I’ve used SCB as part of my assessment of agent skills (superpowers, GSD etc) https://orcabot.com/labs/do-skills-improve-coding-agent-accu...
There is a small but growing community on discord for discussing SCB so if interested please join https://discord.gg/BrC4BA9sVj
It seems like we all tried to contain and organize a system that simply prefers to select its own organization.
Which makes me to think that these skill packs of workflows are really made to make it easier for humans rather than agents.
What is also nice about this benchmark is that it can be used to iterate on prompts/skills for reducing code complexity.
My typical workflow when AI assisted is what I call human gatekeeping... I'll plan out next steps with the agent, updating a TODO.md file with what needs to be done, then a fresh context to implement the next step(s), and review the code before committing to git. I may iterate/stash or even reset a few times before it's "good enough"... it is rarely close to what I would do myself, but often as good as what I've gotten from other developers IRL on projects.
This includes updating the documentation area(s) of a project as well as testing. I also tend to lean on ./run/* for scripts that will run/test various portions of the project... getting the agent to use these is sometimes harder than it should be, as I want it to specifically exercise a lot of things through the process... there are also times where it will try to change a valid test that's failing instead of fixing the code. That's the most irritating part. Some models are annoying, some feel like pure magic at times.
Labs do not train on benchmark data (allegedly). They can train on similar problems, but benchmarks have specific strings in them that labs are supposed to be aggressive in filtering out of their training corpora.
It's especially relevant now that models are good enough to solve ~most point-in-time problems.
Some relevant but disconnected thoughts:
- deterministic scores are so nice
- what "maintainable" is is probably some high dimensional space described by these signals; it'd probably require some human labeling to figure out where this space is
- another signal I've been thinking about and I'm seeing increasingly get brought up is the state space of a system; I'm seeing formal methods pop up a lot recently
State space of a system AND the way to make it accessible / visible to a model. Many times a model can work magic if it can "see" the state of a system in a way that suits it. That's why sometimes having a cli added to the environment seems like such a big unlock. Because that cli usually takes a complex state and allows visibility into it, and possible manipulation in a structured way.
this is a nicely succinct way to put this - a multi-dimensional space where no single metric is really useful
state space of the system is interesting too. I would guess that for any production software with dependencies like databases/third parties that might be too hard to measure, but if you can silo off parts of your system into bounded state machines, it may be a value metric on some module behind a clean interface.
I think the kubernetes control loop model is a great instance of this, a handful of scoped components that own a control loop across a well-defined state machine, that can operate / recover in the face of most network partitions or downtime - the promise of CRDTs but rather more a pragmatic approach to it
There’s this notion of variety popularized by cybernetics folks a long time ago. Variety is like the state space of the system. Then there’s a law that says “only variety absorbs variety”.
So if a method has high variety then it must have an equally complex implementation to handle the variety.
When there is a mismatch it means that either the method has parameters that aren’t useful, or that the body of the method isn’t covering cases it should.
https://fffej.substack.com/p/only-variety-can-absorb-variety was my attempt to write it up more fully.
Maybe, but "maintainable" has a simple definition: minimising the effort to incrementally grow a software system as its size grows to infinity (while maintaining some defect ratio). Humans (called senior software engineers) figure this out over decades by working on a number of large software systems.
So far models haven't figured the same thing out. I can only guess why. All their learning comes from examining code on the internet. Somehow whatever the patterns are that make large software projects like the OSs maintainable by large groups of people working independently has escaped them. Maybe the bulk of code they look at is in the small so they miss it, maybe the patterns are just hard to discern in big systems.
My theory is there are anti-patterns which the larger projects somehow manage to keep to a minimum. It's hard to learn something that's not there. Instead, you learn these anti-patterns by doing them, and watching a system all fall apart over the course of years, and if you're good you manage to pin the blame on the right thing.
If you want to wrap it up neatly in a package, models have learnt how to program, but programming is not the same as design. Design requires very different skills to using a programming language. At a very high level, big systems are sets of interconnected modules. The things that matter are narrow APIs with minimal coupling, and where coupling is unavoidable making it explicit and easy to reason about. Concrete examples of the anti-patterns to be avoided are global variables, leaky abstractions and APIs that require complex sequences of interconnected calls.
Those things don't bite hard until you program in the large. The current crop of LLM's seem to be useless at all of them. If you've got a big context window and you are only writing 100s of kloc, a budget of kilowatts to understand the complexity, it doesn't matter. But humans don't have a budget like that, and so far everyone I've seen who reads large chunks of vibe coded software recoils in horror, gives up, and walks away.
Even with that budget, the models fail anyway once the size gets way beyond their context window - it's just that they fail much later than humans. Which I guess makes learning the lesson so much harder - perhaps near impossible as your "they need labeled examples" hints at. Oddly the solution would be to train with smaller context windows (a less powerful model in some ways), so the failures become apparent much earlier.
It looks like they have been going with your solution for now - giving engineers cheap tokens via flat-rate plans, and watching how they do things. I don't think that will work. Engineers who chew through the billions of tokens offered by these plans are vibe coding. The code they produce is so poor it can't cross the threshold from small to large. There is nothing to see there about programming in the large.
:( what a rant - it looks like an LLMs CoT as it thinks through things. Which is what I was doing, I guess.
I’ve now replaced my use of Opus 4.8 xhigh with Opus 5 medium, and I’m using less tokens and it’s quicker. I can understand people being annoyed by its writing style but for getting work done that really doesn’t bother me. I’ve been really enjoying using it.
I have a suspicion that most models will miss the `database_migration` Checkpoint 2 test that includes a `default_value` because it could be interpreted as either a JSON-literal or a SQL-expression.
There might be other tests as well that are prone to failure for reasons other than the reasons cited in the paper.
I think a cool experiment would be to adjust the order of the features implemented (e.g. checkpoint 3 then 2 then 5 then 4) where dependencies allow it. Then one could account for some checkpoints being more difficult than others.
Many people though are going to read the headline figures and think it means - say - Opus 5 is only a quarter the strength of a human coder.
The original paper cited by this post does try to see if improved prompting will make a big difference in the end using a `plan_first` prompt variant, but find no influence on pass rate at the end of the benchmark. The `plan_first` seems to assume coding agents will just refactor once they finish features, but I don't think they tend to refactor significantly unless they are told to fix bugs rather than build features. The benchmark leaves tests hidden with no fail-to-pass feedback, so that may be why degradation is monotonic.
I have found that models are generally poor at managing refactors / complexity while also implementing new features. But I’ve had some success with a semi-lights-off approach where you decompose it and prompt the model adversarially in a second pass to look for new rough edges and areas of complexity or refactors that might simplify the codebase.
So I’d be very curious to see this benchmark but with something like a periodic “refactor turn” interleaved in.
Also eager to see Fable benchmarked; anecdotally that was the only model whose code I felt I could actually trust to not review closely.
Is this bad? I have McCabe complexity switched on in Ruff and find it a handy watermark for when something should be broken up into smaller, individually testable callables. Five times as many callables could make for much more readable and testable code.
At the same time, I imagine it will be hard for them to prioritize this over improving flashy one-shots of impressive zero-to-one feats that demo so well and attract more customers.
Can we have simonw make "pelican on a bicycle after 1000 requests for iteration" popular?
a 41% improvement is not much higher? come on that's just doomer
If the code is ugly, but defects are low—does it matter?
If the code is hard to read, but clients are happy—should I care?
Genuinely asking. Weird times we live in.
Edit: FWIW the paper the post quoted has repositories as slop baseline https://arxiv.org/html/2603.24755v1#S4.SS2