Audit state that is indexed by time — epochs, checkpoints, historical balance snapshots, delegation records, vesting periods and reward accrual windows. Checks whether a checkpoint appends or overwrites, whether a historical query returns the value that actually held at that block, whether bounded history can lock a user out permanently, which side of a boundary an action lands on, what a discretized reward pays someone who straddles it, and whether two independently-settable windows must satisfy a relation nobody enforces. Use when auditing staking rewards, voting power, delegation, vesting, epoch-based accounting, or any getPastVotes / balanceOfAt / snapshot mechanism.
