AI agents now issue refunds and move money, but top models get irreversible actions right only about 56% of the time. Worlds lets you test your agent locally in exact replicas of Stripe, Zendesk, and Salesforce. Describe a scenario in plain English, inject failures like an expired API key, and fast-forward time to catch delayed mistakes. Every run is graded on real state, is deterministic, and fits your CI/CD: one command, no SDK, free today. Feel free to find us here: usesparta.co