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

#371

Post by yeasku » Wed, Jan 07, 2026, 1:38 AM UTC

simonw wrote: post #248

YesBox wrote: post #245

I've noticed a huge drop in negative comments on HN when discussing LLMs in the last 1-2 months. All the LLM coded projects I've seen shared so far[1] have been tech toys though. I've watched things pop up on my twitter feed (usually games related), then quietly go off air before reaching a gold release (I manually keep up to date with what I've found, so it's not the algorithm). I find this all very interesting: LLM…

It could be that the people who are focused on building monetizable products with LLMs don't feel the need to share what they are doing - they're too busy quietly getting on with building and marketing their products. Sharing how you're using these tools is quite a lot of work!

What would be more likely,

That people making startups is too bussy working to share it on HN or that AI is useless in real projects.

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

#372

Post by arcfour » Wed, Jan 07, 2026, 1:39 AM UTC

libraryofbabel wrote: post #311

ryandrake wrote: post #198

Earlier quoted context omitted.

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…

Thanks for posting this. It's a nice reminder that despite all the noise from hype-mongers and skeptics in the past few years, most of us here are just trying to figure this all out with an open mind and are ready to change our opinions when the facts change. And a lot of people in the industry that I respect on HN or elsewhere have changed their minds about this stuff in the last year, having previously been quite j…

The AI bubble is kind of like the dot-com bubble in that it's a revolutionary technology that will certainly be a huge part of the future, but it's still overhyped (i.e. people are investing without regard for logic).

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

#373

Post by andrekandre » Wed, Jan 07, 2026, 1:39 AM UTC

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…

  > we have another Claude Code agent that does a full PR review, following a detailed markdown checklist we’ve written for it.

(if you know) how is that compared to coderabbit? i'm seriously looking for something better rn...

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

#374

Post by winterbloom » Wed, Jan 07, 2026, 1:41 AM UTC

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…

Didn't feel like reading all this so I shortened it! sorry!

I shortened it for anyone else that might need it

----

Software engineers are sleeping on Claude Code agents. By teaching it your conventions, you can automate your entire workflow:

Custom Skills: Generates code matching your UI library and API patterns.

Quality Ops: Automates ESLint, doc syncing, and E2E coverage audits.

Agentic Reviews: Performs deep PR checks against custom checklists.

Smart Triage: Pre-analyzes tickets to give devs a head start.

Check out the showcase repo to see these patterns in action.

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

#375

Post by rectang » Wed, Jan 07, 2026, 1:41 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…

Adding capacity to software engineering through LLMs is like adding lanes to a highway — all the new capacity will be utilized.

By getting the LLM to keep changes minimal I’m able to keep quality high while increasing velocity to the point where productivity is limited by my review bandwidth.

I do not fear competition from junior engineers or non-technical people wielding poorly-guided LLMs for sustained development. Nor for prototyping or one offs, for that matter — I’m confident about knowing what to ask for from the LLM and how to ask.

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

#376

Post by fragmede » Wed, Jan 07, 2026, 1:43 AM UTC

babelfish wrote: post #352

estimator7292 wrote: post #345

Earlier quoted context omitted.

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.

[citation needed]

you mean https://www.tomshardware.com/tech-industry/data-centers-turn... ?

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

#377

Post by majormajor » Wed, Jan 07, 2026, 1:43 AM UTC

whatever1 wrote: post #329

multisport wrote: post #324

Earlier quoted context omitted.

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

The whole point of good engineering was not about just hitting the hard specs, but also have extendable, readable, maintainable code. But if today it’s so cheap to generate new code that meets updated specs, why care about the quality of the code itself? Maybe the engineering work today is to review specs and tests and let LLMs do whatever behind the scenes to hit the specs. If the specs change, just start from scrat…

"Write the specs and let the outsourced labor hit them" is not a new tale.

Let's assume the LLM agents can write tests for, and hit, specs better and cheaper than the outsourced offshore teams could.

So let's assume now you can have a working product that hits your spec without understanding the code. How many bugs and security vulnerabilities have slipped through "well tested" code because of edge cases of certain input/state combinations? Ok, throw an LLM at the codebase to scan for vulnerabilities; ok, throw another one at it to ensure no nasty side effects of the changes that one made; ok, add some functionality and a new set of tests and let it churn through a bunch of gross code changes needed to bolt that functionality into the pile of spaghetti...

How long do you want your critical business logic relying on not-understood code with "100% coverage" (of lines of code and spec'd features) but super-low coverage of actual possible combinations of input+machine+system state? How big can that codebase get before "rewrite the entire world to pass all the existing specs and tests" starts getting very very very slow?

We've learned MANY hard lessons about security, extensibility, and maintainability of multi-million-LOC-or-larger long-lived business systems and those don't go away just because you're no longer reading the code that's making you the money. They might even get more urgent. Is there perhaps a reason Google and Amazon didn't just hire 10x the number of people at 1/10th the salary to replace the vast majority of their engineering teams year ago?

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

#378

Post by jonstewart » Wed, Jan 07, 2026, 1:44 AM UTC

jaggederest wrote: post #342

wild_egg wrote: post #330

Earlier quoted context omitted.

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.

It can do this at the level of a function, and that's -useful-, but like the parent reply to top-level comment, and despite investing the time, using skills & subagents, etc., I haven't gotten it to do well with C++ or Rust projects of sufficient complexity. I'm not going to say they won't some day, but, it's not today.

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

#379

Post by verdverm » Wed, Jan 07, 2026, 1:51 AM UTC

HawtAds wrote: post #249

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…

Copilot and many coding agents truncates the context window and uses dynamic summarization to keep costs low for them. That's how they are able to provide flat fee plans. You can see some of the context limits here: https://models.dev/ If you want the full capability, use the API and use something like opencode. You will find that a single PR can easily rack up 3 digits of consumption costs.

Gerring off of their plans and prompts is so worth it, I know from experience, I'm paying less and getting more so far, paying by token, heavy gemini-3-flash user, it's a really good model, this is the future (distillations into fast, good enough for 90% of tasks), not mega models like Claude. Those will still be created for distillations and the harder problems

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

#380

Post by ern » Wed, Jan 07, 2026, 1:51 AM UTC

everfrustrated wrote: post #357

ern wrote: post #306

Earlier quoted context omitted.

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…

As someone coming from GitHub copilot in vscode and recently trying Claude Code plugin for vscode I don't get the fuss about Claude. Copilot has by far the best and most intuitive agent UI. Just make sure you're in agent mode and choose Sonnet or Opus models. I've just cancelled my Claude sub and gone back and will upgrade to the GH Pro+ to get more sonnet/opus.

I'd used both CC and Copilot Agent Mode in VSCode, but not the combination of CC + Opus 4.5, and I agree, I was happy enough with Copilot.

The gap didn't seem big, but in November (which admittedly was when Opus 4.5 was in preview on Copilot) Opus 4.5 with Copilot was awful.