Fix naked-stop regression: speed cache made the guard strip live brackets

The get_positions TTL cache (added for the speed fix) silently broke the
naked-stop guard: _broker_held_symbols read 2.5s-stale positions, so a
just-filled entry wasn't seen as held, the guard thought it was unfilled, and
cancelled its bracket on a price dip -> NAKED position (APWC bled -12.8%
unprotected today). Fixes:
- client.get_positions(fresh=True) bypasses the cache; the guard uses it.
- entry_grace_seconds (default 5): never cancel an entry within N seconds of
  arming, so a marketable fill can confirm before the bracket could be stripped.
Regression test added.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

trading_execution.py

@@ -96,6 +96,10 @@ class ExecutionSettings:
     # cap the marketable limit so a breakout FILLS on a runner instead of
     # resting forever at the trigger, while still bounding slippage.
     trigger_slippage_pct: float = 0.004
+    # don't cancel an entry within this many seconds of arming — a marketable
+    # fill needs a moment to confirm at the broker; cancelling first strips its
+    # bracket (the naked-stop failure mode).
+    entry_grace_seconds: float = 5.0
     # --- account-aware sizing (matters most on a small REAL account) -------
     # one position's dollar value <= this fraction of equity, so a single trade
     # can't exceed buying power (critical at $300: 3 positions must fit, so ~1/3).
@@ -137,6 +141,7 @@ class ExecutionSettings:
             trigger_slippage_pct=float(
                 values.get("TRADING_TRIGGER_SLIP_PCT", "0.004")
             ),
+            entry_grace_seconds=float(values.get("TRADING_ENTRY_GRACE_SECONDS", "5")),
             max_position_pct=float(values.get("TRADING_MAX_POSITION_PCT", "0.33")),
             liquidity_max_volume_pct=float(
                 values.get("TRADING_LIQUIDITY_MAX_VOLUME_PCT", "0.0")
@@ -251,7 +256,7 @@ class TradingExecutionService:
         if client is None or not hasattr(client, "get_positions"):
             return None
         try:
-            positions = client.get_positions() or []
+            positions = client.get_positions(fresh=True) or []
             return {str(p.get("symbol")) for p in positions if p.get("symbol")}
         except Exception as exc:  # noqa: BLE001
             logger.warning("broker positions unreadable in entry guard: %s", exc)
@@ -855,6 +860,11 @@ class TradingExecutionService:
             if symbol in broker_held:
                 self._armed.pop(order_id, None)
                 continue
+            # grace window: a just-armed entry may still be filling — don't strip
+            # its bracket before the fill can confirm (belt to the fresh-positions
+            # check above; together they close the naked-stop race)
+            if (now - armed["armed_at"]).total_seconds() < self.settings.entry_grace_seconds:
+                continue
 
             armed["checks"] += 1
             reason = None