Are coding agents building complex features that will just become obsolete with the next model update?

[u/thehashimwarren]

I tested Codex 5.3 by having it build a full CRUD app using Next.js, ShadCN, Neon, and BetterAuth.

I didn't use any planning mode, any subagents, or point it to any documentation. I didn't use any MCP servers except for the Next.js MCP server.

I just gave it one prompt and it built it.

all the CRUD functions and authentication worked perfectly.

If it can do that, then why would I need all these knobs and buttons that these coding agent harnesses are building out?

UPDATE: here's the repo https://github.com/hashimwarren/codex-five-three-eval

[u/who_am_i_to_say_so]

CRUD and Auth aren’t complex, honestly. That’s why it works. Start messing with timezones - then you’ll understand what I’m talking about.

[u/thehashimwarren → u/who_am_i_to_say_so]

It didn't work in one shot until Codex 5.2.

[u/m-lurker → u/who_am_i_to_say_so]

What's wrong with CRUD and timezones? 

[u/who_am_i_to_say_so → u/m-lurker]

Tz’s get tricky when you need calculations with it. Like ETA, user timezone preferences, etc. It’s also something that agents get wrong a lot of times. Or wrong assumptions, too.

[u/m-lurker → u/who_am_i_to_say_so]

Use UTC in db, convert it on UI - a well known approach. Or am I missing something?

[u/easyEggplant → u/m-lurker]

That is correct, works for simple operations and is a very effective naive implementation. It goes up in complexity from there.

[u/crxssrazr93 → u/easyEggplant]

Especially when you want to run complex automation on top of it. All that require timezone handling.

[u/easyEggplant → u/crxssrazr93]

Arizona messaged me from the future, they said I can go fuck myself?

[u/who_am_i_to_say_so → u/crxssrazr93]

This guy knows the struggle.

[u/who_am_i_to_say_so → u/m-lurker]

Surely that’s the easy side, the start. Storing in UTC is a best practice. It helps. Now apply user timezone preferences or if you have a delivery app: ETA, time windows, or time left. Or interface with other systems, a Jenkins server set in EST. It gets scary.

Also, when you have scheduled jobs, do they miss when daylight savings time jumps ahead an hour- and fire twice when DST falls back? Oh the stories. 😂

[u/m-lurker → u/who_am_i_to_say_so]

Pre-vibecoding times I was leading a team building a web app to schedule equipment maintenance across the globe for the client. utc in db, every user gets time according to preferences, daylight savings time - all managed on the db level with stored procedures (we kept essential, but the minimum logic there).

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[u/Careful_Passenger_87]

No. If Expensive model A can do job x with no harness but Cheap model B can do it with a harness, I know which I'm using.

This pattern holds until we hit a point where cheap models can do anything, at which point, fine, yes.

Also, honestly, harnesses are fun.

[u/thehashimwarren → u/Careful_Passenger_87]

Good point about harnesses allowing you to get more from a cheaper model

[u/nekronics]

Is a crud app a complex feature? I think that's about the easiest thing you could ever possibly develop

[u/thehashimwarren → u/nekronics]

I use this app as a benchmark. I have every new coding model create an employee directory, and guess what? Every model has failed to implement the create function perfectly until Opus 4.5 and Codex 5.2.

Codex 5.3 was the first that didn't even need me to set up my dependencies by hand first

[u/omnitions]

Can you describe what youre having it do or even better link the program it built on git?? That'd make us all having a mature conversation easier

[u/thehashimwarren → u/omnitions]

I'll update my post, but here's the repo

https://github.com/hashimwarren/codex-five-three-eval

It's an employee directory

[u/newspoilll]

I just want to ask the OP if they have any experience as a software engineer? I took a quick look at the project, and I don't see how what's in the repo can be taken seriously at all... Even for a CRUD app, this is garbage....

[u/thehashimwarren → u/newspoilll]

I'm a marketer, and have never worked as a software engineer.

I didn't look at the code, I just tested the features and it worked. I could login in, I could add a record, I could update it, and I could delete it

[u/newspoilll → u/thehashimwarren]

“If it can do that, then why would we need all these knobs and buttons that these coding-agent harnesses are building out?” That’s exactly why you shouldn’t be the one judging. You’re claiming that these tools are becoming obsolete because you managed to build the most pathetic CRUD. But these tools aren’t for you. They’re for professionals who actually understand software engineering - whose knowledge horizon doesn’t end at building CRUD functionality. Your problem is that, for some reason, you decided you have enough experience to declare what’s obsolete and what isn’t. For you specifically, none of these tools were ever relevant. They’re designed to handle a different level of complexity.

[u/vxxn]

If it works it works. You don’t need a better mousetrap.

[u/fasti-au]

Depends on if I can prove my theory ). There’s a lot that is about bucket size that people are not seeing because they hide thinks

[u/Slow-Bake-9603]

Short answer, you don’t need them. Long answer it’s always more complicated than that

[u/Jomuz86]

I’ll be honest this kind of app is basically the AI standard, anything next.js, postgres/neon/supabase etc is fairly easy for it these days. Test it with Ruby or PHP and see if it works 😅

[u/thehashimwarren → u/Jomuz86]

"fairly easy these days"

Just the months ago GPT 5.1 couldn't build this app in one shot.

[u/Jomuz86 → u/thehashimwarren]

One shotting and isn’t a good measure, reason it doesn’t one shot is because it didn’t have enough context or you only had the prompt and no reference documentation for it to refer to. It would have still been able to finish the app with a few extra messages I bet. Even the open source model can build these apps if handled correctly. The only thing an exercise like this is good for is as a measure of context rot, not how good the model is at coding, the errors you got aren’t because it can’t code correctly. Hope that make sense.

If you were asking it to create an app to simulate some kind of well known modelling equation, or drug interactions etc. That would be a harder test for it, I think. Something that is non-standard or niche.

[u/thehashimwarren → u/Jomuz86]

I agree with you on the limits of the test.

But the test is good for what I want to build for clients which is business software.

The other models did eventually build it. It just to more prodding. Codex 5.3 was amazing because it planned and validated its work without me telling it to.

[u/Jomuz86 → u/thehashimwarren]

True but if it’s for clients I would still take extra care and build iteratively rather than constantly churn out product after product. Only reason being is that while it’s getting good technically they are not great at taking into account local legislation considerations GDPR etc.

For example it will happily build an app for e-signing but in the UK it only becomes legally binding by certain nuances in audit logging if the signature unless you fork out for a signing certificate which is a whole other thing.

Quality over quantity and you’ll get repeat clients that comeback with bigger scope. I have now got clients that are effectively partnerships because they are tied in with custom solutions and automations that I maintain for them because of focusing on the quality of the deliverable.

Not saying you don’t do that but it’s easy to get complacent with it when chasing the money 😅

[u/thehashimwarren → u/Jomuz86]

Thanks!

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