The seller net-sheet (no-code rung)

The purest no-code app: fixed inputs (price, loan payoff, commission %, closing costs), fixed math, one number out. This is the 'Artifact for speed' case — no flexibility needed because the formula never changes, so describe it in chat and let Claude build a runnable Artifact, or a single-file tool in Claude Code with a tiny form. The logic is the whole app. (B12 already named the net sheet as your model first endpoint — this is that math, made real.)