Use hub exchange instances for calculator contract precision.

Load enabled instances from settings, fetch market info via /api/hub/market, and apply exchange-specific amount and price precision in trend and roll calculators.

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

hub_market_info_lib.py

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+"""实例 USDT 永续合约信息（与实盘 ccxt 精度一致）。"""
+
+from __future__ import annotations
+
+from typing import Any, Callable, Optional, Tuple
+
+from hub_calculator_market_lib import (
+    amount_decimals_from_exchange,
+    normalize_base_symbol,
+    price_decimals_from_exchange,
+    resolve_usdt_perp_symbol,
+)
+from hub_ohlcv_lib import normalize_price_tick, price_tick_from_market
+
+
+def fetch_usdt_swap_market_info(
+    *,
+    base_or_symbol: str,
+    normalize_symbol_input: Callable[[str], str],
+    normalize_exchange_symbol: Callable[[str], str],
+    ensure_markets_loaded: Callable[[], None],
+    exchange: Any,
+    exchange_id: str = "",
+) -> dict[str, Any]:
+    """供各实例 /api/hub/market 调用。"""
+    raw = str(base_or_symbol or "").strip()
+    if not raw:
+        return {"ok": False, "msg": "请输入币种，如 ETH"}
+
+    try:
+        ensure_markets_loaded()
+    except Exception as exc:
+        return {"ok": False, "msg": f"加载市场失败: {exc}"}
+
+    base_u = normalize_base_symbol(raw)
+    hub_sym = normalize_symbol_input(raw if base_u else raw)
+    try:
+        ex_sym = normalize_exchange_symbol(hub_sym)
+    except Exception:
+        ex_sym = hub_sym
+
+    sym, err = resolve_usdt_perp_symbol(exchange, base_u or hub_sym)
+    if err and ex_sym:
+        markets = getattr(exchange, "markets", None) or {}
+        if ex_sym in markets:
+            sym = ex_sym
+            err = None
+    if err or not sym:
+        return {"ok": False, "msg": err or f"未找到 {base_u or raw}/USDT 永续合约"}
+
+    market = exchange.market(sym)
+    try:
+        contract_size = float(market.get("contractSize") or 1.0)
+    except (TypeError, ValueError):
+        contract_size = 1.0
+    if contract_size <= 0:
+        contract_size = 1.0
+
+    price_tick = normalize_price_tick(price_tick_from_market(exchange, sym))
+    amt_dec = amount_decimals_from_exchange(exchange, sym)
+    px_dec = price_decimals_from_exchange(exchange, sym, price_tick)
+    min_amount = None
+    try:
+        min_amount = float((market.get("limits") or {}).get("amount", {}).get("min"))
+    except (TypeError, ValueError):
+        min_amount = None
+
+    base_out = (market.get("base") or base_u or "").upper() or base_u
+    return {
+        "ok": True,
+        "exchange": (exchange_id or "").strip().lower(),
+        "base": base_out,
+        "exchange_symbol": sym,
+        "display_symbol": f"{base_out}/USDT" if base_out else sym,
+        "contract_size": contract_size,
+        "price_tick": price_tick,
+        "price_decimals": px_dec,
+        "amount_decimals": amt_dec,
+        "min_amount": min_amount,
+    }
+