A LONG-SHORT, SINGLE-INSTRUMENT, SINGLE-VENUE RANGE mean-reversion strategy on BNBUSDT.BINANCE USD-M perpetual. This is a deliberately different STRATEGY TYPE from my in-flight ideas (all of which are momentum/continuation or extreme-fade reversals) and it uses OPEN INTEREST in a genuinely new ROLE: not as a directional-momentum confirm (OI expansion), but as a RANGING-REGIME CLASSIFIER via OI FLATNESS. Rationale for the regime gate: naive band mean-reversion (Bollinger/Keltner fade) fails in crypto because it gets run over in trends — but trends in perps are built by fresh leverage ENTERING (rising OI), whereas balanced, mean-reverting ranges occur when open interest is FLAT (no net new leverage, participants two-sided and rotating). So the strategy only fades the range when OI is flat (the market is genuinely balanced and reverts), and stands completely aside when OI is expanding (leverage is building a directional move — do NOT fade it). The OI-flatness gate is orthogonal to price and is the element that makes this not a dead pure-OHLCV mean-reversion (satisfies L42) — it is a regime filter, not another price indicator. Reliability note: this stays on BINANCE USD-M where OI is well-populated in the sandbox (unlike COIN-M, whose OI feed loops in verification), uses core OHLCV + the USD-M OI series only, and is kept to THREE real parameters after a prior strategy died at Layer-2 from parameter bloat. Single-venue, single-instrument — no cross-venue leg problem (L44), no options feed (L43), no taker/premium feeds (which have shown Layer-2 fragility). BNBUSDT chosen as a liquid major perp that spends long stretches range-bound (frequent fade setups) with wide-enough bands that reversion targets clear the 0.10% USD-M round trip, and it is a fresh instrument vs BTC/ETH/SOL/DOGE/AVAX/LINK already in flight. ENTRY (4h bars + same-venue OI): compute a `band_len`-period moving average and ±`band_k`×stdev bands, and oi_change = OI_now/OI[`band_len`]-1; require |oi_change| < a flatness threshold (derived from band_len, not a 4th free param — e.g. within ±3%) to classify a RANGING regime; then ENTER LONG on a close at/below the lower band, ENTER SHORT on a close at/above the upper band; skip all signals when OI is expanding (trend regime) or when OI is stale/missing. Risk 2% equity/trade, ATR(14) hard stop beyond the band extreme, max exposure 25%, leverage 2x. EXIT on first of: price reverts to the mid-band (primary target); opposite band reached (stop-and-reverse candidate); ATR stop beyond the entry band (range broke — likely a regime change to trend); 18-bar (~3 day) time stop. Instruments: ["BNBUSDT.BINANCE"]. venue_type: futures. data_requirements: ["ohlcv", "open_interest"].