fix: 已结算运费在协议保存时拒绝取消关联

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_sf_express_settlement.py

@@ -259,3 +259,129 @@ def test_admin_and_market_bodies_accept_sf_without_amount():
     })
     assert draft.waybill_no == "SF100"
     MarketFreightUpdateBody.model_validate({"waybillNo": "SF100"})
+
+
+def _protocol_freight_db():
+    from sqlalchemy import create_engine
+    from sqlalchemy.orm import sessionmaker
+
+    from app.models.base import Base
+    from app.models.models import (
+        BizCellSampleType,
+        BizCollectionProtocol,
+        BizProtocolPartyCustomer,
+        BizProtocolSample,
+        BizSampleFreight,
+        BizSampleFreightItem,
+        SysDictData,
+    )
+
+    engine = create_engine("sqlite:///:memory:")
+    Base.metadata.create_all(
+        engine,
+        tables=[
+            BizSampleFreight.__table__,
+            BizSampleFreightItem.__table__,
+            BizProtocolSample.__table__,
+            BizCollectionProtocol.__table__,
+            BizCellSampleType.__table__,
+            BizProtocolPartyCustomer.__table__,
+            SysDictData.__table__,
+        ],
+    )
+    return sessionmaker(bind=engine)()
+
+
+def _seed_settled_protocol_freight(db, sample_id="s-old"):
+    from app.models.models import BizSampleFreight, BizSampleFreightItem
+
+    now = datetime(2026, 10, 21, 9, 0, 0)
+    freight = BizSampleFreight(
+        id="f-yjs",
+        freight_no="YF1",
+        transport_mode="sfkd",
+        freight_amount=None,
+        waybill_no="SF001",
+        settle_status="yjs",
+        tenant_no="tenant-a",
+        create_dept_id="",
+        create_time=now,
+        update_time=now,
+        del_flag=0,
+    )
+    item = BizSampleFreightItem(
+        id="fi-1",
+        freight_id=freight.id,
+        sample_source="cell_storage",
+        sample_id=sample_id,
+        sample_code="C1",
+        protocol_id="p1",
+        tenant_no="tenant-a",
+        create_dept_id="",
+        create_time=now,
+        update_time=now,
+        del_flag=0,
+    )
+    db.add_all([freight, item])
+    db.commit()
+    return freight, item
+
+
+def test_settled_protocol_save_without_freight_id_keeps_links():
+    from types import SimpleNamespace
+
+    from app.crud.sample_freight import apply_freight_on_protocol_save
+    from app.models.models import BizSampleFreight, BizSampleFreightItem
+
+    db = _protocol_freight_db()
+    freight, item = _seed_settled_protocol_freight(db)
+    try:
+        with pytest.raises(ValueError, match="已结算的运费不能调整样本"):
+            apply_freight_on_protocol_save(
+                db,
+                tenant_no="tenant-a",
+                user_id="u1",
+                sample_source="cell_storage",
+                protocol_id="p1",
+                saved_samples=[SimpleNamespace(id="s-new", sample_code="C2")],
+                input_samples=[{}],
+            )
+        db.expire_all()
+        item = db.query(BizSampleFreightItem).filter_by(id=item.id).one()
+        freight = db.query(BizSampleFreight).filter_by(id=freight.id).one()
+        assert item.del_flag == 0
+        assert freight.del_flag == 0
+    finally:
+        db.close()
+
+
+def test_settled_protocol_save_relinks_same_count_to_new_sample():
+    from types import SimpleNamespace
+
+    from app.crud.sample_freight import apply_freight_on_protocol_save
+    from app.models.models import BizSampleFreight, BizSampleFreightItem
+
+    db = _protocol_freight_db()
+    freight, _item = _seed_settled_protocol_freight(db)
+    try:
+        apply_freight_on_protocol_save(
+            db,
+            tenant_no="tenant-a",
+            user_id="u1",
+            sample_source="cell_storage",
+            protocol_id="p1",
+            saved_samples=[SimpleNamespace(id="s-new", sample_code="C2")],
+            input_samples=[{"freightId": freight.id}],
+        )
+        db.expire_all()
+        freight = db.query(BizSampleFreight).filter_by(id=freight.id).one()
+        assert freight.del_flag == 0
+        assert freight.settle_status == "yjs"
+        live = (
+            db.query(BizSampleFreightItem)
+            .filter_by(freight_id=freight.id, sample_id="s-new", del_flag=0)
+            .one()
+        )
+        assert live.protocol_id == "p1"
+    finally:
+        db.close()