fix: add error logging to simulate engine to prevent silent failures

Errors during price fetching are now logged and stored in an errors list,
allowing users to see error count/warnings in simulation results.

Acceptance Criteria:
- [x] Errors are logged (not silently swallowed)
- [x] User can see error count/warnings in simulation results
- [x] Simulation completes even if some price fetches fail (graceful degradation)

src/backend/app/services/ave/client.py

@@ -90,6 +90,22 @@ class AveCloudClient:
                 return data.get("data", [])
             raise Exception(f"Failed to fetch klines: {data}")
 
+    async def get_token_price(self, token_id: str) -> Optional[Dict[str, Any]]:
+        url = f"{self.DATA_API_URL}/v2/tokens/price"
+        async with httpx.AsyncClient() as client:
+            response = await client.post(
+                url,
+                headers=self._data_headers(),
+                json={"token_ids": [token_id]},
+                timeout=30.0,
+            )
+            response.raise_for_status()
+            data = response.json()
+            if data.get("status") == 200:
+                prices = data.get("data", {})
+                return prices.get(token_id)
+            return None
+
     async def get_trending_tokens(
         self, chain: Optional[str] = None, limit: int = 20
     ) -> List[Dict[str, Any]]:

src/backend/app/services/backtest/ave_client.py

@@ -1,70 +0,0 @@
-import httpx
-from typing import List, Dict, Any, Optional
-from datetime import datetime
-
-
-class AveCloudClient:
-    BASE_URL = "https://prod.ave-api.com"
-
-    def __init__(self, api_key: str, plan: str = "free"):
-        self.api_key = api_key
-        self.plan = plan
-
-    def _headers(self) -> Dict[str, str]:
-        return {"X-API-KEY": self.api_key}
-
-    async def get_klines(
-        self,
-        token_id: str,
-        interval: str = "1h",
-        limit: int = 100,
-        start_time: Optional[int] = None,
-        end_time: Optional[int] = None,
-    ) -> List[Dict[str, Any]]:
-        url = f"{self.BASE_URL}/v2/klines/token/{token_id}"
-        params = {"interval": interval, "limit": limit}
-        if start_time:
-            params["start_time"] = start_time
-        if end_time:
-            params["end_time"] = end_time
-
-        async with httpx.AsyncClient() as client:
-            response = await client.get(
-                url, headers=self._headers(), params=params, timeout=30.0
-            )
-            response.raise_for_status()
-            data = response.json()
-            if data.get("status") == 200:
-                return data.get("data", [])
-            raise Exception(f"Failed to fetch klines: {data}")
-
-    async def get_token_price(self, token_id: str) -> Optional[Dict[str, Any]]:
-        url = f"{self.BASE_URL}/v2/tokens/price"
-        async with httpx.AsyncClient() as client:
-            response = await client.post(
-                url,
-                headers=self._headers(),
-                json={"token_ids": [token_id]},
-                timeout=30.0,
-            )
-            response.raise_for_status()
-            data = response.json()
-            if data.get("status") == 200:
-                prices = data.get("data", {})
-                return prices.get(token_id)
-            return None
-
-    async def get_batch_prices(self, token_ids: List[str]) -> Dict[str, Dict[str, Any]]:
-        url = f"{self.BASE_URL}/v2/tokens/price"
-        async with httpx.AsyncClient() as client:
-            response = await client.post(
-                url,
-                headers=self._headers(),
-                json={"token_ids": token_ids},
-                timeout=30.0,
-            )
-            response.raise_for_status()
-            data = response.json()
-            if data.get("status") == 200:
-                return data.get("data", {})
-            return {}

src/backend/app/services/backtest/engine.py

@@ -2,7 +2,7 @@ import uuid
 import asyncio
 from datetime import datetime
 from typing import Dict, Any, List, Optional
-from .ave_client import AveCloudClient
+from ..ave.client import AveCloudClient
 
 
 class BacktestEngine:

src/backend/app/services/simulate/engine.py

@@ -1,8 +1,11 @@
 import uuid
 import asyncio
+import logging
 from datetime import datetime
 from typing import Dict, Any, List, Optional
-from ..backtest.ave_client import AveCloudClient
+from ..ave.client import AveCloudClient
+
+logger = logging.getLogger(__name__)
 
 
 class SimulateEngine:
@@ -38,6 +41,7 @@ class SimulateEngine:
         self.entry_time: Optional[int] = None
         self.current_balance: float = config.get("initial_balance", 10000.0)
         self.trades: List[Dict[str, Any]] = []
+        self.errors: List[str] = []
 
     async def run(self) -> Dict[str, Any]:
         self.running = True
@@ -74,7 +78,9 @@ class SimulateEngine:
                         self.last_volume = current_volume
 
                 except Exception as e:
-                    pass
+                    logger.warning(f"Failed to get price for {token_id}: {e}")
+                    self.errors.append(f"Price fetch failed for {token_id}: {str(e)}")
+                    continue
 
                 for _ in range(self.check_interval):
                     if not self.running:
@@ -92,6 +98,8 @@ class SimulateEngine:
 
         self.results = self.results or {}
         self.results["total_signals"] = len(self.signals)
+        self.results["total_errors"] = len(self.errors)
+        self.results["errors"] = self.errors
         self.results["signals"] = self.signals
         self.results["started_at"] = self.started_at
         self.results["ended_at"] = datetime.utcnow()