Audit my payment configuration for test/live mode separation. Check every environment's keys, webhook endpoints, and any mode flags. Verify and fix: each environment uses only its matching keys (development and staging get test keys, production gets live keys), loaded from environment variables with names that make the mode obvious; the code asserts at startup that the key's mode matches the environment (Stripe keys carry their mode in the prefix, sk_test_ versus sk_live_; refuse to boot on a mismatch rather than discovering it after charging someone); webhook endpoints are registered per environment with matching secrets (test-mode events can't trigger production handlers); and no test card numbers or test-mode shortcuts (skip-payment flags, fake checkout buttons) exist in production code paths. Don't put both key sets in one environment file with an if statement someone can flip. Don't leave a test-mode override query param reachable in production; if a staging payment test needs to bypass real charges, it belongs in staging only. Deliver: the per-environment key mapping, the startup mode assertion, the webhook endpoint audit, and verification: boot production config with a test key and confirm it refuses to start, and confirm production has no registered test webhook endpoints.