typescript-modelinglisted

# TypeScript modeling Use the type system to express relationships that matter at runtime. ## Shapes Choose `type` or `interface` for local semantics and ecosystem fit, not dogma. Use discriminated unions for variants and exhaustive switches where missing cases would be a bug. ## Contracts Annotate exported APIs and external boundaries. Let inference handle obvious locals. Use `satisfies` when a value should be checked against a contract without widening away useful literal information. ## Mutability and generics Mark data `readonly` when mutation is not part of the contract. Use generics only when they express a real relationship between inputs and outputs; avoid type puzzles that make maintenance harder.