csharp-api-design

Extend-only design prevents breaking changes in C# NuGet packages by adding new overloads or new types instead of modifying existing public APIs. This maintains backward and forward compatibility while introducing new features and deprecation paths.

Extend-only design in C# API development is a principle where public APIs are only extended, never modified or removed. It enables stable library evolution by introducing new functionality via new overloads and types while keeping existing members intact.

Plan wire compatibility for distributed C# components by applying versioning strategies that keep serialized data formats stable across releases. This Skill guides wire-compatibility planning to ensure distributed systems handle schema evolution without breaking communication.

Yes, extend-only design supports binary, source, and API compatibility for C# libraries. By avoiding removal or modification of public members, it ensures consumers can update packages without recompilation failures or runtime breaks across different releases.

The best way to deprecate old members in a C# public API is to use migration-ready versioning strategies that mark old members as obsolete while introducing new overloads. This enforces non-breaking changes and provides smooth migration paths for consumers.

Enforce non-breaking API changes during PR reviews by applying extend-only design prompts that verify new features are added via overloads or new types. This ensures migration paths are documented and existing public APIs remain stable for library consumers.