lookahead-free

What it is

A zero-dependency Python checker for whether a declared data pipeline reads only information that was already knowable at each decision. Reads, windows, point-in-time cutoffs, and decisions are described as a temporally annotated graph, and the check gives an exact verdict on the value-independent fragment, including windowing, resampling, joins, and vintage reads. Researchers assembling A-share price, filing, and corporate-action pipelines can run it before they treat a backtest as evidence. Steps whose timing depends on the data values are only flagged at a heuristic boundary, and declaring the graph does not replace a manual check of the vendor files or of whether a person revised a claim after seeing results.