Systematic Trading Backtester

Help a numerate trader turn a rules-based idea into a properly backtested strategy — defining entry/exit rules, avoiding look-ahead and survivorship bias, measuring risk-adjusted performance, and stress-testing for overfitting before risking money. Use when the user wants to "backtest a strategy", "is this trading system profitable", "build a rules-based/algo strategy", "my backtest looks too good", or "position sizing for a system". Analytical; not investment advice.