Split up Wasm binaries so Cloudflare deployments stay below 25 MB per file

frontend/src/utility-functions/wasm-loader.ts

@@ -0,0 +1,25 @@
+import init from "/wrapper/pkg/graphite_wasm_wrapper";
+import wasmBinaryUrl from "/wrapper/pkg/graphite_wasm_wrapper_bg.wasm?url";
+
+// Initializes the editor's Wasm module, rejoining the parts that CI deployments split the binary into
+// to fit under the single-file size limit (see `wasmSplitting` in `vite.config.ts`)
+export async function initWasm() {
+	// Local and native builds keep the binary whole, letting the wasm-bindgen glue code load it directly
+	if (__WASM_PART_COUNT__ <= 1) return init();
+
+	// Fetch all parts in parallel (served from the service worker's precache once it is installed)
+	const partRequests = [];
+	for (let index = 0; index < __WASM_PART_COUNT__; index += 1) {
+		partRequests.push(fetch(wasmBinaryUrl.replace(/\.wasm$/, `-part${index}.wasm`)));
+	}
+	const partResponses = await Promise.all(partRequests);
+
+	const failedResponse = partResponses.find((response) => !response.ok);
+	if (failedResponse) throw new Error(`Failed to fetch Wasm binary part (status ${failedResponse.status}): ${failedResponse.url}`);
+
+	// Rejoin the parts and hand them to wasm-bindgen as a single response, with the MIME type needed for streaming compilation
+	const parts = await Promise.all(partResponses.map((response) => response.blob()));
+	const joined = new Response(new Blob(parts), { headers: { "Content-Type": "application/wasm" } });
+	// eslint-disable-next-line camelcase
+	return init({ module_or_path: joined });
+}