test: add download zip flow

web/src/lib/zip.ts

@@ -1,7 +1,21 @@
 import { zipSync } from "fflate";
 import { downloadBlob, encode } from "./core/io";
+import type { PixelImage } from "./core/types";
 import type { ToolImageFile } from "./registry";
 
+export type ZipImageEncoder = (image: PixelImage) => Promise<Uint8Array>;
+
+export async function buildZipEntries(
+	files: ToolImageFile[],
+	encodeImage: ZipImageEncoder,
+): Promise<Record<string, Uint8Array>> {
+	const entries: Record<string, Uint8Array> = {};
+	for (const file of files) {
+		entries[file.name] = await encodeImage(file.image);
+	}
+	return entries;
+}
+
 /**
  * Собирает набор картинок (1 → many) в zip-архив и скачивает его.
  * Картинки кодируются как PNG; кодирование требует DOM — вызов из UI-слоя.
@@ -11,11 +25,10 @@ export async function downloadZip(
 	zipName: string,
 ): Promise<void> {
 	if (files.length === 0) return;
-	const entries: Record<string, Uint8Array> = {};
-	for (const file of files) {
-		const blob = await encode(file.image, "image/png");
-		entries[file.name] = new Uint8Array(await blob.arrayBuffer());
-	}
+	const entries = await buildZipEntries(files, async (image) => {
+		const blob = await encode(image, "image/png");
+		return new Uint8Array(await blob.arrayBuffer());
+	});
 	const zipped = zipSync(entries);
 	downloadBlob(new Blob([zipped], { type: "application/zip" }), zipName);
 }