A LONG-ONLY, single-instrument SPOT trend-regime timing strategy on ETHUSDT.BINANCE_SPOT (daily bars). Rule: hold a full ETH position only when the daily close is above its 200-day SMA AND 20-day momentum (close vs close 20 bars ago) is positive; hold 100% cash otherwise. This is a re-attempt of a previously abandoned hypothesis whose abandon was an ENGINE BUG (corrupted close-date daily-return Sharpe, fixed 2026-07-24 commit 59c8a73 — Sharpe/vol now from per-bar MTM equity), not a strategy verdict; QA credited the code. It is the ETH sibling of the in-pipeline BtcSpot200SmaLongFlatRegimeTiming cell, differentiated by asset and by the momentum-confirmation second leg. It is deliberately and materially different from the long-SHORT 200-MA perp and long-short Donchian siblings that died this session to overfit/PBO/single-regime: (1) it is LONG/FLAT, not long/short — a false bear signal forgoes upside (sit in cash), never a symmetric short loss into a whipsaw, the exact mechanism that inflated the siblings' PBO and OOS instability; (2) it is UNLEVERED SPOT — no margin, no second instrument, no funding, so it cannot risk-reject on implausible returns or throw non-diagnostic high-vol artifacts; (3) it is 2 PARAMETERS (200-day SMA window, 20-day momentum lookback), overfit-resistant, in the best-odds low_parameter / no_supplementary_data families; (4) pure daily OHLCV on a deep-history instrument — cannot data-wall like the liquidation/options siblings. ETH-specific rationale: ETH's downside tail is fatter than BTC's (~-94% 2018, ~-80% 2022 vs BTC ~-84%/-77%), and those collapses unfolded almost entirely below the 200-day SMA, so the regime filter removes a LARGER share of realized variance on ETH — bigger Sharpe/drawdown improvement per unit of foregone upside. Value proposition is NOT raw return but higher Sharpe and lower max-drawdown than ETH buy-and-hold. Sizing = full available equity at spot (leverage 1.0); the SMA/momentum exit is the sole risk control; max exposure 100% of equity by design (single unlevered spot asset).