fix(gate): never block hub account on live balance fetch

Under RS alert ccxt contention, sync get_exchange_capitals made /api/hub/account time out. Return cache immediately and refresh in a background thread when force=False.

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

crypto_monitor_gate/app.py

@@ -2834,13 +2834,13 @@ def friendly_exchange_error(err, available_usdt=None):
     return f"交易所下单失败:{clean}"
 
 
-def get_exchange_capitals(force=False):
-    ok_live, _ = ensure_exchange_live_ready()
-    if not ok_live:
-        return None, None
+_BALANCE_REFRESH_LOCK = threading.Lock()
+_BALANCE_REFRESH_INFLIGHT = False
+
+
+def _fetch_exchange_capitals_sync():
+    """同步拉取资金/交易账户余额并写入缓存(会占用 ccxt,勿在中控热路径直接调用)."""
     now_ts = time.time()
-    if (not force) and ACCOUNT_BALANCE_CACHE["updated_at"] and now_ts - ACCOUNT_BALANCE_CACHE["updated_at"] < BALANCE_REFRESH_SECONDS:
-        return ACCOUNT_BALANCE_CACHE["funding_usdt"], ACCOUNT_BALANCE_CACHE["trading_usdt"]
     try:
         ACCOUNT_BALANCE_CACHE["funding_usdt"] = _fetch_gate_funding_usdt()
     except Exception:
@@ -2854,6 +2854,43 @@ def get_exchange_capitals(force=False):
     return ACCOUNT_BALANCE_CACHE["funding_usdt"], ACCOUNT_BALANCE_CACHE["trading_usdt"]
 
 
+def _kick_exchange_capitals_refresh():
+    """后台刷新余额;与 key_rs 争用时不阻塞看板/中控请求."""
+    global _BALANCE_REFRESH_INFLIGHT
+    with _BALANCE_REFRESH_LOCK:
+        if _BALANCE_REFRESH_INFLIGHT:
+            return
+        _BALANCE_REFRESH_INFLIGHT = True
+
+    def _worker():
+        global _BALANCE_REFRESH_INFLIGHT
+        try:
+            _fetch_exchange_capitals_sync()
+        except Exception:
+            pass
+        finally:
+            with _BALANCE_REFRESH_LOCK:
+                _BALANCE_REFRESH_INFLIGHT = False
+
+    threading.Thread(target=_worker, name="gate-balance-refresh", daemon=True).start()
+
+
+def get_exchange_capitals(force=False):
+    ok_live, _ = ensure_exchange_live_ready()
+    if not ok_live:
+        return None, None
+    now_ts = time.time()
+    has_cache = bool(ACCOUNT_BALANCE_CACHE["updated_at"])
+    fresh = has_cache and (now_ts - ACCOUNT_BALANCE_CACHE["updated_at"] < BALANCE_REFRESH_SECONDS)
+    if (not force) and fresh:
+        return ACCOUNT_BALANCE_CACHE["funding_usdt"], ACCOUNT_BALANCE_CACHE["trading_usdt"]
+    if not force:
+        # 过期/冷缓存:先返回现有值(可空),后台刷新,避免 /api/hub/account 被 RS 监控拖死
+        _kick_exchange_capitals_refresh()
+        return ACCOUNT_BALANCE_CACHE["funding_usdt"], ACCOUNT_BALANCE_CACHE["trading_usdt"]
+    return _fetch_exchange_capitals_sync()
+
+
 def execute_transfer_usdt(amount, from_account, to_account):
     from lib.exchange.gate_transfer_lib import execute_transfer_usdt as _gate_execute_transfer_usdt