For a long time I was skeptical of LLMs—whenever I reached for them I was disappointed by the results. Last year I tried Copilot and Cursor to tweak a game I’d built, and neither generated working changes. At a previous job I tried Gemini to outline product briefs and generate wireframes, but ended up throwing them all away. Every time I tried LLMs it was for something I was already good at, and they did a worse job than I would have. Having joined Jane Street this past summer, I’m finding AI support indispensable. There’s just so much that’s new to me, and so much I’m not good at yet, like OCaml and Bonsai . But one big surprise is how much it’s changed the thing I’m best at: my design workflow. Instead of laboring over spec docs, building Figma mockups, writing proposals, and reviewing the implementation with devs, I find myself building prototype features that just do the exact thing I have in mind.…