diff --git a/yunke-server/app/analytics/metrics.py b/yunke-server/app/analytics/metrics.py
index a7c4c80..85ebbcf 100644
--- a/yunke-server/app/analytics/metrics.py
+++ b/yunke-server/app/analytics/metrics.py
@@ -342,14 +342,20 @@ def _now_ms() -> int:
 
 
 def _next_tier(tier: int) -> int:
-    return {30: 60, 60: 90, 90: 10_000}[tier]
+    try:
+        return {30: 60, 60: 90, 90: 10_000}[tier]
+    except KeyError:
+        raise ValueError(f"bad tier: {tier!r}") from None
 
 
 async def churn(
     session: AsyncSession, *, channel: str, kind: str, tier: int,
     min_msgs: int, page: int, page_size: int,
 ) -> dict:
-    """A3 三分法(spec §3.3)。tier ∈ {30,60,90} 分层区间 [tier, next) ,90=≥90。"""
+    """A3 三分法(spec §3.3)。tier ∈ {30,60,90} 分层区间 [tier, next) ,90=≥90。
+
+    active_days=历史活跃天数(distinct 自然日;peer 跨账号转移同日多行只计一日)。
+    """
     day_ms = 86_400_000
     now = _now_ms()
     base = [
@@ -379,16 +385,19 @@ async def churn(
                 )
             )
         )
-        order = Customer.last_chat_time.asc()
+        # 决胜列 friend_id:count/分页两查询间同 last_chat_time 组内顺序稳定
+        order = [Customer.last_chat_time.asc(), Customer.friend_id.asc()]
     elif kind == "inactive":
         base += [Customer.last_chat_time.is_(None)]
-        order = Customer.friend_id.asc()
+        order = [Customer.friend_id.asc()]
     elif kind == "handover":
         base += [Customer.user_id.in_(
             sa.select(Staff.user_id).where(Staff.is_on_job.is_(False))
         )]
-        # MySQL 由 compat.py 编译补丁剥 NULLS LAST(DESC 下语义天然等价)
-        order = Customer.last_chat_time.desc().nulls_last()
+        # MySQL 由 compat.py 编译补丁剥 NULLS LAST(DESC 下语义天然等价);
+        # NULL 尾部密集(离职员工的未激活客户),必须带 friend_id 决胜列防翻页重复
+        order = [Customer.last_chat_time.desc().nulls_last(),
+                 Customer.friend_id.asc()]
     else:
         raise ValueError(f"bad kind: {kind!r}")
 
@@ -399,12 +408,13 @@ async def churn(
     ).scalar_one()
     rows = (
         await session.execute(
-            sa.select(Customer).where(*base).order_by(order)
+            sa.select(Customer).where(*base).order_by(*order)
             .offset((page - 1) * page_size).limit(page_size)
         )
     ).scalars().all()
 
-    # enrich:历史消息量/活跃天数(msg_daily_stats 按 peer 聚合)
+    # enrich:历史消息量/活跃天数(msg_daily_stats 按 peer 聚合;
+    # 活跃天数按 distinct 自然日计——peer 跨账号同日多行不重复计)
     items = []
     if rows:
         ids = [c.friend_id for c in rows]
@@ -415,7 +425,7 @@ async def churn(
                     sa.func.coalesce(
                         sa.func.sum(MsgDailyStats.send_cnt + MsgDailyStats.recv_cnt), 0
                     ),
-                    sa.func.count(),
+                    sa.func.count(sa.distinct(MsgDailyStats.day)),
                 )
                 .where(
                     MsgDailyStats.channel == channel,
diff --git a/yunke-server/tests/test_analytics_churn_unreplied.py b/yunke-server/tests/test_analytics_churn_unreplied.py
index 75897dc..8e1814c 100644
--- a/yunke-server/tests/test_analytics_churn_unreplied.py
+++ b/yunke-server/tests/test_analytics_churn_unreplied.py
@@ -1,6 +1,8 @@
 """A3 三分法流失 + B2 该回未回。"""
 from __future__ import annotations
 
+import pytest
+
 from app.analytics import metrics
 from app.db.models import Customer, MsgDailyStats, Staff
 
@@ -77,3 +79,58 @@ async def test_churn_endpoint_422(make_client):
     assert r.status_code == 422
     r2 = await client.get("/api/analytics/churn", params={"channel": "sms"})
     assert r2.status_code == 422
+
+
+async def test_churn_tier_membership_and_min_msgs_boundary(make_client, monkeypatch):
+    """tier60/90 会员资格([tier, next) 区间)+ min_msgs 恰等阈值的包含边界。"""
+    monkeypatch.setattr(metrics, "_now_ms", lambda: _NOW)
+    day_ms = 86_400_000
+
+    async def seed(session):
+        # 沉默 75 天:∈[60,90) → tier60 含、tier30 不含
+        session.add(_cust("c75", last_chat=_NOW - 75 * day_ms))
+        # 沉默 100 天:≥90 → tier90 含、tier60 不含
+        session.add(_cust("c100", last_chat=_NOW - 100 * day_ms))
+        # 历史消息恰好 5 条(=min_msgs,含边界)+ 沉默 45 天 → 入 tier30
+        session.add(_cust("c5", last_chat=_NOW - 45 * day_ms))
+        for peer, n in (("c75", 6), ("c100", 6), ("c5", 5)):
+            session.add(MsgDailyStats(channel="wechat", owner_account_id="wx1",
+                                      peer_kind="friend", peer_id=peer, day=20260601,
+                                      send_cnt=n, recv_cnt=0,
+                                      last_ts=_NOW - 110 * day_ms,
+                                      last_is_send=True))
+        await session.commit()
+
+        t30 = await metrics.churn(session, channel="wechat", kind="real",
+                                  tier=30, min_msgs=5, page=1, page_size=20)
+        assert {r["friend_id"] for r in t30["items"]} == {"c5"}
+        t60 = await metrics.churn(session, channel="wechat", kind="real",
+                                  tier=60, min_msgs=5, page=1, page_size=20)
+        assert {r["friend_id"] for r in t60["items"]} == {"c75"}
+        t90 = await metrics.churn(session, channel="wechat", kind="real",
+                                  tier=90, min_msgs=5, page=1, page_size=20)
+        assert {r["friend_id"] for r in t90["items"]} == {"c100"}
+
+    await make_client(seed)
+
+
+async def test_churn_handover_excludes_null_user(make_client, monkeypatch):
+    """user_id NULL(未映射归属)的客户不进待交接名单。"""
+    monkeypatch.setattr(metrics, "_now_ms", lambda: _NOW)
+    async def seed(session):
+        session.add(Staff(user_id="u9", name="离职的", is_on_job=False))
+        session.add(_cust("c_hand", user_id="u9"))
+        session.add(_cust("c_nouser", user_id=None))
+        await session.commit()
+        p = await metrics.churn(session, channel="wechat", kind="handover",
+                                tier=30, min_msgs=5, page=1, page_size=20)
+        assert {r["friend_id"] for r in p["items"]} == {"c_hand"}
+
+    await make_client(seed)
+
+
+def test_next_tier_bad_tier_raises_value_error():
+    """非法 tier 报 ValueError(与 churn 的 kind 分支报错类型一致)。"""
+    with pytest.raises(ValueError):
+        metrics._next_tier(45)
+    assert metrics._next_tier(90) == 10_000  # 90 档=≥90 的开区间上限