diff --git a/adapters/baseline_diagnosis_store.py b/adapters/baseline_diagnosis_store.py
index 75bc44a..a4cb9ca 100644
--- a/adapters/baseline_diagnosis_store.py
+++ b/adapters/baseline_diagnosis_store.py
@@ -10,9 +10,13 @@ from __future__ import annotations
 
 import sqlite3
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 from core.evolution.types import DiagnosisSignalRow
 
+if TYPE_CHECKING:
+    from types import TracebackType
+
 # 表列顺序即 DiagnosisSignalRow 字段顺序（question_id..session_id），
 # upsert 写入与 load 还原共用，避免手写列名两处漂移。
 _COLUMNS: tuple[str, ...] = (
@@ -152,3 +156,18 @@ class SqliteDiagnosisSignalStore:
             )
             for r in cursor.fetchall()
         ]
+
+    def close(self) -> None:
+        """关闭底层 SQLite 连接，释放文件描述符与锁。"""
+        self._conn.close()
+
+    def __enter__(self) -> SqliteDiagnosisSignalStore:
+        return self
+
+    def __exit__(
+        self,
+        exc_type: type[BaseException] | None,
+        exc_val: BaseException | None,
+        exc_tb: TracebackType | None,
+    ) -> None:
+        self.close()
diff --git a/core/evolution/protocols.py b/core/evolution/protocols.py
index ecadb06..df4039c 100644
--- a/core/evolution/protocols.py
+++ b/core/evolution/protocols.py
@@ -1,8 +1,10 @@
-"""core/evolution/ 子包的只读 Protocol 定义。
+"""core/evolution/ 子包的持久化 Protocol 定义。
 
-三个 Protocol 均为只读——core/ 返回结果 dataclass，写入由 app/ 持久化。
-SkillStore / PromptStore 为同步（文件读取量小且快），RunLog 为异步
-（隔离 SQLite 查询，core/ 不写 SQL）。
+SkillStore / PromptStore / RunLog 为只读——core/ 返回结果 dataclass，
+读取由 app/ 落盘的资源。SkillStore / PromptStore 同步（文件读取量小且快），
+RunLog 异步（隔离 SQLite 查询，core/ 不写 SQL）。
+DiagnosisSignalStore 兼具读写：逐题 upsert 诊断信号并支持断点续跑查询，
+同样隔离 SQLite 实现，app/core 不写裸 SQL。
 """
 
 from __future__ import annotations
diff --git a/tests/unit/test_baseline_diagnosis_store.py b/tests/unit/test_baseline_diagnosis_store.py
index 0702704..00a654d 100644
--- a/tests/unit/test_baseline_diagnosis_store.py
+++ b/tests/unit/test_baseline_diagnosis_store.py
@@ -4,7 +4,12 @@
 load 往返还原，以及 INFRA 行的可空字段处理。
 """
 
-from adapters.baseline_diagnosis_store import DiagnosisSignalRow, SqliteDiagnosisSignalStore
+import sqlite3
+
+import pytest
+
+from adapters.baseline_diagnosis_store import SqliteDiagnosisSignalStore
+from core.evolution.types import DiagnosisSignalRow
 
 
 def _store(tmp_path):
@@ -78,3 +83,16 @@ def test_null_fields_for_infra_row(tmp_path):
     )
     rows = s.load("r", "fp")
     assert rows[0].error_type is None and rows[0].evolution_target is None and rows[0].infra is True
+
+
+def test_context_manager_closes_connection(tmp_path):
+    # with 块退出后连接关闭，再操作应报 ProgrammingError
+    with SqliteDiagnosisSignalStore(str(tmp_path / "h.db")) as s:
+        s.upsert(
+            DiagnosisSignalRow(
+                "q4", "v4", "r", "fp", "Counting", None, None, "T0", None, False, True, None
+            )
+        )
+        assert s.done_question_ids("r", "fp") == {"q4"}
+    with pytest.raises(sqlite3.ProgrammingError):
+        s.done_question_ids("r", "fp")