TOEIC Speaking practice and AI feedback app
A TOEIC Speaking app that assesses mock-test answers and provides learning feedback. I redesigned the existing architecture, integrated in-app payments and resolved refund and duplicate-transaction issues.
Screens
Restructuring an existing app
I redesigned the Flutter architecture and connected payments and push notifications. The work reorganized service flows around the learning features already in use.
Purchases and duplicate transactions
Store transactions are checked against requests being processed and saved orders. New transactions update access after order completion; repeated transactions do not create another order.
A separate refund flow
Store refund notifications are handled separately from purchases. Access expires only when the refund matches the original order. I checked purchase, duplicate-request and refund paths while correcting the existing payment issues.
Architecture
