principle-boundary-discipline

What problem does it solve? Scattered validation and redundant defensive checks make code noisy, hard to test, and give a false sense of safety. This Skill guides you to place validation, type narrowing, and error handling only at system boundaries (CLI, config, network, external APIs) so internal code can trust its types and business logic stays in pure, framework-free functions. ## Core Features & Use Cases - Boundary Validation: Validate config at parse time, parse raw data into domain types at the edge, and handle external API errors defensively. - Pure Business Logic: Keep parsing, prompt construction, scoring, and assessment as pure transforms with no framework dependencies, so they can be tested without the framework. - Clean Public Surface: Avoid re-exporting transport, storage, or wire types through the public API; expose domain concepts instead. - Use Case: When wiring a CLI tool or framework adapter, apply this Skill to decide where each validation check belongs and extract testable pure functions from the shell. ## Quick Start Ask the AI to review your validation and error handling placement using the boundary discipline principle, concentrating guards at the CLI, config, and network edges.