GLM-5.1: Towards Long-Horizon Tasks

<p><strong><a href="https://z.ai/blog/glm-5.1">GLM-5.1: Towards Long-Horizon Tasks</a></strong></p> Chinese AI lab Z.ai's latest model is a giant 754B parameter 1.51TB (on <a href="https://huggingface.co/zai-org/GLM-5.1">Hugging Face</a>) MIT-licensed monster - the same size as their previous GLM-5 release, and sharing the <a href="https://huggingface.co/papers/2602.15763">same paper</a>.</p> <p>It's available <a href="https://openrouter.ai/z-ai/glm-5.1">via OpenRouter</a> so I asked it to draw me a pelican:</p> <pre><code>llm install llm-openrouter llm -m openrouter/z-ai/glm-5.1 'Generate an SVG of a pelican on a bicycle' </code></pre> <p>And something new happened... unprompted, the model <a href="https://gist.github.com/simonw/af7170f54256cc007ef28a8721564be8">decided to give me</a> an HTML page that included both the SVG and a separate set of CSS animations!</p> <p>The SVG was excellent, and might be my new favorite from an open weights model:</p> <p><img alt="The bicycle is red and has a frame the correct shape and wheels with spokes. The pelican is a perky little fella." src="https://static.simonwillison.net/static/2026/glm-5.1-pelican.png" /></p> <p>But the animation <a href="https://gisthost.github.io/?73bb6808b18c2482f66e5f082c75f36e">broke it</a>:</p> <p><img alt="Animation - the wheels and pedals rotate, the clouds move... and the pelican has vanished, but there is a little blob bobbing up and down in the top left corner." src="https://static.simonwillison.net/static/2026/glm-5.1-broken-light-lossy.gif" /></p> <p>That's the pelican, floating up in the top left corner.</p> <p>I usually don't do follow-up prompts for the pelican test, but in this case I made an exception:</p> <pre><code>llm -c 'the animation is a bit broken, the pelican ends up positioned off the screen at the top right' </code></pre> <p>GLM 5.1 replied:</p> <blockquote> <p>The issue is that CSS <code>transform</code> animations on SVG elements override the SVG <code>transform</code> attrib