diff --git a/scripts/selftest_m5b.py b/scripts/selftest_m5b.py
index dc7a36e..6507608 100644
--- a/scripts/selftest_m5b.py
+++ b/scripts/selftest_m5b.py
@@ -50,7 +50,10 @@ _CAPTURED = {'sql': [], 'params': []}
 
 
 def _row(idx, etype, learner='S01', session='101', blueprint='9', artifact=0,
-         occurred='2026-09-20 10:00:0%d' % (idx % 9), payload=None, source=None):
+         occurred=None, payload=None, source=None):
+    # 默认值不能在签名里引用形参 idx（定义时求值 -> NameError），挪到函数体内。
+    if occurred is None:
+        occurred = '2026-09-20 10:00:%02d' % (idx % 9)
     return {
         'id': idx, 'tenant_id': TENANT, 'artifact_id': artifact, 'evidence_type': etype,
         'source_event_id': source or ('EV%03d' % idx), 'session_id': session,
@@ -385,8 +388,11 @@ def test_watermark_contract():
     assert q['watermark']['max_occurred_at'] == '2026-09-21 08:00:00', q['watermark']
 
 
+# 不能直接对 function 对象排序（'<' not supported between functions），
+# 按函数名排序保证输出顺序稳定可复现。
 ALL_TESTS = sorted([v for k, v in list(globals().items())
-                    if k.startswith('test_') and callable(v)])
+                    if k.startswith('test_') and callable(v)],
+                   key=lambda fn: fn.__name__)
 
 
 def main():