fix: upload actual chat/route.ts content — FastAPI fallback, session docs, input validation

web/app/api/chat/route.ts

@@ -1 +1,129 @@
-file:/app/web_api_chat_route.ts
+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";
+
+/**
+ * FIX v4.1: The chat endpoint now properly documents its limitations.
+ *
+ * ARCHITECTURE NOTE:
+ * The Gradio ChatInterface uses gr.State to store RAG embeddings per-session.
+ * This state is NOT accessible via the Gradio API from an external caller —
+ * each API call creates a new session with empty state.
+ *
+ * For the Next.js web app, chat should either:
+ * 1. Use the FastAPI backend (/api/chat) which manages its own RAG sessions, OR
+ * 2. Embed the Gradio Space in an iframe for direct interaction
+ *
+ * This route attempts to use the Gradio API as a best-effort fallback,
+ * but will clearly communicate to the user if the session is unavailable.
+ */
+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, session_id } = body;
+
+    if (!message) {
+      return NextResponse.json(
+        { error: "message is required" },
+        { status: 400 }
+      );
+    }
+
+    // FIX v4.1: Input validation
+    if (message.length > 2000) {
+      return NextResponse.json(
+        { error: "Message too long (max 2000 characters)" },
+        { status: 400 }
+      );
+    }
+
+    // Try the FastAPI backend first (it has proper RAG session management)
+    const apiUrl = process.env.CLAUSEGUARD_API_URL || "";
+    if (apiUrl && session_id) {
+      try {
+        const apiRes = await fetch(`${apiUrl}/api/chat`, {
+          method: "POST",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({ message, session_id, history: history || [] }),
+        });
+        if (apiRes.ok) {
+          const data = await apiRes.json();
+          return NextResponse.json({ response: data.response });
+        }
+      } catch {
+        // Fall through to Gradio attempt
+      }
+    }
+
+    // Fallback: Try the Gradio API
+    const submitRes = await fetch(`${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}): ${errText}`);
+    }
+
+    const { event_id } = await submitRes.json();
+    if (!event_id) throw new Error("No event_id from Gradio chat");
+
+    // Poll for result with timeout
+    let resultText = "";
+    let attempts = 0;
+    const maxAttempts = 30;
+
+    while (attempts < maxAttempts) {
+      const resultRes = await fetch(
+        `${GRADIO_URL}/gradio_api/call/chat/${event_id}`,
+        { headers: { Accept: "text/event-stream" } }
+      );
+
+      if (!resultRes.ok) {
+        throw new Error(`Chat result failed: ${resultRes.status}`);
+      }
+
+      resultText = await resultRes.text();
+
+      if (resultText.includes("event: complete")) break;
+      if (resultText.includes("event: error")) {
+        const errMatch = resultText.match(/event:\s*error\s*\ndata:\s*(.+)/);
+        if (errMatch) throw new Error(`Chat error: ${errMatch[1]}`);
+        throw new Error("Chat error from backend");
+      }
+
+      await new Promise(r => setTimeout(r, 1000));
+      attempts++;
+    }
+
+    // Find the complete event data
+    const dataMatch = resultText.match(/event:\s*complete\s*\ndata:\s*(.+)/);
+    if (!dataMatch) {
+      return NextResponse.json({
+        response: "⚠️ Chat is unavailable. The contract needs to be analyzed in the same session. " +
+          "Please analyze a contract first in the Gradio Space, then use the chat tab there directly."
+      });
+    }
+
+    const responseData = JSON.parse(dataMatch[1]);
+    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 first." },
+      { status: 500 }
+    );
+  }
+}