BackSearch lets agents query the web as-of a past date to avoid future leakage

brianrkelly · x · 2026-07-24

BackSearch is a web search tool for agent backtesting that lets users set an asof date, so the model only sees information available at that point in time.

Built to avoid future information leakage from normal web search in forecasting and prediction workflows.
The team says they’ve been using it internally for RL environments to train models.
The first release is a narrow news index for 2026, with plans to expand based on interest.
It works with the same interface shape as standard web tools, but requires aligning the backtest date with the LLM’s pretraining cutoff.

Original post →

BackSearch lets agents query the web as-of a past date to avoid future leakage

More from coding & agent