improve signed reads, crypto hardening, and scraper transport

app/services/binance.py

@@ -4,7 +4,6 @@ import logging
 from datetime import datetime, timezone
 from typing import Optional
 
-import httpx
 import websockets
 
 from app.config import settings
@@ -127,19 +126,19 @@ async def fetch_historical(asset: str, symbol: str, interval: str = "1m", limit:
     """Fetch historical klines from Binance REST API to pre-fill price_store."""
     url = f"{settings.binance_rest_url}/api/v3/klines?symbol={symbol.upper()}&interval={interval}&limit={limit}"
     try:
-        async with httpx.AsyncClient(timeout=15) as client:
-            resp = await client.get(url)
-            resp.raise_for_status()
-            for row in resp.json():
-                candle = {
-                    "time": row[0],           # open time ms
-                    "open": float(row[1]),
-                    "high": float(row[2]),
-                    "low": float(row[3]),
-                    "close": float(row[4]),
-                    "volume": float(row[5]),
-                }
-                price_store.update(asset, candle)
+        from app.services.http_client import get_client
+        resp = await get_client().get(url, timeout=15)
+        resp.raise_for_status()
+        for row in resp.json():
+            candle = {
+                "time": row[0],           # open time ms
+                "open": float(row[1]),
+                "high": float(row[2]),
+                "low": float(row[3]),
+                "close": float(row[4]),
+                "volume": float(row[5]),
+            }
+            price_store.update(asset, candle)
         logger.info("Loaded %d historical %s candles for %s", limit, interval, asset)
     except Exception as exc:
         logger.error("Failed to fetch historical data for %s: %s", asset, exc)