Design APIs with a minimal public surface area by carefully controlling which methods and properties are exposed. Start with a restricted set of public methods and expand only when there's clear evidence of need. This approach makes APIs easier to maintain and evolve while reducing the risk of breaking changes. Key principles: - Expose only methods that are essential for client usage - Prefer specific, focused public methods over general-purpose ones - Document the rationale for making methods public Example: ```ruby class ErrorReporter # BAD: Exposing internal state directly attr_accessor :context_middlewares # GOOD: Controlled public interface def add_middleware(&block) context_middlewares << block end private attr_reader :context_middlewares end ``` When adding new public methods, consider: 1. Is this functionality truly needed by API consumers? 2. Could this be implemented using existing public methods? 3. Are we prepared to support this method long-term? Remember: It's easier to add methods later than to remove them, as removal requires a deprecation cycle.