Stock Pattern Screener

WHENWhen writing DataRequirements.merge() implementation

ACTIONUnion each boolean flags and select the longest price_period

CONSEQUENCEIncorrect merge logic causes missing data for some screeners. The union of needs (OR operation for booleans) ensures every screener receives data it requires, while the longest period accommodates all indicator lookbacks.

WHENWhen implementing data fetching with yfinance

ACTIONEnforce yfinance rate limit of 1 request per second

CONSEQUENCEExceeding the yfinance rate limit causes API errors and data fetch failures. The self-imposed 1 req/sec limit (settings.yfinance_rate_limit) prevents triggering provider-side throttling that could affect all users.

WHENWhen validating screener result scores

ACTIONenforce score values are in the 0-100 range via post-init validation

CONSEQUENCEScores outside 0-100 would cause incorrect composite calculations and corrupt rating thresholds, producing invalid stock recommendations