refactor(catalog): unify commands and embed guarded catalog workspace

src/features/catalog/client/catalog-selection-url.ts

@@ -0,0 +1,29 @@
+export interface CatalogSelection {
+	rootId: number | null;
+	pageId: number | null;
+}
+function positiveId(value: string | null) {
+	if (!value || !/^\d+$/.test(value)) return null;
+	const id = Number(value);
+	return Number.isSafeInteger(id) && id > 0 ? id : null;
+}
+export function readCatalogSelection(url: URL): CatalogSelection {
+	return {
+		rootId: positiveId(url.searchParams.get("root")),
+		pageId: positiveId(url.searchParams.get("category")),
+	};
+}
+export function writeCatalogSelection(
+	url: URL,
+	selection: CatalogSelection,
+): URL {
+	const next = new URL(url);
+	for (const [key, value] of [
+		["root", selection.rootId],
+		["category", selection.pageId],
+	] as const) {
+		if (value === null) next.searchParams.delete(key);
+		else next.searchParams.set(key, String(value));
+	}
+	return next;
+}