fix: make stop response instant with optimistic UI update and parallel requests

Author: Algorithm5838

src/lib/components/chat/Chat.svelte

@@ -2207,17 +2207,11 @@
 
 	const stopResponse = async () => {
 		if (taskIds) {
-			for (const taskId of taskIds) {
-				const res = await stopTask(localStorage.token, taskId).catch((error) => {
-					toast.error(`${error}`);
-					return null;
-				});
-			}
-
+			const _taskIds = [...taskIds];
 			taskIds = null;
 
+			// Immediately mark all response messages as done for instant UI feedback
 			const responseMessage = history.messages[history.currentId];
-			// Set all response messages to done
 			if (responseMessage.parentId && history.messages[responseMessage.parentId]) {
 				for (const messageId of history.messages[responseMessage.parentId].childrenIds) {
 					history.messages[messageId].done = true;
@@ -2229,6 +2223,15 @@
 			if (autoScroll) {
 				scrollToBottom();
 			}
+
+			// Send stop requests to backend in parallel, non-blocking
+			Promise.all(
+				_taskIds.map((taskId) =>
+					stopTask(localStorage.token, taskId).catch((error) => {
+						console.error(`Failed to stop task ${taskId}:`, error);
+					})
+				)
+			);
 		}
 
 		if (generating) {