Preserve partial creation replies on stream failure

src/services/creation-agent/creationAgentSse.test.ts

@@ -51,3 +51,28 @@ test('readCreationAgentSessionFromSse flushes decoder tail and handles CRLF boun
     title: '世界共创',
   });
 });
+
+test('readCreationAgentSessionFromSse keeps streamed updates before error event', async () => {
+  const encoder = new TextEncoder();
+  const response = createChunkedStreamResponse([
+    encoder.encode(
+      'event: reply_delta\ndata: {"text":"先把方洞万能的反差定住。"}\n\n',
+    ),
+    encoder.encode(
+      'event: error\ndata: {"message":"方洞挑战聊天生成失败：LLM 请求超时"}\n\n',
+    ),
+  ]);
+  const updates: string[] = [];
+
+  await expect(
+    readCreationAgentSessionFromSse(response, {
+      fallbackMessage: '发送失败',
+      incompleteMessage: '结果不完整',
+      onUpdate: (text) => {
+        updates.push(text);
+      },
+    }),
+  ).rejects.toThrow('方洞挑战聊天生成失败：LLM 请求超时');
+
+  expect(updates).toEqual(['先把方洞万能的反差定住。']);
+});