perf(import): adjustable concurrency and skip redundant SWF downloads

Raise batch concurrency (furni 3->12, clone 10->12) with a Speed control next to Translate. Skip the SWF download when a .nitro bundle already exists on disk (color variants share the base nitro), and stop flagging that as a failed download.

src/app/api/admin/import/furni/batch/route.ts

@@ -43,7 +43,7 @@ export const POST = withAdmin(
 	async (request, ctx) => {
 		const body = await request.json();
 		const rawItems: BatchItem[] = body.items || [];
-		const concurrency = Math.min(Math.max(body.concurrency || 1, 1), 3);
+		const concurrency = Math.min(Math.max(body.concurrency || 3, 1), 12);
 		const sourceId: string | undefined = body.sourceId;
 
 		if (rawItems.length === 0) return apiError("No items to import", 400);

src/components/admin/studio/studio-client.tsx

@@ -269,6 +269,8 @@ export function StudioClient({
 		null,
 	);
 	const batchAbortRef = useRef<AbortController | null>(null);
+	// How many items the batch endpoints process in parallel.
+	const [concurrency, setConcurrency] = useState(4);
 
 	// Nitro editor
 	const [editingClassname, setEditingClassname] = useState<string | null>(null);
@@ -834,7 +836,7 @@ export function StudioClient({
 						revision: i.revision,
 						category: i.category,
 					})),
-					concurrency: 3,
+					concurrency,
 					translate,
 					langs:
 						translate && translateLangs.length > 0 ? translateLangs : undefined,
@@ -979,7 +981,7 @@ export function StudioClient({
 				body: JSON.stringify({
 					sourceId: activeSource,
 					classnames: failed,
-					concurrency: 10,
+					concurrency,
 					final: true,
 				}),
 				signal: abort.signal,
@@ -1561,6 +1563,33 @@ export function StudioClient({
 				</summary>
 				<div className="flex max-h-48 flex-wrap items-center gap-3 overflow-auto py-3">
 					{" "}
+					{/* ── Import speed (parallel items per batch) ─────────── */}
+					<div className="flex items-center gap-2">
+						<span className="text-xs font-medium text-[var(--admin-text-muted)]">
+							Speed
+						</span>
+						<Select
+							value={String(concurrency)}
+							onValueChange={(value) =>
+								setConcurrency(Math.max(1, Number(value)))
+							}
+						>
+							<SelectTrigger
+								aria-label="Import speed"
+								className="h-8 w-24 text-xs"
+							>
+								<SelectValue>{`${concurrency} parallel`}</SelectValue>
+							</SelectTrigger>
+							<SelectContent>
+								<SelectItem value="1">1 (gentle)</SelectItem>
+								<SelectItem value="2">2</SelectItem>
+								<SelectItem value="4">4 (recommended)</SelectItem>
+								<SelectItem value="6">6</SelectItem>
+								<SelectItem value="8">8</SelectItem>
+								<SelectItem value="12">12 (turbo)</SelectItem>
+							</SelectContent>
+						</Select>
+					</div>
 					{/* ── Translate control (per-import) ─────────────── */}
 					<div className="flex items-center gap-2">
 						<div className="flex h-8 items-center gap-1.5 rounded-md border border-[var(--admin-border)] px-2.5">

src/lib/services/furni-import-repair.test.ts

@@ -152,6 +152,7 @@ describe("completion of existing furniture", () => {
 
 it("imports recycler_kintsugiB with an allocated ID throughout SQL and furnidata", async () => {
 	vi.clearAllMocks();
+	mocks.nitroExists = false;
 	const selections = [[], [{ itemName: "recycler_kintsugi" }]];
 	mocks.select.mockImplementation(() => ({
 		from: () => ({ where: () => ({ limit: async () => selections.shift() }) }),

src/lib/services/furni-import.ts

@@ -711,7 +711,13 @@ export async function importSingleFurni(params: {
 					iconFailure = detail;
 					warnings.push(`Icon download failed: ${detail}`);
 				}),
-		params.providedNitro || (params.preserveAssets && existsSync(nitroPath))
+		// Skip the SWF download entirely when a .nitro bundle already exists on
+		// disk — this happens for colour variants that share the base classname's
+		// nitro file. The SWF is only used for Nitro conversion (not needed) and
+		// icon extraction (the nitro bundle is used as a fallback for that below).
+		existsSync(/*turbopackIgnore: true*/ nitroPath) ||
+		params.providedNitro ||
+		(params.preserveAssets && existsSync(nitroPath))
 			? Promise.resolve(false)
 			: (preservingExisting || params.preserveAssets) && existsSync(swfPath)
 				? Promise.resolve(true)
@@ -766,6 +772,7 @@ export async function importSingleFurni(params: {
 		!swfOk &&
 		!nitroDownloadOk &&
 		!params.providedNitro &&
+		!existsSync(/*turbopackIgnore: true*/ nitroPath) &&
 		!(params.preserveAssets && existsSync(nitroPath))
 	)
 		warnings.push(`SWF download failed: ${swfFailure || "unknown cause"}`);

src/lib/services/import/core/sse-batch.ts

@@ -33,7 +33,7 @@ export interface RunSseBatchOptions<T> {
  */
 export function runSseBatch<T>(opts: RunSseBatchOptions<T>): Response {
 	const { items, labelOf, worker, signal, flush } = opts;
-	const concurrency = Math.min(Math.max(opts.concurrency || 3, 1), 10);
+	const concurrency = Math.min(Math.max(opts.concurrency || 3, 1), 12);
 	const encoder = new TextEncoder();
 	const ac = new AbortController();