When evaluating or improving a component, check the expectations for each area you're working in. Each area lists what to look for across user experience (UX), developer experience (DX), and maintainability (MX).

---

Implementation code quality expectations.

UX (User Experience):

• Visual Design
  • Engaging presentation with appropriate shadows, animations, depths
  • Consistent with platform design language (spacing, typography, brushes)
  • Polished and professional appearance
• Accessibility
  • Screen reader support (narration, semantic structure)
  • Localization support (multiple languages, cultures)
  • High contrast theme support
  • Keyboard navigation (all functionality accessible without mouse)
• Interaction
  • Stable and intuitive behavior
  • Delightful to use (smooth, responsive, predictable)
  • Component works correctly (no broken functionality)
• Flexibility
  • Responsive layouts (adapts to different screen sizes)
  • Adaptive input (touch, mouse, keyboard, pen)
  • Natural fit on every device (TV, desktop, tablet, phone)
• Performance
  • Feels responsive and performant
  • No unnecessary delays or sluggishness
  • Smooth animations and transitions
• Keep choices accessible
  • Sensible defaults for common scenarios
  • Don't suppress or erase user choice
  • Manage choice complexity (schemas, styles)

DX (Developer Experience):

• API Design Quality
  • Clear, consistent, well-designed public API surface
  • Not monolithic (piecemeal, focused responsibilities)
  • Follows platform patterns and conventions
  • Sensible defaults with flexibility for edge cases
• Discoverability
  • IntelliSense tooltips clear and helpful (XML comments)
  • API surface intuitive and predictable
  • Non-trivial descriptions (not just property name repetition)
  • Conceptual documentation available
• Learning Curve
  • Easy to learn from samples and documentation
  • Common use cases demonstrated clearly
  • Progressive disclosure (simple scenarios easy, complex possible)
• Flexibility
  • Composable (components work together naturally)
  • Extensible (can derive, retemplate, extend behavior)
  • Platform differences accommodated (UWP/WinUI3/Uno)
• Edge Case Accommodation
  • API handles non-default scenarios
  • Doesn't require workarounds for uncommon needs
  • Balances MVP convenience with edge case flexibility

MX (Maintainability):

• Architectural Quality
  • Self-isolated domains (changes don't cascade between components)
  • Piecemeal composition (clear responsibilities, reusable parts)
  • Appropriate abstraction levels
  • Clear boundaries between functional areas
• Code Maintainability
  • Readable, understandable structure
  • Comments detail rationale, especially for non-obvious solutions
  • SOLID principles applied
  • MVVM patterns where applicable
  • Technical debt minimal or explicitly tracked
• Test Coverage
  • Prevents regressions
  • Adequate MVP functionality coverage
  • Maintainable test code (easy to read, reuse, update)
  • Tests pass consistently (local and CI)
• Breaking Change Minimization
  • Evolution paths considered upfront
  • API designed to minimize future breaks

---

Example code quality expectations.

DX:

• Easy to learn from (clear, progressive complexity)
• Demonstrates common use cases
• Shows edge cases and flexibility
• Simple examples first, advanced scenarios available
• Demonstrates composability patterns
• Shows sensible defaults and customization options

MX:

• Demonstrates best practices (MVVM, SOLID, patterns)
• Maintainable example code (not overly complex)
• Examples show proper domain isolation
• Samples stay current with source changes

UX:

• Samples demonstrate good UX patterns
• Show accessibility features in action (RTL, High Contrast, Narrator)
• Showcase visual design capabilities

---

Documentation quality expectations.

DX:

• Discoverable via IntelliSense (XML comments complete)
• Clear conceptual explanations
• API reference complete and accurate
• Non-trivial descriptions (meaningful, not property name repetition)
• Shows how to integrate and use
• Progressive disclosure (getting started → advanced)
• Edge cases documented

MX:

• Reference docs: XMLDoc comments with rationale for non-obvious solutions
• Concept docs: Complement samples, demonstrate basic and advanced usage
• Accurate (reflects current behavior)
• Up-to-date (no stale information)
• Documentation process itself documented and maintainable

---

Test code quality expectations.

MX:

• Prevents regressions (catches behavior changes)
• Adequate coverage (MVP functionality and edge cases)
• Maintainable test code (not brittle, survives refactoring)
• Tests pass consistently (local and CI)
• Test structure clear and organized

DX:

• Tests document expected behavior
• Tests serve as usage examples
• Test names describe scenarios clearly

---

Quality flows from maintainability through developer experience to user experience:

MX → DX → UX

Gaps earlier in this chain affect everything downstream:

• Poor maintainability makes it hard to improve the API
• Poor API design makes it hard to create good user experiences

MX gaps (maintainability):

• Highest impact — affects your ability to improve DX and UX
• Address early to avoid compounding technical debt
• Examples: unclear code structure, missing tests, undocumented behavior

DX gaps (developer experience):

• Blocks good UX — hard to build great experiences on a difficult API
• Address before focusing on UX polish
• Examples: confusing API surface, poor discoverability, missing docs

UX gaps (user experience):

• Can be addressed once MX and DX are solid
• Polish is easier when the foundation supports it
• Examples: visual refinement, accessibility improvements, interaction tuning

Non-breaking improvements (can address in mainline):

• Visual polish and style updates (UX)
• Additive API enhancements (DX)
• Code quality refinements, test additions (MX)
• Track as improvements, address incrementally

Breaking changes depend on component status:

For porting, new components, or Labs incubation:

• Breaking changes allowed during incubation
• Community validation before mainline commitment
• Iterate via sub-issue → PR loop until quality requirements met
• Quality assessed throughout Labs lifecycle
• Graduate to mainline when HIGH quality achieved across all dimensions

For stable mainline components:

• Avoid parallel APIs if possible through proactive API design
• When unavoidable, ship new API alongside deprecated old API ([Obsolete]) well before major version
• Provide migration roadmap before release
• Breaking removal only in major version bumps
• Do not make major breaking changes to already stable-released parallel APIs
• If too complex → component may return to Labs for redesign