fix(catalog): stream single imports and preserve response errors

src/lib/furni/import-response.ts

@@ -0,0 +1,52 @@
+import { readSseStream } from "@/lib/sse-client";
+
+interface ImportResponse {
+	status: number;
+	data: Record<string, unknown>;
+}
+export async function readImportResponse(
+	response: Response,
+): Promise<ImportResponse> {
+	if (
+		response.ok &&
+		response.headers.get("content-type")?.includes("text/event-stream")
+	) {
+		if (!response.body)
+			throw Error(
+				"Import response is empty. Check the furniture status before retrying.",
+			);
+		let result: ImportResponse | undefined;
+		await readSseStream(response.body, (event) => {
+			if (
+				event.type === "result" &&
+				typeof event.status === "number" &&
+				event.data &&
+				typeof event.data === "object"
+			)
+				result = {
+					status: event.status,
+					data: event.data as Record<string, unknown>,
+				};
+		});
+		if (!result)
+			throw Error(
+				"Import connection ended before confirmation. Some changes may already be saved. Check the furniture status before retrying.",
+			);
+		return result;
+	}
+	const text = await response.text();
+	let data: Record<string, unknown>;
+	try {
+		data = JSON.parse(text);
+	} catch {
+		const reason = [502, 503, 504, 524].includes(response.status)
+			? "Server or proxy unavailable, or request timed out"
+			: "Server returned an unexpected response";
+		throw Error(
+			`${reason} (HTTP ${response.status}). Check the furniture status before retrying.`,
+		);
+	}
+	if (!data || typeof data !== "object")
+		throw Error(`Invalid import response (HTTP ${response.status}).`);
+	return { status: response.status, data };
+}