Designing a Node/Express OTP State Machine for SMS 2FA Delivery Failures
TL;DR For a simple SMS 2FA login flow, keep a short-lived attempt record in your backend, let a verification service own the OTP secret, and authorize only after a successful code check. Poll your own attempt state for user experience, ingest delivery updates asynchronously, and handle a failed send with a bounded retry or a previously enrolled fallback factor. Delivery status is evidence for…
The brief discusses designing a Node/Express OTP State Machine for SMS 2FA delivery failures. It emphasizes keeping a short-lived attempt record in the backend, letting a verification service own the OTP secret, and authorizing only after a successful code check. The backend should poll its own attempt state for user experience, ingest delivery updates asynchronously, and handle failed sends with retries or fallback factors.
The architecture decision recommends a managed verification workflow plus a local attempt state machine, with the verification component generating and checking the code while the application owns the user session, abuse controls, attempt lifecycle, fallback policy, and audit trail. The brief provides guidelines on invariant states and the importance of distinguishing between delivery status and proof of identity.
Brief written by urgent.news from Dev.to's own syndicated text. Machine-written — may contain errors; check the original before relying on it.
