Midpoint ranking + bid floor. Default. Ranks candidates by midpoint, but rejects anything whose bid-based rent fails the hard floor.

Bid only. Most conservative. Scores rent only from executable bid.

Midpoint only. Clean ranking signal, but less execution-safe than the default.

Delta first + gates. Default. Picks closest target delta after DTE, rent, buffer, and liquidity gates.

Rent first + delta guard. Maximizes rent among candidates that remain inside delta guardrails.

Buffer first + rent floor. Prioritizes distance from short strike while requiring acceptable rent.

Underlying option IV. Uses Alpaca option-chain IV for live Kairos structure setup. Massive API historical data belongs to the separate ML/backtesting path.