feat(pools): 三池切分以 unit 为原子，孪生对同池不被拆散

build_pools/_sample_excluding 与 PerCategoryPoolStrategy._split_one_category/ build_incremental 两条切分路径均改为以 QuestionUnit 为采样原子：progressive exclusion 互斥集合与 train/val 分层划分都按 unit_id 计数（pair 计 1 个 unit），命中单元整体展开，AR 孪生对两题永不落入不同池/split。复用 app.harness.question_units 的 build_units/flatten_units，不重写分组逻辑。 single-only 输入下 unit 与 question 一一对应、rng 消耗量不变，采样与划分结果与逐题口径完全一致；抽出 _unit_correct/_assert_correctness_complete 两个 helper 将 _split_one_category 复杂度压回基线以下。新增 tests/unit/test_pools_pair_atomic.py 覆盖两条路径的 pair 原子性回归。
2026-07-15 06:09:14 -04:00
parent 5ef5f2b8b7
commit ddb9a44f75
2 changed files with 214 additions and 48 deletions
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+"""pair 原子性回归测试：三池切分不得把孪生对劈到不同池。
+
+覆盖 pools.py 的两条切分路径：
+- GlobalPoolStrategy 路径（build_pools 的 test->val->diag progressive exclusion）；
+- PerCategoryPoolStrategy 路径（_split_one_category 的 train/val 分层划分）。
+
+核心不变量：同一 pair_id 的两题必落在同一个池（或同一 split），绝不被拆散。
+"""
+
+from __future__ import annotations
+
+from app.harness.pools import PerCategoryPoolStrategy, build_pools
+from core.types import GeneratedQuestion, PoolConfig
+
+
+def _pair(pid: str) -> list[GeneratedQuestion]:
+    """构造一个合法孪生对（original + mirror），共享 pair_id / unit_id / flip_axis。
+
+    参数:
+        pid: 该孪生对的共享标识。
+
+    返回:
+        含 original 与 mirror 两条题目的列表。
+    """
+    base = {
+        "video_id": "v",
+        "task_type": "Action Reasoning",
+        "question": "?",
+        "options": ("A. a", "B. b", "C. c", "D. d"),
+        "answer": "A",
+        "source_nodes": ("n",),
+        "difficulty": "hard",
+        "pair_id": pid,
+        "flip_axis": "before_after",
+    }
+    return [
+        GeneratedQuestion(question_id=f"{pid}_o", question_role="pair_original", **base),
+        GeneratedQuestion(question_id=f"{pid}_m", question_role="pair_mirror", **base),
+    ]
+
+
+def test_pair_never_split_across_pools() -> None:
+    """build_pools（Global 路径）三池切分后，任一 pair_id 只出现在一个池。"""
+    qs = [q for pid in [f"p{i:02d}" for i in range(12)] for q in _pair(pid)]
+    cfg = {
+        "size": 4,
+        "correct_ratio": None,
+        "task_types": None,
+        "seed": 7,
+        "min_per_class": None,
+    }
+    pools = build_pools(
+        qs,
+        correctness={},
+        diag_cfg=cfg,
+        val_cfg=cfg,
+        test_cfg={"size": 4, "seed": 7},
+        baseline_run_id="b",
+    )
+
+    by_name = {
+        "diagnosis": pools.diagnosis,
+        "validation": pools.validation,
+        "test": pools.test,
+    }
+    loc: dict[str, set[str]] = {}
+    for name, pool in by_name.items():
+        for q in pool:
+            loc.setdefault(q.pair_id, set()).add(name)
+
+    split = {pid: names for pid, names in loc.items() if len(names) > 1}
+    assert not split, f"pair 被劈到多个池: {split}"
+
+    # 每个被选中的 pair 必须两题齐全（同池内成对），不得只落单题
+    per_pool_pair_count: dict[tuple[str, str], int] = {}
+    for name, pool in by_name.items():
+        for q in pool:
+            key = (name, q.pair_id)
+            per_pool_pair_count[key] = per_pool_pair_count.get(key, 0) + 1
+    assert all(c == 2 for c in per_pool_pair_count.values()), (
+        f"存在池内落单的 pair 成员: {per_pool_pair_count}"
+    )
+
+
+def test_pair_never_split_across_train_val() -> None:
+    """PerCategoryPoolStrategy 路径：孪生对不得被 train/val 划分劈开。"""
+    qs = [q for pid in [f"p{i:02d}" for i in range(15)] for q in _pair(pid)]
+    # 让部分 pair 正确、部分错误，触发分层划分（非退化随机）
+    correctness: dict[str, bool] = {}
+    for i, pid in enumerate(f"p{i:02d}" for i in range(15)):
+        val = i < 9
+        correctness[f"{pid}_o"] = val
+        correctness[f"{pid}_m"] = val
+
+    config = PoolConfig(
+        task_types=None,
+        seed=42,
+        baseline_run_id="b",
+        diag_size=0,
+        diag_correct_ratio=0.0,
+        val_size=0,
+        val_correct_ratio=0.0,
+        test_size=0,
+        eval_min_per_class=0,
+        train_ratio=2 / 3,
+        test_questions_dir=None,
+    )
+    pools = PerCategoryPoolStrategy().build(qs, correctness, config)
+
+    loc: dict[str, set[str]] = {}
+    for name, pool in (("diagnosis", pools.diagnosis), ("validation", pools.validation)):
+        for q in pool:
+            loc.setdefault(q.pair_id, set()).add(name)
+
+    split = {pid: names for pid, names in loc.items() if len(names) > 1}
+    assert not split, f"pair 被 train/val 划分劈开: {split}"