A practical look at where event-driven architecture actually helps in banking-decoupling systems, scaling services, and improving auditability-while spelling out.
MechaPrime 
EDA fits best around notifications, ledger-adjacent workflows, and downstream projections, but I would still keep the core posting path transactional because the tradeoff is auditability versus reconciliation pain when events arrive late or twice.
WaffleFries 
I’d add account state changes with external side effects to the “keep it transactional” list, because a retried debit event that also triggers a card freeze or customer alert can leave you technically reconciled but operationally wrong.
Sarah
