diff --git a/backend/app/routers/dinsar_production.py b/backend/app/routers/dinsar_production.py
index 4e4ae6e..f145dcc 100644
--- a/backend/app/routers/dinsar_production.py
+++ b/backend/app/routers/dinsar_production.py
@@ -8,8 +8,8 @@ from fastapi import APIRouter, Depends, HTTPException
 from pydantic import BaseModel, Field
 
 from .dependencies import _get_current_user, _require_admin
+from .. import database
 from ..config import read_int_env, settings
-from ..database import AsyncSessionLocal
 from ..models import AuthUserORM
 from ..services.dinsar_production_service import dinsar_production_service
 from ..services.job_queue_service import job_queue_service
@@ -51,6 +51,14 @@ def _get_registry():
     return registry
 
 
+def _new_session():
+    if database.AsyncSessionLocal is None:
+        database.init_db()
+    if database.AsyncSessionLocal is None:
+        raise RuntimeError("Database session factory is not initialized.")
+    return database.AsyncSessionLocal()
+
+
 @router.get("/engines")
 async def list_engines():
     registry = _get_registry()
@@ -184,9 +192,7 @@ async def submit_run(
 
     try:
         if req.engine_code == "sarscape":
-            if AsyncSessionLocal is None:
-                raise RuntimeError("Database session factory is not initialized.")
-            async with AsyncSessionLocal() as db:
+            async with _new_session() as db:
                 result = await dinsar_production_service.create_run(
                     engine_code=req.engine_code,
                     profile_code=req.profile,
@@ -239,8 +245,6 @@ async def submit_run(
 
 @router.get("/runs")
 async def list_runs(limit: int = 20):
-    if AsyncSessionLocal is None:
-        raise HTTPException(status_code=500, detail="Database session factory is not initialized.")
-    async with AsyncSessionLocal() as db:
+    async with _new_session() as db:
         result = await dinsar_production_service.list_runs(db, limit=limit)
     return result
diff --git a/backend/app/routers/tasks.py b/backend/app/routers/tasks.py
index 6ae1196..a2f596e 100644
--- a/backend/app/routers/tasks.py
+++ b/backend/app/routers/tasks.py
@@ -8,6 +8,7 @@ from fastapi import APIRouter, Depends, HTTPException, Request
 from fastapi.responses import StreamingResponse
 from pydantic import BaseModel
 
+from .. import database
 from ..auth_utils import verify_password
 from ..models import AuthUserORM, TaskInfo
 from ..services.dinsar_production_service import dinsar_production_service
@@ -20,7 +21,6 @@ from ..services.task_service import (
     task_service,
 )
 from ..auth_service import SESSION_COOKIE_NAME, get_user_by_session_token
-from ..database import AsyncSessionLocal
 from .dependencies import _require_admin
 
 router = APIRouter()
@@ -30,6 +30,14 @@ class ForceCancelRequest(BaseModel):
     password: str
 
 
+def _new_session():
+    if database.AsyncSessionLocal is None:
+        database.init_db()
+    if database.AsyncSessionLocal is None:
+        raise RuntimeError("Database session factory is not initialized.")
+    return database.AsyncSessionLocal()
+
+
 @router.get("/tasks/active", response_model=List[TaskInfo])
 async def get_active_tasks(limit: int = TASK_ACTIVE_DEFAULT_LIMIT, offset: int = 0):
     """获取当前正在运行的所有后台任务"""
@@ -44,12 +52,12 @@ async def stream_active_tasks(request: Request):
     """SSE 端点：每 3s 推送一次活跃任务列表，替代前端轮询。"""
     # Authenticate via Cookie at connection establishment
     token = request.cookies.get(SESSION_COOKIE_NAME)
-    if token and AsyncSessionLocal:
-        async with AsyncSessionLocal() as db:
+    if token:
+        async with _new_session() as db:
             user = await get_user_by_session_token(db, token)
         if not user:
             raise HTTPException(status_code=401, detail="Authentication required.")
-    elif not token:
+    else:
         raise HTTPException(status_code=401, detail="Authentication required.")
 
     async def event_generator():
@@ -127,14 +135,13 @@ async def force_cancel_task(
     if task.status not in ("PENDING", "RUNNING"):
         raise HTTPException(status_code=400, detail="任务已结束，无需取消")
     killed_pid = None
-    if AsyncSessionLocal is not None:
-        async with AsyncSessionLocal() as db:
-            run = await dinsar_production_service.request_cancel(task_id, db=db)
-            if run is not None:
-                killed_pid = await dinsar_production_service.kill_active_execution_by_task_id(
-                    task_id,
-                    db=db,
-                )
+    async with _new_session() as db:
+        run = await dinsar_production_service.request_cancel(task_id, db=db)
+        if run is not None:
+            killed_pid = await dinsar_production_service.kill_active_execution_by_task_id(
+                task_id,
+                db=db,
+            )
     await task_service.update_task(task_id, status="CANCELLED", message="管理员强制取消")
     return {
         "message": "任务已强制取消",
diff --git a/backend/app/services/job_handlers.py b/backend/app/services/job_handlers.py
index b2e024d..4832b58 100644
--- a/backend/app/services/job_handlers.py
+++ b/backend/app/services/job_handlers.py
@@ -17,8 +17,8 @@ logger = logging.getLogger(__name__)
 
 from sqlalchemy import select
 
+from .. import database
 from ..config import settings
-from ..database import AsyncSessionLocal
 from ..models import SystemJobORM, DinsarResultORM, HazardPointORM, DinsarTaskItemORM, PsTaskItemORM, SARSceneGeoORM, FloodDetectionORM, WaterDetectionORM, GF3ProcessingORM, AiDiagnosisORM
 from ..scheduler import scan_data_job
 from .data_service import data_service
@@ -80,6 +80,14 @@ JOB_TYPE_REBUILD_PSINSAR_CATALOG = "REBUILD_PSINSAR_CATALOG"
 COPY_ALLOWED_STATUSES = {"PENDING", "IN_PROGRESS", "COMPLETED", "FAILED"}
 
 
+def AsyncSessionLocal():
+    if database.AsyncSessionLocal is None:
+        database.init_db()
+    if database.AsyncSessionLocal is None:
+        raise RuntimeError("Database session factory is not initialized.")
+    return database.AsyncSessionLocal()
+
+
 def _normalize_copy_statuses(raw_statuses: Any) -> List[str]:
     if not raw_statuses:
         return ["COMPLETED"]