prefer-foreach

get() reads a signal once. Map over that and you have rendered the list as it was at mount, with nothing left subscribed to change it:

// renders once and never updates
Ul(...rows.get().map((row) => Li(row)));

// re-renders as `rows` changes
Ul(
	ForEach(
		rows,
		(row) => row.id,
		(row) => Li(row),
	),
);

The rule reports .get().map() only in a rendered position — as an argument, or a spread argument, of a PascalCase callee. That is what separates a list being rendered from one being sent somewhere, and it keeps the rule quiet on the case where reading the current value is exactly right:

// fine — an event handler wants the value it has now
Button({ onClick: () => save(rows.get().map(toDto)) }, "Save");

Map.prototype.get takes a key, so byId.get(id).map(...) is never mistaken for the snapshot read.