How I Design Systems
Architecture follows constraints, not trends. I pick patterns based on the problem domain, not what's popular on Hacker News.
Battle Engine (Professor Basil's Lab)
Pokemon battle damage requires deterministic output. Same inputs, same damage range, every time. useReducer gives me pure state transitions that are replay-capable and testable without mocking. A global store would add indirection for zero benefit. The damage formula is a pure function with modifiers composed as a multiplier chain, where each mechanic (STAB, weather, crits, Tera, Mega, Dynamax) is a state transformation in the reducer.
Case Management (Accenture)
Government case routing requires SLA enforcement, multi-agency handoffs, and audit trails. The state machine pattern maps directly: each case state has defined transitions, guards (eligibility rules), and side effects (escalations, notifications). Multi-agency means the form engine is configuration-driven. Visibility rules are data, not code. Adding a new agency's form configuration is a config change, not a deployment.
REST Integration Layer
Connect-REST with scoped data pages. Request mapping and error handling as a dedicated layer consumed by frontend components, not scattered across the UI. Each data page isolates its own fetch failures, so one integration going down doesn't cascade into the entire UI breaking.