https://blog.abhipraya.dev/tags/design-patterns/Recent content in Design-Patterns on Daffa AbhiprayaHugoen-us© Daffa AbhiprayaThu, 09 Apr 2026 00:00:00 +0700https://blog.abhipraya.dev/ppl/part-a/solid/Thu, 09 Apr 2026 00:00:00 +0700https://blog.abhipraya.dev/ppl/part-a/solid/<p>SIRA (Smart Invoice Reminder AI) is a system that automates invoice collection reminders. It monitors payment status, scores client risk using a weighted formula, and sends personalized reminders by email or messaging. The backend is built with FastAPI, Supabase (Postgres via REST), Celery for background jobs, and Redis as the message broker.</p> <p>This blog walks through how SOLID principles shaped the architecture at three levels: the overall layer structure, service-level design patterns, and individual function design. The goal is not to explain what SOLID stands for (there are plenty of articles for that), but to show what it looks like in production code and why certain design choices were made over simpler alternatives.</p>