config.json.example: data_providers.active = "oanda" (credentials stay
in env/.env or the top-level oanda block; TD and Tiingo remain
registered fallbacks). Backtest parquet cache is now keyed per provider
— Oanda and TD bars diverge (2026-07-24 study), so a feed switch must
never serve another feed's cached bars; twelve_data keeps the legacy
un-prefixed filename so pinned-book caches stay valid. 254 tests green;
live smoke-tested against the practice API (66 contract checks: all
scanned TFs, boundary/freshness guarantees, real spread $0.71,
fetch_range pagination, typed error paths, CLI + backtest end-to-end).
Claude-Session: https://claude.ai/code/session_01Mc7XKYyPySVXiUpcN82QEK
Harwinder Sekhon
637c39e201