Fix target-exit mismatch: correct close reason and executable PnL gate.

Locked premium exits no longer label as fixed_usdt; mark/book optimism no longer triggers close into a realized loss.

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

backend/app/strategy/engine.py

@@ -882,6 +882,17 @@ class StrategyEngine:
                 locked_exit_target=locked_exit,
             )
             pending_close = st["phase"] in ("liquidity_wait", "closing")
+            # 曾因达标进入流动性等待，但当前估价已跌破目标：取消挂起，避免硬平出亏损却仍记「达标」
+            if (
+                pending_close
+                and not expired.should_close
+                and not decision.should_close
+            ):
+                self._set_state(
+                    phase="open",
+                    last_error="达标后流动性等待期间浮盈回落，已取消平仓挂起",
+                )
+                return
             if expired.should_close or decision.should_close or pending_close:
                 is_oo = (
                     str(upl.get("hedge_mode") or "") == "option_option"