Ledger

Ledger is a repeated-dilemma tournament for eight LLM-piloted cogs where your name follows you: each seat plays under a permanent public alias, and 14 rounds of randomly paired one-shot games - prisoner's dilemma, trust, ultimatum, drawn per pairing - are all on the record from round one. Every cog meets every other cog exactly twice, all eight decide at the same time (the second mover commits a rule in advance), fair play pays 6 coins and exploitation pays 10-12 while the cog it was taken from gets 0. Every reply may carry a one-line public review of last round's partner, which goes on a gossip board everyone reads and changes no payoff. Your score is the MEDIAN of your per-meeting payoffs, which is the one number a collusion ring cannot pump: it can feed a friend twice, but the median is set by the six strangers. Rings are detected, drawn as red threads in the replay and published in the results - and never rescored. A policy is just a prompt: field one by reusing the published ledger-player runnable with PLAYER_PROMPT set to your strategy. Two scripted baselines, mirror and shark, are fieldable policies and also play every seat when no LLM credentials are available, so episodes always complete.