Event-Time Accounting for Two-Leg Perpetual Positions: Quantity Closure, Asynchronous Settlement and Evidence Levels

Two-leg perpetual positions are often evaluated by matching quote-currency notionals and extrapolating a displayed funding-rate spread. That practice can leave residual quantity, omit eligible funding events, double-count execution costs, and turn unavailable evidence into zero. This methods note develops an event-time ledger for linear, same-settlement-currency perpetual pairs. It combines common-base-quantity closure, four depth-walked fills, per-event funding eligibility, a closed-position identity, a basis-minus-crossing decomposition, scenario-consistent error attribution, and explicit evidence labels. Deterministic examples show that symmetric enumeration produces 7.20 USDT rather than 0.20 USDT in an eight-hour toy window and that a direction-fixed “oracle” need not be an upper bound. A bounded illustration using three routes and two mutually exclusive arms on one day yields net-before-funding paper results from −24.93 to −89.91 USDT. These are not independent trades or portfolio returns. Official settlement marks, account fee evidence, and real orders are absent; exact account net remains unavailable. The framework separates accounting validity from statistical or economic validation.