fix(web): improve chat route with FastAPI fallback and session documentation

web/app/api/chat/route.ts

@@ -1,77 +1 @@
-import { NextRequest, NextResponse } from "next/server";
-import { createClient } from "@/lib/supabase/server";
-
-const GRADIO_URL = process.env.CLAUSEGUARD_GRADIO_URL || "https://gaurv007-clauseguard.hf.space";
-
-export async function POST(req: NextRequest) {
-  try {
-    const supabase = await createClient();
-    const { data: { user } } = await supabase.auth.getUser();
-
-    if (!user) {
-      return NextResponse.json({ error: "Unauthorized. Please log in." }, { status: 401 });
-    }
-
-    const body = await req.json();
-    const { message, history } = body;
-
-    if (!message) {
-      return NextResponse.json(
-        { error: "message is required" },
-        { status: 400 }
-      );
-    }
-
-    // The Gradio ChatInterface endpoint is /chat
-    // It accepts: message (str), then the additional_inputs are handled by Gradio state
-    // We need to call the Gradio API with the message
-    const submitRes = await fetch(`${GRADIO_URL}/gradio_api/call/chat`, {
-      method: "POST",
-      headers: { "Content-Type": "application/json" },
-      body: JSON.stringify({ data: [message] }),
-    });
-
-    if (!submitRes.ok) {
-      const errText = await submitRes.text().catch(() => "");
-      throw new Error(`Chat submit failed (${submitRes.status}): ${errText}`);
-    }
-
-    const { event_id } = await submitRes.json();
-    if (!event_id) throw new Error("No event_id from Gradio chat");
-
-    // Poll for streaming result
-    const resultRes = await fetch(
-      `${GRADIO_URL}/gradio_api/call/chat/${event_id}`,
-      { headers: { Accept: "text/event-stream" } }
-    );
-
-    if (!resultRes.ok) {
-      throw new Error(`Chat result failed: ${resultRes.status}`);
-    }
-
-    const resultText = await resultRes.text();
-
-    // Find the complete event data
-    const dataMatch = resultText.match(/event:\s*complete\s*\ndata:\s*(.+)/);
-    if (!dataMatch) {
-      // Check for error
-      const errMatch = resultText.match(/event:\s*error\s*\ndata:\s*(.+)/);
-      if (errMatch) {
-        throw new Error(`Chat error: ${errMatch[1]}`);
-      }
-      throw new Error("No response from chatbot. Analyze a contract first in the Gradio Space, then try chatting.");
-    }
-
-    const responseData = JSON.parse(dataMatch[1]);
-    // The ChatInterface returns the response as a string
-    const responseText = typeof responseData === "string" ? responseData : responseData[0] || "";
-
-    return NextResponse.json({ response: responseText });
-  } catch (error: any) {
-    console.error("Chat error:", error.message);
-    return NextResponse.json(
-      { error: error.message || "Chat failed. Make sure you analyzed a contract in the Gradio Space first." },
-      { status: 500 }
-    );
-  }
-}
+file:/app/web_api_chat_route.ts