perf: prevent import hanging with timeouts and batching

- verifyAndFixInteractionModesCount: paginated DB queries (500/batch)
  instead of loading all items into memory at once
- withFurniDataLock: add 60s chain timeout to prevent deadlocks
  when a lock holder stalls or crashes
- withGamedataLock: same timeout protection for gamedata locks
- conversion-pool: add 60s per-job timeout, fall back to main thread
- furni/batch: abort signal + post_import progress events + skip
  post-import steps when client disconnects
- furni/batch-regen: abort signal + early exit when disconnected
- clone/sync-all: pre-fetch furnidata once per source instead of
  per item (eliminates 2000+ redundant fetches)
- sse-client: add 60s idle timeout to prevent infinite hangs

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

@@ -47,9 +47,16 @@ export const POST = withAdmin(
 		const { swfDir, nitroDir } = await getFurniAssetDirs();
 		const encoder = new TextEncoder();
 
+		// Wire client disconnect to abort controller
+		let aborted = false;
+		request.signal.addEventListener("abort", () => {
+			aborted = true;
+		});
+
 		const stream = new ReadableStream({
 			async start(controller) {
 				const send = (data: unknown) => {
+					if (aborted) return;
 					try {
 						controller.enqueue(
 							encoder.encode(`data: ${JSON.stringify(data)}\n\n`),
@@ -240,6 +247,18 @@ export const POST = withAdmin(
 					await new Promise((r) => setImmediate(r));
 				}
 
+				if (aborted) {
+					send({
+						type: "regen_complete",
+						succeeded,
+						failed,
+						skipped,
+						aborted: true,
+					});
+					controller.close();
+					return;
+				}
+
 				// Batch write FurnitureData.json
 				if (furniDataEntries.length > 0) {
 					try {
@@ -291,25 +310,27 @@ export const POST = withAdmin(
 					);
 				}
 
-				send({
-					type: "regen_complete",
-					succeeded,
-					failed,
-					skipped,
-					furniDataAdded: furniDataEntries.length,
-					ownershipFixed: ownership.fixed,
-					nitrosSynced: assetsSynced.copiedNitros,
-					iconsSynced: assetsSynced.copiedIcons,
-					furniDataFixedIds: furniReconcile.fixedIds,
-					furniDataMissing: furniReconcile.missing,
-					furniDataConflicts: furniReconcile.conflicts,
-					offerRebuildChecked: offerRebuild.checked,
-					offerRebuildFixed: offerRebuild.fixed,
-					spriteChecked: spriteVerify.checked,
-					spriteFixed: spriteVerify.fixed,
-					languages,
-					duration: Date.now() - startTime,
-				});
+				if (!aborted) {
+					send({
+						type: "regen_complete",
+						succeeded,
+						failed,
+						skipped,
+						furniDataAdded: furniDataEntries.length,
+						ownershipFixed: ownership.fixed,
+						nitrosSynced: assetsSynced.copiedNitros,
+						iconsSynced: assetsSynced.copiedIcons,
+						furniDataFixedIds: furniReconcile.fixedIds,
+						furniDataMissing: furniReconcile.missing,
+						furniDataConflicts: furniReconcile.conflicts,
+						offerRebuildChecked: offerRebuild.checked,
+						offerRebuildFixed: offerRebuild.fixed,
+						spriteChecked: spriteVerify.checked,
+						spriteFixed: spriteVerify.fixed,
+						languages,
+						duration: Date.now() - startTime,
+					});
+				}
 
 				controller.close();
 			},

src/lib/services/furni-data.ts

@@ -184,14 +184,42 @@ export async function findFurniDataIdConflict(
 	}
 }
 
+const CHAIN_TIMEOUT_MS = 60_000;
+
+/**
+ * Wait for the previous lock holder with a timeout.
+ * If the holder stalled (e.g. process crash, unhandled rejection),
+ * we break the chain instead of waiting forever.
+ */
+async function waitForFurniDataLock(): Promise<void> {
+	const prev = furniDataLock;
+	if (prev === Promise.resolve()) return;
+
+	try {
+		await Promise.race([
+			prev,
+			new Promise((_, reject) =>
+				setTimeout(
+					() => reject(new Error("furni-data chain timeout")),
+					CHAIN_TIMEOUT_MS,
+				),
+			),
+		]);
+	} catch {
+		// Chain holder timed out or crashed — break the chain
+		furniDataLock = Promise.resolve();
+	}
+}
+
 export async function withFurniDataLock<T>(fn: () => Promise<T>): Promise<T> {
 	let release!: () => void;
 	const acquired = new Promise<void>((r) => {
 		release = r;
 	});
-	const prev = furniDataLock;
+
+	await waitForFurniDataLock();
 	furniDataLock = acquired;
-	await prev;
+
 	const lockBase = await getFurnitureDataReadPath();
 	await fs.mkdir(path.dirname(lockBase), { recursive: true });
 	const lockPath = `${lockBase}.lock`;
@@ -200,6 +228,7 @@ export async function withFurniDataLock<T>(fn: () => Promise<T>): Promise<T> {
 		return await fn();
 	} finally {
 		await fs.unlink(lockPath).catch(() => {});
+		furniDataLock = Promise.resolve();
 		release?.();
 	}
 }

src/lib/services/import/core/gamedata-json.ts

@@ -2,10 +2,12 @@ import { promises as fs } from "node:fs";
 
 const LOCK_STALE_MS = 60_000;
 const LOCK_ACQUIRE_TIMEOUT_MS = 30_000;
+const CHAIN_TIMEOUT_MS = 60_000;
 
 // In-process serialization, keyed by absolute file path, layered on top of the
 // on-disk lock so multiple awaiters in the same Node process queue cleanly.
 const chains = new Map<string, Promise<void>>();
+const chainTimestamps = new Map<string, number>();
 
 async function acquireDiskLock(lockPath: string): Promise<void> {
 	const deadline = Date.now() + LOCK_ACQUIRE_TIMEOUT_MS;
@@ -34,6 +36,48 @@ async function acquireDiskLock(lockPath: string): Promise<void> {
 	}
 }
 
+/**
+ * Wait for the previous chain holder with a timeout.
+ * If the chain holder stalled (e.g. process crash, unhandled rejection),
+ * we break the chain instead of waiting forever.
+ */
+async function waitForChain(filePath: string): Promise<void> {
+	const prev = chains.get(filePath);
+	if (!prev) return;
+
+	const timestamp = chainTimestamps.get(filePath) ?? 0;
+	const elapsed = Date.now() - timestamp;
+
+	if (elapsed > CHAIN_TIMEOUT_MS) {
+		// Previous holder took too long — break the chain
+		console.warn(
+			`[gamedata-lock] Breaking stale chain for ${filePath} (held for ${elapsed}ms)`,
+		);
+		chains.delete(filePath);
+		chainTimestamps.delete(filePath);
+		return;
+	}
+
+	try {
+		await Promise.race([
+			prev,
+			new Promise((_, reject) =>
+				setTimeout(
+					() => reject(new Error("chain timeout")),
+					Math.max(1, CHAIN_TIMEOUT_MS - elapsed),
+				),
+			),
+		]);
+	} catch {
+		// Chain holder timed out or crashed — break the chain
+		console.warn(
+			`[gamedata-lock] Chain timeout for ${filePath}, breaking chain`,
+		);
+		chains.delete(filePath);
+		chainTimestamps.delete(filePath);
+	}
+}
+
 export async function withGamedataLock<T>(
 	filePath: string,
 	fn: () => Promise<T>,
@@ -42,15 +86,20 @@ export async function withGamedataLock<T>(
 	const acquired = new Promise<void>((r) => {
 		release = r;
 	});
-	const prev = chains.get(filePath) ?? Promise.resolve();
+
+	await waitForChain(filePath);
+
 	chains.set(filePath, acquired);
-	await prev;
+	chainTimestamps.set(filePath, Date.now());
+
 	const lockPath = `${filePath}.lock`;
 	await acquireDiskLock(lockPath);
 	try {
 		return await fn();
 	} finally {
 		await fs.unlink(/*turbopackIgnore: true*/ lockPath).catch(() => {});
+		chains.delete(filePath);
+		chainTimestamps.delete(filePath);
 		release();
 	}
 }

src/lib/services/swf/conversion-pool.ts

@@ -87,6 +87,8 @@ function pump() {
 	}
 }
 
+const CONVERSION_TIMEOUT_MS = 60_000;
+
 function run(req: Omit<WorkerRequest, "id">): Promise<WorkerResponse> {
 	if (!ensurePool()) {
 		try {
@@ -118,6 +120,33 @@ function run(req: Omit<WorkerRequest, "id">): Promise<WorkerResponse> {
 		};
 		queue.push(job);
 		pump();
+
+		// Timeout: if a job takes too long, remove it from the queue
+		// and reject so the caller can fall back to main-thread conversion.
+		const timer = setTimeout(() => {
+			const idx = queue.findIndex((j) => j.req.id === job.req.id);
+			if (idx !== -1) {
+				queue.splice(idx, 1);
+				pending.delete(job.req.id);
+				reject(new Error("Conversion timed out"));
+			} else {
+				// Already dispatched to a worker — the worker is
+				// responsible for timing out its own task.
+				reject(new Error("Conversion timed out"));
+			}
+		}, CONVERSION_TIMEOUT_MS);
+
+		// Clear the timer once the job resolves/rejects
+		const origResolve = resolve;
+		const origReject = reject;
+		job.resolve = (r) => {
+			clearTimeout(timer);
+			origResolve(r);
+		};
+		job.reject = (e) => {
+			clearTimeout(timer);
+			origReject(e);
+		};
 	});
 }