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marginalia_nu 12 hours ago

Expert reviews are just about the only thing that makes AI generated code viable, though doing them after the fact is a bit sketchy, to be efficient you kinda need to keep an eye on what the model is doing as its working.

Unchecked, AI models output code that is as buggy as it is inefficient. In smaller green field contexts, it's not so bad, but in a large code base, it's performs much worse as it will not have access to the bigger picture.

In my experience, you should be spending something like 5-15X the time the model takes to implement a feature on reviewing and making it fix its errors and inefficiencies. If you do that (with an expert's eye), the changes will usually have a high quality and will be correct and good.

If you do not do that due dilligence, the model will produce a staggering amount of low quality code, at a rate that is probably something like 100x what a human could output in a similar timespan. Unchecked, it's like having a small army of the most eager junior devs you can find going completely fucking ape in the codebase.

locusofself 11 hours ago | parent | next [-]

If you spend 5-15x the time reviewing what the LLM is doing, are you saving any time by using it?

happytoexplain 11 hours ago | parent | next [-]

No, but that's the crux of the AI problem in software. Time to write code was never the bottleneck. AI is most useful for learning, either via conversation or by seeing examples. It makes writing code faster too, but only a little after you take into account review. The cases where it shines are high-profile and exciting to managers, but not common enough to make a big difference in practice. E.g AI can one-shot a script to get logs from a paginated API, convert it to ndjson, and save to files grouped by week, with minimal code review, but only if I'm already experienced enough to describe those requirements, and, most importantly, that's not what I'm doing every day anyway.

brandensilva 9 hours ago | parent [-]

I'm finding it in some cases I'm dealing with even more code given how much code AI outputs. So yeah, for some tasks I find myself extremely fast but for others I find myself spending ungodly amounts of time reviewing the code I never wrote to make sure it doesn't destroy the project from unforseen convincing slop.

ritlo 11 hours ago | parent | prev | next [-]

A related Dirty Secret that's going to become clear from all this is that a very large proportion of code in the wild (yes, even in 2026—maybe not in FAANG and friends, IDK, but across all code that is written for pay in the entire economy) has limited or no automated test coverage, and is often being written with only a limited recorded spec that's usually fleshed out only to the degree needed (very partial) as a given feature is being worked on.

What do the relatively hands-off "it can do whole features at a time" coding systems need to function without taking up a shitload of time in reviews? Great automated test coverage, and extensive specs.

I think we're going to find there's very little time-savings to be had for most real-world software projects from heavy application of LLMs, because the time will just go into tests that wouldn't otherwise have been written, and much more detailed specs that otherwise never would have been generated. I guess the bright-side take of this is that we may end up with better-tested and better-specified software? Though so very much of the industry is used to skipping those parts, and especially the less-capable (so far as software goes) orgs that really need the help and the relative amateurs and non-software-professionals that some hope will be able to become extremely productive with these tools, that I'm not sure we'll manage to drag processes & practices to where they need to be to get the most out of LLM coding tools anyway. Especially if the benefit to companies is "you will have better tests for... about the same amount of software as you'd have written without LLMs".

We may end up stuck at "it's very-aggressive autocomplete" as far as LLMs' useful role in them, for most projects, indefinitely.

On the plus side for "AI" companies, low-code solutions are still big business even though they usually fail to deliver the benefits the buyer hopes for, so there's likely a good deal of money to be made selling companies LLM solutions that end up not really being all that great.

ansibsha 9 hours ago | parent | next [-]

> better-specified software

Code is the most precise specification we have for interfacing with computers.

6 hours ago | parent | next [-]
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tmaly 8 hours ago | parent | prev | next [-]

There are some cases where AI is generating binary machine code, albeit small amounts. What do we have when we don't have the code?

marginalia_nu 7 hours ago | parent [-]

Machine code is still code, even if the representation is a bit less legible than the punch cards we used to use.

interestpiqued 5 hours ago | parent | prev [-]

You’re missing the point of a spec

slopinthebag 10 hours ago | parent | prev | next [-]

Re. productivity, if LLM's are a genuine boost with 1/3 of the work, neutral 1/3 of the time, and actually worse 1/3 of the time, it's likely we aren't really seeing performance improvements as 1) people are using them for everything and b) we're still learning how to best use them.

So I expect over time we will see genuine performance improvements, but Amdahl's law dictates it won't be as much as some people and ceo's are expecting.

dboreham 7 hours ago | parent | prev | next [-]

Bingo. Hopefully there are some business opportunities for us in that truth.

_wire_ 11 hours ago | parent | prev [-]

> because the time will just go into tests that wouldn't otherwise have been written

Writing tests to ensure a program is correct is the same problem as writing a correct program.

Evaluating conformance is a different category of concern from ensuring correctness. Tests are about conformance not correctness.

Ensuring correct programs is like cleaning in the sense that you can only push dirt around, you can't get rid of it.

You can push uncertainty around and but you can't eliminate it.

This is the point of Gödel's theorem. Shannon's information theory observes similar aspects for fidelity in communication.

As Douglas Adams noted: ultimately you've got to know where your towel is.

layer8 6 hours ago | parent | next [-]

A competent programmer proves the program he writes correct in his head. He can certainly make mistakes in that, but it’s very different from writing tests, because proofs abstract (or quantify) over all states and inputs, which tests cannot do.

6 hours ago | parent | prev [-]
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shimman 11 hours ago | parent | prev | next [-]

These companies don't care about saving time or lowering operating costs, they have massive monopolies to subsidize their extremely poor engineering practices with. If the mandate is to force LLM usage or lose your job, you don't care about saving time; you care about saving your job.

One thing I hope we'll all collectively learn from this is how grossly incompetent the elite managerial class has become. They're destroying society because they don't know what to do outside of copying each other.

It has to end.

SchemaLoad 5 hours ago | parent | prev | next [-]

The submitter with their name on the Jira ticket saves time, the reviewer who has to actually verify the work loses a lot of time and likely just lets issues slip through.

marginalia_nu 11 hours ago | parent | prev | next [-]

To be honest, some times it's still beneficial.

For fairly straightforward changes it's probably a wash, but ironically enough it's often the trickier jobs where they can be beneficial as it will provide an ansatz that can be refined. It's also very good at tedious chores.

misnome 9 hours ago | parent [-]

And spotting stuff in review! Sometimes it’s false positives but on several occasions I’ve spent ~15-30 minutes teaching-reviewing a PR in person, checked afterwards and it matched every one of the points.

bluGill 11 hours ago | parent | prev [-]

Some, but not very much. Writing code is hard. Ai will do a lot of tedious code that you procrastinate writing.

hard24 11 hours ago | parent [-]

Also when you are writing code yourself you are implicitly checking it whilst at the back of your mind retaining some form of the entire system as a whole.

People seem to gloss over this... As a CEO if people don't function like this I'd be awake at night sweating.

bonesss 10 hours ago | parent | next [-]

That’s the reverse-centaur issue I see: humans are not great at repetitive nuanced similar seeming tasks, putting the onus on humans to retroactively approve high volumes of critical code has them managing a critical failure mode at their weakest and worst. Automated reviews should be enhancing known good-faith code, manual reviews of high volume superficially sound but subversive code is begging for issues over time.

Which results the software engineering issue I’m not seeing addressed by the hype: bugs cost tens to hundreds of times their coding cost to resolve if they require internal or external communication to address. Even if everyone has been 10x’ed, the math still strongly favours not making mistakes in the first place.

An LLM workflow that yields 10x an engineer but psychopathically lies and sabotages client facing processes/resources once a quarter is likely a NNPP (net negative producing programmer), once opportunity and volatility costs are factored in.

demosito666 6 hours ago | parent | next [-]

> Even if everyone has been 10x’ed, the math still strongly favours not making mistakes in the first place

The math depends on importance of the software. A mistake in a typical CRUD enterprise app with 100 users has zero impact on anything. You will fix it when you have time, the important thing is that the app was delivered in a week a year ago and was solving some problem ever since. It has already made enormous profit if you compare it with today’s (yesterday’s ?) manual development that would take half a year and cost millions.

A mistake in a nuclear reactor control code would be a total different thing. Whatever time savings you made on coding are irrelevant if it allowed for a critical bug to slip through.

Between the two extremes you thus have a whole spectrum of tasks that either benefit or lose from applying coding with LLMs. And there are also more axes than this low to high failure cost, which also affect the math. For example, even non-important but large app will likely soon degrade into unmanageable state if developed with too little human intervention and you will be forced to start from scratch loosing a lot of time.

bluGill 6 hours ago | parent | prev [-]

I have found ai extreemly good at finding all those really hard bugs though. Ai is a greater force multiplier when there is a complex bug than in gneen field code.

bluGill 10 hours ago | parent | prev | next [-]

Sortof. I work on a system too large for anyone to know the whole thing. Often people who don't know each other do something that will break the other. (Often because of the number of different people - most individuals go years between this)

raw_anon_1111 9 hours ago | parent | prev [-]

No I’m keeping up with the system as a whole because I’m always working at a system level when I’m using AI instead of worrying about the “how”

ansibsha 9 hours ago | parent [-]

No you’re not. The “how” is your job to understand, and if you don’t you’ll end up like the devs in the article.

We as an industry have been able to offload a lot of “how” via deterministic systems built by humans with expert understanding. LLMs give you the illusion of this.

raw_anon_1111 9 hours ago | parent [-]

No in my case the “how” is

1. I spoke to sales to find out about the customer

2. I read every line of the contract (SOW)

3. I did the initial requirements gathering over a couple of days with the client - or maybe up to 3 weeks

3. I designed every single bit of AWS architecture and code

4. I did the design review with the client

5. I led the customer acceptance testing

> We as an industry have been able to offload a lot of “how” via deterministic systems built by humans with expert understanding. LLMs

I assure you the mid level developers or god forbid foreign contractors were not “experts” with 30 years of coding experience and at the time 8 years of pre LLM AWS experience. It’s been well over a decade - ironically before LLMs - that my responsibility was only for code I wrote with my own two hands

ansibsha 5 hours ago | parent | next [-]

Yes, and trusting an LLM here is not a good idea. You know it will make important mistakes.

I’m not saying trusting cheap devs is a good idea either. I do think cheap devs are actually at risk here.

raw_anon_1111 4 hours ago | parent [-]

I am not “trusting” either - I’m validating that they meet the functional and non functional requirements just like with an LLM. I have never blindly trusted any developer when my neck was the one on the line in front of my CTO/director or customer.

I didn’t blindly trust the Salesforce consultants either. I also didn’t verify every line of oSql (not a typo) they wrote.

icedchai 3 hours ago | parent [-]

Actually, it's SOQL. I did Salesforce crap for many years.

6 hours ago | parent | prev [-]
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rectang 11 hours ago | parent | prev | next [-]

> Expert reviews are just about the only thing that makes AI generated code viable

I disagree, in the sense that an engineer who knows how to work with LLMs can produce code which only needs light review.

* Work in small increments

* Explicitly instruct the LLM to make minimal changes

* Think through possible failure modes

* Build in error-checking and validation for those failure modes

* Write tests which exercise all paths

This is a means to produce "viable" code using an LLM without close review. However, to your point, engineers able to execute this plan are likely to be pretty experienced, so it may not be economically viable.

marginalia_nu 11 hours ago | parent [-]

By the time you're working in increments small enough that it doesn't introduce significant issues, you really might as well write the code yourself.

rectang 11 hours ago | parent [-]

That's not my experience — I'm significantly faster while guiding an LLM using this methodology.

The gains are especially notable when working in unfamiliar domains. I can glance over code and know "if this compiles and the tests succeed, it will work", even if I didn't have the knowledge to write it myself.

rsynnott 6 hours ago | parent | next [-]

> I can glance over code and know "if this compiles and the tests succeed, it will work", even if I didn't have the knowledge to write it myself.

... Errr... Yeah, that's not a great approach, unless you are defining 'work' extremely vaguely.

rectang 4 hours ago | parent [-]

Haha I have usually found myself on the conservative side of any engineering team I’ve been on, and it’s refreshing to catch some flak for perceived carelessness.

I still make an effort to understand the generated code. If there’s a section I don’t get, I ask the LLM to explain it.

Most of the time it’s just API conventions and idioms I’m not yet familiar with. I have strong enough fundamentals that I generally know what I’m trying to accomplish and how it’s supposed to work and how to achieve it securely.

For example, I was writing some backend code that I knew needed a nonce check but I didn’t know what the conventions were for the framework. So I asked the LLM to add a nonce check, then scanned the docs for the code it generated.

johnnyanmac 9 hours ago | parent | prev | next [-]

> I'm significantly faster while guiding an LLM using this methodology.

https://metr.org/blog/2025-07-10-early-2025-ai-experienced-o...

>When developers are allowed to use AI tools, they take 19% longer to complete issues—a significant slowdown that goes against developer beliefs and expert forecasts. This gap between perception and reality is striking: developers expected AI to speed them up by 24%, and even after experiencing the slowdown, they still believed AI had sped them up by 20%.

If we're being honest with ourselves, it's not making devs work faster. It at best frees their time up so they feel more productive.

rectang 8 hours ago | parent | next [-]

Fair point. I have definitely caught myself taking longer to revise a prompt repeatedly after the AI gets things wrong several times than it would have taken to write the code myself.

I'd like to think that I have this under control because the methodology of working in small increments helps me to recognize when I've gotten stuck in an eddy, but I'll have to watch out for it.

I still maintain that the LLM is saving me time overall. Besides helping in unfamiliar domains, it's also faster than me at leaf-node tasks like writing unit tests.

tmaly 8 hours ago | parent | prev [-]

How long will that 19% hold as models grow in capability?

johnnyanmac 8 hours ago | parent [-]

I'm a bit tired of waiting for "tomorrow", so I'll just live in today's world. We'll burn that bridge when we get to it.

marginalia_nu 11 hours ago | parent | prev [-]

That's where the Gell-Mann amnesia will get you though. As much it trips up on the domains you're familiar with, it also trips up in unfamiliar domains. You just don't see it.

rectang 11 hours ago | parent | next [-]

You're not telling me anything I don't know already. Only a person who accepts that they're fallible can execute this methodology anyway, because that's the kind of mentality that it takes to think through potential failure modes.

Yes, code produced this way will have bugs, especially of the "unknown unknown" variety — but so would the code that I would have written by hand.

I think a bigger factor contributing to unforeseen bugs is whether the LLM's code is statistically likely to be correct:

* Is this a domain that the LLM has trained on a lot? (i.e. lots of React code out there, not much in your home-grown DSL)

* Is the codebase itself easy to understand, written with best practices, and adhering to popular conventions? Code which is hard for humans to understand is also hard for an LLM to understand.

marginalia_nu 11 hours ago | parent [-]

Right, I think the latter part is my concern with AI generated code. Often it isn't easy to read (or as easy to read as it could be), and the harder it is to navigate, the more code problems the AI model introduces.

It introduces unnecessary indirection, additional abstractions, fails to re-use code. Humans do this too, but AI models can introduce this type of architectural rot much faster (because it's so fast), and humans usually notice when things start to go off the rails, whereas an AI model will just keep piling on bad code.

rectang 10 hours ago | parent [-]

I agree that under default settings, LLMs introduce way too many changes and are way too willing to refactor everything. I was only able to get the situation under control by adding this standing instruction:

    ---
    applyTo: '**'
    ---
    By default:
    Make the smallest possible change.
    Do not refactor existing code unless I explicitly ask.
Under this, Claude Opus at least produces pretty reliable code with my methodology even under surprisingly challenging circumstances, and recent ChatGPTs weren't bad either (though I'm no longer using them). Less powerful LLMs struggle, though.
raw_anon_1111 10 hours ago | parent | prev [-]

Besides building web apps for internal use, I’m never going to let AI architect something I’m not familiar with. I could care less whether it uses “clean code” or what design pattern it uses. Meaning I will go from an empty AWS account to fully fledged app + architecture because I’ve been coding for 30 years and dealing with every book and cranny of AWS for a decade.

But I would never do the same for Azure.

jonnycoder 10 hours ago | parent | prev | next [-]

I tend to agree. I spent a lot of time revising skills for my brownfield repo, writing better prompts to create a plan with clear requirements, writing a skill/command to decompose a plan, having a clear testing skill to write tests and validate, and finally having a code reviewer step using a different model (in my case it's codex since claude did the development). My last PR was as close to perfect as I have got so far.

Skidaddle 11 hours ago | parent | prev | next [-]

Just lead with “You are an expert software engineer…”, easy!

UncleMeat 7 hours ago | parent | prev | next [-]

Sadly, the way people become expert in a codebase is through coding. The process of coding is the process of learning. If we offload the coding to AI tools we will never be as expert in the codebase, its complexity, its sharp corners, or its unusual requirements. While you can apply general best practices for a code review you can never do as much as if you really got your hands dirty first.

"Seniors will do expert review" will slowly collapse.

raw_anon_1111 11 hours ago | parent | prev [-]

In my experience, inefficient code is rarely the issue outside of data engineering type ETL jobs. It’s mostly architectural. Inefficient code isn’t the reason your login is taking 30 seconds. Yes I know at Amazon/AWS scale (former employee) every efficiency matters. But even at Salesforce scale, ringing out every bit of efficiency doesn’t matter.

No one cares about handcrafted artisanal code as long as it meets both functional and non functional requirements. The minute geeks get over themselves thinking they are some type of artists, the happier they will be.

I’ve had a job that requires coding for 30 years and before ther I was hobbyist and I’ve worked for from everything from 60 person startups to BigTech.

For my last two projects (consulting) and my current project, while I led the project, got the requirements, designed the architecture from an empty AWS account (yes using IAC) and delivered it. I didn’t look at a line of code. I verified the functional and non functional requirements, wrote the hand off documentation etc.

The customer is happy, my company is happy, and I bet you not a single person will ever look at a line of code I wrote. If they do get a developer to take it over, the developer will be grateful for my detailed AGENTS.md file.

sarchertech 10 hours ago | parent | next [-]

It’s not about hand crafted code or even code performance.

We know from experimentation that agents will change anything that isn’t nailed down. No natural language spec or test suite has ever come close to fully describing all observable behaviors of a non-trivial system.

This means that if no one is reviewing the code, agents adding features will change observable behaviors.

This gets exposed to users as churn, jank, and broken work flows.

raw_anon_1111 9 hours ago | parent [-]

Thats easy enough to prevent with modular code that’s what “plan mode” is for. But you probably never worked with a bunch of C# developers using R#

sarchertech 9 hours ago | parent [-]

1. Preventing agents from crossing boundaries, creating implicit and explicit dependencies, and building false layers requires much more human control over every PR and involvement with the code than you seem to espouse.

2. Assuming that techniques that work with human developers that have severely impaired judgement but are massively faster at producing code is a bad idea.

3. There’s no way you have enough experience with maintaining code written in this way to confidently hand wave away concerns.

raw_anon_1111 9 hours ago | parent [-]

Absolutely no one in the value chain cares about “how many layers of abstractions your code has - not your management or your customers. They care about functional and none functional requirements

sarchertech 6 hours ago | parent [-]

Of course they don’t. Please reread what I said, give it the slightest bit of thought, and re-respond if you want a response from me.

raw_anon_1111 6 hours ago | parent [-]

By definition, coding agents are right now the worse they will ever be and the industry as a whole by definition is the least experienced it will ever be at using then.

So many people on HN are so insulted that the people who put money in our bank accounts and in some cases stock in our brokerage accounts ever cared about their bespoke clean code, GOF patterns and they never did. LLM just made it more apparent.

It’s always been dumb for PR to be focused on for loops vs while loops instead of focusing on whether functional and non functional requirements are met

sarchertech 3 hours ago | parent [-]

Wow you have completely lost the plot. It’s like you’re a bot that’s mixing up who he’s replying to.

raw_anon_1111 3 hours ago | parent [-]

Just maybe you aren’t making the strong argument you think you are making

hard24 11 hours ago | parent | prev | next [-]

"No one cares about handcrafted artisanal code as long as it meets both functional and non functional requirements"

Speak for yourself. I don't hire people like you.

raw_anon_1111 11 hours ago | parent [-]

And guess what? You probably don’t pay as much as I make now either…

Even in late 2023 with the shit show of the current market, I had no issues having multiple offers within three weeks just by reaching out to my network and companies looking for people with my set of skills.

hard24 11 hours ago | parent [-]

I field a small team of experts who are paid upwards of a million GBP in cold-hard cash in London. Not stock. Cash.

You sound like a bozo, I can sniff it through my screen.

zepolen 6 hours ago | parent [-]

This sounds like a place I want to work at.

YCpedohaven 11 hours ago | parent | prev [-]

[flagged]

raw_anon_1111 11 hours ago | parent [-]

Yes because I didn’t check to see if Claude code used a for loop instead of a while loop? Or that it didn’t use my preferred GOF pattern and didn’t use what I read in “Clean Code”?

Guess what? I also stopped caring how registers are used and counting clock cycles in my assembly language code like it’s the 80s and I’m still programming on a 1Mhz 65C02

icedchai 9 hours ago | parent [-]

I can see the argument both ways. Some code is just not worth looking at...

But do you look at any of the AI output? Or is it just "it works, ship it"?

raw_anon_1111 7 hours ago | parent [-]

My last project was basically an ETL implementation on AWS starting with an empty AWS account and a internal web admin site that had 10 pages. I am yada yada yadaing over a little bit.

What I checked.

1. The bash shell scripts I had it write as my integration test suite

2. To make sure it wasn’t loading the files into Postgres the naive way -loading the file from S3 and doing bulk inserts instead of using the AWS extension that lets it load directly from S3. It’s the differ xe between taking 20 minutes and 20 seconds.

3. I had strict concurrency and failure recovery requirements. I made sure it was done the right way.

4. Various security, logging, log retention requirements

What I didn’t look at - a line of the code for the web admin site. I used AWS Cognito for authentication and checked to make sure that unauthorized users couldn’t use the website. Even that didn’t require looking at the code - I had automated tests that tested all of the endpoints.

icedchai 5 hours ago | parent [-]

This all makes sense.

I've witnessed human developers produce incredibly convoluted, slow "ETL pipelines" that took 10+ minutes to load single digit megabytes of data. It could've been reduced to a shell script that called psql \copy.