feat(RECIPE-0009): complete iteration 0 — deduplication, notifications, UI improvements

src/routes/api/queue/+server.ts

@@ -50,15 +50,35 @@ export const POST: RequestHandler = async ({ request }) => {
 			throw new ValidationError(validation.error || 'Invalid Instagram URL');
 		}
 
-		// Enqueue the URL
+		// Check for duplicate before enqueueing
+		const existingItem = queueManager.findByUrl(url);
+
+		if (existingItem) {
+			// Return info response for duplicate
+			return json({
+				duplicate: true,
+				message: 'This recipe is already in the queue',
+				item: {
+					id: existingItem.id,
+					url: existingItem.url,
+					status: existingItem.status,
+					enqueuedAt: existingItem.enqueuedAt
+				}
+			}, { status: 200 }); // 200 OK, not an error
+		}
+
+		// Enqueue new URL
 		const queueItem = queueManager.enqueue(url);
 
-		// Return minimal response (full details available at GET /api/queue/{id})
+		// Return success response
 		return json({
-			id: queueItem.id,
-			url: queueItem.url,
-			status: queueItem.status,
-			enqueuedAt: queueItem.enqueuedAt
+			duplicate: false,
+			item: {
+				id: queueItem.id,
+				url: queueItem.url,
+				status: queueItem.status,
+				enqueuedAt: queueItem.enqueuedAt
+			}
 		});
 	} catch (error) {
 		return handleApiError(error);