ADX — Average Directional Index

What it measures: Trend strength (doesn't indicate direction)

When to use it: Regime filter: ADX > 25 = trending market (good for trend-follow), ADX < 20 = sideways (good for mean-reversion, or stop trading)

Typical period: 14

Caution: Heavy lag (double-layer RMA) — use as a filter, not a trigger

Formula the engine actually uses

+DM/−DM → Wilder RMA → +DI/−DI → DX = 100×|+DI−−DI|/(+DI+−DI) → ADX = RMA(DX, period)

smoothing: Double-layer Wilder RMA (DI, then DX) · warmup: ~2×period or more