GLM-5.1: Towards Long-Horizon Tasks (https://z.ai/blog/glm-5.1)

Chinese AI lab Z.ai’s latest model is a giant 754B parameter 1.51TB (on Hugging Face (https://huggingface.co/zai-org/GLM-5.1)) MIT-licensed monster - the same size as their previous GLM-5 release, and sharing the same paper (https://huggingface.co/papers/2602.15763).

It’s available via OpenRouter (https://openrouter.ai/z-ai/glm-5.1) so I asked it to draw me a pelican:

llm install llm-openrouter llm -m openrouter/z-ai/glm-5.1 ‘Generate an SVG of a pelican on a bicycle’

And something new happened… unprompted, the model decided to give me (https://gist.github.com/simonw/af7170f54256cc007ef28a8721564be8) an HTML page that included both the SVG and a separate set of CSS animations!

The SVG was excellent, and might be my new favorite from an open weights model:

But the animation broke it (https://gisthost.github.io/?73bb6808b18c2482f66e5f082c75f36e):

That’s the pelican, floating up in the top left corner.

I usually don’t do follow-up prompts for the pelican test, but in this case I made an exception:

llm -c ‘the animation is a bit broken, the pelican ends up positioned off the screen at the top right’

GLM 5.1 replied:

The issue is that CSS transform animations on SVG elements override the SVG transform attribute used for positioning, causing the pelican to lose its placement and fly off to the top-right. The fix is to separate positioning (SVG attribute) from animation (inner group) and use <animateTransform> for SVG rotations since it handles coordinate systems correctly.

And spat out fresh HTML (https://static.simonwillison.net/static/2026/glm-5.1-pelican-fixed.html) which fixed the problem!

I particularly like the animation of the beak, which is described in the SVG comments like so:

Tags: css (https://simonwillison.net/tags/css), svg (https://simonwillison.net/tags/svg), ai (https://simonwillison.net/tags/ai), generative-ai (https://simonwillison.net/tags/generative-ai), llms (https://simonwillison.net/tags/llms), pelican-riding-a-bicycle (https://simonwillison.net/tags/pelican-riding-a-bicycle), llm-release (https://simonwillison.net/tags/llm-release), ai-in-china (https://simonwillison.net/tags/ai-in-china), glm (https://simonwillison.net/tags/glm)