fix: read-only baseline queries skip _runs upsert (register_run flag)

tests/unit/test_harness_log.py

@@ -215,6 +215,30 @@ class TestHarnessLogUpsert:
             rows = log3.query("SELECT COUNT(*) as cnt FROM _runs WHERE run_id='run_1'")
             assert rows[0]["cnt"] == 1
 
+    def test_register_run_false_skips_upsert(self, tmp_path: Path) -> None:
+        """register_run=False 时只读打开不改写已有 _runs 行（started_at/status 不变）。"""
+        db = str(tmp_path / "h.db")
+
+        def _read_run_row(run_id: str) -> dict:
+            # 用 register_run=False 只读，避免读取本身污染 _runs
+            with HarnessLog(db, run_id, register_run=False) as log:
+                rows = log.query(
+                    "SELECT started_at, status FROM _runs WHERE run_id=?", (run_id,)
+                )
+            return rows[0]
+
+        with HarnessLog(db, "r1"):
+            pass  # 初次注册 + 正常退出置 completed
+        row0 = _read_run_row("r1")
+
+        time.sleep(0.02)
+        with HarnessLog(db, "r1", register_run=False) as log:
+            log.query("SELECT 1")  # 只读
+        row1 = _read_run_row("r1")
+
+        assert row1["started_at"] == row0["started_at"]
+        assert row1["status"] == row0["status"]
+
 
 # ===========================================================================
 # RunLogImpl 测试