Improve chat navigation, model selection, and streaming

app/api/chat/route.ts

@@ -4,16 +4,20 @@ import {
   stepCountIs,
   pruneMessages,
 } from 'ai';
-import { createOpenRouter } from '@openrouter/ai-sdk-provider';
-import { tools } from '@/chat.config';
+import { getChatModel } from '@/services/chat/model';
+import { getChatInstructions } from '@/services/chat/instructions';
+import { chatTools } from '@/services/chat/tools';
+import { isOpenRouterModelId } from '@/lib/openrouter';
 
-const openrouter = createOpenRouter({
-  apiKey: process.env.OPENROUTER_API_KEY,
-});
+export const maxDuration = 300;
 
 export async function POST(request: Request) {
   try {
-    const { messages } = await request.json();
+    const { messages, modelId } = await request.json();
+
+    if (modelId !== undefined && !isOpenRouterModelId(modelId)) {
+      return Response.json({ error: 'Select a supported model' }, { status: 400 });
+    }
 
     if (!process.env.OPENROUTER_API_KEY) {
       return Response.json(
@@ -22,30 +26,11 @@ export async function POST(request: Request) {
       );
     }
 
-    const model = openrouter(
-      process.env.OPENROUTER_MODEL || 'openai/gpt-5.6-luna-pro'
-    );
+    const model = getChatModel(modelId);
 
     const webSearchEnabled = Boolean(process.env.FIRECRAWL_API_KEY);
 
-    const instructions = webSearchEnabled
-      ? `You are an expert ChatGPT Agent with real-time access to the internet.
-
-Your capabilities:
-- Search the web using Firecrawl to find up-to-date information
-- Fetch and read full web pages to extract detailed content
-- Synthesize information from multiple sources into clear, accurate answers
-- Cite your sources inline so the user can verify information
-
-Guidelines:
-- Always search the web before answering questions that require current or factual information
-- Use multiple searches when needed to get comprehensive answers
-- Cross-reference sources for accuracy
-- Structure your responses clearly with headings, bullet points, and citations where appropriate
-- When fetching pages, extract only the relevant information
-- Be transparent about the sources you used
-- Today's date is ${new Date().toLocaleDateString('en-US', { weekday: 'long', year: 'numeric', month: 'long', day: 'numeric' })}`
-      : `You are a helpful AI research assistant. Answer clearly and accurately. You do not have live web access, so be transparent when a question requires current information. Today's date is ${new Date().toLocaleDateString('en-US', { weekday: 'long', year: 'numeric', month: 'long', day: 'numeric' })}.`;
+    const instructions = getChatInstructions(webSearchEnabled);
 
     const convertedMessages = await convertToModelMessages(messages);
 
@@ -55,12 +40,16 @@ Guidelines:
       toolCalls: 'none',
     });
 
-    const result = await streamText({
+    const result = streamText({
       model,
       instructions,
       messages: prunedMessages,
-      tools: webSearchEnabled ? tools : {},
+      abortSignal: request.signal,
+      tools: webSearchEnabled ? chatTools : {},
       stopWhen: stepCountIs(20),
+      onError: ({ error }) => {
+        if (!request.signal.aborted) console.error('Chat stream error:', error);
+      },
       providerOptions: {
         openrouter: {
           reasoning: {
@@ -71,7 +60,11 @@ Guidelines:
       },
     });
 
-    return result.toUIMessageStreamResponse({ sendReasoning: true });
+    return result.toUIMessageStreamResponse({
+      sendReasoning: true,
+      headers: { 'Cache-Control': 'no-cache, no-transform' },
+      onError: () => 'The response was interrupted. Please try again.',
+    });
   } catch (error) {
     console.error('Chat API error:', error);
     return new Response(