BTC COIN-M Inverse Perp Regime-Gated Mean-Reversion, Long-Short (Single-Leg BTCUSD_PERP.BINANCE_CM, 4H Bars, Fade Z-Score Extremes ONLY in Low-Trend/Ranging Regimes — Exploits COIN-M's 0.06% RT Fee, the Lowest-Cost Futures Venue, to Make a Moderate MR Edge Fee-Viable Where USD-M Cannot, 2-Parameter)

A LONG-SHORT, SINGLE-LEG mean-reversion on the BTC coin-margined inverse perpetual (BTCUSD_PERP.BINANCE_CM, 4H bars). Its thesis is EXECUTION-COST, not a new signal: identical z-score mean-reversion is fee-marginal on BINANCE USD-M (0.10% RT → needs >0.15%/trade) but comfortably viable on COIN-M (0.06% RT → needs only >0.10%/trade). COIN-M is the factory's most under-represented venue that still has clean single-name data (3.1% vs 5% target), and L20 explicitly permits SINGLE-LEG CM on BTC OHLCV (the data_unavailable deaths were MULTI-asset CM funding baskets on thin alts — this is the flagship BTCUSD_PERP contract with multi-year daily/4H history on Binance Vision, which the on-demand collector pulls for BINANCE_CM). It deliberately avoids every graveyard: NOT funding-signal (L13), NOT a rank-rotate basket (L12), NOT liquidation-feed (L3), NOT options (L23), NOT Hyperliquid (L11), NOT cross-venue carry (L1), and NOT the 15m intraday-reversion timeout class (the sibling CM 15m death was sub-hourly bars — this uses 4H, coarser and reliably catalogued). The distinguishing filter vs the fee_edge MR graveyard: mean-reversion fires ONLY in low-trend/ranging regimes (where MR actually has positive expectancy) and stands aside in trends (where MR gets run over) — exactly the confounder that killed the naive single-bar-overreaction and pivot-reversion attempts. Only 2 optimizable parameters (entry_z, regime_threshold) to keep optimizer best-of-N inflation below the true edge. Fills the COIN-M venue gap AND adds long-short/market-facing diversity to an 85%-long-only book.