diff --git a/backend/app/api/alerts.py b/backend/app/api/alerts.py
index f852c7d0..0ac16e31 100644
--- a/backend/app/api/alerts.py
+++ b/backend/app/api/alerts.py
@@ -16,8 +16,10 @@ router = APIRouter(prefix="/api/cma/alerts", tags=["预警"],
 
 @router.get("")
 def list_alerts(status: str = None, page: int = Query(1, ge=1), db: Session = Depends(get_db), entity_id: int = Depends(get_entity_id)):
-    # 账套隔离: join kpi_definitions 按企业过滤 (2026-08-23 P1b)
-    query = db.query(KPIAlert).join(KPIDefinition, KPIDefinition.id == KPIAlert.kpi_id).filter(KPIDefinition.entity_id == entity_id)
+    # 账套隔离(2026-09-19 dama-20260919 C1)：按**预警行自身** entity_id 过滤
+    # 修复前按 KPI 归属企业过滤（2026-08-23 P1b）→ KPI 属他账套而预警行属本账套的行反向泄漏
+    # （实测 entity 2 口径 225 → 223，泄漏 id=589/590）
+    query = db.query(KPIAlert).filter(KPIAlert.entity_id == entity_id)
     if status:
         query = query.filter(KPIAlert.status == status)
     total = query.count()
@@ -26,8 +28,10 @@ def list_alerts(status: str = None, page: int = Query(1, ge=1), db: Session = De
 
 @router.post("/{alert_id}/resolve")
 def resolve_alert(alert_id: int, data: dict, db: Session = Depends(get_db), entity_id: int = Depends(get_entity_id)):
-    alert = db.query(KPIAlert).join(KPIDefinition, KPIDefinition.id == KPIAlert.kpi_id).filter(
-        KPIAlert.id == alert_id, KPIDefinition.entity_id == entity_id).first()
+    # 账套隔离(2026-09-19 dama-20260919 C2)：按预警行自身 entity_id 定位
+    # 修复前按 KPI 归属企业过滤 → KPI 属他账套的行可被本账套端点操作（跨账套泄漏/越权）
+    alert = db.query(KPIAlert).filter(
+        KPIAlert.id == alert_id, KPIAlert.entity_id == entity_id).first()
     if not alert:
         raise HTTPException(404, "预警不存在")
     alert.status = "resolved"
@@ -46,9 +50,11 @@ def resolve_alert(alert_id: int, data: dict, db: Session = Depends(get_db), enti
 
 @router.post("/{alert_id}/process")
 def process_alert(alert_id: int, data: dict, db: Session = Depends(get_db), entity_id: int = Depends(get_entity_id)):
-    """标记预警为处理中（账套隔离: join kpi_definitions 按企业过滤, 2026-09-18）"""
-    alert = db.query(KPIAlert).join(KPIDefinition, KPIDefinition.id == KPIAlert.kpi_id).filter(
-        KPIAlert.id == alert_id, KPIDefinition.entity_id == entity_id).first()
+    """标记预警为处理中（账套隔离: 按预警行自身 entity_id, 2026-09-19）"""
+    # 账套隔离(2026-09-19 dama-20260919 C2)：按预警行自身 entity_id 定位
+    # 修复前按 KPI 归属企业过滤 → KPI 属他账套的行可被本账套端点操作（跨账套泄漏/越权）
+    alert = db.query(KPIAlert).filter(
+        KPIAlert.id == alert_id, KPIAlert.entity_id == entity_id).first()
     if not alert:
         raise HTTPException(404, "预警不存在")
     if alert.status == "resolved":
@@ -65,9 +71,11 @@ def process_alert(alert_id: int, data: dict, db: Session = Depends(get_db), enti
 
 @router.post("/{alert_id}/escalate")
 def escalate_alert(alert_id: int, data: dict, db: Session = Depends(get_db), entity_id: int = Depends(get_entity_id)):
-    """升级预警级别（账套隔离: join kpi_definitions 按企业过滤, 2026-09-18）"""
-    alert = db.query(KPIAlert).join(KPIDefinition, KPIDefinition.id == KPIAlert.kpi_id).filter(
-        KPIAlert.id == alert_id, KPIDefinition.entity_id == entity_id).first()
+    """升级预警级别（账套隔离: 按预警行自身 entity_id, 2026-09-19）"""
+    # 账套隔离(2026-09-19 dama-20260919 C2)：按预警行自身 entity_id 定位
+    # 修复前按 KPI 归属企业过滤 → KPI 属他账套的行可被本账套端点操作（跨账套泄漏/越权）
+    alert = db.query(KPIAlert).filter(
+        KPIAlert.id == alert_id, KPIAlert.entity_id == entity_id).first()
     if not alert:
         raise HTTPException(404, "预警不存在")
     assignee = data.get("assignee")
@@ -107,9 +115,11 @@ def check_alert_timeout(db: Session = Depends(get_db), entity_id: int = Depends(
 
 @router.post("/{alert_id}/create-action-plan")
 def create_action_plan_from_alert(alert_id: int, data: dict, db: Session = Depends(get_db), entity_id: int = Depends(get_entity_id)):
-    """从预警创建改善行动计划（账套隔离: join kpi_definitions 按企业过滤, 2026-09-18）"""
-    alert = db.query(KPIAlert).join(KPIDefinition, KPIDefinition.id == KPIAlert.kpi_id).filter(
-        KPIAlert.id == alert_id, KPIDefinition.entity_id == entity_id).first()
+    """从预警创建改善行动计划（账套隔离: 按预警行自身 entity_id, 2026-09-19）"""
+    # 账套隔离(2026-09-19 dama-20260919 C2)：按预警行自身 entity_id 定位
+    # 修复前按 KPI 归属企业过滤 → KPI 属他账套的行可被本账套端点操作（跨账套泄漏/越权）
+    alert = db.query(KPIAlert).filter(
+        KPIAlert.id == alert_id, KPIAlert.entity_id == entity_id).first()
     if not alert:
         raise HTTPException(404, "预警不存在")
     if alert.action_plan_linked_id:
diff --git a/backend/app/utils/cash_forecast_engine.py b/backend/app/utils/cash_forecast_engine.py
index c0d27a9a..1d6c01a5 100644
--- a/backend/app/utils/cash_forecast_engine.py
+++ b/backend/app/utils/cash_forecast_engine.py
@@ -224,7 +224,10 @@ def calc_trend(values: list) -> float:
 def get_current_cash_balance(db: Session, entity_id: int) -> Optional[float]:
     """获取当前现金余额（万元）— 优先级：KPI实际值 > SystemConfig > None"""
     from app.models import SystemConfig, KPIValue
-    kpi = find_kpi(db, entity_id, KPI_CODE_CANDIDATES["cash_balance"])
+    # C3(2026-09-19 dama-20260919)：补传实体前缀后缀候选（与 F2 的应收/应付路径一致）
+    # 修复前漏传 → 博海/演示企业一条候选都不命中 → 回退 SystemConfig.cash.current_balance(全库唯一键 -9.3)
+    kpi = find_kpi(db, entity_id, KPI_CODE_CANDIDATES["cash_balance"],
+                   KPI_CODE_SUFFIXES["cash_balance"])
     if kpi:
         latest_cash = db.query(KPIValue).filter(
             KPIValue.kpi_id == kpi.id,