Wire up query history: localStorage session persistence + sidebar UI

apps/web/app/api/history/route.ts

@@ -0,0 +1,38 @@
+import { NextResponse } from "next/server";
+
+export const runtime = "nodejs";
+
+const API_GATEWAY_URL =
+  process.env.API_GATEWAY_URL ?? process.env.AI_SERVICE_URL ?? "http://localhost:8000";
+
+export async function GET(request: Request) {
+  const { searchParams } = new URL(request.url);
+  const conversationId = searchParams.get("conversation_id")?.trim() || "";
+
+  if (!conversationId) {
+    return NextResponse.json({ items: [] });
+  }
+
+  try {
+    const targetUrl = API_GATEWAY_URL.includes("/v1/rag")
+      ? `${API_GATEWAY_URL.replace(/\/query$/, "/history")}?conversation_id=${encodeURIComponent(conversationId)}`
+      : `${API_GATEWAY_URL}/v1/rag/history?conversation_id=${encodeURIComponent(conversationId)}`;
+
+    const upstream = await fetch(targetUrl, {
+      method: "GET",
+      headers: {
+        "X-Client-Version": "1.0.0",
+      },
+      cache: "no-store",
+    });
+
+    if (!upstream.ok) {
+      return NextResponse.json({ items: [] });
+    }
+
+    const data = await upstream.json();
+    return NextResponse.json(data);
+  } catch {
+    return NextResponse.json({ items: [] });
+  }
+}