fix: prevent import hanging by adding abort signals and idle timeouts

- Furni batch: wire request.signal to abort controller, send post_import
  progress events, skip post-import steps when aborted
- Clone sync-all: pre-fetch furnidata once per source instead of per item
  (eliminates 2000+ redundant DB reads + HTTP requests)
- SSE client: add 60s idle timeout to prevent infinite hangs when server
  stops responding

src/lib/sse-client.ts

@@ -3,26 +3,46 @@ import { adminFetch } from "@/lib/admin-fetch";
 
 export type SseEvent = Record<string, unknown>;
 
+/** Default idle timeout: if no SSE event arrives for this long, abort. */
+const DEFAULT_IDLE_TIMEOUT_MS = 60_000;
+
 /**
  * Read an SSE response body and invoke `onEvent` for each `data:` JSON payload.
+ * Aborts if no event arrives within `idleTimeoutMs` (default 60s).
  */
 export async function readSseStream(
 	body: ReadableStream<Uint8Array>,
 	onEvent: (event: SseEvent) => void,
 	signal?: AbortSignal,
+	idleTimeoutMs: number = DEFAULT_IDLE_TIMEOUT_MS,
 ): Promise<void> {
 	const reader = body.getReader();
 	const decoder = new TextDecoder();
 	let buf = "";
+	let idleTimer: ReturnType<typeof setTimeout> | undefined;
+	let done = false;
+
+	const resetIdleTimer = () => {
+		if (idleTimer) clearTimeout(idleTimer);
+		if (idleTimeoutMs > 0) {
+			idleTimer = setTimeout(() => {
+				if (!done) {
+					reader.cancel("SSE idle timeout").catch(() => {});
+				}
+			}, idleTimeoutMs);
+		}
+	};
 
 	try {
+		resetIdleTimer();
 		while (true) {
 			if (signal?.aborted) {
 				await reader.cancel();
 				break;
 			}
-			const { value, done } = await reader.read();
-			if (done) break;
+			const { value, done: streamDone } = await reader.read();
+			if (streamDone) break;
+			resetIdleTimer();
 			buf += decoder.decode(value, { stream: true });
 			const parts = buf.split("\n\n");
 			buf = parts.pop() ?? "";
@@ -36,6 +56,8 @@ export async function readSseStream(
 			}
 		}
 	} finally {
+		done = true;
+		if (idleTimer) clearTimeout(idleTimer);
 		reader.releaseLock();
 	}
 }