fix(analytics): churn 排序决胜列+active_days去重日+边界测试

Co-Authored-By: Claude Code <noreply@anthropic.com>

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,