Instruction file imported from zedfauji/pos-app (
.cursor/rules/known-issue-1.mdc). Copyright stays with the author.
trigger: always_on
Framework & API Rules
Framework: Always assume WinUI 3 (Windows App SDK).
❌ Never use APIs/properties from WPF or UWP (e.g., SelectedDateFormat, CalendarDateChangedEventArgs).
✅ Always use WinUI 3 namespaces:
Microsoft.UI.Xaml.Controls
Microsoft.UI.Xaml
Microsoft.UI.Dispatching
🗓 DatePicker Rules
Do not generate or suggest SelectedDateFormat.
Must use:
Event handler must match:
private void DatePicker_DateChanged(object? sender, DatePickerValueChangedEventArgs e) { var newDate = e.NewDate; // DateTimeOffset? }
If formatting needed, use:
A ValueConverter (e.g., DateToStringConverter)
Or format when displaying (.ToString("d"), .ToString("yyyy-MM-dd"))
⚙️ Event Handler Rules
Handlers must match the delegate signature expected by WinUI 3.
❌ Never reuse WPF/UWP event args (e.g., SelectionChangedEventArgs).
✅ Example (correct):
private void ComboBox_SelectionChanged(object? sender, SelectionChangedEventArgs e) { … } private void DatePicker_DateChanged(object? sender, DatePickerValueChangedEventArgs e) { … }
🔄 MVVM vs Code-Behind
Prefer MVVM bindings and ICommand over code-behind event handlers where possible.
Code-behind handlers are acceptable only for lightweight UI interactions.
🧪 CI & Build Consistency
All generated code must compile under WinUI 3 with .NET 8 on Windows.
Must remain compatible with dotnet build on Windows runners (CI).
Generated XAML must be self-contained (no orphaned attributes, no undefined handlers).
🚫 Disallowed Patterns (never output)
SelectedDateFormat
CalendarDateChangedEventArgs
System.Windows.* namespaces (WPF)
Windows.UI.Xaml.* namespaces (UWP)
✅ Preferred Patterns (always output)
Microsoft.UI.Xaml.Controls.DatePicker
DatePickerValueChangedEventArgs
Bind Date (type DateTimeOffset?) via {x:Bind} or {Binding}.
For formatting, use converters instead of unsupported XAML properties.
📋 PR / Review Checklist (auto-checks)
Does all XAML build without errors under WinUI 3?
Are all event handlers using the correct WinUI delegate signatures?
Are WPF/UWP-only APIs absent (SelectedDateFormat, etc.)?
Are converters or ViewModels used instead of unsupported formatting props?
Does the CI Windows build job succeed?
