Concepts

These pages explain the core mechanics that make replaybt different from other backtesting frameworks.

Page	What you'll learn
Execution Loop	The 4-phase bar processing pipeline
Signal Timing	Why signals at T fill at T+1, and how pending orders work
Gap Protection	How open gaps affect stop and target fills
Multi-Timeframe	Computing indicators on higher timeframes from 1m data

The Core Principle

In real trading:

1. A bar closes
2. You see the close price
3. You compute indicators
4. You place an order
5. The order fills at the next bar's open

Most backtesting frameworks skip step 5 and fill at the close of the signal bar. This creates look-ahead bias — you're buying at a price you couldn't have bought at in production.

replaybt enforces realistic execution by design. The engine manages the order lifecycle; your strategy only emits signals.