diff --git a/tests/unit/test_cache.py b/tests/unit/test_cache.py
index 6f4ea19..9b079ba 100644
--- a/tests/unit/test_cache.py
+++ b/tests/unit/test_cache.py
@@ -155,6 +155,29 @@ class TestKeyFormula:
         ) == ("pgw:cache:c54544e8672f4c91373b4a72716a88497445b440b89445aa5379b356b228f58b")
 
 
+    def test_declared_tier_key_is_a_golden(self):
+        """配了档位那一侧同样要有 golden: 字面量变了就是所有该档缓存冷启动。
+
+        存量(不表态)那侧的 golden 由 `test_absent_tier_keeps_legacy_key` 守着,
+        而"档位怎么写进 key"此前没有任何字面量断言——变异实测把 `str(...)` 换成
+        `repr(...)`,全套件依然全绿(2026-09-05 独立验证查出)。
+        """
+        assert build_cache_key(
+            "qwen-max",
+            [{"role": "user", "content": "hi"}],
+            "proj",
+            None,
+            reasoning_effort=Effort.LOW,
+        ) == ("pgw:cache:21d7be93729635b27d4ee54e0e7e7310554bb04faf08919f8ce83794ac33f575")
+        assert build_cache_key(
+            "qwen-max",
+            [{"role": "user", "content": "hi"}],
+            "proj",
+            "s1",
+            reasoning_effort=Effort.NONE,
+        ) == ("pgw:cache:44f4f1ce1ee39e5003a27f4f21a531554cb54d1c66e936d11008d4ff06ddc5e6")
+
+
 class _Terminal:
     def __init__(self, response):
         self.response = response
diff --git a/tests/unit/test_client.py b/tests/unit/test_client.py
index 27b95be..95b8cbe 100644
--- a/tests/unit/test_client.py
+++ b/tests/unit/test_client.py
@@ -516,6 +516,20 @@ class TestModelFingerprint:
         assert build_model_fingerprint([_source(extra_body={"temperature": 0})]) == expected
 
 
+    def test_declared_tier_fingerprint_is_a_golden(self):
+        """配了档位那一侧的指纹字面量也要钉死: 它变了就是该源整段缓存冷启动。
+
+        存量(不表态)那侧由 `test_absent_tier_fingerprint_is_byte_identical_to_before`
+        守着;本条守的是"档位怎么摘要进 mark"。字面量硬编码,不在测试里重算——
+        重算等于把实现抄一遍,实现改了两边一起变,断言就白写了。
+        """
+        from polygateway.client import build_model_fingerprint
+
+        assert build_model_fingerprint([_source(reasoning_effort=Effort.LOW)]) == (
+            "qwen-max|76f2b3e419e1a727f7f31b6144da0b40d62a00ca93c91ce5901b4ebd48c0b8c0"
+        )
+
+
 class TestFactories:
     def test_from_env_assembles(self):
         client = GatewayClient.from_env("LLM", env=_ENV)