engineering-principleslisted

# Engineering principles Use these principles as judgment, not ceremony. ## Shape Prefer simple designs with explicit responsibilities. Keep related decisions close together, and separate code only when the boundary is real: different reasons to change, different lifetimes, or different owners. Favor composition when it keeps behavior visible. Inheritance, frameworks, service containers, and factories earn their place only when they remove concrete complexity. ## Coupling Minimize what modules need to know about each other. Pass the smallest data a collaborator needs, return predictable results, and avoid leaking storage, transport, UI, or provider details through domain APIs. ## Correctness Make invalid states difficult to represent. Use schemas, discriminants, required fields, and exhaustive checks where they clarify the model. Fail explicitly when input is invalid instead of silently repairing it. ## Maintainability Optimize for the next person reading the code. A small amount of duplication can be cheaper than an abstraction that hides the important difference.