Use trading account and USDC/USDT market price for sim convert.

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

lib/sim/wallets_lib.py

@@ -240,18 +240,33 @@ class SimWallets:
         from_ccy: str,
         to_ccy: str,
         amount: float,
-        account: str = "funding",
+        account: str = "trading",
+        to_amount: float | None = None,
+        rate: float | None = None,
+        fee: float | None = None,
+        note: str | None = None,
     ) -> dict[str, Any]:
+        """USDT↔USDC 兑换. 默认交易账户; to_amount 未给时按 rate(USDT/USDC) 换算, 再否则 1:1."""
         amt = float(amount)
         if amt <= 0:
             return {"ok": False, "detail": "数量须大于 0"}
         fa = (from_ccy or "").strip().lower()
         ta = (to_ccy or "").strip().lower()
-        acct = (account or "funding").strip().lower()
+        acct = normalize_sim_account(account) or "trading"
         if acct not in ("funding", "trading"):
             return {"ok": False, "detail": "account 须为 funding / trading"}
         if {fa, ta} != {"usdt", "usdc"}:
-            return {"ok": False, "detail": "仅支持 USDT↔USDC 1:1"}
+            return {"ok": False, "detail": "仅支持 USDT↔USDC"}
+        if to_amount is not None:
+            got = float(to_amount)
+        elif rate is not None and float(rate) > 0:
+            r = float(rate)
+            # rate = USDT per 1 USDC
+            got = (amt / r) if fa == "usdt" else (amt * r)
+        else:
+            got = amt
+        if got <= 0:
+            return {"ok": False, "detail": "兑换所得须大于 0"}
         src_key = _ACCT_MAP[(acct, fa)]
         dst_key = _ACCT_MAP[(acct, ta)]
         conn = self.get_db()
@@ -262,8 +277,9 @@ class SimWallets:
             if amt > src + 1e-9:
                 return {"ok": False, "detail": f"{acct} {fa.upper()} 不足(可用 {src:.4f})"}
             snap[src_key] = src - amt
-            snap[dst_key] = float(snap[dst_key]) + amt
+            snap[dst_key] = float(snap[dst_key]) + got
             self._write(snap, conn=conn)
+            note_s = note or f"to {ta} @{rate if rate is not None else '1:1'}"
             self._ledger(
                 conn,
                 kind="convert",
@@ -271,25 +287,28 @@ class SimWallets:
                 ccy=fa,
                 account=acct,
                 balance_after=snap[src_key],
-                note=f"to {ta}",
+                note=note_s,
             )
             self._ledger(
                 conn,
                 kind="convert",
-                amount=amt,
+                amount=got,
                 ccy=ta,
                 account=acct,
                 balance_after=snap[dst_key],
                 note=f"from {fa}",
             )
             conn.commit()
+            eff_rate = (amt / got) if fa == "usdt" and got > 0 else ((got / amt) if amt > 0 else None)
             return {
                 "ok": True,
                 "detail": "converted",
                 "from_ccy": fa.upper(),
                 "to_ccy": ta.upper(),
                 "amount": amt,
-                "rate": 1.0,
+                "to_amount": got,
+                "rate": float(rate) if rate is not None else eff_rate,
+                "fee": float(fee or 0),
                 "account": acct,
                 "wallets": {k: float(snap[k]) for k in WALLET_KEYS},
                 "total_usdt_equiv": self.total_usdt_equiv(snap),