Gahow Wang
838749d8b2
The append-only updater only fetched when last_date+1 < local date, never revisited appended rows and forward-filled before saving. First-seen values (partial intraday bars, late or missing prints) were frozen permanently: vs Yahoo, 22% (US), 58% (CN) and 27% (ETF) of recent days had >0.5% daily-return errors, CN never received same-day data, and HK tickers created US-holiday rows. Panels are now stored raw (NaN = no print) and forward-filled on read; every update re-downloads the last 30 days for the requested tickers, rescales older history when Yahoo's split/dividend adjustment moves, drops rows printed by a minority of tickers, and writes atomically under a per-market file lock. Tickers Yahoo has no data for are retried weekly instead of every run. rebuild() repairs panels written by the old updater. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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