perf(studio): stream nitro repair progress over SSE and allow cancelling

src/app/api/admin/studio/nitro-cleanup/rebuild/route.ts

@@ -3,9 +3,25 @@ import { withAdmin } from "@/lib/api-handler";
 import { PERMS } from "@/lib/permissions";
 import { logAudit } from "@/lib/services/audit";
 import { clearFurniImportCache } from "@/lib/services/furni-import-cache";
-import { repairBrokenNitros } from "@/lib/services/nitro-cleanup";
+import {
+	type NitroRepairProgress,
+	repairBrokenNitros,
+} from "@/lib/services/nitro-cleanup";
 
-/** Re-download the given broken .nitro bundles from the configured sources. */
+type RepairSummary = {
+	repaired: number;
+	failed: number;
+	errors?: string[];
+};
+
+/**
+ * Re-download the given broken .nitro bundles from the configured nitro
+ * sources. Bundles are pulled in parallel server-side; when the client asks
+ * for `text/event-stream` a `progress` event is streamed after every bundle
+ * settles plus a final `result` event, mirroring the scan endpoint so a large
+ * repair batch cannot be cut off by a reverse-proxy timeout and can be
+ * cancelled client-side.
+ */
 export const POST = withAdmin(
 	{ permission: PERMS.ASSETS_IMPORT },
 	async (request, ctx) => {
@@ -23,8 +39,22 @@ export const POST = withAdmin(
 		if (fileNames.length === 0) {
 			return apiError("fileNames[] is required", 400);
 		}
-		try {
-			const result = await repairBrokenNitros(fileNames);
+
+		const summarize = (result: {
+			repaired: number;
+			failed: number;
+			errors: string[];
+		}): RepairSummary => ({
+			repaired: result.repaired,
+			failed: result.failed,
+			errors: result.errors.length > 0 ? result.errors : undefined,
+		});
+
+		const finish = async (result: {
+			repaired: number;
+			failed: number;
+			errors: string[];
+		}) => {
 			clearFurniImportCache();
 			if (result.repaired > 0) {
 				logAudit({
@@ -39,10 +69,54 @@ export const POST = withAdmin(
 					},
 				});
 			}
-			return apiOk({
-				repaired: result.repaired,
-				failed: result.failed,
-				errors: result.errors.length > 0 ? result.errors : undefined,
+			return summarize(result);
+		};
+
+		const wantsSse = request.headers
+			.get("accept")
+			?.includes("text/event-stream");
+		try {
+			if (!wantsSse) {
+				return apiOk(await finish(await repairBrokenNitros(fileNames)));
+			}
+			const encoder = new TextEncoder();
+			const stream = new ReadableStream({
+				async start(controller) {
+					const send = (data: unknown) => {
+						try {
+							controller.enqueue(
+								encoder.encode(`data: ${JSON.stringify(data)}\n\n`),
+							);
+						} catch {
+							/* stream closed by client */
+						}
+					};
+					try {
+						const result = await repairBrokenNitros(fileNames, {
+							onProgress: (progress: NitroRepairProgress) =>
+								send({ type: "progress", ...progress }),
+						});
+						send({ type: "result", ...(await finish(result)) });
+					} catch (err) {
+						send({
+							type: "error",
+							message: `Nitro repair failed: ${(err as Error).message}`,
+						});
+					}
+					try {
+						controller.close();
+					} catch {
+						/* ignore */
+					}
+				},
+			});
+
+			return new Response(stream, {
+				headers: {
+					"Content-Type": "text/event-stream",
+					"Cache-Control": "no-cache",
+					Connection: "keep-alive",
+				},
 			});
 		} catch (err) {
 			return apiError(`Nitro repair failed: ${(err as Error).message}`, 500);