A LONG-SHORT, single-instrument directional strategy whose LOAD-BEARING signal is a REGIME classifier — the Kaufman Efficiency Ratio (ER = |net price change over M bars| / sum of absolute bar-to-bar moves over the same M bars) — not a moving-average crossover. The premise directly attacks the #1 reason directional strategies die in this factory: pure momentum/breakout bleeds because it fires in CHOPPY, mean-reverting regimes where whipsaw + fees dominate. ER measures exactly that — it is ~1.0 when price travels in a straight (efficient, trending) line and ~0 when it oscillates (inefficient, choppy). We take a directional position in the direction of a channel breakout ONLY when ER ≥ threshold (the market is demonstrably trending), and we STAND FLAT whenever ER is low — precisely the periods where the factory's dead momentum/breakout strategies lost money. This is deliberately DISTINCT from: the promoted BTC dual-timeframe MA momentum-confluence (different confirmation mechanism — a regime scalar, not a second timeframe of the SAME momentum), the dead cross-sectional/relative-strength MOMENTUM baskets (single-instrument directional, not a beta-neutral rank), the dead OI-trend (no supplementary data), and the dead pure Donchian breakout (which had NO regime gate and fired in chop). SOL is chosen as a liquid, high-trend-persistence major with multi-year 4H history (a NEW mechanism on a fresh symbol, not a symbol-swap of a dead mechanism per L62). 3 parameters: ER lookback M, ER threshold, ATR-trailing multiple.