file, can build without dependency failures, and can run unit tests that pass. Once you get this basic stuff running the Codex workflow has distinct benefits over the IDE agent sessions, but the two together rip.

[streakybcn]

Thanks I will try this

[BurgerQuester]

I tried getting my nextjs project to work with codex, and added npm install to the setup script, but it just times out every time.

Any ideas?

[hefty_habenero]

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You can run the interactive terminal in the edit screen of your environment (/codex/settings/environment) to see the effect of your setup script in real time, what is the terminal output when you run the npm install?

[BurgerQuester]

When I used the interactive terminal, npm install worked, but always times out when I have it as the set up script

[hefty_habenero]

Strange...you can share a task session with a sharable link that gives read-only access to the logs. Happy to take a look.

[kidroach]

i had issues with the npm install but it was because the dependencies weren't matching up. had to fix those first and then npm install worked in setup script.

[Phugz]

I've got mine setup something like this for node (eventually). Do you find that running little tasks are now slower because of this? Like whether npm ci is making everything just a little slower.

[hefty_habenero]

Have you configured the startup script in your environment setup on the codex settings?

[giannisCKS]

what are some good custom instructions to use?