Red Ledger Rangefinding Monocle

Red Ledger Rangefinding Monocle is a sealed optical monocle that measures distance, relative motion, and angle while leaving one eye free for ladders, hand signals, and incoming trouble. It must be zeroed to the wearer and helmet; loaners produce small errors that become large ones across a docking span. Every sighted object enters a rolling cache, so the monocle can quietly become a record of who stood where when negotiations failed. Every significant action receives a signed timestamp that cannot be casually erased. Auditors adore the chain of custody, smugglers do not, and owners eventually learn that "delete" means "hide pending subpoena."