diff --git a/packages/ai/streams/assistant-response.ts b/packages/ai/streams/assistant-response.ts
index c4d872483c8f..40e4f83a880a 100644
--- a/packages/ai/streams/assistant-response.ts
+++ b/packages/ai/streams/assistant-response.ts
@@ -92,6 +92,7 @@ export function AssistantResponse(
                 textEncoder.encode(
                   formatStreamPart('assistant_message', {
                     id: value.data.id,
+                    createdAt: value.data.created_at ? new Date(value.data.created_at * 1000) : undefined,
                     role: 'assistant',
                     content: [{ type: 'text', text: { value: '' } }],
                   }),
diff --git a/packages/react/src/use-assistant.ts b/packages/react/src/use-assistant.ts
index 7a366f451fe3..b3ead342bda7 100644
--- a/packages/react/src/use-assistant.ts
+++ b/packages/react/src/use-assistant.ts
@@ -186,6 +186,7 @@ export function useAssistant({
               {
                 id: value.id,
                 role: value.role,
+                createdAt: value.createdAt,
                 content: value.content[0].text.value,
               },
             ]);
@@ -201,6 +202,7 @@ export function useAssistant({
                 {
                   id: lastMessage.id,
                   role: lastMessage.role,
+                  createdAt: lastMessage.createdAt,
                   content: lastMessage.content + value,
                 },
               ];
diff --git a/packages/react/src/use-assistant.ui.test.tsx b/packages/react/src/use-assistant.ui.test.tsx
index 37dd58405b49..80f6164946f1 100644
--- a/packages/react/src/use-assistant.ui.test.tsx
+++ b/packages/react/src/use-assistant.ui.test.tsx
@@ -23,6 +23,7 @@ describe('stream data stream', () => {
           <div data-testid={`message-${idx}`} key={idx}>
             {m.role === 'user' ? 'User: ' : 'AI: '}
             {m.content}
+            {m.createdAt && ` (Created at: ${m.createdAt})`}
           </div>
         ))}
 
@@ -85,6 +86,91 @@ describe('stream data stream', () => {
     );
   });
 
+  it('should show streamed response with createdAt', async () => {
+    const { requestBody } = mockFetchDataStream({
+      url: 'https://example.com/api/assistant',
+      chunks: [
+        formatStreamPart('assistant_control_data', {
+          threadId: 't0',
+          messageId: 'm0',
+        }),
+        formatStreamPart('assistant_message', {
+          id: 'm0',
+          role: 'assistant',
+          createdAt: new Date(1727703377 * 1000),
+          content: [{ type: 'text', text: { value: '' } }],
+        }),
+        // text parts:
+        '0:"Hello"\n',
+        '0:","\n',
+        '0:" world"\n',
+        '0:"."\n',
+      ],
+    });
+
+    await userEvent.click(screen.getByTestId('do-append'));
+
+    await screen.findByTestId('message-0');
+    expect(screen.getByTestId('message-0')).toHaveTextContent('User: hi');
+
+    await screen.findByTestId('message-1');
+    const messageContent = screen.getByTestId('message-1').textContent;
+    console.log(messageContent);
+
+    expect(messageContent).toContain('AI: Hello, world.');
+    expect(messageContent).toContain(`Created at: ${new Date(1727703377 * 1000).toISOString()}`);
+
+    // check that correct information was sent to the server:
+    expect(await requestBody).toStrictEqual(
+      JSON.stringify({
+        threadId: null,
+        message: 'hi',
+      }),
+    );
+  });
+
+  it('should show streamed response without createdAt', async () => {
+    const { requestBody } = mockFetchDataStream({
+      url: 'https://example.com/api/assistant',
+      chunks: [
+        formatStreamPart('assistant_control_data', {
+          threadId: 't0',
+          messageId: 'm0',
+        }),
+        formatStreamPart('assistant_message', {
+          id: 'm0',
+          role: 'assistant',
+          content: [{ type: 'text', text: { value: '' } }],
+        }),
+        // text parts:
+        '0:"Hello"\n',
+        '0:","\n',
+        '0:" world"\n',
+        '0:"."\n',
+      ],
+    });
+
+    await userEvent.click(screen.getByTestId('do-append'));
+
+    await screen.findByTestId('message-0');
+    expect(screen.getByTestId('message-0')).toHaveTextContent('User: hi');
+
+    await screen.findByTestId('message-1');
+    const messageContent = screen.getByTestId('message-1').textContent;
+    console.log(messageContent);
+
+    expect(messageContent).toContain('AI: Hello, world.');
+    expect(messageContent).not.toContain('Created at:');
+
+    // check that correct information was sent to the server:
+    expect(await requestBody).toStrictEqual(
+      JSON.stringify({
+        threadId: null,
+        message: 'hi',
+      }),
+    );
+  });
+
   it('should show error response', async () => {
     mockFetchError({ statusCode: 500, errorMessage: 'Internal Error' });
 
diff --git a/packages/ui-utils/src/stream-parts.ts b/packages/ui-utils/src/stream-parts.ts
index 4b5470943ad8..b169c66c7fdb 100644
--- a/packages/ui-utils/src/stream-parts.ts
+++ b/packages/ui-utils/src/stream-parts.ts
@@ -121,7 +121,7 @@ const assistantMessageStreamPart: StreamPart<
 
     return {
       type: 'assistant_message',
-      value: value as AssistantMessage,
+      value: value as unknown as AssistantMessage,
     };
   },
 };
diff --git a/packages/ui-utils/src/types.ts b/packages/ui-utils/src/types.ts
index df59a5d42e34..53a30dd95a8e 100644
--- a/packages/ui-utils/src/types.ts
+++ b/packages/ui-utils/src/types.ts
@@ -604,6 +604,7 @@ export type JSONValue =
 export type AssistantMessage = {
   id: string;
   role: 'assistant';
+  createdAt?: Date;
   content: Array<{
     type: 'text';
     text: {