diff --git a/app/admin/repositories/stats.py b/app/admin/repositories/stats.py
index 202a5ba..3256812 100644
--- a/app/admin/repositories/stats.py
+++ b/app/admin/repositories/stats.py
@@ -280,12 +280,12 @@ def dashboard_overview(
     period_active_user_ids = (
         login_user_ids | compare_start_user_ids | coupon_event_user_ids | coupon_claim_user_ids
     )
-    period_retained_new_user_ids = period_new_user_ids & period_active_user_ids
-    period_retention_rate = (
-        round(len(period_retained_new_user_ids) / len(period_new_user_ids), 4)
-        if period_new_user_ids
-        else None
-    )
+    # 留存口径(2026-07-05 产品改):次日留存——窗口内每天 D,取 **D-1 日(前日)新增**用户,
+    # 统计其 D 日活跃(登录/开始比价/开始领券)比例,逐日累加。默认窗口=昨日单天,即
+    # 「前日新增用户的昨日留存」。原口径(窗口内新增∩窗口内活跃)在单日窗口下≈100% 无意义
+    # (注册即登录,当天新增必然当天活跃)。逐日 cohort 在下方 trend 循环内顺带累计。
+    retention_cohort_total = 0
+    retention_retained_total = 0
     trend_points: list[dict] = []
     for cur_date in _date_range(period_from, period_to):
         day_start_utc, day_end_utc, day_start_local, day_end_local = _period_bounds(
@@ -313,15 +313,25 @@ def dashboard_overview(
                 CouponPromptEngagement.engage_type == "claim_started",
             )
         )
+        daily_active_user_ids = (
+            daily_login_user_ids
+            | daily_compare_start_user_ids
+            | daily_coupon_event_user_ids
+            | daily_coupon_claim_user_ids
+        )
+        # 次日留存:cohort = 前一日(D-1)新增用户,留存 = 其中当日(D)活跃者(口径见上)。
+        cohort_ids = _user_id_set(
+            select(User.id).where(
+                User.created_at >= day_start_utc - timedelta(days=1),
+                User.created_at < day_end_utc - timedelta(days=1),
+            )
+        )
+        retention_cohort_total += len(cohort_ids)
+        retention_retained_total += len(cohort_ids & daily_active_user_ids)
         trend_points.append(
             {
                 "date": cur_date,
-                "active_users": len(
-                    daily_login_user_ids
-                    | daily_compare_start_user_ids
-                    | daily_coupon_event_user_ids
-                    | daily_coupon_claim_user_ids
-                ),
+                "active_users": len(daily_active_user_ids),
                 "new_users": _count(
                     User,
                     User.created_at >= day_start_utc,
@@ -330,6 +340,11 @@ def dashboard_overview(
                 "comparisons": _count(ComparisonRecord, *daily_comparison_conds),
             }
         )
+    period_retention_rate = (
+        round(retention_retained_total / retention_cohort_total, 4)
+        if retention_cohort_total
+        else None
+    )
 
     period_coin_conds = (
         CoinTransaction.created_at >= start_local,
@@ -476,11 +491,13 @@ def dashboard_overview(
             "users": {
                 "new": len(period_new_user_ids),
                 "active": len(period_active_user_ids),
-                "retained_new_users": len(period_retained_new_user_ids),
+                "retained_new_users": retention_retained_total,
+                "retention_cohort": retention_cohort_total,
                 "retention_rate": period_retention_rate,
                 "retention_note": (
-                    "口径:登录(last_login_at)+开始比价(real_compare_start)+"
-                    "开始领券(real_coupon_start/claim_started),按用户去重"
+                    "次日留存:窗口内每天取前一日新增用户,统计其当日活跃"
+                    "(登录/开始比价/开始领券,按用户去重)比例,逐日累加;"
+                    "默认窗口=昨日,即前日新增用户的昨日留存"
                 ),
             },
             "comparison": {
diff --git a/app/admin/schemas/dashboard.py b/app/admin/schemas/dashboard.py
index 56f2c15..b91c6b9 100644
--- a/app/admin/schemas/dashboard.py
+++ b/app/admin/schemas/dashboard.py
@@ -43,7 +43,10 @@ class DashboardComparison(BaseModel):
 class DashboardPeriodUsers(BaseModel):
     new: int
     active: int
+    # 次日留存(2026-07-05 起):retained_new_users = 窗口内逐日「前一日新增且当日活跃」用户数之和,
+    # retention_cohort = 对应的前一日新增基数之和,retention_rate = 两者之比。
     retained_new_users: int
+    retention_cohort: int = 0
     retention_rate: float | None = None
     retention_note: str