StepFun open-sources Step Code CLI coding agent
StepFun's Harness team has released and open-sourced Step Code v0.1.0, the command-line coding agent it uses daily, aimed at fewer tokens for the same intelligence.
Hey guys! This is the story from StepFun Harness Team. Let's talk about Step Code. Step Code launched and went open source today. It's nothing fancy — just a plain CLI, the same one we use every single day. Here's the story behind it. 1. Why the logo is a duck (it's actually a pelican) It goes back to our first usable agent model, Flash 3.5. It wasn't strong, but it was fast. The results were rough. That was the moment a simple idea hit us: what if we could make our model perform better by strengthening the harness itself? The meme came from Pic 1 & Pic 2 2. We screwed up At one point we dreamed up a voice-based coding CLI. We even interviewed blind users for it. Reality slapped us hard. We open-sourced this voice CLI, and it became a ghost project where PRs outnumbered both issues and stars. The only thing that survived from it is the voice mode in our CLI today. 3. So we went back to basics We decided to build a harness we would actually use ourselves. As a model company, our most frequent use case is evaluation. As part of cutting costs, our harness aimed at one thing from day one: same smarts, fewer tokens. It did make a difference like Pic 3 4. Eval reports got out of hand Our evaluation outputs came in all shapes and sizes — HTML reports started outnumbering our Feishu docs by a mile. So we added static site hosting, just to make sharing HTML artifacts easier. (You do need a plan for it though.) https://swift-otter-ca0f.page.stepcloud.com/ That's it. That's all. As a v0.1.0 release, it doesn't do formal reasoning like DSH, and it's nowhere near as polished as Claude Code. It's just a tool we use every day. We'll keep throwing our own use cases at it — like drawing pelicans. 🦩 If any of this sounds interesting and you want to give it a try: https://platform.stepfun.com/step-code Oh, and it's open source. Issues welcome: GitHub - stepfun-ai/Step-Code Let me know if you want it shorter (Twitter thread style) or adjusted.
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