Paper trader Phase 1.B.3 + 1.C.1: market clock via Alpaca + scoring dispatch log

- _is_market_open() now queries Alpaca's get_clock() so holidays, early
  closes, and halted markets no longer skip orders; falls back to weekday
  9:30–16:00 ET only on broker error (1.B.3)
- AlpacaBroker.get_clock() + MarketClock dataclass wrapping alpaca-py's
  TradingClient.get_clock()
- PaperTradingEngine logs scoring_model at session startup (WARNING level)
  so multi-session daemon makes the live-path scorer dispatch explicit
  in every boot log — verifies v7.356 config's return_max_long_v13e
  actually reaches _compute_score (1.C.1)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/paper_trader/alpaca_broker.py

@@ -61,6 +61,13 @@ class PortfolioHistory:
     profit_loss_pct: list[float]
 
 
+@dataclass
+class MarketClock:
+    is_open: bool
+    next_open: dt.datetime | None
+    next_close: dt.datetime | None
+
+
 class AlpacaBroker:
     """Thin wrapper around alpaca-py TradingClient for paper trading."""
 
@@ -99,6 +106,15 @@ class AlpacaBroker:
     # Account
     # ------------------------------------------------------------------ #
 
+    def get_clock(self) -> MarketClock:
+        """Return Alpaca's market clock (respects holidays, early closes, halts)."""
+        clk = self._trading.get_clock()
+        return MarketClock(
+            is_open=bool(clk.is_open),
+            next_open=clk.next_open,
+            next_close=clk.next_close,
+        )
+
     def get_account(self) -> AccountInfo:
         acct = self._trading.get_account()
         equity = float(acct.equity or 0)

apps/paper_trader/engine.py

@@ -134,6 +134,14 @@ class PaperTradingEngine:
         self._parking_brake_cooldown_remaining: int = 0
         self._parking_brake_skip_buy_today: bool = False  # skip same-day re-buy after brake fires
 
+        logger.warning(
+            "paper_trader_scoring_dispatch",
+            session_id=session.session_id,
+            session_name=session.session_name,
+            scoring_model=self._config.signal.scoring_model,
+            config_path=session.config_path,
+        )
+
     def _get_candidate_capital_bucket_id(self, candidate: Candidate) -> str | None:
         return candidate.engine_capital_bucket_id
 
@@ -438,12 +446,21 @@ class PaperTradingEngine:
         )
         return None, reason
 
-    @staticmethod
-    def _is_market_open() -> bool:
-        """Return True if US equity market is currently open (9:30–16:00 ET, weekdays)."""
+    def _is_market_open(self) -> bool:
+        """Return True if US equity market is currently open.
+
+        Authoritative: Alpaca `get_clock()` — respects holidays, early closes,
+        halted markets. Falls back to a weekday 9:30–16:00 ET clock-only check
+        on any broker error (better to fail-open during rare API hiccups than
+        miss an event entirely; Alpaca will reject rejected orders downstream).
+        """
+        try:
+            return self._broker.get_clock().is_open
+        except Exception as exc:
+            logger.warning("paper_engine_clock_fallback", error=str(exc))
             import zoneinfo
             now_et = dt.datetime.now(tz=zoneinfo.ZoneInfo("America/New_York"))
-        if now_et.weekday() >= 5:  # Saturday=5, Sunday=6
+            if now_et.weekday() >= 5:
                 return False
             market_open = now_et.replace(hour=9, minute=30, second=0, microsecond=0)
             market_close = now_et.replace(hour=16, minute=0, second=0, microsecond=0)