fix(frontend): wait for async chat submit before clearing (#2940)

* fix(frontend): wait for async chat submit before clearing

* test(frontend): cover pending attachment uploads

* fix(frontend): preserve sync submit semantics

frontend/src/app/workspace/agents/[agent_name]/chats/[thread_id]/page.tsx

@@ -66,6 +66,7 @@ export default function AgentChatPage() {
     thread,
     pendingUsageMessages,
     sendMessage,
+    isUploading,
     isHistoryLoading,
     hasMoreHistory,
     loadMoreHistory,
@@ -106,7 +107,11 @@ export default function AgentChatPage() {
 
   const handleSubmit = useCallback(
     (message: PromptInputMessage) => {
-      void sendMessage(threadId, message, { agent_name });
+      const sendPromise = sendMessage(threadId, message, { agent_name });
+      if (message.files.length > 0) {
+        return sendPromise;
+      }
+      void sendPromise;
     },
     [sendMessage, threadId, agent_name],
   );
@@ -243,7 +248,10 @@ export default function AgentChatPage() {
                       <AgentWelcome agent={agent} agentName={agent_name} />
                     )
                   }
-                  disabled={env.NEXT_PUBLIC_STATIC_WEBSITE_ONLY === "true"}
+                  disabled={
+                    env.NEXT_PUBLIC_STATIC_WEBSITE_ONLY === "true" ||
+                    isUploading
+                  }
                   onContextChange={(context) => setSettings("context", context)}
                   onSubmit={handleSubmit}
                   onStop={handleStop}

frontend/src/app/workspace/chats/[thread_id]/page.tsx

@@ -109,7 +109,11 @@ export default function ChatPage() {
 
   const handleSubmit = useCallback(
     (message: PromptInputMessage) => {
-      void sendMessage(threadId, message);
+      const sendPromise = sendMessage(threadId, message);
+      if (message.files.length > 0) {
+        return sendPromise;
+      }
+      void sendPromise;
     },
     [sendMessage, threadId],
   );

frontend/src/components/ai-elements/prompt-input.tsx

@@ -499,6 +499,10 @@ export const PromptInput = ({
   // Keep a ref to files for cleanup on unmount (avoids stale closure)
   const filesRef = useRef(files);
   filesRef.current = files;
+  const providerTextRef = useRef("");
+  if (usingProvider) {
+    providerTextRef.current = controller.textInput.value;
+  }
 
   const openFileDialogLocal = useCallback(() => {
     inputRef.current?.click();
@@ -768,6 +772,24 @@ export const PromptInput = ({
     }
 
     // Convert blob URLs to data URLs asynchronously
+    const submittedFileIds = files.map((file) => file.id);
+    const clearSubmittedState = () => {
+      const currentFileIds = new Set(filesRef.current.map((file) => file.id));
+      const submittedFileIdsStillPresent = submittedFileIds.filter((id) =>
+        currentFileIds.has(id),
+      );
+      if (submittedFileIdsStillPresent.length === filesRef.current.length) {
+        clear();
+      } else {
+        for (const id of submittedFileIdsStillPresent) {
+          remove(id);
+        }
+      }
+      if (usingProvider && providerTextRef.current === text) {
+        controller.textInput.clear();
+      }
+    };
+
     Promise.all(
       files.map(async ({ id, ...item }) => {
         if (item.file instanceof File) {
@@ -793,20 +815,14 @@ export const PromptInput = ({
           if (result instanceof Promise) {
             result
               .then(() => {
-                clear();
+                clearSubmittedState();
-                if (usingProvider) {
-                  controller.textInput.clear();
-                }
               })
               .catch(() => {
                 // Don't clear on error - user may want to retry
               });
           } else {
             // Sync function completed without throwing, clear attachments
-            clear();
+            clearSubmittedState();
-            if (usingProvider) {
-              controller.textInput.clear();
-            }
           }
         } catch {
           // Don't clear on error - user may want to retry

frontend/src/components/workspace/input-box.tsx

@@ -110,6 +110,7 @@ export function InputBox({
   threadId,
   initialValue,
   onContextChange,
+  onFollowupsVisibilityChange,
   onSubmit,
   onStop,
   ...props
@@ -142,7 +143,8 @@ export function InputBox({
       reasoning_effort?: "minimal" | "low" | "medium" | "high";
     },
   ) => void;
-  onSubmit?: (message: PromptInputMessage) => void;
+  onFollowupsVisibilityChange?: (visible: boolean) => void;
+  onSubmit?: (message: PromptInputMessage) => void | Promise<void>;
   onStop?: () => void;
 }) {
   const { t } = useI18n();
@@ -251,12 +253,12 @@ export function InputBox({
   );
 
   const handleSubmit = useCallback(
-    async (message: PromptInputMessage) => {
+    (message: PromptInputMessage) => {
       if (status === "streaming") {
         onStop?.();
         return;
       }
-      if (!message.text) {
+      if (!message.text.trim() && message.files.length === 0) {
         return;
       }
       setFollowups([]);
@@ -274,11 +276,14 @@ export function InputBox({
             selectedModel?.supports_thinking ?? false,
           ),
         });
-        setTimeout(() => onSubmit?.(message), 0);
+        return new Promise<void>((resolve, reject) => {
-        return;
+          setTimeout(() => {
+            Promise.resolve(onSubmit?.(message)).then(resolve).catch(reject);
+          }, 0);
+        });
       }
 
-      onSubmit?.(message);
+      return onSubmit?.(message);
     },
     [
       context,
@@ -348,6 +353,14 @@ export function InputBox({
     !followupsHidden &&
     (followupsLoading || followups.length > 0);
 
+  useEffect(() => {
+    onFollowupsVisibilityChange?.(showFollowups);
+  }, [onFollowupsVisibilityChange, showFollowups]);
+
+  useEffect(() => {
+    return () => onFollowupsVisibilityChange?.(false);
+  }, [onFollowupsVisibilityChange]);
+
   useEffect(() => {
     messagesRef.current = thread.messages;
   }, [thread.messages]);

frontend/tests/e2e/chat.spec.ts

@@ -48,4 +48,66 @@ test.describe("Chat workspace", () => {
       timeout: 10_000,
     });
   });
+
+  test("keeps attachments visible while upload submit is pending", async ({
+    page,
+  }) => {
+    let releaseUpload!: () => void;
+    const uploadCanFinish = new Promise<void>((resolve) => {
+      releaseUpload = resolve;
+    });
+    let uploadStarted!: () => void;
+    const uploadStartedPromise = new Promise<void>((resolve) => {
+      uploadStarted = resolve;
+    });
+
+    await page.route("**/api/threads/*/uploads", async (route) => {
+      uploadStarted();
+      await uploadCanFinish;
+      return route.fulfill({
+        status: 200,
+        contentType: "application/json",
+        body: JSON.stringify({
+          success: true,
+          message: "Uploaded",
+          files: [
+            {
+              filename: "report.docx",
+              size: 12,
+              path: "report.docx",
+              virtual_path: "/mnt/user-data/uploads/report.docx",
+              artifact_url: "/api/threads/test/uploads/report.docx",
+              extension: ".docx",
+            },
+          ],
+        }),
+      });
+    });
+
+    await page.goto("/workspace/chats/new");
+
+    const textarea = page.getByPlaceholder(/how can i assist you/i);
+    await expect(textarea).toBeVisible({ timeout: 15_000 });
+    const promptForm = page.locator("form").filter({ has: textarea });
+
+    await page.getByLabel("Upload files").setInputFiles({
+      name: "report.docx",
+      mimeType:
+        "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+      buffer: Buffer.from("fake docx"),
+    });
+    await expect(promptForm.getByText("report.docx")).toBeVisible();
+
+    await textarea.fill("Summarize this document");
+    await textarea.press("Enter");
+
+    await uploadStartedPromise;
+    await expect(promptForm.getByText("report.docx")).toBeVisible();
+
+    releaseUpload();
+    await expect(page.getByText("Hello from DeerFlow!")).toBeVisible({
+      timeout: 10_000,
+    });
+    await expect(promptForm.getByText("report.docx")).toBeHidden();
+  });
 });