fix: hyperliquid doesn't provide "average" in fetch_order

therefore this needs to be filled from trades to have a good price
 for market orders

freqtrade/exchange/hyperliquid.py

@@ -7,7 +7,8 @@ from freqtrade.constants import BuySell
 from freqtrade.enums import MarginMode, TradingMode
 from freqtrade.exceptions import ExchangeError, OperationalException
 from freqtrade.exchange import Exchange
-from freqtrade.exchange.exchange_types import FtHas
+from freqtrade.exchange.exchange_types import CcxtOrder, FtHas
+from freqtrade.util.datetime_helpers import dt_from_ts
 
 
 logger = logging.getLogger(__name__)
@@ -155,3 +156,26 @@ class Hyperliquid(Exchange):
             except ExchangeError:
                 logger.warning(f"Could not update funding fees for {pair}.")
         return 0.0
+
+    def fetch_order(self, order_id: str, pair: str, params: dict | None = None) -> CcxtOrder:
+        order = super().fetch_order(order_id, pair, params)
+
+        if (
+            order["average"] is None
+            and order["status"] in ("canceled", "closed")
+            and order["filled"] > 0
+        ):
+            # Hyperliquid does not fill the average price in the order response
+            # Fetch trades to calculate the average price to have the actual price
+            # the order was executed at
+            trades = self.get_trades_for_order(order_id, pair, since=dt_from_ts(order["timestamp"]))
+
+            if trades:
+                total_amount = sum(t["amount"] for t in trades)
+                order["average"] = (
+                    sum(t["price"] * t["amount"] for t in trades) / total_amount
+                    if total_amount
+                    else None
+                )
+
+        return order

tests/exchange/test_hyperliquid.py

@@ -372,3 +372,46 @@ def test_hyperliquid__lev_prep(default_conf, mocker):
 
     assert api_mock.set_margin_mode.call_count == 1
     api_mock.set_margin_mode.assert_called_with("isolated", "BTC/USDC:USDC", {"leverage": 19})
+
+
+def test_hyperliquid_fetch_order(default_conf_usdt, mocker):
+    default_conf_usdt["dry_run"] = False
+
+    api_mock = MagicMock()
+    api_mock.fetch_order = MagicMock(
+        return_value={
+            "id": "12345",
+            "symbol": "ETH/USDC:USDC",
+            "status": "closed",
+            "filled": 0.1,
+            "average": None,
+            "timestamp": 1630000000,
+        }
+    )
+
+    mocker.patch(f"{EXMS}.exchange_has", return_value=True)
+    gtfo_mock = mocker.patch(
+        f"{EXMS}.get_trades_for_order",
+        return_value=[
+            {
+                "order_id": "12345",
+                "price": 1000,
+                "amount": 3,
+                "filled": 3,
+                "remaining": 0,
+            },
+            {
+                "order_id": "12345",
+                "price": 3000,
+                "amount": 1,
+                "filled": 1,
+                "remaining": 0,
+            },
+        ],
+    )
+    exchange = get_patched_exchange(mocker, default_conf_usdt, api_mock, exchange="hyperliquid")
+    o = exchange.fetch_order("12345", "ETH/USDC:USDC")
+    # Uses weighted average
+    assert o["average"] == 1500
+
+    assert gtfo_mock.call_count == 1