Qwen 3.8 27B on my laptop can interpret model weights, too (simonwillison.net)

Not making any claims about a specific model's capabilities, but all these "can interpret model weights" posts brings to mind the line in Shakespeare's Henry IV

GLENDOWE: I can call spirits from the vasty deep.

HOTSPUR: Why, so can I, or so can any man, but will they come when you do call for them?

I can interpret weights too, but will that interpretation be correct?

> I’m not ready to declare that the age of source code is over and our future involves incomprehensible machines editing their own model weights in incomprehensible ways.

That sounds a bit like biology; maybe AI will become like that.

Hopefully we get a new benchmark: How well can a model tweak a set of weights to produce pelican on a bike?

Why would you want to change weights directly versus running through a new training cycle? For example, I have collected a bunch of data I would like to train weights that I use local inference for. I figured a LoRa would be the way to go, perhaps be more cost effective and generalized too.

I wonder how far this can be taken. Could Qwen 3.8 can interpret and make improvements to Qwen 3.5 0.8B weights, or even its own weights?

Why do people keep calling this a paper?

It's a blog post which received feedback from collaborators.

It hasn't gone through the academic paper lifecycle ... the authors themselves refer to it as a post and as preliminary.

I feel like I'm taking crazy pills, but can we be precise when talking about work of this form? It started with referring to arXiv pre-prints as papers, and now we're at blog posts with an academic template as papers.

A paper is a fucking paper: something which has been vetted by the scientific community, with at least some form (often, a few rounds) of anonymous review from people outside your circle of collaborators

This is not there yet, and clearly so due to the various feedback from people (including the two pushback posts on HN) critiquing the lack of discussion about the existence of these techniques in mech interp, etc?

  @misc{takehi2026weightspace,
    title        = {{Sparks of Weight-Space Programming: LLMs can natively read \& write neural network weights}},
    author       = {Takehi, Rikiya and Teoh, Jayden and Zhang, Alex and Khattab, Omar},
    year         = {2026},
    month        = nov,
    howpublished = {\url{https://rikiyat.github.io/blog/weight-space-programming/}},
    note         = {Blog post}
  }

Still amazing to me that a model that good, Qwen3.8:27b, runs on a laptop.

Wasn’t this one of the main marketing points for the Inkling model as well?

> It’s a cool paper, but some of the wider commentary I’ve seen around it does not feel justified. I’m not ready to declare that the age of source code is over and our future involves incomprehensible machines editing their own model weights in incomprehensible ways.

The age of source code is definitely not going to end anytime soon if ever. But the future will involve incomprehensible machines editing other models in a "fairly certain" way, but we are going to need a lot of tooling to keep up with the process and not just take the model updates as "trust me bro".

I did exactly the same thing with Qwen 3.8 27B but i also asked it something else: a couple years ago i wrote a simple upscaler[0] when i was learning about neural networks. The network is dead simple: it takes a 25 inputs for a 5x5 grid around a pixel and outputs the 2x2 pixel grid that the input pixel should be replaced for a (width2)x(height2) upscale. I trained it on a bunch of random images (in hindsight i should have trained it on game screenshots but w/e) and it looked quite nice.

So i asked Qwen 3.8 27B two things:

1. What it is this network all about? I only gave it the ann.c code that implemented a simple artificial neural network library in C and the setup code that specified the network's shape but not its purpose.

Qwen 3.8 27B tried a bunch of stuff, taking the layers one by one, proding numbers through it, etc and finally figured out it is some sort of 5x5 to 2x2 filter, most likely working with pixels (i never mentioned pixels or graphics), though it wasn't certain about the exact purpose. It did rule out a bunch of uses like being a downscaler or classifier, from its behavior.

2. After i revealed what it was, i asked it if it can improve it but keep it 100% compatible with the existing program that used the weights file. And sure enough, it did improve it. I gave it the original training C code and dataset. It made a few experiments (and wrote its own training C code because it found mine too slow :-P) and ended up improving the weights. The difference[1] is small, but it basically eliminated some small noise that was always there and made some transitions less "halo-y". Of course for the purpose i wanted it (use it to upscale games in realtime) it isn't that great (too heavy) but it was learning material anyway. Though one bonus thing i noticed is that it upscales my random doodles much better than any Krita filter[2] :-P.

The above isn't Qwen 3.8 27B observing the weights directly and making sense out of them (ok actually it did seem to make some sense of the weights in the "#1" but i didn't dump the entire network to it - though thinking about it, it is only around 16384 floats so it might work). It just used a bunch of scripts it wrote in Python (and later C) but i still found it interesting to watch it go at it.

[0] https://mastodon.gamedev.place/@badsector/113765818432603610

[1] http://runtimeterror.com/pages/iv/images/a3d94ea369ff95ecf05...

[2] http://runtimeterror.com/pages/iv/images/4e29d027a8aa6e89db5...

  > the 2x2 pixel grid that the input pixel should be replaced for a (width2)x(height2) upscale.