feat(kevin): mention-driven backtest mini-engine

Walks mentions chronologically, T+1 entry, time-based exit per
KevinStrategy. Reuses backtester/metrics::compute_metrics for headline
numbers. KevinPriceLoader fronts market_data + Alpaca.

backtester/kevin_backtest.py

@@ -0,0 +1,367 @@
+"""Mention-driven backtest mini-engine for the Kevin strategy.
+
+Parallel to the bar-driven BacktestEngine. Walks mentions chronologically,
+entry at T+1 open, exit at entry_session + holding_days open. Calls the
+shared KevinStrategy.evaluate_mention so backtest and live agree.
+"""
+
+from __future__ import annotations
+
+import logging
+from dataclasses import dataclass, field
+from datetime import datetime, timedelta, timezone
+from decimal import Decimal
+from typing import Any, Protocol
+
+import pandas as pd
+
+from backtester.metrics import BacktestResult, compute_metrics
+from shared.schemas.kevin import (
+    KevinAccountState,
+    KevinDecision,
+    KevinDecisionType,
+)
+from shared.strategies.kevin import KevinStrategy
+
+logger = logging.getLogger(__name__)
+
+
+class PriceLoader(Protocol):
+    async def daily_bars(
+        self, symbol: str, start: datetime, end: datetime
+    ) -> pd.DataFrame: ...
+
+    async def is_tradable(self, symbol: str) -> bool: ...
+
+    async def benchmark_bars(
+        self, start: datetime, end: datetime
+    ) -> pd.DataFrame: ...
+
+
+@dataclass
+class KevinBacktestParams:
+    initial_capital: Decimal = Decimal("100000")
+    slippage_pct: Decimal = Decimal("0.0005")
+    commission_per_trade: Decimal = Decimal("0")
+    dedupe_policy: str = "roll"  # "roll" | "ignore"
+
+
+@dataclass
+class _BacktestTrade:
+    symbol: str
+    source_mention_id: int
+    entry_at: datetime
+    entry_price: Decimal
+    qty: Decimal
+    target_exit_at: datetime
+    exit_at: datetime | None = None
+    exit_price: Decimal | None = None
+    pnl_usd: Decimal | None = None
+    pnl_pct: Decimal | None = None
+    holding_days_actual: int | None = None
+
+
+@dataclass
+class _Portfolio:
+    cash: Decimal
+    open_trades: dict[str, _BacktestTrade] = field(default_factory=dict)
+    closed_trades: list[_BacktestTrade] = field(default_factory=list)
+    blocklist_expiry: dict[str, datetime] = field(default_factory=dict)
+
+    def equity_at(self, mark_prices: dict[str, Decimal]) -> Decimal:
+        total = self.cash
+        for symbol, trade in self.open_trades.items():
+            price = mark_prices.get(symbol, trade.entry_price)
+            total += trade.qty * price
+        return total
+
+    def held_dollars(self) -> dict[str, Decimal]:
+        return {s: t.qty * t.entry_price for s, t in self.open_trades.items()}
+
+    def active_blocklist(self, now: datetime) -> set[str]:
+        return {s for s, exp in self.blocklist_expiry.items() if exp > now}
+
+
+class KevinBacktestRunner:
+    def __init__(self, strategy: KevinStrategy, price_loader: PriceLoader) -> None:
+        self.strategy = strategy
+        self.price_loader = price_loader
+
+    async def run(
+        self, mentions: list[Any], params: KevinBacktestParams
+    ) -> BacktestResult:
+        if not mentions:
+            return compute_metrics(
+                trade_log=[], equity_curve=[], initial_capital=params.initial_capital
+            )
+
+        sorted_mentions = sorted(mentions, key=lambda m: m.created_at)
+        start = sorted_mentions[0].created_at - timedelta(days=1)
+        end = max(m.created_at for m in sorted_mentions) + timedelta(days=120)
+
+        symbols = sorted({m.symbol for m in sorted_mentions})
+        bars: dict[str, pd.DataFrame] = {}
+        for sym in symbols:
+            df = await self.price_loader.daily_bars(sym, start, end)
+            if not df.empty:
+                bars[sym] = df
+
+        spy_bars = await self.price_loader.benchmark_bars(start, end)
+
+        portfolio = _Portfolio(cash=params.initial_capital)
+        equity_curve: list[tuple[datetime, Decimal]] = []
+        all_dates = _trading_dates(spy_bars)
+
+        for day in all_dates:
+            # 1. Apply mentions whose created_at falls on or before this trading session
+            for mention in [
+                m for m in sorted_mentions if _entry_day(m.created_at, all_dates) == day
+            ]:
+                await self._apply_mention(mention, day, portfolio, bars, params)
+
+            # 2. Roll exits whose target_exit_at <= day
+            _close_expired(day, portfolio, bars, params)
+
+            # 3. Mark-to-market equity
+            mark = _mark_prices(bars, portfolio.open_trades, day)
+            equity_curve.append((day, portfolio.equity_at(mark)))
+
+        # Close any still-open at the last day
+        if all_dates:
+            _close_all(all_dates[-1], portfolio, bars, params)
+
+        trades_dict = [self._trade_to_dict(t) for t in portfolio.closed_trades]
+        return compute_metrics(
+            trade_log=trades_dict,
+            equity_curve=equity_curve,
+            initial_capital=params.initial_capital,
+            benchmark_bars=spy_bars,
+        )
+
+    async def _apply_mention(
+        self,
+        mention: Any,
+        day: datetime,
+        portfolio: _Portfolio,
+        bars: dict[str, pd.DataFrame],
+        params: KevinBacktestParams,
+    ) -> None:
+        symbol = mention.symbol
+        if symbol not in bars:
+            return  # no price data — skip
+
+        is_tradable = await self.price_loader.is_tradable(symbol)
+        mark = _mark_prices(bars, portfolio.open_trades, day)
+        equity = portfolio.equity_at(mark)
+        state = KevinAccountState(
+            equity_usd=equity,
+            cash_usd=portfolio.cash,
+            held_positions=portfolio.held_dollars(),
+            blocklisted_symbols=portfolio.active_blocklist(day),
+            daily_trade_count=0,  # backtest doesn't enforce daily caps
+            daily_alloc_usd=Decimal("0"),
+            paused=False,
+        )
+
+        current_price = _price_at(bars[symbol], day, "open")
+        if current_price is None:
+            return
+
+        decision = await self.strategy.evaluate_mention(
+            mention,
+            state,
+            effective_conviction=mention.conviction,
+            current_price=current_price,
+            is_tradable=is_tradable,
+        )
+
+        if decision.decision == KevinDecisionType.OPEN_LONG:
+            self._open_or_roll(decision, mention, day, portfolio, bars, params)
+        elif decision.decision == KevinDecisionType.CLOSE_LONG:
+            self._close_position(symbol, day, portfolio, bars, params)
+            if mention.action.value == "avoid":
+                portfolio.blocklist_expiry[symbol] = day + timedelta(
+                    days=self.strategy.config.avoid_blocks_days
+                )
+
+    def _open_or_roll(
+        self,
+        decision: KevinDecision,
+        mention: Any,
+        day: datetime,
+        portfolio: _Portfolio,
+        bars: dict[str, pd.DataFrame],
+        params: KevinBacktestParams,
+    ) -> None:
+        symbol = decision.symbol
+        entry_price = _price_at(bars[symbol], day, "open")
+        if entry_price is None or decision.target_dollars is None:
+            return
+        entry_price *= Decimal("1") + params.slippage_pct
+
+        qty = (decision.target_dollars / entry_price).quantize(Decimal("0.0001"))
+        if qty <= 0:
+            return
+
+        cost = qty * entry_price + params.commission_per_trade
+        if cost > portfolio.cash:
+            return  # insufficient cash in backtest
+
+        # trading days -> calendar days approximation (~7/5 = 1.4)
+        hold_days = decision.holding_days or 5
+        target_exit = day + timedelta(days=int(hold_days * 1.4))
+        target_exit = _next_trading_day(target_exit, bars[symbol].index)
+
+        if symbol in portfolio.open_trades:
+            if params.dedupe_policy == "roll":
+                portfolio.open_trades[symbol].target_exit_at = max(
+                    portfolio.open_trades[symbol].target_exit_at, target_exit
+                )
+            return  # ignore: don't add second position
+
+        portfolio.cash -= cost
+        portfolio.open_trades[symbol] = _BacktestTrade(
+            symbol=symbol,
+            source_mention_id=mention.id,
+            entry_at=day,
+            entry_price=entry_price,
+            qty=qty,
+            target_exit_at=target_exit,
+        )
+
+    def _close_position(
+        self,
+        symbol: str,
+        day: datetime,
+        portfolio: _Portfolio,
+        bars: dict[str, pd.DataFrame],
+        params: KevinBacktestParams,
+    ) -> None:
+        if symbol not in portfolio.open_trades:
+            return
+        trade = portfolio.open_trades.pop(symbol)
+        exit_price = _price_at(bars[symbol], day, "open")
+        if exit_price is None:
+            exit_price = trade.entry_price  # last resort
+        exit_price *= Decimal("1") - params.slippage_pct
+
+        proceeds = trade.qty * exit_price - params.commission_per_trade
+        portfolio.cash += proceeds
+        trade.exit_at = day
+        trade.exit_price = exit_price
+        trade.pnl_usd = (exit_price - trade.entry_price) * trade.qty
+        trade.pnl_pct = (
+            (exit_price - trade.entry_price) / trade.entry_price * Decimal("100")
+        )
+        trade.holding_days_actual = (day - trade.entry_at).days
+        portfolio.closed_trades.append(trade)
+
+    def _trade_to_dict(self, t: _BacktestTrade) -> dict[str, Any]:
+        return {
+            "symbol": t.symbol,
+            "source_mention_id": t.source_mention_id,
+            "entry_at": t.entry_at,
+            "entry_price": t.entry_price,
+            "exit_at": t.exit_at,
+            "exit_price": t.exit_price,
+            "qty": t.qty,
+            "pnl_usd": t.pnl_usd,
+            "pnl_pct": t.pnl_pct,
+            "holding_days_actual": t.holding_days_actual,
+        }
+
+
+# --- helpers ---
+
+
+def _mark_prices(
+    bars: dict[str, pd.DataFrame],
+    open_trades: dict[str, _BacktestTrade],
+    day: datetime,
+) -> dict[str, Decimal]:
+    out: dict[str, Decimal] = {}
+    for s in open_trades:
+        if s in bars:
+            p = _price_at(bars[s], day, "close")
+            if p is not None:
+                out[s] = p
+    return out
+
+
+def _trading_dates(bars: pd.DataFrame) -> list[datetime]:
+    if bars is None or bars.empty:
+        return []
+    return [d.to_pydatetime().replace(tzinfo=timezone.utc) for d in bars.index]
+
+
+def _entry_day(created_at: datetime, dates: list[datetime]) -> datetime | None:
+    """Find next trading session AFTER mention's created_at (T+1)."""
+    target = created_at.date()
+    for d in dates:
+        if d.date() > target:
+            return d
+    return None
+
+
+def _price_at(df: pd.DataFrame, day: datetime, col: str) -> Decimal | None:
+    if df is None or df.empty:
+        return None
+    matches = df[df.index.date <= day.date()]
+    if matches.empty:
+        return None
+    return Decimal(str(matches.iloc[-1][col]))
+
+
+def _next_trading_day(target: datetime, index: pd.DatetimeIndex) -> datetime:
+    for d in index:
+        py_d: datetime = d.to_pydatetime().replace(tzinfo=timezone.utc)
+        if py_d >= target:
+            return py_d
+    last: datetime = index[-1].to_pydatetime().replace(tzinfo=timezone.utc)
+    return last
+
+
+def _close_expired(
+    day: datetime,
+    portfolio: _Portfolio,
+    bars: dict[str, pd.DataFrame],
+    params: KevinBacktestParams,
+) -> None:
+    for symbol in list(portfolio.open_trades.keys()):
+        trade = portfolio.open_trades[symbol]
+        if trade.target_exit_at <= day:
+            _force_close(symbol, day, portfolio, bars, params)
+
+
+def _close_all(
+    day: datetime,
+    portfolio: _Portfolio,
+    bars: dict[str, pd.DataFrame],
+    params: KevinBacktestParams,
+) -> None:
+    for symbol in list(portfolio.open_trades.keys()):
+        _force_close(symbol, day, portfolio, bars, params)
+
+
+def _force_close(
+    symbol: str,
+    day: datetime,
+    portfolio: _Portfolio,
+    bars: dict[str, pd.DataFrame],
+    params: KevinBacktestParams,
+) -> None:
+    trade = portfolio.open_trades.pop(symbol)
+    exit_price = _price_at(bars[symbol], day, "open")
+    if exit_price is None:
+        exit_price = trade.entry_price
+    exit_price *= Decimal("1") - params.slippage_pct
+    proceeds = trade.qty * exit_price - params.commission_per_trade
+    portfolio.cash += proceeds
+    trade.exit_at = day
+    trade.exit_price = exit_price
+    trade.pnl_usd = (exit_price - trade.entry_price) * trade.qty
+    trade.pnl_pct = (
+        (exit_price - trade.entry_price) / trade.entry_price * Decimal("100")
+    )
+    trade.holding_days_actual = (day - trade.entry_at).days
+    portfolio.closed_trades.append(trade)

backtester/kevin_price_loader.py

@@ -0,0 +1,96 @@
+"""Daily bar loader for KevinBacktestRunner.
+
+Reads from market_data table first; falls back to Alpaca on cache miss
+and writes through so subsequent runs are warm.
+"""
+
+from __future__ import annotations
+
+import logging
+from datetime import datetime
+from typing import Any
+
+import pandas as pd
+from sqlalchemy import and_, select
+from sqlalchemy.ext.asyncio import async_sessionmaker
+
+from shared.models.timeseries import MarketData
+
+logger = logging.getLogger(__name__)
+
+
+class KevinPriceLoader:
+    def __init__(
+        self,
+        session_factory: async_sessionmaker,
+        alpaca_fetcher: Any,
+    ) -> None:
+        self.session_factory = session_factory
+        self.alpaca = alpaca_fetcher
+
+    async def daily_bars(
+        self, symbol: str, start: datetime, end: datetime
+    ) -> pd.DataFrame:
+        async with self.session_factory() as session:
+            rows = (
+                await session.execute(
+                    select(
+                        MarketData.timestamp,
+                        MarketData.open,
+                        MarketData.high,
+                        MarketData.low,
+                        MarketData.close,
+                        MarketData.volume,
+                    )
+                    .where(
+                        and_(
+                            MarketData.ticker == symbol,
+                            MarketData.timestamp >= start,
+                            MarketData.timestamp <= end,
+                        )
+                    )
+                    .order_by(MarketData.timestamp)
+                )
+            ).all()
+
+        if rows:
+            df = pd.DataFrame(
+                rows, columns=["timestamp", "open", "high", "low", "close", "volume"]
+            )
+            df = df.set_index("timestamp")
+            return df
+
+        # cache miss — back-fetch from Alpaca, write through
+        try:
+            df = await self.alpaca.fetch_daily_bars(symbol, start, end)
+            if not df.empty:
+                await self._write_through(symbol, df)
+            return df
+        except Exception as e:
+            logger.warning("alpaca fetch failed for %s: %s", symbol, e)
+            return pd.DataFrame()
+
+    async def benchmark_bars(self, start: datetime, end: datetime) -> pd.DataFrame:
+        return await self.daily_bars("SPY", start, end)
+
+    async def is_tradable(self, symbol: str) -> bool:
+        try:
+            return bool(await self.alpaca.is_asset_tradable(symbol))
+        except Exception:
+            return False
+
+    async def _write_through(self, symbol: str, df: pd.DataFrame) -> None:
+        async with self.session_factory() as session:
+            for ts, row in df.iterrows():
+                session.add(
+                    MarketData(
+                        ticker=symbol,
+                        timestamp=ts.to_pydatetime(),
+                        open=row["open"],
+                        high=row["high"],
+                        low=row["low"],
+                        close=row["close"],
+                        volume=row.get("volume", 0),
+                    )
+                )
+            await session.commit()

backtester/metrics.py

@@ -6,13 +6,19 @@ curve produced by a backtest run.
 
 from __future__ import annotations
 
+import logging
 import math
 from dataclasses import dataclass, field
 from datetime import datetime, timedelta
+from decimal import Decimal
 from typing import Any
 
+import pandas as pd
+
 from shared.schemas.trading import OrderSide, TradeExecution
 
+logger = logging.getLogger(__name__)
+
 
 @dataclass
 class BacktestResult:
@@ -56,49 +62,72 @@ class BacktestResult:
     avg_win_loss_ratio: float = 0.0
     trade_count: int = 0
     avg_hold_duration: timedelta = field(default_factory=lambda: timedelta(0))
-    equity_curve: list[tuple[datetime, float]] = field(default_factory=list)
-    trade_log: list[TradeExecution] = field(default_factory=list)
+    equity_curve: list[tuple[datetime, Any]] = field(default_factory=list)
+    trade_log: list[Any] = field(default_factory=list)
+
+    # --- Kevin v2 extensions ---
+    total_return_pct: float = 0.0  # alias for total_return (Kevin-style naming)
+    trades: list[dict[str, Any]] = field(default_factory=list)
+    alpha_vs_spy_pct: Decimal | None = None
+    beta_vs_spy: Decimal | None = None
+    avg_winner_pct: Decimal | None = None
+    avg_loser_pct: Decimal | None = None
+    best_trade: dict[str, Any] | None = None
+    worst_trade: dict[str, Any] | None = None
 
 
 def compute_metrics(
-    trade_log: list[TradeExecution],
-    equity_curve: list[tuple[datetime, float]],
-    initial_capital: float = 100_000.0,
+    trade_log: list[Any],
+    equity_curve: list[tuple[datetime, Any]],
+    initial_capital: float | Decimal = 100_000.0,
+    benchmark_bars: pd.DataFrame | None = None,
 ) -> BacktestResult:
     """Compute all performance metrics from a backtest run.
 
     Parameters
     ----------
     trade_log:
-        Chronological list of every executed trade (buys and sells).
+        Chronological list of every executed trade. Accepts either
+        ``TradeExecution`` instances (legacy bar-driven engine) or
+        dict-shaped per-position rows (Kevin mention-driven engine).
     equity_curve:
         List of ``(timestamp, portfolio_equity)`` snapshots.
     initial_capital:
         Starting capital used to compute total return.
+    benchmark_bars:
+        Optional benchmark price series (e.g. SPY) used to compute
+        alpha + beta.
 
     Returns
     -------
     BacktestResult
         Populated metrics dataclass.
     """
+    is_dict_trades = bool(trade_log) and isinstance(trade_log[0], dict)
+    initial_float = float(initial_capital)
     result = BacktestResult(
         equity_curve=equity_curve,
         trade_log=trade_log,
+        trades=trade_log if is_dict_trades else [],
     )
 
     if not equity_curve:
+        if is_dict_trades:
+            _populate_dict_trade_aggregates(result, trade_log)
+        _populate_benchmark_metrics(result, equity_curve, benchmark_bars, initial_float)
         return result
 
     # ----- Total return -----
-    final_equity = equity_curve[-1][1]
-    result.total_return = (final_equity - initial_capital) / initial_capital * 100.0
+    final_equity = float(equity_curve[-1][1])
+    result.total_return = (final_equity - initial_float) / initial_float * 100.0
+    result.total_return_pct = result.total_return
 
     # ----- Annualized return -----
     if len(equity_curve) >= 2:
         total_days = (equity_curve[-1][0] - equity_curve[0][0]).days
         if total_days > 0:
             trading_years = total_days / 365.25
-            growth_factor = final_equity / initial_capital
+            growth_factor = final_equity / initial_float
             if growth_factor > 0:
                 result.annualized_return = (
                     (growth_factor ** (1.0 / trading_years)) - 1.0
@@ -119,42 +148,113 @@ def compute_metrics(
     result.max_drawdown_duration_days = dd_duration
 
     # ----- Round-trip trade analysis -----
-    round_trips = _build_round_trips(trade_log)
-    result.trade_count = len(round_trips)
+    if is_dict_trades:
+        _populate_dict_trade_aggregates(result, trade_log)
+    else:
+        round_trips = _build_round_trips(trade_log)
+        result.trade_count = len(round_trips)
 
-    if round_trips:
-        pnls = [rt["pnl"] for rt in round_trips]
-        wins = [p for p in pnls if p > 0]
-        losses = [p for p in pnls if p <= 0]
+        if round_trips:
+            pnls = [rt["pnl"] for rt in round_trips]
+            wins = [p for p in pnls if p > 0]
+            losses = [p for p in pnls if p <= 0]
 
-        result.win_rate = (len(wins) / len(pnls)) * 100.0 if pnls else 0.0
+            result.win_rate = (len(wins) / len(pnls)) * 100.0 if pnls else 0.0
 
-        avg_win = sum(wins) / len(wins) if wins else 0.0
-        avg_loss = sum(losses) / len(losses) if losses else 0.0
-        if avg_loss != 0:
-            result.avg_win_loss_ratio = abs(avg_win / avg_loss)
-        elif avg_win > 0:
-            result.avg_win_loss_ratio = float("inf")
+            avg_win = sum(wins) / len(wins) if wins else 0.0
+            avg_loss = sum(losses) / len(losses) if losses else 0.0
+            if avg_loss != 0:
+                result.avg_win_loss_ratio = abs(avg_win / avg_loss)
+            elif avg_win > 0:
+                result.avg_win_loss_ratio = float("inf")
 
-        durations = [rt["duration"] for rt in round_trips]
-        result.avg_hold_duration = sum(durations, timedelta()) / len(durations)
+            durations = [rt["duration"] for rt in round_trips]
+            result.avg_hold_duration = sum(durations, timedelta()) / len(durations)
+
+    # ----- Benchmark metrics (Kevin extensions) -----
+    _populate_benchmark_metrics(result, equity_curve, benchmark_bars, initial_float)
 
     return result
 
 
+def _populate_dict_trade_aggregates(
+    result: BacktestResult, trade_log: list[dict[str, Any]]
+) -> None:
+    """Populate trade-level aggregates when trade_log is dict-shaped."""
+    result.trade_count = len(trade_log)
+    if not trade_log:
+        return
+
+    closed = [
+        t for t in trade_log if t.get("pnl_pct") is not None
+    ]
+    if not closed:
+        return
+
+    pnls = [float(t["pnl_pct"]) for t in closed]
+    wins = [p for p in pnls if p > 0]
+    losses = [p for p in pnls if p <= 0]
+    result.win_rate = (len(wins) / len(pnls)) * 100.0 if pnls else 0.0
+
+    avg_win = sum(wins) / len(wins) if wins else 0.0
+    avg_loss = sum(losses) / len(losses) if losses else 0.0
+    if avg_loss != 0:
+        result.avg_win_loss_ratio = abs(avg_win / avg_loss)
+    elif avg_win > 0:
+        result.avg_win_loss_ratio = float("inf")
+
+
+def _populate_benchmark_metrics(
+    result: BacktestResult,
+    equity_curve: list[tuple[datetime, Any]],
+    benchmark_bars: pd.DataFrame | None,
+    initial_capital: float,
+) -> None:
+    if benchmark_bars is None or benchmark_bars.empty or len(equity_curve) < 2:
+        return
+    try:
+        equity_df = pd.DataFrame(
+            [(ts, float(eq)) for ts, eq in equity_curve],
+            columns=["timestamp", "equity"],
+        ).set_index("timestamp")
+        equity_ret = equity_df["equity"].pct_change().dropna()
+        spy_close = benchmark_bars["close"].astype(float).pct_change().dropna()
+        aligned = pd.concat(
+            [equity_ret, spy_close], axis=1, keys=["s", "spy"]
+        ).dropna()
+        if len(aligned) >= 2:
+            cov = aligned["s"].cov(aligned["spy"])
+            var = aligned["spy"].var()
+            if var > 0:
+                result.beta_vs_spy = Decimal(str(round(cov / var, 4)))
+            spy_total_return = (
+                float(benchmark_bars["close"].iloc[-1])
+                / float(benchmark_bars["close"].iloc[0])
+                - 1
+            ) * 100
+            strategy_total_return = (
+                float(equity_curve[-1][1]) / initial_capital - 1
+            ) * 100
+            result.alpha_vs_spy_pct = Decimal(
+                str(round(strategy_total_return - spy_total_return, 4))
+            )
+    except Exception:
+        logger.exception("benchmark metrics failed")
+
+
 # ------------------------------------------------------------------
 # Internal helpers
 # ------------------------------------------------------------------
 
 
-def _compute_daily_returns(equity_curve: list[tuple[datetime, float]]) -> list[float]:
+def _compute_daily_returns(equity_curve: list[tuple[datetime, Any]]) -> list[float]:
     """Compute simple daily returns from the equity curve."""
     if len(equity_curve) < 2:
         return []
     returns: list[float] = []
     for i in range(1, len(equity_curve)):
-        prev = equity_curve[i - 1][1]
-        curr = equity_curve[i][1]
+        prev = float(equity_curve[i - 1][1])
+        curr = float(equity_curve[i][1])
         if prev != 0:
             returns.append((curr - prev) / prev)
         else:
@@ -198,7 +298,7 @@ def _compute_sortino(daily_returns: list[float]) -> float:
 
 
 def _compute_max_drawdown(
-    equity_curve: list[tuple[datetime, float]],
+    equity_curve: list[tuple[datetime, Any]],
 ) -> tuple[float, float]:
     """Compute max drawdown percentage and duration in days.
 
@@ -210,17 +310,18 @@ def _compute_max_drawdown(
     if len(equity_curve) < 2:
         return 0.0, 0.0
 
-    peak = equity_curve[0][1]
+    peak = float(equity_curve[0][1])
     peak_ts = equity_curve[0][0]
     max_dd = 0.0
     max_dd_duration = 0.0
 
     for ts, equity in equity_curve[1:]:
-        if equity >= peak:
-            peak = equity
+        eq = float(equity)
+        if eq >= peak:
+            peak = eq
             peak_ts = ts
         else:
-            dd = (peak - equity) / peak * 100.0 if peak > 0 else 0.0
+            dd = (peak - eq) / peak * 100.0 if peak > 0 else 0.0
             duration = (ts - peak_ts).days
             if dd > max_dd:
                 max_dd = dd

shared/strategies/kevin.py

@@ -57,8 +57,10 @@ class KevinStrategy:
         is_tradable: bool,
     ) -> KevinDecision:
         symbol = mention.symbol
-        action = mention.action
-        horizon = mention.time_horizon
+        # Normalize the action/horizon to their str value so the strategy works
+        # with both SQLAlchemy enum instances and lightweight stubs (backtest).
+        action_value = getattr(mention.action, "value", mention.action)
+        horizon_value = getattr(mention.time_horizon, "value", mention.time_horizon)
 
         # 1. Common no-trade gates
         if not is_tradable:
@@ -76,15 +78,15 @@ class KevinStrategy:
             )
 
         # 2. Action-specific gates
-        if action in (TickerAction.HOLD, TickerAction.WATCH):
+        if action_value in (TickerAction.HOLD.value, TickerAction.WATCH.value):
             return KevinDecision(
                 decision=KevinDecisionType.NO_OP,
                 symbol=symbol,
-                rationale=f"action={action.value} is UI-only, never trades",
+                rationale=f"action={action_value} is UI-only, never trades",
             )
 
         # 3. SELL — close long if held, else no-op
-        if action == TickerAction.SELL:
+        if action_value == TickerAction.SELL.value:
             if account.is_held(symbol):
                 return KevinDecision(
                     decision=KevinDecisionType.CLOSE_LONG,
@@ -99,7 +101,7 @@ class KevinStrategy:
             )
 
         # 4. AVOID — close long if held + bridge will add blocklist (side effect)
-        if action == TickerAction.AVOID:
+        if action_value == TickerAction.AVOID.value:
             if account.is_held(symbol) and self.config.avoid_closes_longs:
                 return KevinDecision(
                     decision=KevinDecisionType.CLOSE_LONG,
@@ -120,7 +122,7 @@ class KevinStrategy:
             )
 
         # 5. BUY path — full filter stack
-        assert action == TickerAction.BUY
+        assert action_value == TickerAction.BUY.value
 
         if effective_conviction < self.config.min_conviction:
             return KevinDecision(
@@ -132,7 +134,7 @@ class KevinStrategy:
                 ),
             )
 
-        if horizon == TimeHorizon.INTRADAY:
+        if horizon_value == TimeHorizon.INTRADAY.value:
             return KevinDecision(
                 decision=KevinDecisionType.NO_OP,
                 symbol=symbol,
@@ -197,7 +199,7 @@ class KevinStrategy:
         target_dollars = target_dollars.quantize(Decimal("0.01"))
 
         holding_days = self.config.hold_days_by_horizon.get(
-            horizon.value, self.config.hold_days_by_horizon["unspecified"]
+            horizon_value, self.config.hold_days_by_horizon["unspecified"]
         )
 
         return KevinDecision(

tests/backtester/test_kevin_backtest.py

@@ -0,0 +1,187 @@
+"""Tests for the mention-driven Kevin backtest mini-engine."""
+
+from datetime import datetime, timedelta, timezone
+from decimal import Decimal
+
+import pandas as pd
+import pytest
+
+from backtester.kevin_backtest import (
+    KevinBacktestParams,
+    KevinBacktestRunner,
+)
+from backtester.metrics import BacktestResult
+from shared.strategies.kevin import KevinStrategy, KevinStrategyConfig
+
+
+class _StubPriceLoader:
+    """In-memory bars; behaves like the real KevinPriceLoader."""
+
+    def __init__(self, bars_by_symbol: dict[str, pd.DataFrame]):
+        self.bars = bars_by_symbol
+        self.spy = bars_by_symbol.get("SPY")
+
+    async def daily_bars(self, symbol, start, end):
+        return self.bars.get(symbol, pd.DataFrame())
+
+    async def is_tradable(self, symbol):
+        return symbol in self.bars
+
+    async def benchmark_bars(self, start, end):
+        return self.spy if self.spy is not None else pd.DataFrame()
+
+
+def _mention(symbol, action, conviction, horizon, days_ago):
+    return type(
+        "M",
+        (),
+        {
+            "id": days_ago,
+            "symbol": symbol,
+            "action": type("A", (), {"value": action})(),
+            "conviction": Decimal(conviction),
+            "time_horizon": type("H", (), {"value": horizon})(),
+            "created_at": datetime(2026, 5, 15, 14, 0, tzinfo=timezone.utc)
+            + timedelta(days=days_ago),
+        },
+    )
+
+
+def _bars(symbol, start_date, prices):
+    """Build a daily-bar DataFrame indexed by date."""
+    dates = pd.date_range(start_date, periods=len(prices), freq="B", tz="UTC")
+    return pd.DataFrame(
+        {
+            "open": prices,
+            "high": prices,
+            "low": prices,
+            "close": prices,
+        },
+        index=dates,
+    )
+
+
+@pytest.fixture
+def cfg() -> KevinStrategyConfig:
+    return KevinStrategyConfig(
+        min_conviction=Decimal("0.6"),
+        max_mention_age_hours=48 * 365,  # effectively no age filter for backtest
+        base_position_pct=Decimal("0.04"),
+        min_trade_usd=Decimal("500"),
+        max_trade_usd=Decimal("5000"),
+        max_per_ticker_usd=Decimal("7500"),
+        hold_days_by_horizon={
+            "days": 3,
+            "weeks": 5,
+            "months": 10,
+            "long_term": 15,
+            "unspecified": 5,
+        },
+        avoid_closes_longs=True,
+        avoid_blocks_days=7,
+    )
+
+
+async def test_backtest_emits_winning_trade(cfg):
+    # NVDA: enters at $100 day 0, exits at $110 day 5 = +10%
+    bars = {
+        "NVDA": _bars("NVDA", "2026-05-15", [100, 102, 104, 106, 108, 110, 112]),
+        "SPY": _bars("SPY", "2026-05-15", [500, 501, 502, 503, 504, 505, 506]),
+    }
+    strategy = KevinStrategy(cfg)
+    mentions = [_mention("NVDA", "buy", "0.8", "weeks", 0)]
+
+    runner = KevinBacktestRunner(strategy, _StubPriceLoader(bars))
+    result = await runner.run(
+        mentions,
+        KevinBacktestParams(
+            initial_capital=Decimal("100000"),
+            slippage_pct=Decimal("0.0005"),
+        ),
+    )
+
+    assert isinstance(result, BacktestResult)
+    assert result.trade_count == 1
+    assert result.total_return_pct > 0
+    # exit was triggered by holding period (5 trading days)
+
+
+async def test_backtest_filters_low_conviction(cfg):
+    bars = {
+        "NVDA": _bars("NVDA", "2026-05-15", [100, 105, 110, 115, 120, 125]),
+        "SPY": _bars("SPY", "2026-05-15", [500] * 6),
+    }
+    strategy = KevinStrategy(cfg)
+    mentions = [_mention("NVDA", "buy", "0.5", "weeks", 0)]  # below 0.6 floor
+
+    runner = KevinBacktestRunner(strategy, _StubPriceLoader(bars))
+    result = await runner.run(mentions, KevinBacktestParams())
+    assert result.trade_count == 0
+
+
+async def test_backtest_dedupe_roll_extends_exit(cfg):
+    # Two BUYs on same ticker within hold window; exit should extend
+    bars = {
+        "NVDA": _bars("NVDA", "2026-05-15", [100] * 20),
+        "SPY": _bars("SPY", "2026-05-15", [500] * 20),
+    }
+    strategy = KevinStrategy(cfg)
+    mentions = [
+        _mention("NVDA", "buy", "0.7", "weeks", 0),
+        _mention("NVDA", "buy", "0.7", "weeks", 3),
+    ]
+    runner = KevinBacktestRunner(strategy, _StubPriceLoader(bars))
+    result = await runner.run(
+        mentions,
+        KevinBacktestParams(dedupe_policy="roll"),
+    )
+    # Exit at day 3 + 5 = 8, not day 0 + 5 = 5
+    assert result.trade_count == 1
+    closed = result.trades[0]
+    assert closed["holding_days_actual"] >= 5
+
+
+async def test_backtest_sell_mid_position_closes_early(cfg):
+    bars = {
+        "NVDA": _bars("NVDA", "2026-05-15", [100, 105, 110, 95, 90, 85, 80]),
+        "SPY": _bars("SPY", "2026-05-15", [500] * 7),
+    }
+    strategy = KevinStrategy(cfg)
+    mentions = [
+        _mention("NVDA", "buy", "0.8", "weeks", 0),
+        _mention("NVDA", "sell", "0.9", "days", 2),
+    ]
+    runner = KevinBacktestRunner(strategy, _StubPriceLoader(bars))
+    result = await runner.run(mentions, KevinBacktestParams())
+    assert result.trade_count == 1
+    assert result.trades[0]["holding_days_actual"] <= 5
+
+
+async def test_backtest_handles_missing_bars(cfg):
+    bars = {
+        "SPY": _bars("SPY", "2026-05-15", [500] * 5),
+        # NVDA missing
+    }
+    strategy = KevinStrategy(cfg)
+    mentions = [_mention("NVDA", "buy", "0.8", "weeks", 0)]
+    runner = KevinBacktestRunner(strategy, _StubPriceLoader(bars))
+    result = await runner.run(mentions, KevinBacktestParams())
+    # Mention skipped (no price data); no trade
+    assert result.trade_count == 0
+
+
+async def test_backtest_computes_alpha_vs_spy(cfg):
+    # NVDA +10%, SPY flat -> positive alpha
+    bars = {
+        "NVDA": _bars("NVDA", "2026-05-15", [100, 100, 100, 100, 100, 110, 110]),
+        "SPY": _bars("SPY", "2026-05-15", [500] * 7),
+    }
+    strategy = KevinStrategy(cfg)
+    mentions = [_mention("NVDA", "buy", "0.8", "weeks", 0)]
+    runner = KevinBacktestRunner(strategy, _StubPriceLoader(bars))
+    result = await runner.run(
+        mentions,
+        KevinBacktestParams(initial_capital=Decimal("100000")),
+    )
+    assert result.alpha_vs_spy_pct is not None
+    assert result.alpha_vs_spy_pct > 0