A classical cash-and-carry basis arbitrage on Binance COIN-M inverse quarterly futures, hedged by long BTCUSDT spot. The mechanism: BINANCE_CM lists dated quarterly BTC futures (BTCUSD_YYMMDD) that MUST converge to spot price at expiry by contract design. When the annualized basis between the spot price and the next-quarterly future price exceeds 6% (a documented threshold above which the trade is profitable net of fees), simultaneously go LONG BTC on BINANCE_SPOT and SHORT the next-expiry BTCUSD quarterly on BINANCE_CM at matching notional. Hold to expiry (or until basis converges below 2% annualized for early profit-take). At expiry, the futures contract settles in BTC, automatically delivering against the spot leg. This fills FOUR critical under-represented buckets simultaneously: COIN-M venue (0% → first-ever slot toward 5% target), cross-venue (2.2% → toward 15%), long-short direction (14.2% → toward 45%), and long-horizon market-neutral (only 0.2% macro_1w_plus). Mechanism is COMPLETELY orthogonal to every failure this session — does NOT depend on BTC price patterns, does NOT depend on a regime, does NOT depend on parameter optimization. Quarterly basis convergence is mathematically forced by the contract's settlement formula. Position sizing: 30% of equity in spot leg + 30% notional short futures (BTC-margined position on COIN-M sized to deliver against spot at expiry). Risk per trade: 1.5% of equity capped by basis-divergence stop. Expected setups: 3-6 per year (basis crosses 6% during persistent bull-momentum phases or post-funding-spike periods).