Payrein

Payrein lets an AI agent buy things from a NEAR Intents balance that a small Rust contract holds, not the agent. The agent has one function-call key that can only ask the vault to pay. The vault pays only allowlisted merchants, in one token, within a per-payment and a daily limit, and anything above an approval threshold waits until the owner approves that exact payment in their wallet. A hijacked prompt, a replaced agent binary or a leaked key changes none of that, because the checks run in the contract that moves the funds.

What is in the repository: the contract (near-sdk), 27 unit tests, 25 sandbox attack tests that run against the pinned intents.near binary that is live on mainnet (injected instructions, leaked key, tampered approval, replayed and expired payments, eight concurrent requests, stuck callbacks), a mutation check in which five targeted mutations are each caught by their covering test, a demo merchant that delivers only after verifying the payment on chain, an agent runner with a scripted or a NEAR AI Cloud model, an owner app that shows the exact call the wallet will sign, a one-command local demo, and a testnet bootstrap. The demo video shows the seven demo steps on the local devnet. Landing page: https://payrein.vercel.app. The README's threat model says what the contract does not protect: the owner key and Intents are trusted, a swapped but genuinely awaiting payment is caught only by reading the wallet, and the contract is unaudited. Work started on 21 October 2026, after the 19 October announcement; the git history is dated.