Yfinance Market Data

WHENWhen implementing HTTP session initialization for Yahoo API

ACTIONUse curl_cffi.requests.Session with impersonate='chrome'

CONSEQUENCEYahoo's non-browser client blocking detects and rejects requests from standard HTTP libraries, resulting in 403 Forbidden errors and complete data access failure

WHENWhen handling HTTP request errors for Yahoo API

ACTIONRetry only transient errors (TimeoutError, socket.error, OSError, ConnectionError) and raise for permanent errors

CONSEQUENCERetrying permanent errors like ValueError or KeyError wastes resources and masks underlying code bugs instead of surfacing them for proper debugging

WHENWhen making HTTP requests to Yahoo API endpoints

ACTIONInclude crumb and cookie authentication with every request

CONSEQUENCEWithout proper crumb authentication, Yahoo API returns 401 Unauthorized or HTML error pages instead of JSON data, breaking all downstream data processing