Opus 4.5 is not the normal AI agent experience that I have had thus far • Hacker News Board

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#341

Post by rdedev » Wed, Jan 07, 2026, 1:01 AM UTC

ryandrake wrote: post #198

spaceman_2020 wrote: post #54

Earlier quoted context omitted.

I really think a lof of people tried AI coding earlier, got frustrated at the errors and gave up. That's where the rejection of all these doomer predictions comes from. And I get it. Coding with Claude Code really was prompting something, getting errors, and asking it to fix it. Which was still useful but I could see why a skilled coder adding a feature to a complex codebase would just give up Opus 4.5 really is at a…

This was me. I was a huge AI coding detractor on here for a while (you can check my comment history). But, in order to stay informed and not just be that grouchy curmudgeon all the time, I kept up with the models and regularly tried them out. Opus 4.5 is so much better than anything I've tried before, I'm ready to change my mind about AI assistance. I even gave -True Vibe Coding- a whirl. Yesterday, from a blank dire…

I decided to vibe code something myself last week at work. I've been wanting to create a poc that involves a coding agent create custom bokeh plots that a user can interact with and ask follow up questions. All this had to be served using a holoview panel library

At work I only have access to calude using the GitHub copilot integration so this could be the cause of my problems. Claude was able to get slthe first iteration up pretty quick. At that stage the app could create a plot and you could interact with it and ask follow up questions.

Then I asked it to extend the app so that it could generate multiple plots and the user could interact with all of them one at a time. It made a bunch of changes but the feature was never implemented. I asked it to do again but got the same outcome. I completely accept the fact that it could just be all because I am using vscode copilot or my promoting skills are not good but the LLM got 70% of the way there and then completely failed

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#342

Post by jaggederest » Wed, Jan 07, 2026, 1:02 AM UTC

wild_egg wrote: post #330

klaussilveira wrote: post #325

Earlier quoted context omitted.

I made a similar comment on a different thread, but I think it also fits here: I think the disconnect between engineers is due to their own context. If you work with frontend applications, specially React/React Native/HTML/Mobile, your experience with LLMs is completely different than the experience of someone working with OpenGL, io_uring, libev and other lower level stuff. Sure, Opus 4.5 can one shot Windows utilit…

I've had Opus 4.5 hand rolling CUDA kernels and writing a custom event loop on io_uring lately and both were done really well. Need to set up the right feedback loops so it can test its work thoroughly but then it flies.

Yeah I've handed it a naive scalar implementation and said "Make this use SIMD for Mac Silicon / NEON" and it just spits out a working implementation that's 3-6x faster and passes the tests, which are binary exact specifications.

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#343

Post by NSPG911 » Wed, Jan 07, 2026, 1:02 AM UTC

mcv wrote: post #133

Opus 4.5 ate through my Copilot quota last month, and it's already halfway through it for this month. I've used it a lot, for really complex code. And my conclusion is: it's still not as smart as a good human programmer. It frequently got stuck, went down wrong paths, ignored what I told it to do to do something wrong, or even repeat a previous mistake I had to correct. Yet in other ways, it's unbelievably good. I ca…

> Opus 4.5 ate theough my Copilot quota last month

Sure, Copilot charges 3x tokens for using Opus 4.5, but, how were you still able to use up half the allocated tokens not even one week into January?

I thought using up 50% was mad for me (inline completions + opencode), that's even worse

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#344

Post by bennydog224 » Wed, Jan 07, 2026, 1:04 AM UTC

Don't want to discredit Opus at all, it's easy at directed tasks but it's not the silver bullet yet.

It is best in its class, but trips up frequently with complicated engineering tasks involving dynamic variables. Think: Browser page loading, designing for a system where it will "forget" to account for race conditions, etc.

Still, this gets me very excited for the next generation of models from Anthropic for heavy tasks.

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#345

Post by estimator7292 » Wed, Jan 07, 2026, 1:04 AM UTC

whatever1 wrote: post #323

multisport wrote: post #320

What bothers me about posts like this is: mid-level engineers are not tasked with atomic, greenfield projects. If all an engineer did all day was build apps from scratch, with no expectation that others may come along and extend, build on top of, or depend on, then sure, Opus 4.5 could replace them. The hard thing about engineering is not "building a thing that works", its building it the right way, in an easily unde…

Their thesis is that code quality does not matter as it is now a cheap commodity. As long as it passes the tests today it's great. If we need to refactor the whole goddamn app tomorrow, no problem, we will just pay up the credits and do it in a few hours.

The fundamental assumption is completely wrong. Code is not a cheap commodity. It is in fact so disastrously expensive that the entire US economy is about to implode while we're unbolting jet engines from old planes to fire up in the parking lots of datacenters for electricity.

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#346

Post by tjr » Wed, Jan 07, 2026, 1:05 AM UTC

lacunary wrote: post #332

multisport wrote: post #324

Earlier quoted context omitted.

Yes agreed, and tbh even if that thesis is wrong, what does it matter?

in my experience, what happens is the code base starts to collapse under its own weight. it becomes impossible to fix one thing without breaking another. the coding agent fails to recognize the global scope of the problem and tries local fixes over and over. progress gets slower, new features cost more. all the same problems faced by an inexperienced developer on a greenfield project! has your experience been otherwi…

Why not have the LLM rewrite the entire codebase?

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#347

Post by Dusseldorf » Wed, Jan 07, 2026, 1:05 AM UTC

ern wrote: post #306

spaceman_2020 wrote: post #54

Earlier quoted context omitted.

I really think a lof of people tried AI coding earlier, got frustrated at the errors and gave up. That's where the rejection of all these doomer predictions comes from. And I get it. Coding with Claude Code really was prompting something, getting errors, and asking it to fix it. Which was still useful but I could see why a skilled coder adding a feature to a complex codebase would just give up Opus 4.5 really is at a…

I have been out of the loop for a couple of months (vacation). I tried Claude Opus 4.5 at the end of November 2025 with the corporate Github Copilot subscription in Agent mode and it was awful: basically ignoring code and hallucinating. My team is using it with Claude Code and say it works brilliantly, so I'll be giving it another go. How much of the value comes from Opus 4.5, how much comes from Claude Code, and how…

I suspect that's the other thing at play here; many people have only tried Copilot because it's cheap with all the other Microsoft subscriptions many companies have. Copilot frankly is garbage compared to Cursor/Claude, even with the same exact models.

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#348

Post by ivm » Wed, Jan 07, 2026, 1:06 AM UTC

klaussilveira wrote: post #325

OldGreenYodaGPT wrote: post #33

Most software engineers are seriously sleeping on how good LLM agents are right now, especially something like Claude Code. Once you’ve got Claude Code set up, you can point it at your codebase, have it learn your conventions, pull in best practices, and refine everything until it’s basically operating like a super-powered teammate. The real unlock is building a solid set of reusable “skills” plus a few agents for th…

I made a similar comment on a different thread, but I think it also fits here: I think the disconnect between engineers is due to their own context. If you work with frontend applications, specially React/React Native/HTML/Mobile, your experience with LLMs is completely different than the experience of someone working with OpenGL, io_uring, libev and other lower level stuff. Sure, Opus 4.5 can one shot Windows utilit…

> Mobile

From what I've seen, CC has troubles with the latest Swift too, partially because of it being latest and partially because it's so convoluted nowadays.

But it's übercharged™ for C#

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#349

Post by wilg » Wed, Jan 07, 2026, 1:07 AM UTC

multisport wrote: post #320

What bothers me about posts like this is: mid-level engineers are not tasked with atomic, greenfield projects. If all an engineer did all day was build apps from scratch, with no expectation that others may come along and extend, build on top of, or depend on, then sure, Opus 4.5 could replace them. The hard thing about engineering is not "building a thing that works", its building it the right way, in an easily unde…

you can definitely just tell it what abstractions you want when adding a feature and do incremental work on existing codebase. but i generally prefer gpt-5.2

Re: Opus 4.5 is not the normal AI agent experience that I have had thus far

#350

Post by sfink » Wed, Jan 07, 2026, 1:09 AM UTC

zmmmmm wrote: post #173

mcv wrote: post #133

Opus 4.5 ate through my Copilot quota last month, and it's already halfway through it for this month. I've used it a lot, for really complex code. And my conclusion is: it's still not as smart as a good human programmer. It frequently got stuck, went down wrong paths, ignored what I told it to do to do something wrong, or even repeat a previous mistake I had to correct. Yet in other ways, it's unbelievably good. I ca…

yes just using AI for code analysis is way under appreciated I think. Even the most sceptical people on using it for coding should try it out as a tool for Q&A style code interrogation as well as generating documentation. I would say it zero-shots documentation generation better than most human efforts would to the point it begs the question of whether it's worth having the documentation in the first place. Obviously…

(I haven't used AI much, so feel free to ignore me.)

This is one thing I've tried using it for, and I've found this to be very, very tricky. At first glance, it seems unbelievably good. The comments read well, they seem correct, and they even include some very non-obvious information.

But almost every time I sit down and really think about a comment that includes any of that more complex analysis, I end up discarding it. Often, it's right but it's missing the point, in a way that will lead a reader astray. It's subtle and I really ought to dig up an example, but I'm unable to find the session I'm thinking about.

This was with ChatGPT 5, fwiw. It's totally possible that other models do better. (Or even newer ChatGPT; this was very early on in 5.)

Code review is similar. It comes up with clever chains of reasoning for why something is problematic, and initially convinces me. But when I dig into it, the review comment ends up not applying.

It could also be the specific codebase I'm using this on? (It's the SpiderMonkey source.)