ci: enforce complexity reduction ratchet

tests/test_complexity_gate.py

@@ -0,0 +1,41 @@
+"""复杂度只降不增 ratchet 测试。"""
+
+from scripts.architecture.complexity import compare_complexity
+
+
+def test_complexity_ratchet_allows_removal_and_reduction() -> None:
+    """既有超限入口被删除或缩短必须允许合并。"""
+    baseline = {
+        "api_endpoint": {"app/api/endpoints/a.py:large": 100},
+        "application_public": {"app/application/a.py:Service.run": 180},
+        "chain_public": {},
+    }
+    current = {
+        "api_endpoint": {"app/api/endpoints/a.py:large": 90},
+        "application_public": {},
+        "chain_public": {},
+    }
+
+    assert compare_complexity(baseline, current) == []
+
+
+def test_complexity_ratchet_rejects_growth_and_new_oversize() -> None:
+    """既有入口增长和新增超预算入口必须同时给出精确诊断。"""
+    baseline = {
+        "api_endpoint": {"app/api/endpoints/a.py:large": 100},
+        "application_public": {},
+        "chain_public": {},
+    }
+    current = {
+        "api_endpoint": {
+            "app/api/endpoints/a.py:large": 101,
+            "app/api/endpoints/b.py:new_endpoint": 81,
+        },
+        "application_public": {},
+        "chain_public": {},
+    }
+
+    problems = compare_complexity(baseline, current)
+
+    assert any("既有超限增长" in problem for problem in problems)
+    assert any("新增超限" in problem for problem in problems)