feat(app): add PoolStrategy Protocol to application ports

app/ports.py

@@ -8,8 +8,9 @@ from typing import TYPE_CHECKING, Any, Protocol, runtime_checkable
 if TYPE_CHECKING:
     import numpy as np
 
+    from app.harness.pools import Pools
     from app.tree.index import TreeIndex
-    from core.types import GeneratedQuestion
+    from core.types import GeneratedQuestion, PoolConfig
 
 
 @runtime_checkable
@@ -144,3 +145,27 @@ class PromptBuilderFactory(Protocol):
         skills_dir: Path | None = None,
         prompts_dir: Path | None = None,
     ) -> PromptBuilderFn: ...
+
+
+@runtime_checkable
+class PoolStrategy(Protocol):
+    """池构建策略端口。
+
+    应用层端口（非 core 层），因为返回类型 Pools 定义在 app/harness/pools.py。
+    两个具体策略（GlobalPoolStrategy / PerCategoryPoolStrategy）实现此接口。
+    """
+
+    def build(
+        self,
+        questions: list[GeneratedQuestion],
+        correctness: dict[str, bool],
+        config: PoolConfig,
+    ) -> Pools: ...
+
+    def build_incremental(
+        self,
+        new_task_types: list[str],
+        questions: list[GeneratedQuestion],
+        correctness: dict[str, bool],
+        config: PoolConfig,
+    ) -> dict[str, dict[str, list[str]]]: ...