MyAiConfiguration/shared/rules/wpf/references/collections-and-xaml.md

Collections

• Use ObservableCollection<T> only when collection change notifications are required.
• Do not use ObservableCollection<T> as a general-purpose collection.
• Use List<T> or other suitable collections for non-observable internal data.
• Avoid replacing entire observable collections when incremental updates are sufficient.
• Avoid thousands of individual collection notifications when a bulk update is more appropriate.
• Keep collection mutations on the correct thread.
• Avoid exposing mutable internal collections unnecessarily.
• Prefer read-only views where consumers should not modify data.

XAML

• Keep XAML readable and focused.
• Avoid excessively large view files.
• Split complex views into focused controls when it improves maintainability.
• Use resources for repeated values and styles.
• Avoid magic numbers in XAML.
• Keep styles and templates consistent.
• Avoid excessive inline styling.
• Prefer reusable resources over duplicated markup.
• Avoid deeply nested panels.
• Keep visual trees as shallow as practical.
• Use semantic control choices.
• Avoid unnecessary containers.
• Do not overuse triggers when simpler state representation is possible.
• Keep templates understandable.
• Avoid XAML tricks that make behavior hard to discover.

Layout

• Prefer Grid for structured layouts.
• Use StackPanel only where its layout behavior is actually appropriate.
• Avoid unnecessary nested panels.
• Avoid fixed sizes unless the design requires them.
• Prefer responsive sizing with Auto and *.
• Avoid layout configurations that cause excessive measure/arrange passes.
• Be careful with large visual trees inside scrolling containers.
• Avoid disabling virtualization accidentally.

Virtualization

• Keep UI virtualization enabled for large collections.
• Do not use container layouts that disable virtualization without a reason.
• Avoid wrapping large virtualized item lists in additional scrolling containers.
• Use virtualizing panels where appropriate.
• Verify virtualization when displaying large data sets.
• Avoid rendering thousands of controls simultaneously.
• Prefer paging, incremental loading or virtualization for very large data sets.