Read references/patterns.md before making a recommendation or reviewing an implementation.
Workflow
- Identify what varies: one product, a product family, assembly steps, initial state, or lifetime.
- Establish whether a constructor, function, or dependency injection already solves the problem.
- Choose the narrowest matching pattern and name a credible alternative.
- Keep selection and construction at the composition boundary when possible.
- Preserve product invariants and make ownership or lifetime explicit.
- Test the promised variation: add a fake product, switch a family, build a variant, clone safely, or prove instance cardinality under concurrency.
Use the language's natural construction tools. A pattern's collaboration matters more than class names or inheritance.