feat: add grid level suggestions

tests/test_services.py

@@ -223,3 +223,38 @@ def test_service_refresh_quotes_uses_realtime_price_in_summaries(tmp_path):
     assert position.current_price == Decimal("4.12")
     assert position.price_source == "tencent"
     assert summary.market_value == Decimal("4120.00")
+
+
+def test_service_generates_grid_level_suggestions_from_realtime_price(tmp_path):
+    service = TradingService(tmp_path / "grid.db", quote_provider=FakeQuoteProvider())
+    service.ensure_defaults()
+    account = service.get_active_account()
+    instrument = service.add_instrument(Instrument(id=None, code="510300", name="沪深300ETF", market="ETF"))
+    service.save_trade(
+        Trade(
+            id=None,
+            account_id=account.id,
+            instrument_id=instrument.id,
+            trade_date=date(2026, 7, 7),
+            side=TradeSide.BUY,
+            price=Decimal("4.00"),
+            quantity=1000,
+            trade_group=TradeGroup.BASE,
+        )
+    )
+    service.refresh_quotes()
+
+    levels = service.get_grid_level_suggestions(instrument.id, levels=2)
+
+    assert [item.buy_price for item in levels] == [Decimal("4.00"), Decimal("3.88")]
+    assert [item.sell_price for item in levels] == [Decimal("4.12"), Decimal("4.00")]
+    assert [item.buy_amount for item in levels] == [Decimal("5000.00"), Decimal("5000.00")]
+    assert [item.suggested_quantity for item in levels] == [1200, 1200]
+
+
+def test_service_returns_empty_grid_levels_without_realtime_price(tmp_path):
+    service = TradingService(tmp_path / "grid.db")
+    service.ensure_defaults()
+    instrument = service.add_instrument(Instrument(id=None, code="510300", name="沪深300ETF", market="ETF"))
+
+    assert service.get_grid_level_suggestions(instrument.id, levels=10) == []