Retry failed rewrite batches in smaller chunks

tests/test_stage4_rewrite.py

@@ -132,6 +132,42 @@ class Stage4RewriteTests(unittest.TestCase):
         self.assertEqual([item.title for item in rewritten], ["OpenAI launches GPT-5 API", "OpenAI launches GPT-5 API"])
         self.assertEqual(report["fallback_count"], 2)
 
+    def test_rewrite_items_retries_failed_large_batch_as_smaller_batches_by_default(self):
+        items = [news_item(str(index)) for index in range(30)]
+        calls = []
+
+        def llm_call(prompt):
+            payload = json.loads(prompt)
+            ids = [item["id"] for item in payload["items"]]
+            calls.append(ids)
+            if len(ids) == 30:
+                return "not json"
+            return json.dumps(
+                {
+                    "rewrites": [
+                        {
+                            "id": item_id,
+                            "title": f"title {item_id}",
+                            "summary": f"summary {item_id}",
+                            "section": "模型与能力",
+                            "flags": [],
+                        }
+                        for item_id in ids
+                    ]
+                },
+                ensure_ascii=False,
+            )
+
+        rewritten, report = rewrite_items(items, llm_call=llm_call)
+
+        self.assertEqual([len(call) for call in calls], [30, 10, 10, 10])
+        self.assertEqual(report["rewritten_count"], 30)
+        self.assertEqual(report["llm_section_count"], 30)
+        self.assertEqual(report["fallback_count"], 0)
+        self.assertEqual(report["batch_retry_count"], 3)
+        self.assertEqual(report["blocking_errors"], [])
+        self.assertEqual(rewritten[0].title, "title 0")
+
     def test_rewrite_items_keeps_partial_batch_rewrites_when_some_ids_are_missing(self):
         items = [news_item("a"), news_item("b"), news_item("c")]