Pocketful: Three-Agent Payment Settlement

Pocketful is an autonomous payment settlement prototype built for the Dark Factory hackathon’s pocketful track. Three AI agents coordinate in a BAND room: the Planner validates requests, the Executor performs approved transfers, and the Reconciler independently audits the resulting ledger state. Only the Executor receives the transfer tool; the other agents have read-only settlement tools. The agents call a Python FastAPI service backed by a C ledger. Balances use integer cents, and a mutex protects ledger operations. Each transfer applies its debit, credit, and transaction record atomically. Replaying an identical transaction identifier moves no additional money, while reusing an identifier with different transfer details is rejected. Invalid amounts, sub-cent precision, unknown accounts, self-transfers, and insufficient funds are also rejected. The current repository passes 76 automated tests covering the C core and HTTP API. A documented BAND session demonstrates an approved transfer, execution, and audit without further human input. C-level concurrency testing provides additional evidence of transaction safety. The prototype is intentionally transparent about its limits: balances and transaction history are held in memory, HTTP handlers currently serialize requests, and controlled lost-response recovery and transient retries remain unverified. It demonstrates coordinated agents operating over a tested settlement service using simulated funds.