Non-Breaking Changes

Non-breaking changes are modifications to a design system that maintain backwards compatibility with existing consumer implementations. These changes allow consumers to upgrade without modifying their code, making them lower risk and easier to adopt. Understanding what qualifies as non-breaking helps teams version releases accurately and enables consumers to update confidently.

What Are Non-Breaking Changes

Non-breaking changes preserve the existing contract between a design system and its consumers. After upgrading, all previously working code continues to function correctly. Consumers may gain access to new capabilities, but they are not required to change anything to maintain current functionality.

Non-breaking changes fall into two categories based on semantic versioning: minor changes that add new features and patch changes that fix bugs. Both maintain backwards compatibility, but they differ in scope. Minor changes expand capabilities while patch changes correct existing behavior.

How Non-Breaking Changes Work

Identifying non-breaking changes requires evaluating modifications against the existing public API and documented behaviors. Changes that extend functionality without altering existing interfaces qualify as non-breaking.

Feature additions form the primary category of minor version changes. Adding a new optional prop to a component is non-breaking because existing code does not use the new prop and continues working. Introducing entirely new components adds capabilities without affecting existing consumers. Exposing additional CSS custom properties or slots provides new customization options while preserving current behavior.

Bug fixes constitute patch version changes when they correct behavior to match documentation without changing the API. Fixing visual rendering issues, correcting accessibility problems, or improving performance maintains backwards compatibility. The key criterion is that the fix aligns behavior with documented expectations rather than changing fundamental functionality.

Internal refactoring that does not affect public interfaces is non-breaking regardless of scope. Restructuring code, improving internal algorithms, or updating internal dependencies can improve quality without impacting consumers. These changes typically warrant patch versions unless they include visible improvements.

Key Considerations

• New optional props are non-breaking; new required props are breaking
• Widening TypeScript types is non-breaking; narrowing types is breaking
• Adding new exports is non-breaking; removing or renaming exports is breaking
• Default value changes may be non-breaking if documented as implementation details
• Performance improvements are typically non-breaking unless they change behavior

Common Questions

Can visual changes be non-breaking?

Visual changes can be non-breaking when they fall within the scope of minor refinements that do not significantly alter component appearance. Small adjustments to spacing, subtle color shifts, or typography refinements typically maintain backwards compatibility from a consumer’s perspective.

However, visual changes exist on a spectrum. Design system teams should establish clear guidelines about what visual changes constitute breaking modifications. Consumers who rely on specific visual output, particularly those with visual regression testing, benefit from understanding these guidelines. Documentation should clarify the team’s approach to visual versioning.

How do documentation updates affect versioning?

Documentation updates generally do not require version increments since they do not change the design system package itself. However, documentation quality affects consumer experience, and significant documentation improvements may be highlighted in release notes.

One exception involves code examples in documentation. If consumers copy code directly from documentation, changing those examples could affect their implementations. While not technically a version change, updating critical code examples alongside relevant package changes helps maintain alignment. Some teams version their documentation separately from package code.

Summary

Non-breaking changes enable design system evolution while maintaining compatibility with existing consumer implementations. Feature additions receive minor version increments, while bug fixes receive patch increments. Clear criteria for identifying non-breaking changes ensures accurate versioning and builds consumer confidence in adopting updates.