fix: count units not questions in trainability pre-flight; fail-fast when all types filtered

tests/unit/test_harness_runner.py

@@ -75,6 +75,26 @@ class _FakeQuestion:
             object.__setattr__(self, "unit_id", self.pair_id or self.question_id)
 
 
+def _fake_pair(pair_id: str, task_type: str, video_id: str = "v1") -> list[_FakeQuestion]:
+    """构造合法孪生对（original + mirror），共享 pair_id/video_id/task_type/flip_axis。"""
+    return [
+        _FakeQuestion(
+            question_id=f"{pair_id}-o",
+            video_id=video_id,
+            task_type=task_type,
+            pair_id=pair_id,
+            question_role="pair_original",
+        ),
+        _FakeQuestion(
+            question_id=f"{pair_id}-m",
+            video_id=video_id,
+            task_type=task_type,
+            pair_id=pair_id,
+            question_role="pair_mirror",
+        ),
+    ]
+
+
 @dataclass
 class _FakePools:
     """Pools 替身。"""
@@ -426,19 +446,59 @@ class TestFilterUntrainableTypes:
         assert new_types == ["A"]
 
     def test_units_below_threshold_filtered(self) -> None:
-        """val 达标但 diag+val 单元数 < trainable_min_units 的题型被剔除。"""
-        # 题型 C：val=2（>=2）但 units=2+0=... 补 diag 使总数不足
-        val = [_FakeQuestion(question_id=f"C-v{i}", task_type="C") for i in range(2)]
-        diag = [_FakeQuestion(question_id="C-d0", task_type="C")]  # units=3 < 8
+        """val 达标但 diag+val 单元数 < trainable_min_units 的题型被剔除（保留另一可训题型）。"""
+        # 可训题型 A：diag=8 + val=2 → units=10、val=2，保留
+        keep_diag = [_FakeQuestion(question_id=f"A-d{i}", task_type="A") for i in range(8)]
+        keep_val = [_FakeQuestion(question_id=f"A-v{i}", task_type="A") for i in range(2)]
+        # 题型 C：val=2（>=2）但 units=2+1=3 < 8 → 剔除
+        val = keep_val + [_FakeQuestion(question_id=f"C-v{i}", task_type="C") for i in range(2)]
+        diag = keep_diag + [_FakeQuestion(question_id="C-d0", task_type="C")]
         pools = _FakePools(diagnosis=diag, validation=val, test=[])
 
         new_pools, new_types = _filter_untrainable_types(
             pools, task_types=None, eval_min_per_class=2, trainable_min_units=8
         )
 
-        assert new_pools.diagnosis == []
-        assert new_pools.validation == []
-        assert new_types == []
+        assert {q.task_type for q in new_pools.diagnosis} == {"A"}
+        assert {q.task_type for q in new_pools.validation} == {"A"}
+        assert new_types == ["A"]
+
+    def test_ar_pair_counted_as_units_not_questions(self) -> None:
+        """AR pair 按单元折叠计数：题目数达标但单元数不足的题型仍被剔除。"""
+        # 可训题型 A：diag=8 + val=2 single → units=10，保留
+        keep_diag = [_FakeQuestion(question_id=f"A-d{i}", task_type="A") for i in range(8)]
+        keep_val = [_FakeQuestion(question_id=f"A-v{i}", task_type="A") for i in range(2)]
+        # 题型 P：diag 3 对（6 题=3 单元）+ val 2 对（4 题=2 单元）→ 单元数=5<8，
+        # 但题目数=10>=8。按单元计数须剔除（按题目计数会误通过）。
+        pair_diag: list[_FakeQuestion] = []
+        for i in range(3):
+            pair_diag.extend(_fake_pair(f"P-d{i}", "P"))
+        pair_val: list[_FakeQuestion] = []
+        for i in range(2):
+            pair_val.extend(_fake_pair(f"P-v{i}", "P"))
+        pools = _FakePools(
+            diagnosis=keep_diag + pair_diag,
+            validation=keep_val + pair_val,
+            test=[],
+        )
+
+        new_pools, new_types = _filter_untrainable_types(
+            pools, task_types=None, eval_min_per_class=2, trainable_min_units=8
+        )
+
+        assert "P" not in {q.task_type for q in new_pools.diagnosis}
+        assert "P" not in new_types
+        assert "A" in new_types
+
+    def test_all_filtered_raises(self) -> None:
+        """所有题型都被剔除时 fail-fast：raise RuntimeError 并列出剔除原因。"""
+        diag = [_FakeQuestion(question_id="B-d0", task_type="B")]  # val=0 < 2
+        pools = _FakePools(diagnosis=diag, validation=[], test=[])
+
+        with pytest.raises(RuntimeError, match="可训练"):
+            _filter_untrainable_types(
+                pools, task_types=None, eval_min_per_class=2, trainable_min_units=8
+            )
 
     def test_test_pool_untouched(self) -> None:
         """test 池不参与过滤（继续报告全题型准确率）。"""