diff --git a/agent-office/tests/test_lotto_task_wrap.py b/agent-office/tests/test_lotto_task_wrap.py
index 5cf72dc..965b21f 100644
--- a/agent-office/tests/test_lotto_task_wrap.py
+++ b/agent-office/tests/test_lotto_task_wrap.py
@@ -18,6 +18,8 @@ db.DB_PATH = _TMP
 
 @pytest.fixture(autouse=True)
 def fresh_db():
+    # Re-patch DB_PATH at the start of every test (cross-file isolation)
+    db.DB_PATH = _TMP
     gc.collect()
     if os.path.exists(_TMP):
         os.remove(_TMP)
diff --git a/agent-office/tests/test_sync_evolver_activity.py b/agent-office/tests/test_sync_evolver_activity.py
index 88b39ad..8ce1826 100644
--- a/agent-office/tests/test_sync_evolver_activity.py
+++ b/agent-office/tests/test_sync_evolver_activity.py
@@ -19,6 +19,8 @@ db.DB_PATH = _TMP
 
 @pytest.fixture(autouse=True)
 def fresh_db():
+    # Re-patch DB_PATH at the start of every test (cross-file isolation)
+    db.DB_PATH = _TMP
     gc.collect()
     if os.path.exists(_TMP):
         os.remove(_TMP)