refactor(fc2c-i): sweep blueprints + ml tasks onto shared get_session (covers tasks/ml.py, a survey gap)

backend/app/api/import_admin.py

@@ -5,22 +5,11 @@ from datetime import UTC, datetime, timedelta
 from quart import Blueprint, jsonify, request
 from sqlalchemy import delete, select, update
 
-from ..extensions import make_engine, make_session_factory
+from ..extensions import get_session
 from ..models import ImportBatch, ImportTask
 
 import_admin_bp = Blueprint("import_admin", __name__, url_prefix="/api/import")
 
-_engine = None
-_Session = None
-
-
-def _session_factory():
-    global _engine, _Session
-    if _engine is None:
-        _engine = make_engine()
-        _Session = make_session_factory(_engine)
-    return _Session
-
 
 @import_admin_bp.route("/trigger", methods=["POST"])
 async def trigger_scan():
@@ -39,8 +28,7 @@ async def trigger_scan():
 
 @import_admin_bp.route("/status", methods=["GET"])
 async def status():
-    Session = _session_factory()
-    async with Session() as session:
+    async with get_session() as session:
         active = (
             await session.execute(
                 select(ImportBatch)
@@ -72,8 +60,7 @@ async def list_tasks():
     cursor_raw = request.args.get("cursor")
     cursor_id = int(cursor_raw) if cursor_raw else None
 
-    Session = _session_factory()
-    async with Session() as session:
+    async with get_session() as session:
         stmt = select(ImportTask).order_by(ImportTask.created_at.desc(), ImportTask.id.desc())
         if status_filter:
             stmt = stmt.where(ImportTask.status == status_filter)
@@ -107,8 +94,7 @@ async def list_tasks():
 
 @import_admin_bp.route("/retry-failed", methods=["POST"])
 async def retry_failed():
-    Session = _session_factory()
-    async with Session() as session:
+    async with get_session() as session:
         failed_ids = (
             await session.execute(select(ImportTask.id).where(ImportTask.status == "failed"))
         ).scalars().all()
@@ -140,8 +126,7 @@ async def clear_completed():
         datetime.now(UTC) - timedelta(days=int(age_days)) if age_days else None
     )
 
-    Session = _session_factory()
-    async with Session() as session:
+    async with get_session() as session:
         stmt = delete(ImportTask).where(ImportTask.status.in_(status_filter))
         if cutoff is not None:
             stmt = stmt.where(ImportTask.finished_at < cutoff)