diff --git a/tests/unit/test_monkey_ocr.py b/tests/unit/test_monkey_ocr.py
index 87f052c..77c4461 100644
--- a/tests/unit/test_monkey_ocr.py
+++ b/tests/unit/test_monkey_ocr.py
@@ -312,7 +312,12 @@ class TestErrorTranslation:
 
     @pytest.mark.parametrize(
         ("status", "exc_type"),
-        [(502, TransientError), (401, SourceDeadError), (404, RequestRejectedError)],
+        [
+            (502, TransientError),
+            (429, TransientError),  # 与 5xx 共用分支,但仍单列: 漏分支正是 issue #10 的成因
+            (401, SourceDeadError),
+            (404, RequestRejectedError),
+        ],
     )
     async def test_body_survives_every_branch(self, status, exc_type):
         """issue #10: OCR 侧 message 原本只有 HTTP 状态码,拒绝理由同样丢失。"""
diff --git a/tests/unit/test_openai_compat.py b/tests/unit/test_openai_compat.py
index 62c7389..2e2067c 100644
--- a/tests/unit/test_openai_compat.py
+++ b/tests/unit/test_openai_compat.py
@@ -16,6 +16,7 @@ from polygateway.errors import (
 )
 from polygateway.middleware.telemetry import TelemetryEmitter
 from polygateway.pricing import ModelPrice, PricingTable
+from polygateway.transports._http_errors import summarize_body
 from polygateway.transports.openai_compat import (
     OpenAICompatTransport,
     _iter_sse_deltas,
@@ -754,11 +755,20 @@ class TestErrorBodyRetention:
 
         摘要会破坏 JSON 结构,若改用摘要解析,超长 body 的配额耗尽将退化成普通
         限速——配额已耗尽的源不再 force_open,一个诊断改进就变成了治理 bug。
+
+        **填充必须是多个键**,不能是单个超长字符串值: 后者的截断点落在字符串
+        *内部*,省略标记成了合法的字符串内容,而头尾保留又让尾部的 error 对象
+        幸存——摘要照样解析得出 `insufficient_quota`,用例即告空转(2026-08-16
+        verifier 变异测试发现: 按错误写法实现,全套件 824 项依然全绿)。多键
+        填充让截断点落在结构记号之间,摘要才真正不可解析。
         """
         body = json.dumps(
-            {"padding": "P" * 4000, "error": {"type": "insufficient_quota", "message": "spent"}}
+            {**{f"k{i}": "v" * 10 for i in range(300)}, "error": {"type": "insufficient_quota"}}
         )
         assert len(body) > 2048
+        with pytest.raises(json.JSONDecodeError):
+            # 判别力的前提: 摘要确实不再是合法 JSON,读它必然拿不到 type
+            json.loads(summarize_body(body))
 
         def handler(request):
             return httpx.Response(429, content=body.encode())