feat: add AdversarialFilterConfig for Phase B post-hoc filter layer

app/question_gen/adversarial_config.py

@@ -0,0 +1,59 @@
+"""Phase B 对抗过滤层配置 — filter 层配置（非 strategy 属性）。
+
+设计: research-wiki/designs/2026-07-14-adversarial-question-gen-phaseB-design.md §8
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import TYPE_CHECKING
+
+import yaml
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+
+@dataclass(frozen=True)
+class AdversarialFilterConfig:
+    """后置对抗过滤配置。
+
+    属性:
+        filter_task_types: 被过滤的题型（仅这些走 agent 门），默认仅 AR。
+        adversarial_max_rounds: 补生成迭代上限。
+        adversarial_agent_max_steps: agent 试答步数上限。
+        difficulty_warn_threshold: 批次 agent 正确率告警阈值。
+    """
+
+    filter_task_types: tuple[str, ...] = ("Action Recognition",)
+    adversarial_max_rounds: int = 5
+    adversarial_agent_max_steps: int = 40
+    difficulty_warn_threshold: float = 0.85
+
+
+def load_adversarial_config(config_path: Path) -> AdversarialFilterConfig:
+    """从 YAML 的 adversarial_filter 区段加载配置，缺段/缺键用默认值。
+
+    参数:
+        config_path: YAML 配置文件路径。
+
+    返回:
+        AdversarialFilterConfig 实例。
+    """
+    with open(config_path, encoding="utf-8") as f:
+        raw = yaml.safe_load(f) or {}
+    section = raw.get("adversarial_filter", {}) or {}
+    default = AdversarialFilterConfig()
+    types = section.get("filter_task_types")
+    return AdversarialFilterConfig(
+        filter_task_types=tuple(types) if types else default.filter_task_types,
+        adversarial_max_rounds=int(
+            section.get("adversarial_max_rounds", default.adversarial_max_rounds)
+        ),
+        adversarial_agent_max_steps=int(
+            section.get("adversarial_agent_max_steps", default.adversarial_agent_max_steps)
+        ),
+        difficulty_warn_threshold=float(
+            section.get("difficulty_warn_threshold", default.difficulty_warn_threshold)
+        ),
+    )