fix: fast-path pure greetings in agent mode

app/(chat)/api/chat/route.ts

@@ -1233,6 +1233,15 @@ function normalizeAssistantPartsForPersistence(parts: Array<Record<string, any>>
   });
 }
 
+function isPureGreetingTurnRequest(text: string): boolean {
+  const normalized = String(text || "").toLowerCase().replace(/\s+/g, "").trim();
+  if (!normalized) return false;
+
+  return /^(你好|您好|hello|hi|嗨|哈喽|在吗|早上好|中午好|下午好|晚上好|深夜好|谢谢|感谢|收到|好的|ok|okay|明白了|了解了)$/.test(
+    normalized,
+  );
+}
+
 function buildAgentToolImageMarkdown(params: {
   originalUrl: string;
   thumbnailUrl?: string | null;
@@ -3149,6 +3158,49 @@ export async function POST(request: Request) {
       }
     }
 
+    const hasCurrentMessageMediaInput = message.parts.some((part: any) =>
+      part?.type === "file" || part?.type === "image" || part?.type === "image_url"
+    );
+    if (
+      shouldRunAgentConversation &&
+      isPureGreetingTurnRequest(requestTextContent) &&
+      !hasCurrentMessageMediaInput
+    ) {
+      const session = await auth();
+
+      if (!session?.user) {
+        return new ChatSDKError("unauthorized:chat").toResponse();
+      }
+
+      const greetingMessage = "你好，我在。你可以直接告诉我想做什么：生图、修图、生成视频、分析图片都可以。";
+      const greetingStream = createUIMessageStream({
+        execute: async ({ writer }) => {
+          const messageId = generateUUID();
+          writeAssistantTextChunk(writer, greetingMessage, "greeting-fast-path", messageId);
+
+          await saveMessages({
+            messages: [
+              {
+                id: messageId,
+                chatId: id,
+                role: "assistant",
+                parts: [{ type: "text", text: greetingMessage }],
+                attachments: [],
+                createdAt: new Date(),
+                videoStorageStatus: null,
+                temporaryVideoUrl: null,
+                permanentVideoUrl: null,
+                archivedAt: null,
+                videoMetadata: null,
+              },
+            ],
+          });
+        },
+      });
+
+      return createSseResponse(greetingStream);
+    }
+
     const allowAgentVideoGeneration =
       Boolean(requestBody.videoParams) || isVideoProviderType(requestedModelProviderType);
     let smartAutoWorkflowDecision: