Add project files.

src/framework/Elsa.Studio.Core/Abstractions/FeatureBase.cs

@@ -0,0 +1,12 @@
+using Elsa.Studio.Contracts;
+
+namespace Elsa.Studio.Abstractions;
+
+/// <summary>
+/// A base class for modules.
+/// </summary>
+public abstract class FeatureBase : IFeature
+{
+    /// <inheritdoc />
+    public virtual ValueTask InitializeAsync(CancellationToken cancellationToken = default) => ValueTask.CompletedTask;
+}

src/framework/Elsa.Studio.Core/Abstractions/FieldExtensionHandlerBase.cs

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+using Elsa.Studio.Contracts;
+using Elsa.Studio.Enums;
+using Elsa.Studio.Models;
+using Microsoft.AspNetCore.Components;
+
+namespace Elsa.Studio.Abstractions;
+
+/// <summary>
+/// Provides a base handler for field extensions.
+/// </summary>
+public abstract class FieldExtensionHandlerBase : IUIFieldExtensionHandler
+{
+    /// <summary>
+    /// <inheritdoc/>
+    /// </summary>
+    public virtual int DisplayOrder { get; set; } = 1;
+
+    /// <summary>
+    /// <inheritdoc/>
+    /// </summary>
+    public virtual bool IncludeForAll { get; set; } = false;
+
+    /// <summary>
+    /// <inheritdoc/>
+    /// </summary>
+    public virtual FieldExtensionPosition Position { get; set; } = FieldExtensionPosition.Top;
+
+    /// <summary>
+    /// <inheritdoc/>
+    /// </summary>
+    public virtual string UIHintComponent { get; set; } = string.Empty;
+
+    /// <summary>
+    /// <inheritdoc/>
+    /// </summary>
+    public virtual List<string> ActivityTypes { get; set; } = [];
+
+    /// <summary>
+    /// <inheritdoc/>
+    /// </summary>
+    public virtual List<string> Syntaxes { get; set; } = [];
+
+    /// <summary>
+    /// <inheritdoc/>
+    /// </summary>
+    public virtual bool GetExtensionForInputComponent(string componentName) =>
+        (string.IsNullOrEmpty(UIHintComponent) && !ActivityTypes.Any() && !Syntaxes.Any() && IncludeForAll)
+            || UIHintComponent.Equals(componentName, StringComparison.OrdinalIgnoreCase);
+
+    /// <summary>
+    /// <inheritdoc/>
+    /// </summary>
+    public abstract RenderFragment DisplayExtension(DisplayInputEditorContext context);
+}