Refactor DeerFlow to use Gateway's LangGraph-compatible API

- Updated documentation and comments to reflect the transition from LangGraph Server to Gateway.
- Changed default URLs in ChannelManager and tests to point to Gateway.
- Removed references to LangGraph Server in deployment scripts and configurations.
- Updated Nginx configuration to route API traffic to Gateway.
- Adjusted frontend configurations to utilize Gateway's API.
- Removed LangGraph service from Docker Compose files, consolidating services under Gateway.
- Added regression tests to ensure Gateway integration works as expected.

Co-authored-by: Copilot <copilot@github.com>

frontend/.env.example

@@ -14,10 +14,3 @@
 # Only set these if you need to connect to backend services directly
 # NEXT_PUBLIC_BACKEND_BASE_URL="http://localhost:8001"
 # NEXT_PUBLIC_LANGGRAPH_BASE_URL="http://localhost:2024"
-
-# LangGraph API base URL
-# Default: /api/langgraph (uses langgraph dev server via nginx)
-# Set to /api/langgraph-compat to use the experimental Gateway-backed runtime
-# Requires: SKIP_LANGGRAPH_SERVER=1 in serve.sh (optional, saves resources)
-# NEXT_PUBLIC_LANGGRAPH_BASE_URL=/api/langgraph-compat
-

frontend/next.config.js

@@ -23,10 +23,6 @@ const config = {
   devIndicators: false,
   async rewrites() {
     const rewrites = [];
-    const langgraphURL = getInternalServiceURL(
-      "DEER_FLOW_INTERNAL_LANGGRAPH_BASE_URL",
-      "http://127.0.0.1:2024",
-    );
     const gatewayURL = getInternalServiceURL(
       "DEER_FLOW_INTERNAL_GATEWAY_BASE_URL",
       "http://127.0.0.1:8001",
@@ -35,11 +31,11 @@ const config = {
     if (!process.env.NEXT_PUBLIC_LANGGRAPH_BASE_URL) {
       rewrites.push({
         source: "/api/langgraph",
-        destination: langgraphURL,
+        destination: `${gatewayURL}/api`,
       });
       rewrites.push({
         source: "/api/langgraph/:path*",
-        destination: `${langgraphURL}/:path*`,
+        destination: `${gatewayURL}/api/:path*`,
       });
     }
 
@@ -66,8 +62,8 @@ const config = {
       // their own NEXT_PUBLIC_* env var toggle.
       //
       // NOTE: this must come AFTER the /api/langgraph rewrite above so that
-      // LangGraph routes are matched first when NEXT_PUBLIC_LANGGRAPH_BASE_URL
-      // is unset.
+      // LangGraph-compatible routes keep their public prefix while Gateway
+      // receives its native /api/* paths.
       rewrites.push({
         source: "/api/:path*",
         destination: `${gatewayURL}/api/:path*`,

frontend/src/core/api/api-client.ts

@@ -13,8 +13,8 @@ import { sanitizeRunStreamOptions } from "./stream-mode";
  *
  * Reading the cookie per-request (rather than baking it into the SDK's
  * ``defaultHeaders`` at construction) handles login / logout / password
- * change cookie rotation transparently. Both the ``/langgraph-compat/*``
- * SDK path and the direct REST endpoints in ``fetcher.ts:fetchWithAuth``
+ * change cookie rotation transparently. Both the ``/api/langgraph/*`` SDK
+ * path and the direct REST endpoints in ``fetcher.ts:fetchWithAuth``
  * share :func:`readCsrfCookie` and :const:`STATE_CHANGING_METHODS` so
  * the contract stays in lockstep.
  */
@@ -32,8 +32,10 @@ function injectCsrfHeader(_url: URL, init: RequestInit): RequestInit {
 }
 
 function createCompatibleClient(isMock?: boolean): LangGraphClient {
+  const apiUrl = getLangGraphBaseURL(isMock);
+  console.log(`Creating API client with base URL: ${apiUrl}`);
   const client = new LangGraphClient({
-    apiUrl: getLangGraphBaseURL(isMock),
+    apiUrl,
     onRequest: injectCsrfHeader,
   });
 

frontend/src/core/config/index.ts

@@ -19,6 +19,10 @@ export function getBackendBaseURL() {
 }
 
 export function getLangGraphBaseURL(isMock?: boolean) {
+  console.log(
+    "env.NEXT_PUBLIC_LANGGRAPH_BASE_URL",
+    env.NEXT_PUBLIC_LANGGRAPH_BASE_URL,
+  );
   if (env.NEXT_PUBLIC_LANGGRAPH_BASE_URL) {
     return new URL(
       env.NEXT_PUBLIC_LANGGRAPH_BASE_URL,