I'd like to highlight a different part of the article:
> In general, when I talk to software folks about testing, I'm coming from such a different place that they immediately look at me like I'm an alien, so let's talk about how we tested at this hardware company I worked for, Centaur, which informs my biases about how I like to work. Some of the things that we did that were or are unorthodox in the software world are:
> Hired dedicated QA / test engineers, with testing being a first-class career path on par with being a developer - No code review by default - Virtually no hand-written tests - Constant testing via what programmers sometimes called property based testing, randomized testing, fuzzing, etc., although we just called those tests (hand-written tests were called "hand tests"). - Large regeression test suite (3 months wall clock to execute on compute farm) - No unit tests
Anybody here tried that (or a similar) approach? Especially going all-in on property based testing and fuzzing with no unit tests.
I tried that approach somewhere before and the initial results were promising, but ran into political issues so the idea was canned.
No code review by default goes against actual established evidence (there is little of this for software development practice) that code review is the best way to find defects.
I always get the impression from using hardware and other anecdotes like this that it is rare for hardware companies to know how to do software development well because their core competency is hardware. In fairness, it is uncommon for software companies to know how to do software development well.
Every form of testing has its value when done well and they are using several forms that most software developers don't use- probably helps make up for the lack of code review and unit tests. But if they incorporated code review and unit tests their software would likely be even higher quality.
Property based testing is amazing, but it won't provide full coverage.
Regression suites are amazing, but generally the most expensive form of testing in terms of time to write and maintain tests and time to run them.
Today AI can crank out unit tests so its silly not to have them.
I bake MCP tools into everything now, including doing screenshots. Any LLM can run just about every function, including resizing the window. I just watched Fabel 5 do a full usability test on a new project, copying the release cycle for my agentic terminal, relaunching the app like 20 times as it went, ensuring the move to a built and signed release was working. It installed the program like 5 times (something I do daily multiple times).
I noticed map tiles were not working and started to tell it, but then all of a sudden they reappeared and checking the logs it had found the issue and autocorrected itself.
The key here is feedback loops and systems annealing.
As for Dan, my God I love this guy. Glad someone posted it!
I really wonder what "randomixed testing" looks like in practice. What is the measure of success/failure?
I undrestand for fuzzing you have a very basic "doesn't crash" metric. Property based tests.... you gotta write properties for the PBTs to work on. What is the randomized testing hitting?
Should be, judging by their LinkedIn from the bottom of the page (Centaur Technology - Member of Technical Staff: 2005 - 2013)
This is a blast from the past. Centaur was doing VIA Technology's CPUs, and I was at VIA (in Taiwan) while this author was in Centaur (in the US). I was on the embedded side, but I remember some distinct collaborations with the US team, so there's a non-zero chance to have crossed path.
OP's alt text makes it clear that by "Galapagos Island" they mean Vancouver. I assumed that this was some sort of local nickname, but all of the references to "Galápagos of Canada" I could find are talking about Haida Gwaii instead.
Realizing he's just using it to mean remote place in terms of AI bubble (Vancouver! What does that make all the other places that are not major tech hubs?) was a bummer.
Who cares about AI, I wanted to read about living in Galapagos
I'm saddened to have gotten this far and had my bubble burst, I legitimately thought someone was on the real GI's and was able to compose such a treatise, nevertheless.
A lot of the crazy ideas seem to have melted away in the face of massive context sizes. Today, I can put roughly a megabyte of utf8 text into my system prompt before things start to get weird.
That is a massive amount of information even if we are being sloppy with it. You can read The Hobbit and the first Harry Potter book cover-to-cover and still have room to spare. I would deeply struggle to develop a world model this detailed for any business. Anything that needs to get more specific than these narratives can be a SQL query tool into the data warehouse, grep over the codebase, MS graph API lookup, etc.
Giving the business a balanced way to collaborate over this one shared model of the world is a new challenge I am beginning to engage with. I've also noticed that the world model will compound on itself in terms of self-detection of update opportunities. The more constraints there are, the more likely we appear to violate one.
I learned some nuance. Small context is important if the context isn't cachable. If most of it is the same prefix every time, the situation changes pretty significantly.
> melted away in the face of massive context sizes
If only. There is a huge difference between "Gives good responses/can easily spot things within N context size" and "Technically works but sucks within N context size", almost all models basically become cave-people once you go beyond 50% of the "supported" context size, meaning while they may technically work with 1 million output tokens, those last 500K tokens are gonna be massively "dumber" than the first 500k tokens.
I can agree with Dan on two things: LLMs do often produce incorrect results and that it's still useful for productivity when used in moderation. For me the wrong results actually cause some kind of ragebait response so I become much more motivated to learn more about the subject to actually generate correct response. After I've learnt the subject area enough I find I'm better off having LLM review my code instead of writing it.
I haven't even begun to try to comprehend how to use fuzzing testing to improve the ability to find bugs, but it sounds really interesting. I've seen mutation testing to be very useful for finding gaps in tests, so I can only imagine that fuzzing + LLMs might produce insane results.
There's a lot people will do for equal quality and faster work at a 100th the cost. Like being OK with character changing and adapting to it. You are not seeing this in your workplace?
Fable changes the game yet again, because it's API-only.
You're not likely to want to run Fable in a loop any more than you want to take a bunch of dollar bills and light them on fire. Every invocation of Fable has to be intentional, its context carefully managed. I feel like a babysitter.
Every metric becomes a target (Goodhart's law). Also, the plural of anecdote is not data.
The subjective anecdotes from HN users matter because they are not data and are much harder to game. Not impossible to game, always be aware of users with low karma, but more difficult than gaming a benchmark.
But they’re not at all meaningful after a certain point, because they’re not even attempting to explain why it works well for them. It’s just noise like this.
I make Claude, Codex and Gemini review each other's design plan and implementation. Each always found a lot of things the others missed...until Fable 5 came out. Whatever plan or code Fable 5 comes up with, now it's very hard for Codex and Gemini to find any serious hole in it.
Anthropic says the change is about capacity and is temporary. In its launch announcement on June 9, 2026, it says:
"After this point—when sufficient capacity allows us to do so—we aim to restore Fable 5 as a standard part of subscription plans. We intend to do this as quickly as we can."
They can’t keep their current models working on subscriptions[1], so we’ll see if this is marketing or not in the future.
It’s smart to tease it no matter what, ”insert classic first hit is free drug reference”.
I just had Fable run overnight in a loop, and it fixed ~150 compiler crashing bugs that Opus had kept deferring.
I wouldn't start with Fable - when I use burndown loops I tend to include instructions to document progress and set aside anything that turns out to be harder than expected, and solve the easy stuff first. When a model runs out of easy stuff and start struggling to make progress on what is left, I can let it keep churning on that - they get there eventually - or I can bump it up to a smarter model if one is available.
Opus had churned a week driving down spec failures, and did a great job. The 150 Fable took overnight were the ones Opus had kept putting aside.
I agree with you that you don't need fable for everything, and you have to be careful on what you run it on. CRUD stuff, sure even the small models can do it. But there certainly are tasks that are very much suited for the absolute SotA and you'd leave money on the table by not using it. And how much a task is worth is dependant on how much it improves your bottom line. So the cost/token becomes largely irrelevant.
Let's take this [1] benchmark. A bit more context here [2].
Here models are asked to create kernels for running inference on models. This is a benchmark perfectly suited and highly relevant right now. It's easily verifiable, an active are of research, and the results are immediately useful.
Say you have 1 unit of compute, it costs 300k $ and serves 1x users. In comes Fable and after one session it gives you 30% speed-up on your 1 unit of compute. It can now serve 1.3x users. How much is that one session worth for you? How much is it worth for a company using 10 units? 100 units? How much is it worth for a hyper-scaler running 10.000 units? How much is it worth for a lab that trains the next frontier model and then serves it from 100.000 units? 30% is relative. And the cost for one session is really meaningless. It can cost 1m$ / session and it would still be worth it for someone.
> You're not likely to want to run Fable in a loop any more than you want to take a bunch of dollar bills and light them on fire. Every invocation of Fable has to be intentional, its context carefully managed.
Eh, that's just because it's the current frontier model. Give it a few weeks, and prices will drop.
API prices are the new normal. I doubt that prices will drop to the level of the subsidized subscriptions any time soon. Usage is growing exponentially but capacity cannot. There is no reason for them to waste their capacity on subscription users if they can sell that same capacity to API users.
Like with Uber and Lyft, the low prices were a fight for market share, but now they have successfully captured that market share the focus changes to balancing their books.
I suspect subscriptions will stay. But you will see more and more roadblocks that the 'barely goes to the gym' user barely notices, but that the power user will chafe under.
I make that prediction, because the people who pay for subscriptions but only use them moderately at best are truly profitable.
I'd like to highlight a different part of the article:
> In general, when I talk to software folks about testing, I'm coming from such a different place that they immediately look at me like I'm an alien, so let's talk about how we tested at this hardware company I worked for, Centaur, which informs my biases about how I like to work. Some of the things that we did that were or are unorthodox in the software world are:
> Hired dedicated QA / test engineers, with testing being a first-class career path on par with being a developer - No code review by default - Virtually no hand-written tests - Constant testing via what programmers sometimes called property based testing, randomized testing, fuzzing, etc., although we just called those tests (hand-written tests were called "hand tests"). - Large regeression test suite (3 months wall clock to execute on compute farm) - No unit tests
Anybody here tried that (or a similar) approach? Especially going all-in on property based testing and fuzzing with no unit tests.
I tried that approach somewhere before and the initial results were promising, but ran into political issues so the idea was canned.
No code review by default goes against actual established evidence (there is little of this for software development practice) that code review is the best way to find defects.
I always get the impression from using hardware and other anecdotes like this that it is rare for hardware companies to know how to do software development well because their core competency is hardware. In fairness, it is uncommon for software companies to know how to do software development well.
Every form of testing has its value when done well and they are using several forms that most software developers don't use- probably helps make up for the lack of code review and unit tests. But if they incorporated code review and unit tests their software would likely be even higher quality.
Property based testing is amazing, but it won't provide full coverage. Regression suites are amazing, but generally the most expensive form of testing in terms of time to write and maintain tests and time to run them.
Today AI can crank out unit tests so its silly not to have them.
I bake MCP tools into everything now, including doing screenshots. Any LLM can run just about every function, including resizing the window. I just watched Fabel 5 do a full usability test on a new project, copying the release cycle for my agentic terminal, relaunching the app like 20 times as it went, ensuring the move to a built and signed release was working. It installed the program like 5 times (something I do daily multiple times).
I noticed map tiles were not working and started to tell it, but then all of a sudden they reappeared and checking the logs it had found the issue and autocorrected itself.
The key here is feedback loops and systems annealing.
As for Dan, my God I love this guy. Glad someone posted it!
I feel like Dan is one of the most consistently interesting writers in tech at the moment.
This is most likely because we take similar approaches towards things.
I really wonder what "randomixed testing" looks like in practice. What is the measure of success/failure?
I undrestand for fuzzing you have a very basic "doesn't crash" metric. Property based tests.... you gotta write properties for the PBTs to work on. What is the randomized testing hitting?
Dogfood everything, all the time.
The first thing I started wondering was "is this the same Centaur that comes up as 'CentaurHauls' on a CPUID (EAX=0)?"
Should be, judging by their LinkedIn from the bottom of the page (Centaur Technology - Member of Technical Staff: 2005 - 2013)
This is a blast from the past. Centaur was doing VIA Technology's CPUs, and I was at VIA (in Taiwan) while this author was in Centaur (in the US). I was on the embedded side, but I remember some distinct collaborations with the US team, so there's a non-zero chance to have crossed path.
OP's alt text makes it clear that by "Galapagos Island" they mean Vancouver. I assumed that this was some sort of local nickname, but all of the references to "Galápagos of Canada" I could find are talking about Haida Gwaii instead.
I think it’s just a metaphor for being isolated from the wider tech community.
Nobody calls it that.
Yeah I was like “woa a PGConf on the galapagos, i gotta get my ass to one if those!”
Realizing he's just using it to mean remote place in terms of AI bubble (Vancouver! What does that make all the other places that are not major tech hubs?) was a bummer.
Who cares about AI, I wanted to read about living in Galapagos
I visited a decade or so ago. Most of the islands you are forbidden from staying overnight on. No running water. No power. No phone signal.
You're going to need a big big solar panel to run local inference during the day, but luckily there is plenty of sun!
Looks like there is Starlink though! https://dplnews.com/cnt-ecuador-y-starlink-conectan-las-4-is...
I'm saddened to have gotten this far and had my bubble burst, I legitimately thought someone was on the real GI's and was able to compose such a treatise, nevertheless.
A lot of the crazy ideas seem to have melted away in the face of massive context sizes. Today, I can put roughly a megabyte of utf8 text into my system prompt before things start to get weird.
That is a massive amount of information even if we are being sloppy with it. You can read The Hobbit and the first Harry Potter book cover-to-cover and still have room to spare. I would deeply struggle to develop a world model this detailed for any business. Anything that needs to get more specific than these narratives can be a SQL query tool into the data warehouse, grep over the codebase, MS graph API lookup, etc.
Giving the business a balanced way to collaborate over this one shared model of the world is a new challenge I am beginning to engage with. I've also noticed that the world model will compound on itself in terms of self-detection of update opportunities. The more constraints there are, the more likely we appear to violate one.
You’re forgetting that keeping the context small is better economically and delivers better results.
I learned some nuance. Small context is important if the context isn't cachable. If most of it is the same prefix every time, the situation changes pretty significantly.
Forgetting? I think you mean to say your advice was auto-compacted to keep our context small and deliver better results.
> melted away in the face of massive context sizes
If only. There is a huge difference between "Gives good responses/can easily spot things within N context size" and "Technically works but sucks within N context size", almost all models basically become cave-people once you go beyond 50% of the "supported" context size, meaning while they may technically work with 1 million output tokens, those last 500K tokens are gonna be massively "dumber" than the first 500k tokens.
There's at least one benchmark that attempts to measure this, but it has been running for a year plus so it's quite infrequently updated now.
https://fiction.live/stories/Fiction-liveBench-Mar-25-2025/o...
I don’t find that to be true?
I can agree with Dan on two things: LLMs do often produce incorrect results and that it's still useful for productivity when used in moderation. For me the wrong results actually cause some kind of ragebait response so I become much more motivated to learn more about the subject to actually generate correct response. After I've learnt the subject area enough I find I'm better off having LLM review my code instead of writing it.
I haven't even begun to try to comprehend how to use fuzzing testing to improve the ability to find bugs, but it sounds really interesting. I've seen mutation testing to be very useful for finding gaps in tests, so I can only imagine that fuzzing + LLMs might produce insane results.
There is a reasone we use left and right margin/padding.
This blog is quite unreadable for 27/32" monitors.
The point of a wide monitor for me is to have two 720 wide windows side by side, not a single gigantic 1440 window with impossibly long lines.
Toggle to "reader view" or resize your window. It is up to you and really isn't that hard.
There’s a reason not to maximize your browser windows. How do you handle HN threads on that monitor?
Why would you work with anything other than maximized windows unless you have a super ultra wide display?
URL typo: "hange how he works](/productivity-velocity/)". (I make this kind of Markdown syntax error all the time and set up a lint for '](/'.)
You should talk to https://www.mechanize.work/ for sponsorship/credits and about environments.
It's really coming down to "Do we want to subscribe to a human with a salary of many ~$10000(s) ", or "Do we spend 100(s)$ on an AI subscription"
Even with it's issues, the latest models are going to disrupt the labor economics.
It’s going to even out on both eventually, the diffusion will be painful though.
On the other hand, you have many more humans to choose from than models, and they don’t change their character every few months.
There's a lot people will do for equal quality and faster work at a 100th the cost. Like being OK with character changing and adapting to it. You are not seeing this in your workplace?
This seems like the beginnings of AI psychosis, tbh.
How do you figure?
The immensely desperate search for meaning in the mundane, perhaps?
TW;DR (too wide didn't read) ;)
It's "Galapagos" or "Galápagos," not "Galapogos."
He's not referring to the real islands, but rather the state of mind imposed upon existence on Vancouver Island.
You miswrote OP’s miswriting in the third version :)
Argh, autocorrect got me. Thanks, fixed.
Aaand now OP has fixed it in the HN post title. Still wrong in the linked article.
Fable changes the game yet again, because it's API-only.
You're not likely to want to run Fable in a loop any more than you want to take a bunch of dollar bills and light them on fire. Every invocation of Fable has to be intentional, its context carefully managed. I feel like a babysitter.
Compared to Opus 4.8 I really haven't been impressed
And I've been quite impressed. Opus talks the talk, Fable walks the walk.
I don’t understand what these comments add to the discussion, you always see these and it’s just noise at this point.
Every metric becomes a target (Goodhart's law). Also, the plural of anecdote is not data.
The subjective anecdotes from HN users matter because they are not data and are much harder to game. Not impossible to game, always be aware of users with low karma, but more difficult than gaming a benchmark.
But they’re not at all meaningful after a certain point, because they’re not even attempting to explain why it works well for them. It’s just noise like this.
They add nothing, meaningless anecdotes. I was kind of riffing on that.
Posting meaningless comments isn’t suddenly useful because you’re aware of it and “riffing on that”.
And now you've added to the pile, congratulations.
So you added BS, on purpose? There is nothing meaningless about anecdotes. The plural is data
Yeah come on, if these endless dialectic statements get made, at least post more detailed information about how your position was attained.
I make Claude, Codex and Gemini review each other's design plan and implementation. Each always found a lot of things the others missed...until Fable 5 came out. Whatever plan or code Fable 5 comes up with, now it's very hard for Codex and Gemini to find any serious hole in it.
In my experience, audit findings decrease in frequency as a codebase matures. Was Fable doing greenfield work?
Damn that was a cringe comment
Fable is supposed to return to subscription plans, unless I'm missing something: https://jacob.gold/posts/fable-5-removal-is-temporary/
They can’t keep their current models working on subscriptions[1], so we’ll see if this is marketing or not in the future. It’s smart to tease it no matter what, ”insert classic first hit is free drug reference”.
[1] https://status.claude.com
Apple claims their price increases are temporary too. I'll believe it when I see it. The capacity limitations are not going away any time soon.
I just had Fable run overnight in a loop, and it fixed ~150 compiler crashing bugs that Opus had kept deferring.
I wouldn't start with Fable - when I use burndown loops I tend to include instructions to document progress and set aside anything that turns out to be harder than expected, and solve the easy stuff first. When a model runs out of easy stuff and start struggling to make progress on what is left, I can let it keep churning on that - they get there eventually - or I can bump it up to a smarter model if one is available.
Opus had churned a week driving down spec failures, and did a great job. The 150 Fable took overnight were the ones Opus had kept putting aside.
I agree with you that you don't need fable for everything, and you have to be careful on what you run it on. CRUD stuff, sure even the small models can do it. But there certainly are tasks that are very much suited for the absolute SotA and you'd leave money on the table by not using it. And how much a task is worth is dependant on how much it improves your bottom line. So the cost/token becomes largely irrelevant.
Let's take this [1] benchmark. A bit more context here [2].
Here models are asked to create kernels for running inference on models. This is a benchmark perfectly suited and highly relevant right now. It's easily verifiable, an active are of research, and the results are immediately useful.
Say you have 1 unit of compute, it costs 300k $ and serves 1x users. In comes Fable and after one session it gives you 30% speed-up on your 1 unit of compute. It can now serve 1.3x users. How much is that one session worth for you? How much is it worth for a company using 10 units? 100 units? How much is it worth for a hyper-scaler running 10.000 units? How much is it worth for a lab that trains the next frontier model and then serves it from 100.000 units? 30% is relative. And the cost for one session is really meaningless. It can cost 1m$ / session and it would still be worth it for someone.
[1] - https://kernelbench.com/mega
[2] - https://x.com/elliotarledge/status/2072814573753975266
For now, I can use Fable from the web just fine.
> You're not likely to want to run Fable in a loop any more than you want to take a bunch of dollar bills and light them on fire. Every invocation of Fable has to be intentional, its context carefully managed.
Eh, that's just because it's the current frontier model. Give it a few weeks, and prices will drop.
API prices are the new normal. I doubt that prices will drop to the level of the subsidized subscriptions any time soon. Usage is growing exponentially but capacity cannot. There is no reason for them to waste their capacity on subscription users if they can sell that same capacity to API users.
Like with Uber and Lyft, the low prices were a fight for market share, but now they have successfully captured that market share the focus changes to balancing their books.
I suspect subscriptions will stay. But you will see more and more roadblocks that the 'barely goes to the gym' user barely notices, but that the power user will chafe under.
I make that prediction, because the people who pay for subscriptions but only use them moderately at best are truly profitable.
The $200 sub is the new free tier, has been for a while now.