Start with a template. Work through each step. Ask Coach when you need a second opinion.
Company tags are community-reported. Counts on cards show how many people reported that design.
Any request can time out after the server has already acted. The client cannot tell that from a request that never arrived, and the only safe response to uncertainty is to retry — which, without help, charges the card twice.
Charge cards through the networks exactly once: idempotency keys, a card vault, timeouts as unknowns, signed webhooks, a double-entry ledger and reconciliation. One-hour boards for junior, senior and staff, with the theory behind them.
An order checkout across payment, inventory and shipping, run as a saga.
Ten charities, three days, $100 M: charge through a third-party processor exactly once, queue the broadcast spikes, keep live totals on sharded counters. One-hour boards for junior, senior and staff, with the theory behind them.