Scales a recipe by servings, a factor, or pan size (square, rectangle, round, loaf), converts between US cups and spoons, metric volume and grams with an ingredient density table, rounds to measurable amounts, and flags baking caveats such as fractional eggs, leavening at large factors, batter depth and bake time when the pan changes, tiny amounts, seasoning and cooking time. Includes a stdlib Python scaler with --self-test.