diff --git a/yunke-server/app/api/routers/staff_chat_stats.py b/yunke-server/app/api/routers/staff_chat_stats.py
index 2dbc620..5223258 100644
--- a/yunke-server/app/api/routers/staff_chat_stats.py
+++ b/yunke-server/app/api/routers/staff_chat_stats.py
@@ -36,7 +36,7 @@ def _private_window(msg, owner: str, start: int, end: int):
     ]
 
 
-async def _aggregate(session: AsyncSession, owner: str, start: int, end: int):
+async def _aggregate(session: AsyncSession, owner: str, start: int, end: int) -> tuple[list, dict[str, bool | None]]:
     """返回 [(talker_id, send, recv, interaction_days, last_time)] + last_is_send map。"""
     # 跨库日期提取：从 ms-epoch 取日期。镜像 repos.py 方言检测。
     dialect = session.bind.name  # 镜像 app/storage/repos.py（.name 等价 .dialect.name）
@@ -56,6 +56,7 @@ async def _aggregate(session: AsyncSession, owner: str, start: int, end: int):
         )
         .where(*base)
         .group_by(Message.talker_id)
+        .order_by(Message.talker_id)
     )
     agg_rows = (await session.execute(agg_stmt)).all()
 
diff --git a/yunke-server/tests/test_api_staff_chat_stats.py b/yunke-server/tests/test_api_staff_chat_stats.py
index 6ed7c3d..2921e6e 100644
--- a/yunke-server/tests/test_api_staff_chat_stats.py
+++ b/yunke-server/tests/test_api_staff_chat_stats.py
@@ -135,3 +135,47 @@ async def test_default_window_returns_ok(make_client):
     r = await client.get("/api/staff-chat-stats", params={"owner_account_id": OWNER})
     assert r.status_code == 200
     assert "summary" in r.json() and "customers" in r.json()
+
+
+async def test_last_is_send_none_excluded_from_rates(make_client):
+    """最后一条私聊 is_send IS NULL → last_is_send=None，计入 chat_count/
+    interaction_days，但被 ==1/==0 同时排除（两率都不计）。"""
+    async def seed(session: AsyncSession) -> None:
+        session.add(
+            Message(
+                msg_id="n1",
+                channel="wechat",
+                owner_account_id=OWNER,
+                talker_id="t_n",
+                room_id=None,
+                is_send=None,
+                timestamp=WIN_START,
+                type="text",
+                type_raw=1,
+                text="unknown-dir",
+            )
+        )
+        await session.commit()
+
+    client = await make_client(seed)
+    r = await client.get(
+        "/api/staff-chat-stats",
+        params={"owner_account_id": OWNER, "start": WIN_START, "end": WIN_END},
+    )
+    assert r.status_code == 200
+    body = r.json()
+    customers = body["customers"]
+    assert len(customers) == 1
+    c = customers[0]
+    assert c["talker_id"] == "t_n"
+    assert c["last_is_send"] is None
+    assert c["send_count"] == 0
+    assert c["receive_count"] == 0
+    assert c["interaction_days"] == 1
+    assert body["summary"] == {
+        "chat_count": 1,
+        "effective_count": 0,
+        "follow_count": 0,
+        "last_reply_count": 0,
+        "no_reply_count": 0,
+    }