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DISPATCH LOG: WB 09
FEATURED SPECIFICATION · 01/04
SYSTEM INTERFACE GALLERY [4 SCREENS]
What needed to be engineered
Clinic billing systems need high-reliability invoice generation and async queuing without stalling HTTP request threads or producing inconsistent financial records.
Boundaries & non-negotiables
- [01]PostgreSQL ACID transaction isolation on multi-item dental invoices.
- [02]Decoupled domain repositories with composition root for test isolation.
- [03]Offloaded headless PDF generation to BullMQ/Redis worker pipelines.
System flow & boundary isolation
Modular REST API in TypeScript and Express with Clean Architecture, transactional invoice accounting on PostgreSQL, and async BullMQ/Redis email workers.
Why this choice over alternatives
Decoupled Domain Repositories
Isolated business billing rules from database drivers via dependency injection interfaces.
Async Worker Queueing
Offloaded headless Puppeteer invoice rendering to async BullMQ background jobs to protect HTTP response latency.
05 — RETROSPECTIVE & WHAT I GOT WRONG
Initial Puppeteer rendering ran on the main request cycle before moving to worker queues.
Verified delivery & outcomes
Delivered robust production backend with dynamic PDF invoicing, JWT TOTP/2FA security, and OpenAPI documentation.