Notes
Working notes on the systems we build.
Running Our Own AI Gateway Instead of Handing Everyone a Provider Key
A self-hosted AI gateway gives us centralized control over access, budgets, routing, and cost attribution without distributing provider credentials.
Deriving a Loyalty Wallet Balance with a Database Trigger
We keep the ledger as the source of truth and use a database trigger to derive the current loyalty wallet balance safely under concurrency.
Backdating an Order Without Letting It Borrow Today’s Promotion
A backdated order should use promotion rules that were valid on its effective date, while preserving a clear audit trail for accounting correctness.
Why the Server Decides the Price of Every Order
Clients may display prices, but the server must calculate and authorize the final order total.
Why We Took the Offline Sync Layer Out of a Point-of-Sale App
We removed offline synchronization from a Flutter point-of-sale app because its conflict handling and operational risk outweighed the value it provided.
Running Speech Recognition on the Phone Instead of a Server: What It Costs Us
On-device ASR can improve privacy and enable offline transcription, but it shifts costs into the app, the device, and our engineering workflow.