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polymarket-bot/bot/metrics/sharpe.py
chemavxandClaude Fable 5 43d9577fb2
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feat(metrics): real Sharpe ratio from daily PnL curve with minimum-sample gate
sharpe_ratio was hardcoded to 0.0 in MetricsTracker and exposed as
'or 0' in /api/summary. With only 1 resolved trade (~40 flat days plus
one +299 jump) any computed Sharpe is statistically meaningless, so:

- bot/metrics/sharpe.py: annualized Sharpe (sqrt(365)) from daily
  total_pnl closes, normalized by bankroll; sharpe_with_gate() returns
  None + status until >=30 days observed AND >=10 resolved trades.
- Database.get_daily_pnl_closes(): last metrics_daily snapshot per UTC
  day, oldest first — the return series input.
- MetricsTracker: stores the real (gated) Sharpe in the snapshot, NULL
  below the gate; log line now includes sharpe.
- /api/summary: live Sharpe + sharpe_status/days_observed/min_* fields
  explaining why it is null; resolved_count now live from COUNT(*).
- promotion_ready: requires resolved>=10, days>=30, and non-null
  win_rate/calibration/sharpe plus existing thresholds — a single lucky
  resolved trade can no longer promote.
- Dashboard Sharpe card shows the insufficient-sample explanation when
  null instead of a bare em dash.

Tests: 13 new in tests/test_sharpe_gate.py (formula, gate, API contract,
tracker snapshot); verified failing pre-fix. Suite: 62 passed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-06-12 07:12:55 +00:00

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"""
Sharpe ratio from the paper portfolio's daily PnL curve, with a minimum-sample gate.
The input series is the closing total_pnl of each observed UTC day
(Database.get_daily_pnl_closes). Daily returns are PnL deltas normalized by
the paper bankroll:
r_t = (pnl_t pnl_{t1}) / bankroll
Sharpe = mean(r) / sample_std(r) × √365, annualized — prediction markets
resolve every calendar day, so 365 is used instead of 252 trading days.
Risk-free rate is taken as 0.
Gate: with a tiny sample (e.g. 1 resolved trade over a flat curve plus one
+299 jump) any Sharpe value is statistically meaningless — artificially huge
or tiny depending on where the jump lands. So no numeric Sharpe is exposed
until BOTH minimums are met:
days observed >= MIN_DAYS_OBSERVED (30)
resolved trades >= MIN_RESOLVED_TRADES (10)
Below either minimum the value is None with status "insufficient_sample".
A perfectly flat curve (zero variance) also yields None ("zero_variance"):
Sharpe is undefined there, not infinite.
"""
from statistics import mean, stdev
from typing import Optional
MIN_DAYS_OBSERVED = 30
MIN_RESOLVED_TRADES = 10
ANNUALIZATION_DAYS = 365
SHARPE_OK = "ok"
SHARPE_INSUFFICIENT = "insufficient_sample"
SHARPE_ZERO_VARIANCE = "zero_variance"
def daily_returns(daily_pnl_closes: list[float], bankroll: float) -> list[float]:
"""Bankroll-normalized day-over-day returns from a daily PnL-close series."""
return [
(curr - prev) / bankroll
for prev, curr in zip(daily_pnl_closes, daily_pnl_closes[1:])
]
def compute_sharpe(daily_pnl_closes: list[float], bankroll: float) -> Optional[float]:
"""Annualized Sharpe of the daily PnL curve, or None if undefined.
None when there are fewer than 2 returns (need 3+ daily closes) or the
return series has zero variance. No sample-size gate here — see
sharpe_with_gate() for the exposed value.
"""
returns = daily_returns(daily_pnl_closes, bankroll)
if len(returns) < 2:
return None
sd = stdev(returns)
if sd == 0:
return None
return mean(returns) / sd * ANNUALIZATION_DAYS ** 0.5
def sharpe_with_gate(
daily_pnl_closes: list[float],
bankroll: float,
resolved_count: int,
) -> tuple[Optional[float], str]:
"""Return (sharpe, status) applying the minimum-sample gate.
status: "ok" — sharpe is a meaningful float
"insufficient_sample" — sample below minimums, sharpe is None
"zero_variance" — sample OK but flat curve, sharpe is None
"""
days_observed = len(daily_pnl_closes)
if days_observed < MIN_DAYS_OBSERVED or resolved_count < MIN_RESOLVED_TRADES:
return None, SHARPE_INSUFFICIENT
sharpe = compute_sharpe(daily_pnl_closes, bankroll)
if sharpe is None:
return None, SHARPE_ZERO_VARIANCE
return sharpe, SHARPE_OK