How it was built. Entirely in Flowstep during the challenge window — and entirely driven from Claude Code through the Flowstep MCP: 28 of my 80 agent messages. The working, honestly: one design-system block pasted into every prompt (real hex values, JetBrains Mono for anything numeric, "closer to Linear than a generic SaaS template"); single-target edits only, after an early multi-target edit corrupted two screens; the exact brand logo attached by public URL; and when the generator kept eating one button label, I patched the screen's JSX directly and re-imported it — Flowstep takes raw code, which turned out to be its sharpest feature. The 58-second walkthrough video was produced by the same agent that drove the design.