Most open banking tutorials stop at "make a GET request." In production, you need consent flows, token refresh, pagination across thousands of transactions, deduplication, and rate-limit handling. This guide walks through the full sync pipeline — what actually breaks at 3am when your cron job fires.

The sync lifecycle

A real bank-data sync has four phases:

Onboard: User consents to read-only access → you get a consent token

Initial fetch: Pull all historical transactions (can be thousands)