feat(lib): Enable Nullable analysis and fix warnings

.github/copilot-instructions.md

@@ -85,6 +85,9 @@ This repository is the **source code for the Ignite UI for Blazor component libr
 
 - Use the latest C# version supported by the target frameworks; prefer modern features (pattern matching, file-scoped namespaces) when they compile on all TFMs
 - Use strict nullability (`#nullable enable`) in new files
+- Annotate honestly: a member is `T?` only when `null` is a meaningful state; never use `!`, `null!` or `default!` to satisfy the analyzer, and keep runtime null checks at public entry points, since annotations are not enforced at runtime
+- Prefer non-nullable collections: array and collection properties, parameters and return values are non-nullable and default to an empty collection, unless the web component treats a missing collection differently from an empty one
+- Mirror the web component contract on data and option types: a field the `.d.ts` declares required is non-nullable (`required` when only user code constructs the type); a field declared optional or `| null` is `T?`; a definite-assignment attribute (`name!: string`) that the template renders with `ifDefined` is optional too, so check the render when the `.d.ts` shows a bare attribute string
 - All public types live in `namespace IgniteUI.Blazor.Controls`
 - Use PascalCase for public members; camelCase for private fields
 - Prefix interfaces with `I` (e.g., `IIgniteUIBlazor`)

CHANGELOG.md

@@ -7,6 +7,22 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Breaking Changes
+
+#### Public API nullability
+
+> [!NOTE]
+> As part of this release the public API was annotated for nullable reference types. Beyond the members listed below, reference-type parameters, properties, and return values now declare whether they accept or produce `null`. Consumers building with nullable reference types enabled may see new nullable warnings — or errors, if warnings are treated as errors — and may need to update their code accordingly.
+
+The following public members changed from nullable to non-nullable. Value-type changes (`double?` → `double`) are binary-breaking.
+
+| Type | Member | Before | After |
+|------|--------|--------|-------|
+| `IgbTile` | `ColStart` | `double?` | `double` |
+| `IgbTile` | `RowStart` | `double?` | `double` |
+| `IgbCalendar` | `SpecialDates` | `IgbDateRangeDescriptor[]?` | `IgbDateRangeDescriptor[]` |
+| `IgbCalendar` | `DisabledDates` | `IgbDateRangeDescriptor[]?` | `IgbDateRangeDescriptor[]` |
+
 ## 0.1.0 - 2026-07-14
 
 This release updates the Ignite UI for Blazor to the latest [igniteui-webcomponents@7.2.4 release](https://github.com/IgniteUI/igniteui-webcomponents/releases/tag/7.2.4) and matching related changes from `IgniteUI.Blazor` [25.2.77 (March 2026)](https://www.infragistics.com/products/ignite-ui-blazor/blazor/components/general-changelog-dv-blazor#25277-march-2026), [25.2.102 (May 2026)](https://www.infragistics.com/products/ignite-ui-blazor/blazor/components/general-changelog-dv-blazor#252102-may-2026) and [26.1.51 (June 2026)](https://www.infragistics.com/products/ignite-ui-blazor/blazor/components/general-changelog-dv-blazor#26151-june-2026) with highlights noted below:

Directory.Build.props

@@ -4,6 +4,7 @@
     <Copyright>Infragistics</Copyright>
     <Deterministic>true</Deterministic>
     <Nullable>enable</Nullable>
+    <WarningsAsErrors>$(WarningsAsErrors);nullable</WarningsAsErrors>
     <ImplicitUsings>enable</ImplicitUsings>
     <!-- Run the .editorconfig IDExxxx style rules as analyzers during build
          so formatting violations surface as warnings locally and in CI. -->

src/IgniteUI.Blazor.Lite.csproj

@@ -2,9 +2,6 @@
 
   <PropertyGroup>
     <PackageIdSuffix>.Lite</PackageIdSuffix>
-    <!-- TODO: opts out of the repo-wide <Nullable>enable</Nullable> for now — the generated
-         component sources are not annotated and would emit thousands of nullable warnings. -->
-    <Nullable>disable</Nullable>
   </PropertyGroup>
 
   <!-- Removed as pinning the language to an older version prevents building in net10 where global usings files are autogenerated  -->

src/components/Blazor/Accordion.cs

@@ -80,7 +80,7 @@ public bool SingleExpand
         }
 
         /// <inheritdoc />
-        public override object FindByName(string name)
+        public override object? FindByName(string name)
         {
             var baseResult = base.FindByName(name);
             if (baseResult != null)
@@ -103,34 +103,34 @@ public override object FindByName(string name)
         /// </summary>
         public async Task HideAllAsync()
         {
-            await InvokeMethod("hideAll", new object[] { }, new string[] { });
+            await InvokeMethod("hideAll", new object?[] { }, new string[] { });
         }
 
         /// <summary>
         /// Hides all of the child expansion panels' contents.
         /// </summary>
         public void HideAll()
         {
-            InvokeMethodSync("hideAll", new object[] { }, new string[] { });
+            InvokeMethodSync("hideAll", new object?[] { }, new string[] { });
         }
         /// <summary>
         /// Shows all of the child expansion panels' contents.
         /// </summary>
         public async Task ShowAllAsync()
         {
-            await InvokeMethod("showAll", new object[] { }, new string[] { });
+            await InvokeMethod("showAll", new object?[] { }, new string[] { });
         }
 
         /// <summary>
         /// Shows all of the child expansion panels' contents.
         /// </summary>
         public void ShowAll()
         {
-            InvokeMethodSync("showAll", new object[] { }, new string[] { });
+            InvokeMethodSync("showAll", new object?[] { }, new string[] { });
         }
 
-        private string _openingRef = null;
-        private string _openingScript = null;
+        private string? _openingRef = null;
+        private string? _openingScript = null;
 
         /// <summary>
         /// Name of a client-side function that handles the <see cref="Opening"/> event in the browser instead.
@@ -140,15 +140,15 @@ public void ShowAll()
         /// <c>igRegisterScript("MyHandler", function (args) { }, false)</c>.
         /// </remarks>
         [Parameter]
-        public string OpeningScript
+        public string? OpeningScript
         {
 
             set
             {
                 if (value != this._openingScript)
                 {
                     this._openingScript = value;
-                    this.OnRefChanged("Opening", null, value, true, false, (string refName, object oldValue, object newValue) =>
+                    this.OnRefChanged("Opening", null, value, true, false, (string refName, object? oldValue, object? newValue) =>
                     {
                         this._openingRef = refName;
                         this.MarkPropDirty("OpeningRef");
@@ -201,8 +201,8 @@ public EventCallback<IgbExpansionPanelComponentEventArgs> Opening
             }
         }
 
-        private string _openedRef = null;
-        private string _openedScript = null;
+        private string? _openedRef = null;
+        private string? _openedScript = null;
 
         /// <summary>
         /// Name of a client-side function that handles the <see cref="Opened"/> event in the browser instead.
@@ -212,15 +212,15 @@ public EventCallback<IgbExpansionPanelComponentEventArgs> Opening
         /// <c>igRegisterScript("MyHandler", function (args) { }, false)</c>.
         /// </remarks>
         [Parameter]
-        public string OpenedScript
+        public string? OpenedScript
         {
 
             set
             {
                 if (value != this._openedScript)
                 {
                     this._openedScript = value;
-                    this.OnRefChanged("Opened", null, value, true, false, (string refName, object oldValue, object newValue) =>
+                    this.OnRefChanged("Opened", null, value, true, false, (string refName, object? oldValue, object? newValue) =>
                     {
                         this._openedRef = refName;
                         this.MarkPropDirty("OpenedRef");
@@ -273,8 +273,8 @@ public EventCallback<IgbExpansionPanelComponentEventArgs> Opened
             }
         }
 
-        private string _closingRef = null;
-        private string _closingScript = null;
+        private string? _closingRef = null;
+        private string? _closingScript = null;
 
         /// <summary>
         /// Name of a client-side function that handles the <see cref="Closing"/> event in the browser instead.
@@ -284,15 +284,15 @@ public EventCallback<IgbExpansionPanelComponentEventArgs> Opened
         /// <c>igRegisterScript("MyHandler", function (args) { }, false)</c>.
         /// </remarks>
         [Parameter]
-        public string ClosingScript
+        public string? ClosingScript
         {
 
             set
             {
                 if (value != this._closingScript)
                 {
                     this._closingScript = value;
-                    this.OnRefChanged("Closing", null, value, true, false, (string refName, object oldValue, object newValue) =>
+                    this.OnRefChanged("Closing", null, value, true, false, (string refName, object? oldValue, object? newValue) =>
                     {
                         this._closingRef = refName;
                         this.MarkPropDirty("ClosingRef");
@@ -345,8 +345,8 @@ public EventCallback<IgbExpansionPanelComponentEventArgs> Closing
             }
         }
 
-        private string _closedRef = null;
-        private string _closedScript = null;
+        private string? _closedRef = null;
+        private string? _closedScript = null;
 
         /// <summary>
         /// Name of a client-side function that handles the <see cref="Closed"/> event in the browser instead.
@@ -356,15 +356,15 @@ public EventCallback<IgbExpansionPanelComponentEventArgs> Closing
         /// <c>igRegisterScript("MyHandler", function (args) { }, false)</c>.
         /// </remarks>
         [Parameter]
-        public string ClosedScript
+        public string? ClosedScript
         {
 
             set
             {
                 if (value != this._closedScript)
                 {
                     this._closedScript = value;
-                    this.OnRefChanged("Closed", null, value, true, false, (string refName, object oldValue, object newValue) =>
+                    this.OnRefChanged("Closed", null, value, true, false, (string refName, object? oldValue, object? newValue) =>
                     {
                         this._closedRef = refName;
                         this.MarkPropDirty("ClosedRef");

src/components/Blazor/ActiveStepChangedEventArgs.cs

@@ -13,7 +13,7 @@ public partial class IgbActiveStepChangedEventArgs : BaseRendererElement
 
         private static bool _marshalByValue = true;
 
-        private IgbActiveStepChangedEventArgsDetail _detail;
+        private IgbActiveStepChangedEventArgsDetail _detail = new IgbActiveStepChangedEventArgsDetail();
 
         /// <summary>
         /// The payload of the event, carrying the index of the step that became active.
@@ -25,15 +25,16 @@ public IgbActiveStepChangedEventArgsDetail Detail
             set
             {
                 MarkPropDirty("Detail");
+
                 if (this._detail != null)
                 {
                     this.DetachChild(this._detail);
                 }
+                this._detail = value;
                 if (value != null)
                 {
                     this.AttachChild(value);
                 }
-                this._detail = value;
             }
 
         }
@@ -48,7 +49,7 @@ internal override void SerializeCore(RendererSerializer ser)
         }
 
         /// <inheritdoc />
-        protected internal override void ToEventJson(BaseRendererControl control, Dictionary<string, object> args)
+        protected internal override void ToEventJson(BaseRendererControl control, Dictionary<string, object?> args)
         {
             base.ToEventJson(control, args);
 
@@ -58,13 +59,13 @@ protected internal override void ToEventJson(BaseRendererControl control, Dictio
         }
 
         /// <inheritdoc />
-        protected internal override void FromEventJson(BaseRendererControl control, Dictionary<string, object> args)
+        protected internal override void FromEventJson(BaseRendererControl control, Dictionary<string, object?>? args)
         {
             base.FromEventJson(control, args);
             this.SuppressParentNotify = true;
 
-            if (args.ContainsKey("detail"))
-            { this.Detail = (IgbActiveStepChangedEventArgsDetail)ConvertReturnValue(args["detail"], "ActiveStepChangedEventArgsDetail", true); }
+            if (args != null && args.TryGetValue("detail", out var detailObj) && ConvertReturnValue(detailObj, "ActiveStepChangedEventArgsDetail", true) is IgbActiveStepChangedEventArgsDetail detail)
+            { this.Detail = detail; }
 
             this.SuppressParentNotify = false;
         }

src/components/Blazor/ActiveStepChangedEventArgsDetail.cs

@@ -42,7 +42,7 @@ internal override void SerializeCore(RendererSerializer ser)
         }
 
         /// <inheritdoc />
-        protected internal override void ToEventJson(BaseRendererControl control, Dictionary<string, object> args)
+        protected internal override void ToEventJson(BaseRendererControl control, Dictionary<string, object?> args)
         {
             base.ToEventJson(control, args);
 
@@ -52,12 +52,12 @@ protected internal override void ToEventJson(BaseRendererControl control, Dictio
         }
 
         /// <inheritdoc />
-        protected internal override void FromEventJson(BaseRendererControl control, Dictionary<string, object> args)
+        protected internal override void FromEventJson(BaseRendererControl control, Dictionary<string, object?>? args)
         {
             base.FromEventJson(control, args);
             this.SuppressParentNotify = true;
 
-            if (args.ContainsKey("index"))
+            if (args != null && args.ContainsKey("index"))
             { this.Index = ReturnToDouble(args["index"]); }
 
             this.SuppressParentNotify = false;

src/components/Blazor/ActiveStepChangingEventArgs.cs

@@ -13,7 +13,7 @@ public partial class IgbActiveStepChangingEventArgs : BaseRendererElement
 
         private static bool _marshalByValue = true;
 
-        private IgbActiveStepChangingEventArgsDetail _detail;
+        private IgbActiveStepChangingEventArgsDetail _detail = new IgbActiveStepChangingEventArgsDetail();
 
         /// <summary>
         /// The payload of the event, carrying the index of the currently active step and the index of
@@ -30,11 +30,11 @@ public IgbActiveStepChangingEventArgsDetail Detail
                 {
                     this.DetachChild(this._detail);
                 }
+                this._detail = value;
                 if (value != null)
                 {
                     this.AttachChild(value);
                 }
-                this._detail = value;
             }
 
         }
@@ -49,7 +49,7 @@ internal override void SerializeCore(RendererSerializer ser)
         }
 
         /// <inheritdoc />
-        protected internal override void ToEventJson(BaseRendererControl control, Dictionary<string, object> args)
+        protected internal override void ToEventJson(BaseRendererControl control, Dictionary<string, object?> args)
         {
             base.ToEventJson(control, args);
 
@@ -59,13 +59,13 @@ protected internal override void ToEventJson(BaseRendererControl control, Dictio
         }
 
         /// <inheritdoc />
-        protected internal override void FromEventJson(BaseRendererControl control, Dictionary<string, object> args)
+        protected internal override void FromEventJson(BaseRendererControl control, Dictionary<string, object?>? args)
         {
             base.FromEventJson(control, args);
             this.SuppressParentNotify = true;
 
-            if (args.ContainsKey("detail"))
-            { this.Detail = (IgbActiveStepChangingEventArgsDetail)ConvertReturnValue(args["detail"], "ActiveStepChangingEventArgsDetail", true); }
+            if (args != null && args.TryGetValue("detail", out var detailObj) && ConvertReturnValue(detailObj, "ActiveStepChangingEventArgsDetail", true) is IgbActiveStepChangingEventArgsDetail detail)
+            { this.Detail = detail; }
 
             this.SuppressParentNotify = false;
         }

src/components/Blazor/ActiveStepChangingEventArgsDetail.cs

@@ -63,7 +63,7 @@ internal override void SerializeCore(RendererSerializer ser)
         }
 
         /// <inheritdoc />
-        protected internal override void ToEventJson(BaseRendererControl control, Dictionary<string, object> args)
+        protected internal override void ToEventJson(BaseRendererControl control, Dictionary<string, object?> args)
         {
             base.ToEventJson(control, args);
 
@@ -75,14 +75,14 @@ protected internal override void ToEventJson(BaseRendererControl control, Dictio
         }
 
         /// <inheritdoc />
-        protected internal override void FromEventJson(BaseRendererControl control, Dictionary<string, object> args)
+        protected internal override void FromEventJson(BaseRendererControl control, Dictionary<string, object?>? args)
         {
             base.FromEventJson(control, args);
             this.SuppressParentNotify = true;
 
-            if (args.ContainsKey("oldIndex"))
+            if (args != null && args.ContainsKey("oldIndex"))
             { this.OldIndex = ReturnToDouble(args["oldIndex"]); }
-            if (args.ContainsKey("newIndex"))
+            if (args != null && args.ContainsKey("newIndex"))
             { this.NewIndex = ReturnToDouble(args["newIndex"]); }
 
             this.SuppressParentNotify = false;