fix: keep cross_segment rule single-dimension, guard no-absent-events

app/question_gen/strategy_action_recognition.py

@@ -180,7 +180,7 @@ _CROSS_SEGMENT_ENTITY_TRACKING = SubPattern(
     ],
     distractor_rules=(
         "干扰项须是视频中【另一真实实体】在相应片段真实做过的动作，"
-        "仅在【动作主体】这一单一维度上与正解不同；或构造只覆盖部分片段的真实子集。"
+        "仅在【动作主体】这一单一维度上与正解不同。"
         "严禁编造任何实体未做过的缺席动作。"
     ),
 )

tests/unit/test_ar_sub_pattern_counterfactual.py

@@ -2,14 +2,13 @@
 
 from app.question_gen.strategy_action_recognition import AR_SUB_PATTERNS
 
-_REQUIRED = ["真实", "单一维度"]  # 每个 distractor_rules 都需强调 grounded + 单维
-
 
 def test_all_sub_patterns_enforce_single_dimension_counterfactual():
     for sp in AR_SUB_PATTERNS:
         rules = sp.distractor_rules
         assert "真实" in rules, sp.name  # 干扰项须真实发生
         assert ("单一维度" in rules or "只在" in rules or "仅在" in rules), sp.name
+        assert ("缺席" in rules or "未出现" in rules or "凭空" in rules), sp.name
 
 
 def test_sub_pattern_count_unchanged():