feat: enhance replay mode in static website

web/src/app/chat/components/messages-block.tsx

@@ -14,9 +14,11 @@ import {
   CardTitle,
 } from "~/components/ui/card";
 import { fastForwardReplay } from "~/core/api";
+import { useReplayMetadata } from "~/core/api/hooks";
 import type { Option } from "~/core/messages";
 import { useReplay } from "~/core/replay";
 import { sendMessage, useStore } from "~/core/store";
+import { env } from "~/env";
 import { cn } from "~/lib/utils";
 
 import { ConversationStarter } from "./conversation-starter";
@@ -28,6 +30,7 @@ export function MessagesBlock({ className }: { className?: string }) {
   const messageCount = useStore((state) => state.messageIds.length);
   const responding = useStore((state) => state.responding);
   const { isReplay } = useReplay();
+  const { title: replayTitle, hasError: replayHasError } = useReplayMetadata();
   const [replayStarted, setReplayStarted] = useState(false);
   const abortControllerRef = useRef<AbortController | null>(null);
   const [feedback, setFeedback] = useState<{ option: Option } | null>(null);
@@ -123,7 +126,7 @@ export function MessagesBlock({ className }: { className?: string }) {
                   <CardHeader>
                     <CardTitle>
                       <RainbowText animated={responding}>
-                        {responding ? "Replaying" : "Replay Mode"}
+                        {responding ? "Replaying" : `${replayTitle}`}
                       </RainbowText>
                     </CardTitle>
                     <CardDescription>
@@ -137,26 +140,43 @@ export function MessagesBlock({ className }: { className?: string }) {
                     </CardDescription>
                   </CardHeader>
                 </div>
-                <div className="pr-4">
-                  {responding && (
-                    <Button
-                      className={cn(fastForwarding && "animate-pulse")}
-                      variant={fastForwarding ? "default" : "outline"}
-                      onClick={handleFastForwardReplay}
-                    >
-                      <FastForward size={16} />
-                      Fast Forward
-                    </Button>
-                  )}
-                  {!replayStarted && (
-                    <Button className="w-24" onClick={handleStartReplay}>
-                      <Play size={16} />
-                      Play
-                    </Button>
-                  )}
-                </div>
+                {!replayHasError && (
+                  <div className="pr-4">
+                    {responding && (
+                      <Button
+                        className={cn(fastForwarding && "animate-pulse")}
+                        variant={fastForwarding ? "default" : "outline"}
+                        onClick={handleFastForwardReplay}
+                      >
+                        <FastForward size={16} />
+                        Fast Forward
+                      </Button>
+                    )}
+                    {!replayStarted && (
+                      <Button className="w-24" onClick={handleStartReplay}>
+                        <Play size={16} />
+                        Play
+                      </Button>
+                    )}
+                  </div>
+                )}
               </div>
             </Card>
+            {!replayStarted && env.NEXT_PUBLIC_STATIC_WEBSITE_ONLY && (
+              <div className="text-muted-foreground w-full text-center text-xs">
+                * This site is for demo purposes only. If you want to try your
+                own question, please{" "}
+                <a
+                  className="underline"
+                  href="https://github.com/bytedance/deer-flow"
+                  target="_blank"
+                  rel="noopener noreferrer"
+                >
+                  click here
+                </a>{" "}
+                to clone it locally and run it.
+              </div>
+            )}
           </motion.div>
         </>
       )}

web/src/app/chat/components/welcome.tsx

@@ -26,8 +26,8 @@ export function Welcome({ className }: { className?: string }) {
         >
           🦌 DeerFlow
         </a>
-        , a research tool built on cutting-edge language models, helps you
-        search on web, browse information, and handle complex tasks.
+        , a deep research assistant built on cutting-edge language models, helps
+        you search on web, browse information, and handle complex tasks.
       </div>
     </motion.div>
   );

web/src/core/api/chat.ts

@@ -1,6 +1,8 @@
 // Copyright (c) 2025 Bytedance Ltd. and/or its affiliates
 // SPDX-License-Identifier: MIT
 
+import { env } from "~/env";
+
 import type { MCPServerMetadata } from "../mcp";
 import { extractReplayIdFromSearchParams } from "../replay/get-replay-id";
 import { fetchStream } from "../sse";
@@ -30,7 +32,11 @@ export async function* chatStream(
   },
   options: { abortSignal?: AbortSignal } = {},
 ) {
-  if (location.search.includes("mock") || location.search.includes("replay=")) {
+  if (
+    env.NEXT_PUBLIC_STATIC_WEBSITE_ONLY ||
+    location.search.includes("mock") ||
+    location.search.includes("replay=")
+  ) {
     return yield* chatReplayStream(userMessage, params, options);
   }
   const stream = fetchStream(resolveServiceURL("chat/stream"), {
@@ -77,13 +83,13 @@ async function* chatReplayStream(
     if (replayId) {
       replayFilePath = `/replay/${replayId}.txt`;
     } else {
-      replayFilePath = "/mock/before-interrupt.txt";
+      // Fallback to a default replay
+      replayFilePath = `/replay/eiffel-tower-vs-tallest-building.txt`;
     }
   }
-  const res = await fetch(replayFilePath, {
-    signal: options.abortSignal,
+  const text = await fetchReplay(replayFilePath, {
+    abortSignal: options.abortSignal,
   });
-  const text = await res.text();
   const chunks = text.split("\n\n");
   for (const chunk of chunks) {
     const [eventRaw, dataRaw] = chunk.split("\n") as [string, string];
@@ -116,6 +122,43 @@ async function* chatReplayStream(
   }
 }
 
+const replayCache = new Map<string, string>();
+export async function fetchReplay(
+  url: string,
+  options: { abortSignal?: AbortSignal } = {},
+) {
+  if (replayCache.has(url)) {
+    return replayCache.get(url)!;
+  }
+  const res = await fetch(url, {
+    signal: options.abortSignal,
+  });
+  if (!res.ok) {
+    throw new Error(`Failed to fetch replay: ${res.statusText}`);
+  }
+  const text = await res.text();
+  replayCache.set(url, text);
+  return text;
+}
+
+export async function fetchReplayTitle() {
+  const res = chatReplayStream(
+    "",
+    {
+      thread_id: "__mock__",
+      auto_accepted_plan: false,
+      max_plan_iterations: 3,
+      max_step_num: 1,
+    },
+    {},
+  );
+  for await (const event of res) {
+    if (event.type === "message_chunk") {
+      return event.data.content;
+    }
+  }
+}
+
 export async function sleepInReplay(ms: number) {
   if (fastForwardReplaying) {
     await sleep(0);

web/src/core/api/hooks.ts

@@ -0,0 +1,35 @@
+// Copyright (c) 2025 Bytedance Ltd. and/or its affiliates
+// SPDX-License-Identifier: MIT
+
+import { useEffect, useState } from "react";
+
+import { fetchReplayTitle } from "./chat";
+
+export function useReplayMetadata() {
+  const [title, setTitle] = useState<string | null>(null);
+  const [isLoading, setIsLoading] = useState(false);
+  const [error, setError] = useState<boolean>(false);
+  useEffect(() => {
+    if (title || isLoading) {
+      return;
+    }
+    setIsLoading(true);
+    fetchReplayTitle()
+      .then((title) => {
+        setError(false);
+        setTitle(title ?? null);
+        if (title) {
+          document.title = `${title} - DeerFlow`;
+        }
+      })
+      .catch(() => {
+        setError(true);
+        setTitle("Error: the replay is not available.");
+        document.title = "DeerFlow";
+      })
+      .finally(() => {
+        setIsLoading(false);
+      });
+  }, [isLoading, title]);
+  return { title, isLoading, hasError: error };
+}