feat: Auto-select model from last assistant response

tools/server/webui/src/routes/chat/[id]/+page.svelte

@@ -1,17 +1,62 @@
 <script lang="ts">
 	import { goto } from '$app/navigation';
 	import { page } from '$app/state';
+	import { afterNavigate } from '$app/navigation';
 	import { ChatScreen } from '$lib/components/app';
 	import {
 		chatStore,
 		activeConversation,
 		isLoading,
-		stopGeneration
+		stopGeneration,
+		activeMessages
 	} from '$lib/stores/chat.svelte';
+	import { selectModel, modelOptions, selectedModelId } from '$lib/stores/models.svelte';
 
 	let chatId = $derived(page.params.id);
 	let currentChatId: string | undefined = undefined;
 
+	async function selectModelFromLastAssistantResponse() {
+		const messages = activeMessages();
+		if (messages.length === 0) return;
+
+		let lastMessageWithModel: DatabaseMessage | undefined;
+
+		for (let i = messages.length - 1; i >= 0; i--) {
+			if (messages[i].model) {
+				lastMessageWithModel = messages[i];
+				break;
+			}
+		}
+
+		if (!lastMessageWithModel) return;
+
+		const currentModelId = selectedModelId();
+		const currentModelName = modelOptions().find((m) => m.id === currentModelId)?.model;
+
+		if (currentModelName === lastMessageWithModel.model) {
+			return;
+		}
+
+		const matchingModel = modelOptions().find(
+			(option) => option.model === lastMessageWithModel.model
+		);
+
+		if (matchingModel) {
+			try {
+				await selectModel(matchingModel.id);
+				console.log(`Automatically loaded model: ${lastMessageWithModel.model} from last message`);
+			} catch (error) {
+				console.warn('Failed to automatically select model from last message:', error);
+			}
+		}
+	}
+
+	afterNavigate(() => {
+		setTimeout(() => {
+			selectModelFromLastAssistantResponse();
+		}, 100);
+	});
+
 	$effect(() => {
 		if (chatId && chatId !== currentChatId) {
 			currentChatId = chatId;