For the First Time, AI Was My User - by Claire Tsao

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For the First Time, AI Was My User

Claire Tsao<br>May 27, 2026

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I recently built a small CLI called readable-mermaid. It takes a Mermaid sequence diagram .mmd file — and only sequence diagrams — and outputs a doc-ready diagram image with readable font sizes, proper spacing, and staggered headers. Mermaid’s native output is nearly unreadable once diagrams get complex.<br>While wrapping up the project, writing the README and thinking about how to describe it, something clicked that I hadn’t noticed during development:<br>I built this entire thing for AI. Not for a person.<br>The workflow is: an AI assistant generates a Mermaid sequence diagram as part of writing a design document, calls readable-mermaid to render it, and the output goes straight into the doc. The engineer never runs the command. They probably never even learn its name. They just get a diagram they can actually read.<br>What’s strange is that a human still benefits. Someone will look at the diagram and understand the architecture. But that person has no relationship with the tool that made it. They’re downstream of a process they never see.<br>This was a completely new experience for me. For the first time, I wasn’t using AI — I was working for it.<br>In a way, this isn’t new at all. Writing a utility that gets called by other software is one of the most ordinary things a developer does. But even then, a human always decided where to put the call — someone wrote the line of code that invoked the function. With readable-mermaid, the AI decides on its own that it needs this tool. Right now I still nudge it: a line in a config file that says “when you generate a Mermaid diagram, use this.” But the AI is the one interpreting that, choosing when to act on it, and running the command.<br>readable-mermaid only handles sequence diagrams. That sounds narrow, but I think that’s exactly right. The tool is fully deterministic — same input, same output, every time. It doesn’t need judgment, creativity, or context. It just needs to run. In the same way we write small, single-purpose functions in code, tools for AI work best when they do one thing and do it reliably. The AI handles the judgment: deciding when a diagram needs to be readable. The tool handles the mechanical part.<br>I don’t have a grand theory about what this means for software development. I just know it felt different. This time, the human is not the user — just the beneficiary.<br>It’s a small thing. But it made me look at my work a little differently.<br>readable-mermaid Github

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