diff --git a/src/apps/Elsa.Server.Web/Program.cs b/src/apps/Elsa.Server.Web/Program.cs
index 32fdbfc5c..d26da8a7e 100644
--- a/src/apps/Elsa.Server.Web/Program.cs
+++ b/src/apps/Elsa.Server.Web/Program.cs
@@ -662,7 +662,7 @@ services
             elsa.UseTenantHttpRouting(tenantHttpRouting =>
             {
                 // Override the tenant header name with a custom one.
-                tenantHttpRouting.WithTenantHeader("X-Company-Id");
+                tenantHttpRouting.WithTenantHeader("X-Tenant-ID");
             });
         }
 
diff --git a/src/common/Elsa.Mediator/Contracts/IRequestSender.cs b/src/common/Elsa.Mediator/Contracts/IRequestSender.cs
index de23cd440..82c96fc74 100644
--- a/src/common/Elsa.Mediator/Contracts/IRequestSender.cs
+++ b/src/common/Elsa.Mediator/Contracts/IRequestSender.cs
@@ -12,5 +12,5 @@ public interface IRequestSender
     /// <param name="cancellationToken">The cancellation token.</param>
     /// <typeparam name="T">The type of the response.</typeparam>
     /// <returns>The response.</returns>
-    Task<T?> SendAsync<T>(IRequest<T> request, CancellationToken cancellationToken = default);
+    Task<T> SendAsync<T>(IRequest<T> request, CancellationToken cancellationToken = default);
 }
\ No newline at end of file
diff --git a/src/common/Elsa.Mediator/Middleware/Request/RequestContext.cs b/src/common/Elsa.Mediator/Middleware/Request/RequestContext.cs
index b6093cb68..b6643a567 100644
--- a/src/common/Elsa.Mediator/Middleware/Request/RequestContext.cs
+++ b/src/common/Elsa.Mediator/Middleware/Request/RequestContext.cs
@@ -34,9 +34,9 @@ public class RequestContext
     /// Gets the cancellation token.
     /// </summary>
     public CancellationToken CancellationToken { get; init; }
-    
+
     /// <summary>
     /// Gets the response the request handler.
     /// </summary>
-    public object? Response { get; set; }
+    public object Response { get; set; } = null!;
 }
\ No newline at end of file
diff --git a/src/common/Elsa.Mediator/Services/DefaultMediator.cs b/src/common/Elsa.Mediator/Services/DefaultMediator.cs
index 21b3c36c0..23a68162b 100644
--- a/src/common/Elsa.Mediator/Services/DefaultMediator.cs
+++ b/src/common/Elsa.Mediator/Services/DefaultMediator.cs
@@ -41,13 +41,13 @@ public class DefaultMediator : IMediator
     }
 
     /// <inheritdoc />
-    public async Task<T?> SendAsync<T>(IRequest<T> request, CancellationToken cancellationToken = default)
+    public async Task<T> SendAsync<T>(IRequest<T> request, CancellationToken cancellationToken = default)
     {
         var responseType = typeof(T);
         var context = new RequestContext(request, responseType, cancellationToken);
         await _requestPipeline.ExecuteAsync(context);
 
-        return (T?)context.Response;
+        return (T)context.Response;
     }
 
     /// <inheritdoc />
diff --git a/src/modules/Elsa.Common/Entities/OrderDefinition.cs b/src/modules/Elsa.Common/Entities/OrderDefinition.cs
index 5d1f1ed82..99108ec84 100644
--- a/src/modules/Elsa.Common/Entities/OrderDefinition.cs
+++ b/src/modules/Elsa.Common/Entities/OrderDefinition.cs
@@ -31,5 +31,5 @@ public class OrderDefinition<T, TProp>
     /// <summary>
     /// The key selector to use to order the results.
     /// </summary>
-    public Expression<Func<T, TProp>> KeySelector { get; set; } = default!;
+    public Expression<Func<T, TProp>> KeySelector { get; set; } = null!;
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Features/HttpFeature.cs b/src/modules/Elsa.Http/Features/HttpFeature.cs
index 65c0e42d8..085a5c4ab 100644
--- a/src/modules/Elsa.Http/Features/HttpFeature.cs
+++ b/src/modules/Elsa.Http/Features/HttpFeature.cs
@@ -15,7 +15,6 @@ using Elsa.Http.Services;
 using Elsa.Http.Tasks;
 using Elsa.Http.UIHints;
 using Elsa.Workflows;
-using Elsa.Workflows.Management.Requests;
 using FluentStorage;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.StaticFiles;
diff --git a/src/modules/Elsa.OpenTelemetry/Middleware/OpenTelemetryTracingActivityExecutionMiddleware.cs b/src/modules/Elsa.OpenTelemetry/Middleware/OpenTelemetryTracingActivityExecutionMiddleware.cs
index d5c5fdc7b..0045fde75 100644
--- a/src/modules/Elsa.OpenTelemetry/Middleware/OpenTelemetryTracingActivityExecutionMiddleware.cs
+++ b/src/modules/Elsa.OpenTelemetry/Middleware/OpenTelemetryTracingActivityExecutionMiddleware.cs
@@ -29,16 +29,16 @@ public class OpenTelemetryTracingActivityExecutionMiddleware(ActivityMiddlewareD
         span.SetTag("activity.type", activity.Type);
         span.SetTag("activity.name", activity.Name);
         span.SetTag("activityInstance.id", context.Id);
-        span.SetTag("activityExecution.startTimeUtc", span.StartTimeUtc);
+        span.SetTag("activityExecution.startTimeUtc", span.StartTimeUtc);
         span.SetTag("tenantId", context.WorkflowExecutionContext.Workflow.Identity.TenantId);
         
-        span.AddEvent(new ActivityEvent("Executing", tags: CreateStatusTags(context)));
+        span.AddEvent(new("Executing", tags: CreateStatusTags(context)));
         
         await next(context);
 
         if (context.Status == ActivityStatus.Faulted)
         {
-            span.AddEvent(new ActivityEvent("Faulted", tags: CreateStatusTags(context)));
+            span.AddEvent(new("Faulted", tags: CreateStatusTags(context)));
             span.SetStatus(ActivityStatusCode.Error);
             span.SetTag("error", true);
             span.SetTag("activityInstance.hasIncidents", true);
@@ -51,7 +51,7 @@ public class OpenTelemetryTracingActivityExecutionMiddleware(ActivityMiddlewareD
         }
         else
         {
-            span.AddEvent(new ActivityEvent("Executed", tags: CreateStatusTags(context)));
+            span.AddEvent(new("Executed", tags: CreateStatusTags(context)));
             span.SetStatus(ActivityStatusCode.Ok);
         }
         
@@ -62,7 +62,7 @@ public class OpenTelemetryTracingActivityExecutionMiddleware(ActivityMiddlewareD
     
     private ActivityTagsCollection CreateStatusTags(ActivityExecutionContext context)
     {
-        return new ActivityTagsCollection(new Dictionary<string, object?>
+        return new(new Dictionary<string, object?>
         {
             ["activityInstance.status"] = context.Status.ToString()
         });
diff --git a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/GetByDefinitionId/Endpoint.cs b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/GetByDefinitionId/Endpoint.cs
index 7f87e67f1..4b2fbe9e7 100644
--- a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/GetByDefinitionId/Endpoint.cs
+++ b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/GetByDefinitionId/Endpoint.cs
@@ -1,13 +1,13 @@
 using Elsa.Abstractions;
 using Elsa.Common.Models;
-using Elsa.Mediator.Contracts;
-using Elsa.Workflows.Management.Requests;
+using Elsa.Workflows.Management;
+using Elsa.Workflows.Models;
 using JetBrains.Annotations;
 
 namespace Elsa.Workflows.Api.Endpoints.WorkflowDefinitions.GetByDefinitionId;
 
 [PublicAPI]
-internal class GetByDefinitionId(IMediator mediator, IWorkflowDefinitionLinker linker) : ElsaEndpoint<Request>
+internal class GetByDefinitionId(IWorkflowDefinitionStore store, IWorkflowDefinitionLinker linker) : ElsaEndpoint<Request>
 {
     public override void Configure()
     {
@@ -18,8 +18,8 @@ internal class GetByDefinitionId(IMediator mediator, IWorkflowDefinitionLinker l
     public override async Task HandleAsync(Request request, CancellationToken cancellationToken)
     {
         var versionOptions = request.VersionOptions != null ? VersionOptions.FromString(request.VersionOptions) : VersionOptions.Latest;
-        var findRequest = new FindWorkflowDefinitionRequest(request.DefinitionId, versionOptions);
-        var definition = await mediator.SendAsync(findRequest, cancellationToken);
+        var filter = WorkflowDefinitionHandle.ByDefinitionId(request.DefinitionId, versionOptions).ToFilter();
+        var definition = await store.FindAsync(filter, cancellationToken);
         
         if (definition == null)
         {
diff --git a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/Post/Endpoint.cs b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/Post/Endpoint.cs
index 4b1ba32f4..0c8f9c509 100644
--- a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/Post/Endpoint.cs
+++ b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/Post/Endpoint.cs
@@ -50,7 +50,7 @@ internal class Post(
         // Create a new workflow in case no existing definition was found.
         if (isNew)
         {
-            draft = workflowDefinitionPublisher.New();
+            draft = await workflowDefinitionPublisher.NewAsync(cancellationToken: cancellationToken);
 
             if (!string.IsNullOrWhiteSpace(definitionId))
                 draft.DefinitionId = definitionId;
diff --git a/src/modules/Elsa.Workflows.Api/Models/LinkedWorkflowDefinitionModel.cs b/src/modules/Elsa.Workflows.Api/Models/LinkedWorkflowDefinitionModel.cs
index ae4aa8233..d05d72d30 100644
--- a/src/modules/Elsa.Workflows.Api/Models/LinkedWorkflowDefinitionModel.cs
+++ b/src/modules/Elsa.Workflows.Api/Models/LinkedWorkflowDefinitionModel.cs
@@ -3,4 +3,7 @@ using Elsa.Workflows.Management.Models;
 
 namespace Elsa.Workflows.Api.Models;
 
-public record LinkedWorkflowDefinitionModel(Link[]? Links) : WorkflowDefinitionModel;
+public class LinkedWorkflowDefinitionModel(Link[]? links) : WorkflowDefinitionModel
+{
+    public Link[]? Links { get; init; } = links;
+}
diff --git a/src/modules/Elsa.Workflows.Core/Abstractions/Trigger.cs b/src/modules/Elsa.Workflows.Core/Abstractions/Trigger.cs
index f26460b85..648fbe451 100644
--- a/src/modules/Elsa.Workflows.Core/Abstractions/Trigger.cs
+++ b/src/modules/Elsa.Workflows.Core/Abstractions/Trigger.cs
@@ -6,12 +6,12 @@ namespace Elsa.Workflows;
 public abstract class Trigger : Activity, ITrigger
 {
     /// <inheritdoc />
-    protected Trigger(string? source = default, int? line = default) : base(source, line)
+    protected Trigger(string? source = null, int? line = null) : base(source, line)
     {
     }
 
     /// <inheritdoc />
-    protected Trigger(string activityType, int version = 1, string? source = default, int? line = default) : base(activityType, version, source, line)
+    protected Trigger(string activityType, int version = 1, string? source = null, int? line = null) : base(activityType, version, source, line)
     {
     }
 
@@ -39,11 +39,11 @@ public abstract class Trigger : Activity, ITrigger
 
 public abstract class Trigger<TResult> : Activity<TResult>, ITrigger
 {
-    protected Trigger(string? source = default, int? line = default) : base(source, line)
+    protected Trigger(string? source = null, int? line = null) : base(source, line)
     {
     }
 
-    protected Trigger(string activityType, int version = 1, string? source = default, int? line = default) : base(activityType, version, source, line)
+    protected Trigger(string activityType, int version = 1, string? source = null, int? line = null) : base(activityType, version, source, line)
     {
     }
 
diff --git a/src/modules/Elsa.Workflows.Core/UIHints/CheckList/DropDownOptionsProviderBase.cs b/src/modules/Elsa.Workflows.Core/UIHints/CheckList/DropDownOptionsProviderBase.cs
new file mode 100644
index 000000000..3d68c217d
--- /dev/null
+++ b/src/modules/Elsa.Workflows.Core/UIHints/CheckList/DropDownOptionsProviderBase.cs
@@ -0,0 +1,35 @@
+using System.Reflection;
+
+namespace Elsa.Workflows.UIHints.CheckList;
+
+/// <summary>
+/// A base class for providing options to populate a checklist UI component. This class is intended to be inherited to implement
+/// custom checklist data logic by overriding the `GetItemsAsync` method.
+/// </summary>
+public abstract class CheckListOptionsProviderBase : IPropertyUIHandler
+{
+    /// <inheritdoc />
+    public async ValueTask<IDictionary<string, object>> GetUIPropertiesAsync(PropertyInfo propertyInfo, object? context, CancellationToken cancellationToken = default)
+    {
+        var items = await GetItemsAsync(propertyInfo, context, cancellationToken);
+        var props = new CheckListProps
+        {
+            CheckList = new()
+            {
+                Items = items.ToList()
+            }
+        };
+
+        var options = new Dictionary<string, object>
+        {
+            [InputUIHints.CheckList] = props
+        };
+
+        return options;
+    }
+
+    /// <summary>
+    /// Implement this to provide items to the dropdown list.
+    /// </summary>
+    protected abstract ValueTask<ICollection<CheckListItem>> GetItemsAsync(PropertyInfo propertyInfo, object? context, CancellationToken cancellationToken);
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Core/UIHints/CheckList/StaticCheckListOptionsProvider.cs b/src/modules/Elsa.Workflows.Core/UIHints/CheckList/StaticCheckListOptionsProvider.cs
index 38426e266..52ede3106 100644
--- a/src/modules/Elsa.Workflows.Core/UIHints/CheckList/StaticCheckListOptionsProvider.cs
+++ b/src/modules/Elsa.Workflows.Core/UIHints/CheckList/StaticCheckListOptionsProvider.cs
@@ -25,7 +25,7 @@ public class StaticCheckListOptionsProvider : IPropertyUIHandler
 
         var props = new CheckListProps
         {
-            CheckList = new CheckList
+            CheckList = new()
             {
                 Items = selectListItems.ToList() 
             }
diff --git a/src/modules/Elsa.Workflows.Management/Contracts/IWorkflowDefinitionPublisher.cs b/src/modules/Elsa.Workflows.Management/Contracts/IWorkflowDefinitionPublisher.cs
index 40c767e3e..c9df69142 100644
--- a/src/modules/Elsa.Workflows.Management/Contracts/IWorkflowDefinitionPublisher.cs
+++ b/src/modules/Elsa.Workflows.Management/Contracts/IWorkflowDefinitionPublisher.cs
@@ -17,7 +17,16 @@ public interface IWorkflowDefinitionPublisher
     /// </summary>
     /// <param name="root">Optionally provide the root activity. If not specified, <see cref="Sequence" /> will be used/></param>
     /// <returns>The new workflow definition.</returns>
-    WorkflowDefinition New(IActivity? root = default);
+    [Obsolete( "Use NewAsync instead.", error: false)]
+    WorkflowDefinition New(IActivity? root = null);
+    
+    /// <summary>
+    /// Creates a new workflow definition.
+    /// </summary>
+    /// <param name="root">Optionally provide the root activity. If not specified, <see cref="Sequence" /> will be used/></param>
+    /// <param name="cancellationToken">A cancellation token</param>
+    /// <returns>The new workflow definition.</returns>
+    Task<WorkflowDefinition> NewAsync(IActivity? root = null, CancellationToken cancellationToken = default);
 
     /// <summary>
     /// Publishes a workflow definition.
diff --git a/src/modules/Elsa.Workflows.Management/Extensions/WorkflowDefinitionHandleExtensions.cs b/src/modules/Elsa.Workflows.Management/Extensions/WorkflowDefinitionHandleExtensions.cs
new file mode 100644
index 000000000..9d277b76c
--- /dev/null
+++ b/src/modules/Elsa.Workflows.Management/Extensions/WorkflowDefinitionHandleExtensions.cs
@@ -0,0 +1,17 @@
+using Elsa.Workflows.Management.Filters;
+using Elsa.Workflows.Models;
+
+namespace Elsa.Workflows.Management;
+
+public static class WorkflowDefinitionHandleExtensions
+{
+    public static WorkflowDefinitionFilter ToFilter(this WorkflowDefinitionHandle handle)
+    {
+        return new()
+        {
+            DefinitionId = handle.DefinitionId,
+            Id = handle.DefinitionVersionId,
+            VersionOptions = handle.VersionOptions
+        };
+    }
+}
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Management/Extensions/WorkflowInstanceStoreExtensions.cs b/src/modules/Elsa.Workflows.Management/Extensions/WorkflowInstanceStoreExtensions.cs
index f41d0325d..d26e07ea4 100644
--- a/src/modules/Elsa.Workflows.Management/Extensions/WorkflowInstanceStoreExtensions.cs
+++ b/src/modules/Elsa.Workflows.Management/Extensions/WorkflowInstanceStoreExtensions.cs
@@ -15,6 +15,6 @@ public static class WorkflowInstanceStoreExtensions
     /// </summary>
     public static async ValueTask<WorkflowInstance?> FindAsync(this IWorkflowInstanceStore store, string id, CancellationToken cancellationToken = default)
     {
-        return await store.FindAsync(new WorkflowInstanceFilter{ Id = id }, cancellationToken);
+        return await store.FindAsync(new() { Id = id }, cancellationToken);
     }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Management/Features/CachingWorkflowDefinitionsFeature.cs b/src/modules/Elsa.Workflows.Management/Features/CachingWorkflowDefinitionsFeature.cs
index d9d666b75..df939d6cc 100644
--- a/src/modules/Elsa.Workflows.Management/Features/CachingWorkflowDefinitionsFeature.cs
+++ b/src/modules/Elsa.Workflows.Management/Features/CachingWorkflowDefinitionsFeature.cs
@@ -1,7 +1,7 @@
 using Elsa.Features.Abstractions;
 using Elsa.Features.Services;
 using Elsa.Workflows.Management.Handlers;
-using Elsa.Workflows.Management.Handlers.Notification;
+using Elsa.Workflows.Management.Handlers.Notifications;
 using Elsa.Workflows.Management.Services;
 using Elsa.Workflows.Management.Stores;
 using Microsoft.Extensions.DependencyInjection;
diff --git a/src/modules/Elsa.Workflows.Management/Features/WorkflowDefinitionsFeature.cs b/src/modules/Elsa.Workflows.Management/Features/WorkflowDefinitionsFeature.cs
index 916ad3c67..8425c991d 100644
--- a/src/modules/Elsa.Workflows.Management/Features/WorkflowDefinitionsFeature.cs
+++ b/src/modules/Elsa.Workflows.Management/Features/WorkflowDefinitionsFeature.cs
@@ -1,9 +1,5 @@
 using Elsa.Features.Abstractions;
 using Elsa.Features.Services;
-using Elsa.Mediator.Contracts;
-using Elsa.Workflows.Management.Entities;
-using Elsa.Workflows.Management.Handlers.Request;
-using Elsa.Workflows.Management.Requests;
 using Elsa.Workflows.Management.Stores;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -12,25 +8,17 @@ namespace Elsa.Workflows.Management.Features;
 /// <summary>
 /// Configures workflow definition storage.
 /// </summary>
-public class WorkflowDefinitionsFeature : FeatureBase
+public class WorkflowDefinitionsFeature(IModule module) : FeatureBase(module)
 {
-    /// <inheritdoc />
-    public WorkflowDefinitionsFeature(IModule module) : base(module)
-    {
-    }
-    
     /// <summary>
     /// The factory to create new instances of <see cref="IWorkflowDefinitionStore"/>.
     /// </summary>
     public Func<IServiceProvider, IWorkflowDefinitionStore> WorkflowDefinitionStore { get; set; } = sp => sp.GetRequiredService<MemoryWorkflowDefinitionStore>();
-    public Func<Type> FindWorkflowDefinitionHandler { get; set; } = () => typeof(FindWorkflowDefinitionHandler);
 
     /// <inheritdoc />
     public override void Apply()
     {
         Services
-            .AddScoped(WorkflowDefinitionStore)
-            .AddScoped(typeof(IRequestHandler), FindWorkflowDefinitionHandler())
-            ;
+            .AddScoped(WorkflowDefinitionStore);
     }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Management/Features/WorkflowManagementFeature.cs b/src/modules/Elsa.Workflows.Management/Features/WorkflowManagementFeature.cs
index 016bdb488..71bf63fe0 100644
--- a/src/modules/Elsa.Workflows.Management/Features/WorkflowManagementFeature.cs
+++ b/src/modules/Elsa.Workflows.Management/Features/WorkflowManagementFeature.cs
@@ -18,7 +18,7 @@ using Elsa.Workflows.Management.Compression;
 using Elsa.Workflows.Management.Contracts;
 using Elsa.Workflows.Management.Entities;
 using Elsa.Workflows.Management.Handlers;
-using Elsa.Workflows.Management.Handlers.Notification;
+using Elsa.Workflows.Management.Handlers.Notifications;
 using Elsa.Workflows.Management.Mappers;
 using Elsa.Workflows.Management.Materializers;
 using Elsa.Workflows.Management.Models;
@@ -41,8 +41,8 @@ namespace Elsa.Workflows.Management.Features;
 [DependsOn(typeof(WorkflowsFeature))]
 [DependsOn(typeof(WorkflowDefinitionsFeature))]
 [DependsOn(typeof(WorkflowInstancesFeature))]
-[PublicAPI]
-public class WorkflowManagementFeature : FeatureBase
+[UsedImplicitly]
+public class WorkflowManagementFeature(IModule module) : FeatureBase(module)
 {
     private const string PrimitivesCategory = "Primitives";
     private const string LookupsCategory = "Lookups";
@@ -50,15 +50,12 @@ public class WorkflowManagementFeature : FeatureBase
     private const string DataCategory = "Data";
     private const string SystemCategory = "System";
 
+    private Func<IServiceProvider, IWorkflowDefinitionPublisher> _workflowDefinitionPublisher = sp => ActivatorUtilities.CreateInstance<WorkflowDefinitionPublisher>(sp);
+
     private string CompressionAlgorithm { get; set; } = nameof(None);
     private LogPersistenceMode LogPersistenceMode { get; set; } = LogPersistenceMode.Include;
     private bool IsReadOnlyMode { get; set; }
 
-    /// <inheritdoc />
-    public WorkflowManagementFeature(IModule module) : base(module)
-    {
-    }
-
     /// <summary>
     /// A set of activity types to make available to the system. 
     /// </summary>
@@ -194,6 +191,12 @@ public class WorkflowManagementFeature : FeatureBase
         return this;
     }
 
+    public WorkflowManagementFeature WithWorkflowDefinitionPublisher(Func<IServiceProvider, IWorkflowDefinitionPublisher> workflowDefinitionPublisher)
+    {
+        _workflowDefinitionPublisher = workflowDefinitionPublisher;
+        return this;
+    }
+
     /// <inheritdoc />
     [RequiresUnreferencedCode("The assembly containing the specified marker type will be scanned for activity types.")]
     public override void Configure()
@@ -214,7 +217,7 @@ public class WorkflowManagementFeature : FeatureBase
             .AddScoped<IWorkflowDefinitionService, WorkflowDefinitionService>()
             .AddScoped<IWorkflowSerializer, WorkflowSerializer>()
             .AddScoped<IWorkflowValidator, WorkflowValidator>()
-            .AddScoped<IWorkflowDefinitionPublisher, WorkflowDefinitionPublisher>()
+            .AddScoped(_workflowDefinitionPublisher)
             .AddScoped<IWorkflowDefinitionImporter, WorkflowDefinitionImporter>()
             .AddScoped<IWorkflowDefinitionManager, WorkflowDefinitionManager>()
             .AddScoped<IWorkflowInstanceManager, WorkflowInstanceManager>()
diff --git a/src/modules/Elsa.Workflows.Management/Filters/WorkflowInstanceFilter.cs b/src/modules/Elsa.Workflows.Management/Filters/WorkflowInstanceFilter.cs
index f279df52a..15deb1e41 100644
--- a/src/modules/Elsa.Workflows.Management/Filters/WorkflowInstanceFilter.cs
+++ b/src/modules/Elsa.Workflows.Management/Filters/WorkflowInstanceFilter.cs
@@ -134,7 +134,7 @@ public class WorkflowInstanceFilter
 
         if (TimestampFilters != null)
         {
-            foreach (TimestampFilter timestampFilter in TimestampFilters)
+            foreach (var timestampFilter in TimestampFilters)
             {
                 var column = timestampFilter.Column;
                 var timestamp = timestampFilter.Timestamp;
diff --git a/src/modules/Elsa.Workflows.Management/Handlers/Notification/DeleteWorkflowInstances.cs b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/DeleteWorkflowInstances.cs
similarity index 97%
rename from src/modules/Elsa.Workflows.Management/Handlers/Notification/DeleteWorkflowInstances.cs
rename to src/modules/Elsa.Workflows.Management/Handlers/Notifications/DeleteWorkflowInstances.cs
index 01429d33a..3fec484ce 100644
--- a/src/modules/Elsa.Workflows.Management/Handlers/Notification/DeleteWorkflowInstances.cs
+++ b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/DeleteWorkflowInstances.cs
@@ -3,7 +3,7 @@ using Elsa.Workflows.Management.Filters;
 using Elsa.Workflows.Management.Notifications;
 using JetBrains.Annotations;
 
-namespace Elsa.Workflows.Management.Handlers.Notification;
+namespace Elsa.Workflows.Management.Handlers.Notifications;
 
 /// <summary>
 /// Deletes workflow instances when a workflow definition or version is deleted.
diff --git a/src/modules/Elsa.Workflows.Management/Handlers/Notification/EvictWorkflowDefinitionServiceCache.cs b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/EvictWorkflowDefinitionServiceCache.cs
similarity index 97%
rename from src/modules/Elsa.Workflows.Management/Handlers/Notification/EvictWorkflowDefinitionServiceCache.cs
rename to src/modules/Elsa.Workflows.Management/Handlers/Notifications/EvictWorkflowDefinitionServiceCache.cs
index 3cc7f15da..f3802e958 100644
--- a/src/modules/Elsa.Workflows.Management/Handlers/Notification/EvictWorkflowDefinitionServiceCache.cs
+++ b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/EvictWorkflowDefinitionServiceCache.cs
@@ -2,7 +2,7 @@ using Elsa.Mediator.Contracts;
 using Elsa.Workflows.Management.Notifications;
 using JetBrains.Annotations;
 
-namespace Elsa.Workflows.Management.Handlers.Notification;
+namespace Elsa.Workflows.Management.Handlers.Notifications;
 
 /// <summary>
 /// A workflow definition notifications handler for evicting the cache of the workflow definition service.
diff --git a/src/modules/Elsa.Workflows.Management/Handlers/Notification/RefreshActivityRegistry.cs b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/RefreshActivityRegistry.cs
similarity index 98%
rename from src/modules/Elsa.Workflows.Management/Handlers/Notification/RefreshActivityRegistry.cs
rename to src/modules/Elsa.Workflows.Management/Handlers/Notifications/RefreshActivityRegistry.cs
index bad83d829..87aedf89c 100644
--- a/src/modules/Elsa.Workflows.Management/Handlers/Notification/RefreshActivityRegistry.cs
+++ b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/RefreshActivityRegistry.cs
@@ -5,7 +5,7 @@ using Elsa.Workflows.Management.Entities;
 using Elsa.Workflows.Management.Notifications;
 using JetBrains.Annotations;
 
-namespace Elsa.Workflows.Management.Handlers.Notification;
+namespace Elsa.Workflows.Management.Handlers.Notifications;
 
 /// <summary>
 /// Refreshes the <see cref="IActivityRegistry"/> for the <see cref="WorkflowDefinitionActivityProvider"/> provider whenever an <see cref="WorkflowDefinition"/> is published, retracted or deleted.
diff --git a/src/modules/Elsa.Workflows.Management/Handlers/Notification/UpdateConsumingWorkflows.cs b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/UpdateConsumingWorkflows.cs
similarity index 92%
rename from src/modules/Elsa.Workflows.Management/Handlers/Notification/UpdateConsumingWorkflows.cs
rename to src/modules/Elsa.Workflows.Management/Handlers/Notifications/UpdateConsumingWorkflows.cs
index 1e3819d4b..aee801e10 100644
--- a/src/modules/Elsa.Workflows.Management/Handlers/Notification/UpdateConsumingWorkflows.cs
+++ b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/UpdateConsumingWorkflows.cs
@@ -2,7 +2,7 @@ using Elsa.Extensions;
 using Elsa.Mediator.Contracts;
 using Elsa.Workflows.Management.Notifications;
 
-namespace Elsa.Workflows.Management.Handlers.Notification;
+namespace Elsa.Workflows.Management.Handlers.Notifications;
 
 /// <summary>
 /// Updates consuming workflows when a workflow definition is published.
diff --git a/src/modules/Elsa.Workflows.Management/Handlers/Notification/ValidateWorkflow.cs b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/ValidateWorkflow.cs
similarity index 95%
rename from src/modules/Elsa.Workflows.Management/Handlers/Notification/ValidateWorkflow.cs
rename to src/modules/Elsa.Workflows.Management/Handlers/Notifications/ValidateWorkflow.cs
index 4e3ed5258..e56800f81 100644
--- a/src/modules/Elsa.Workflows.Management/Handlers/Notification/ValidateWorkflow.cs
+++ b/src/modules/Elsa.Workflows.Management/Handlers/Notifications/ValidateWorkflow.cs
@@ -3,7 +3,7 @@ using Elsa.Workflows.Management.Models;
 using Elsa.Workflows.Management.Notifications;
 using Elsa.Workflows.Models;
 
-namespace Elsa.Workflows.Management.Handlers.Notification;
+namespace Elsa.Workflows.Management.Handlers.Notifications;
 
 public class ValidateWorkflow : INotificationHandler<WorkflowDefinitionValidating>
 {
diff --git a/src/modules/Elsa.Workflows.Management/Handlers/Request/FindWorkflowDefinitionHandler.cs b/src/modules/Elsa.Workflows.Management/Handlers/Request/FindWorkflowDefinitionHandler.cs
deleted file mode 100644
index 0febd0442..000000000
--- a/src/modules/Elsa.Workflows.Management/Handlers/Request/FindWorkflowDefinitionHandler.cs
+++ /dev/null
@@ -1,23 +0,0 @@
-using Elsa.Common.Entities;
-using Elsa.Mediator.Contracts;
-using Elsa.Workflows.Management.Entities;
-using Elsa.Workflows.Management.Filters;
-using Elsa.Workflows.Management.Requests;
-
-namespace Elsa.Workflows.Management.Handlers.Request;
-
-public class FindWorkflowDefinitionHandler(IWorkflowDefinitionStore store) : IRequestHandler<FindWorkflowDefinitionRequest, WorkflowDefinition?>
-{
-    public async Task<WorkflowDefinition?> HandleAsync(FindWorkflowDefinitionRequest request, CancellationToken cancellationToken)
-    {
-        var filter = new WorkflowDefinitionFilter
-        {
-            DefinitionId = request.DefinitionId,
-            VersionOptions = request.VersionOptions
-        };
-
-        var order = new WorkflowDefinitionOrder<int>(x => x.Version, OrderDirection.Descending);
-        var definition = (await store.FindManyAsync(filter, order, cancellationToken: cancellationToken)).FirstOrDefault();
-        return definition;
-    }
-}
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Management/Models/SaveWorkflowDefinitionRequest.cs b/src/modules/Elsa.Workflows.Management/Models/SaveWorkflowDefinitionRequest.cs
index fad1f539a..14715b618 100644
--- a/src/modules/Elsa.Workflows.Management/Models/SaveWorkflowDefinitionRequest.cs
+++ b/src/modules/Elsa.Workflows.Management/Models/SaveWorkflowDefinitionRequest.cs
@@ -8,7 +8,7 @@
         /// <summary>
         /// The workflow definition to save.
         /// </summary>
-        public WorkflowDefinitionModel Model { get; set; } = default!;
+        public WorkflowDefinitionModel Model { get; set; } = null!;
 
         /// <summary>
         /// Whether the workflow definition should be published.
diff --git a/src/modules/Elsa.Workflows.Management/Models/WorkflowDefinitionModel.cs b/src/modules/Elsa.Workflows.Management/Models/WorkflowDefinitionModel.cs
index 6b1859334..598155655 100644
--- a/src/modules/Elsa.Workflows.Management/Models/WorkflowDefinitionModel.cs
+++ b/src/modules/Elsa.Workflows.Management/Models/WorkflowDefinitionModel.cs
@@ -7,52 +7,80 @@ namespace Elsa.Workflows.Management.Models;
 /// Represents a serializable workflow definition.
 /// </summary>
 [PublicAPI]
-public record WorkflowDefinitionModel(
-    string Id,
-    string DefinitionId,
-    string? TenantId,
-    string? Name,
-    string? Description,
-    DateTimeOffset CreatedAt,
-    int Version,
-    Version? ToolVersion,
-    ICollection<VariableDefinition>? Variables,
-    ICollection<InputDefinition>? Inputs,
-    ICollection<OutputDefinition>? Outputs,
-    ICollection<string>? Outcomes,
-    IDictionary<string, object>? CustomProperties,
-    bool IsReadonly,
-    bool IsSystem,
-    bool IsLatest,
-    bool IsPublished,
-    WorkflowOptions? Options,
-    [property: Obsolete("Use Options.UsableAsActivity instead")]
-    bool? UsableAsActivity,
-    IActivity? Root
-)
+public class WorkflowDefinitionModel
 {
-    /// <inheritdoc />
-    public WorkflowDefinitionModel() : this(
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!,
-        default!)
+    /// <summary>
+    /// Represents a serializable workflow definition.
+    /// </summary>
+    public WorkflowDefinitionModel() { }
+
+    /// <summary>
+    /// Represents a serializable workflow definition.
+    /// </summary>
+    public WorkflowDefinitionModel(string id,
+        string definitionId,
+        string? tenantId,
+        string? name,
+        string? description,
+        DateTimeOffset createdAt,
+        int version,
+        Version? toolVersion,
+        ICollection<VariableDefinition>? variables,
+        ICollection<InputDefinition>? inputs,
+        ICollection<OutputDefinition>? outputs,
+        ICollection<string>? outcomes,
+        IDictionary<string, object>? customProperties,
+        bool isReadonly,
+        bool isSystem,
+        bool isLatest,
+        bool isPublished,
+        WorkflowOptions? options,
+        bool? usableAsActivity,
+        IActivity? root)
     {
+        Id = id;
+        DefinitionId = definitionId;
+        TenantId = tenantId;
+        Name = name;
+        Description = description;
+        CreatedAt = createdAt;
+        Version = version;
+        ToolVersion = toolVersion;
+        Variables = variables;
+        Inputs = inputs;
+        Outputs = outputs;
+        Outcomes = outcomes;
+        CustomProperties = customProperties;
+        IsReadonly = isReadonly;
+        IsSystem = isSystem;
+        IsLatest = isLatest;
+        IsPublished = isPublished;
+        Options = options;
+        UsableAsActivity = usableAsActivity;
+        Root = root;
     }
+
+    public string Id { get; set; }
+    public string DefinitionId { get; set; }
+    public string? TenantId { get; set; }
+    public string? Name { get; set; }
+    public string? Description { get; set; }
+    public DateTimeOffset CreatedAt { get; set; }
+    public int Version { get; set; }
+    public Version? ToolVersion { get; set; }
+    public ICollection<VariableDefinition>? Variables { get; set; }
+    public ICollection<InputDefinition>? Inputs { get; set; }
+    public ICollection<OutputDefinition>? Outputs { get; set; }
+    public ICollection<string>? Outcomes { get; set; }
+    public IDictionary<string, object>? CustomProperties { get; set; }
+    public bool IsReadonly { get; set; }
+    public bool IsSystem { get; set; }
+    public bool IsLatest { get; set; }
+    public bool IsPublished { get; set; }
+    public WorkflowOptions? Options { get; set; }
+
+    [Obsolete("Use Options.UsableAsActivity instead")]
+    public bool? UsableAsActivity { get; set; }
+
+    public IActivity? Root { get; set; }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Management/Models/WorkflowDefinitionSummary.cs b/src/modules/Elsa.Workflows.Management/Models/WorkflowDefinitionSummary.cs
index 718cdd7e7..2f8a71a45 100644
--- a/src/modules/Elsa.Workflows.Management/Models/WorkflowDefinitionSummary.cs
+++ b/src/modules/Elsa.Workflows.Management/Models/WorkflowDefinitionSummary.cs
@@ -51,12 +51,12 @@ public class WorkflowDefinitionSummary
     /// <summary>
     /// The version ID of the workflow definition.
     /// </summary>
-    public string Id { get; set; } = default!;
+    public string Id { get; set; } = null!;
 
     /// <summary>
     /// The ID of the workflow definition.
     /// </summary>
-    public string DefinitionId { get; set; } = default!;
+    public string DefinitionId { get; set; } = null!;
 
     /// <summary>
     /// The name of the workflow definition.
@@ -96,7 +96,7 @@ public class WorkflowDefinitionSummary
     /// <summary>
     /// The materializer name of the workflow definition.
     /// </summary>
-    public string MaterializerName { get; set; } = default!;
+    public string MaterializerName { get; set; } = null!;
 
     /// <summary>
     /// The timestamp when the workflow definition was created.
diff --git a/src/modules/Elsa.Workflows.Management/Models/WorkflowInstanceSummary.cs b/src/modules/Elsa.Workflows.Management/Models/WorkflowInstanceSummary.cs
index 97346b24b..ef673127a 100644
--- a/src/modules/Elsa.Workflows.Management/Models/WorkflowInstanceSummary.cs
+++ b/src/modules/Elsa.Workflows.Management/Models/WorkflowInstanceSummary.cs
@@ -33,32 +33,31 @@ public class WorkflowInstanceSummary
     /// <summary>
     /// Returns a summary view of the specified <see cref="WorkflowInstance"/>.
     /// </summary>
-    public static Expression<Func<WorkflowInstance, WorkflowInstanceSummary>> FromInstanceExpression()
-        => workflowInstance => new WorkflowInstanceSummary
-        {
-            Id = workflowInstance.Id,
-            DefinitionId = workflowInstance.DefinitionId,
-            DefinitionVersionId = workflowInstance.DefinitionVersionId,
-            Version = workflowInstance.Version,
-            Status = workflowInstance.Status,
-            SubStatus = workflowInstance.SubStatus,
-            CorrelationId = workflowInstance.CorrelationId,
-            Name = workflowInstance.Name,
-            IncidentCount = workflowInstance.IncidentCount,
-            CreatedAt = workflowInstance.CreatedAt,
-            UpdatedAt = workflowInstance.UpdatedAt,
-            FinishedAt = workflowInstance.FinishedAt
-        };
+    public static Expression<Func<WorkflowInstance, WorkflowInstanceSummary>> FromInstanceExpression() => workflowInstance => new()
+    {
+        Id = workflowInstance.Id,
+        DefinitionId = workflowInstance.DefinitionId,
+        DefinitionVersionId = workflowInstance.DefinitionVersionId,
+        Version = workflowInstance.Version,
+        Status = workflowInstance.Status,
+        SubStatus = workflowInstance.SubStatus,
+        CorrelationId = workflowInstance.CorrelationId,
+        Name = workflowInstance.Name,
+        IncidentCount = workflowInstance.IncidentCount,
+        CreatedAt = workflowInstance.CreatedAt,
+        UpdatedAt = workflowInstance.UpdatedAt,
+        FinishedAt = workflowInstance.FinishedAt
+    };
 
 
     /// <summary>The ID of the workflow instance.</summary>
-    public string Id { get; set; } = default!;
+    public string Id { get; set; } = null!;
 
     /// <summary>The ID of the workflow definition.</summary>
-    public string DefinitionId { get; set; } = default!;
+    public string DefinitionId { get; set; } = null!;
 
     /// <summary>The version ID of the workflow definition.</summary>
-    public string DefinitionVersionId { get; set; } = default!;
+    public string DefinitionVersionId { get; set; } = null!;
 
     /// <summary>The version of the workflow definition.</summary>
     public int Version { get; set; }
diff --git a/src/modules/Elsa.Workflows.Management/Requests/FindWorkflowDefinitionRequest.cs b/src/modules/Elsa.Workflows.Management/Requests/FindWorkflowDefinitionRequest.cs
deleted file mode 100644
index a539d5aa5..000000000
--- a/src/modules/Elsa.Workflows.Management/Requests/FindWorkflowDefinitionRequest.cs
+++ /dev/null
@@ -1,12 +0,0 @@
-using Elsa.Common.Models;
-using Elsa.Mediator.Contracts;
-using Elsa.Workflows.Management.Entities;
-
-namespace Elsa.Workflows.Management.Requests;
-
-/// <summary>
-/// A request to find a workflow definition.
-/// </summary>
-/// <param name="DefinitionId">The ID of the workflow definition.</param>
-/// <param name="VersionOptions">The version options.</param>
-public record FindWorkflowDefinitionRequest(string DefinitionId, VersionOptions VersionOptions) : IRequest<WorkflowDefinition?>;
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionImporter.cs b/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionImporter.cs
index b63260be4..4081b3b2b 100644
--- a/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionImporter.cs
+++ b/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionImporter.cs
@@ -43,7 +43,7 @@ namespace Elsa.Workflows.Management.Services
             // Create a new workflow in case no existing definition was found.
             if (isNew)
             {
-                draft = _workflowDefinitionPublisher.New();
+                draft = await _workflowDefinitionPublisher.NewAsync(cancellationToken: cancellationToken);
 
                 if (!string.IsNullOrWhiteSpace(definitionId))
                     draft.DefinitionId = definitionId;
diff --git a/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionPublisher.cs b/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionPublisher.cs
index ab60f6558..88640c69d 100644
--- a/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionPublisher.cs
+++ b/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionPublisher.cs
@@ -3,13 +3,12 @@ using Elsa.Common.Entities;
 using Elsa.Common.Models;
 using Elsa.Mediator.Contracts;
 using Elsa.Workflows.Activities;
-using Elsa.Workflows.Management.Activities.WorkflowDefinitionActivity;
 using Elsa.Workflows.Management.Entities;
 using Elsa.Workflows.Management.Filters;
 using Elsa.Workflows.Management.Materializers;
 using Elsa.Workflows.Management.Models;
 using Elsa.Workflows.Management.Notifications;
-using Elsa.Workflows.Management.Requests;
+using Elsa.Workflows.Models;
 
 namespace Elsa.Workflows.Management.Services;
 
@@ -18,9 +17,9 @@ public class WorkflowDefinitionPublisher(
     IWorkflowDefinitionService workflowDefinitionService,
     IWorkflowDefinitionStore workflowDefinitionStore,
     IWorkflowValidator workflowValidator,
-    INotificationSender notificationSender,
     IIdentityGenerator identityGenerator,
     IActivitySerializer activitySerializer,
+    IMediator mediator,
     ISystemClock systemClock)
     : IWorkflowDefinitionPublisher
 {
@@ -45,16 +44,34 @@ public class WorkflowDefinitionPublisher(
         };
     }
 
+    public Task<WorkflowDefinition> NewAsync(IActivity? root = null, CancellationToken cancellationToken = default)
+    {
+        root ??= new Sequence();
+        var id = identityGenerator.GenerateId();
+        var definitionId = identityGenerator.GenerateId();
+        const int version = 1;
+
+        var workflowDefinition = new WorkflowDefinition
+        {
+            Id = id,
+            DefinitionId = definitionId,
+            Version = version,
+            IsLatest = true,
+            IsPublished = false,
+            CreatedAt = systemClock.UtcNow,
+            StringData = activitySerializer.Serialize(root),
+            MaterializerName = JsonWorkflowMaterializer.MaterializerName
+        };
+        
+        return Task.FromResult(workflowDefinition);
+    }
+
     /// <inheritdoc />
     public async Task<PublishWorkflowDefinitionResult> PublishAsync(string definitionId, CancellationToken cancellationToken = default)
     {
-        var filter = new WorkflowDefinitionFilter
-        {
-            DefinitionId = definitionId,
-            VersionOptions = VersionOptions.Latest
-        };
+        var filter = WorkflowDefinitionHandle.ByDefinitionId(definitionId, VersionOptions.Latest).ToFilter();
         var definition = await workflowDefinitionStore.FindAsync(filter, cancellationToken);
-
+        
         if (definition == null)
             return new(false, new List<WorkflowValidationError>
             {
@@ -73,16 +90,15 @@ public class WorkflowDefinitionPublisher(
         if (validationErrors.Any())
             return new(false, validationErrors, new([]));
 
-        await notificationSender.SendAsync(new WorkflowDefinitionPublishing(definition), cancellationToken);
+        await mediator.SendAsync(new WorkflowDefinitionPublishing(definition), cancellationToken);
         var definitionId = definition.DefinitionId;
 
         // Reset current latest and published definitions.
-        var filter = new WorkflowDefinitionFilter
+        var publishedWorkflows = await workflowDefinitionStore.FindManyAsync(new()
         {
             DefinitionId = definitionId,
             VersionOptions = VersionOptions.LatestOrPublished
-        };
-        var publishedWorkflows = await workflowDefinitionStore.FindManyAsync(filter, cancellationToken);
+        }, cancellationToken);
 
         foreach (var publishedAndOrLatestWorkflow in publishedWorkflows)
         {
@@ -92,27 +108,23 @@ public class WorkflowDefinitionPublisher(
             await workflowDefinitionStore.SaveAsync(publishedAndOrLatestWorkflow, cancellationToken);
 
             if (isPublished)
-                await notificationSender.SendAsync(new WorkflowDefinitionVersionRetracted(publishedAndOrLatestWorkflow), cancellationToken);
+                await mediator.SendAsync(new WorkflowDefinitionVersionRetracted(publishedAndOrLatestWorkflow), cancellationToken);
         }
 
-        // Save the new published definition.
+        // Save the newly published definition.
         definition.IsPublished = true;
         definition = Initialize(definition);
         await workflowDefinitionStore.SaveAsync(definition, cancellationToken);
 
         var affectedWorkflows = new AffectedWorkflows(new List<WorkflowDefinition>());
-        await notificationSender.SendAsync(new WorkflowDefinitionPublished(definition, affectedWorkflows), cancellationToken);
+        await mediator.SendAsync(new WorkflowDefinitionPublished(definition, affectedWorkflows), cancellationToken);
         return new(true, validationErrors, affectedWorkflows);
     }
 
     /// <inheritdoc />
     public async Task<WorkflowDefinition?> RetractAsync(string definitionId, CancellationToken cancellationToken = default)
     {
-        var filter = new WorkflowDefinitionFilter
-        {
-            DefinitionId = definitionId,
-            VersionOptions = VersionOptions.Published
-        };
+        var filter = WorkflowDefinitionHandle.ByDefinitionId(definitionId, VersionOptions.Published).ToFilter();
         var definition = await workflowDefinitionStore.FindAsync(filter, cancellationToken);
 
         if (definition == null)
@@ -129,9 +141,9 @@ public class WorkflowDefinitionPublisher(
 
         definition.IsPublished = false;
 
-        await notificationSender.SendAsync(new WorkflowDefinitionRetracting(definition), cancellationToken);
+        await mediator.SendAsync(new WorkflowDefinitionRetracting(definition), cancellationToken);
         await workflowDefinitionStore.SaveAsync(definition, cancellationToken);
-        await notificationSender.SendAsync(new WorkflowDefinitionRetracted(definition), cancellationToken);
+        await mediator.SendAsync(new WorkflowDefinitionRetracted(definition), cancellationToken);
         return definition;
     }
 
@@ -184,10 +196,8 @@ public class WorkflowDefinitionPublisher(
 
         await workflowDefinitionStore.SaveAsync(draft, cancellationToken);
 
-        if (lastVersion is null)
-        {
-            await notificationSender.SendAsync(new WorkflowDefinitionCreated(definition), cancellationToken);
-        }
+        if (lastVersion is null) 
+            await mediator.SendAsync(new WorkflowDefinitionCreated(definition), cancellationToken);
 
         if (lastVersion is { IsPublished: true, IsLatest: true })
         {
diff --git a/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionService.cs b/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionService.cs
index 3ecc175c4..bd3435846 100644
--- a/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionService.cs
+++ b/src/modules/Elsa.Workflows.Management/Services/WorkflowDefinitionService.cs
@@ -19,40 +19,30 @@ public class WorkflowDefinitionService(
         var materializer = workflowMaterializers.FirstOrDefault(x => x.Name == definition.MaterializerName);
 
         if (materializer == null)
-            throw new Exception("Provider not found");
+            throw new("Provider not found");
 
         var workflow = await materializer.MaterializeAsync(definition, cancellationToken);
         return await workflowGraphBuilder.BuildAsync(workflow, cancellationToken);
     }
 
     /// <inheritdoc />
-    public async Task<WorkflowDefinition?> FindWorkflowDefinitionAsync(string definitionId, VersionOptions versionOptions, CancellationToken cancellationToken = default)
+    public Task<WorkflowDefinition?> FindWorkflowDefinitionAsync(string definitionId, VersionOptions versionOptions, CancellationToken cancellationToken = default)
     {
-        var filter = new WorkflowDefinitionFilter
-        {
-            DefinitionId = definitionId,
-            VersionOptions = versionOptions
-        };
-        return await workflowDefinitionStore.FindAsync(filter, cancellationToken);
+        var handle = WorkflowDefinitionHandle.ByDefinitionId(definitionId, versionOptions);
+        return FindWorkflowDefinitionAsync(handle, cancellationToken);
     }
 
     /// <inheritdoc />
-    public async Task<WorkflowDefinition?> FindWorkflowDefinitionAsync(string definitionVersionId, CancellationToken cancellationToken = default)
+    public Task<WorkflowDefinition?> FindWorkflowDefinitionAsync(string definitionVersionId, CancellationToken cancellationToken = default)
     {
-        var filter = new WorkflowDefinitionFilter
-        {
-            Id = definitionVersionId
-        };
-        return await workflowDefinitionStore.FindAsync(filter, cancellationToken);
+        var handle = WorkflowDefinitionHandle.ByDefinitionVersionId(definitionVersionId);
+        return FindWorkflowDefinitionAsync(handle, cancellationToken);
     }
 
     /// <inheritdoc />
     public async Task<WorkflowDefinition?> FindWorkflowDefinitionAsync(WorkflowDefinitionHandle handle, CancellationToken cancellationToken = default)
     {
-        var filter = new WorkflowDefinitionFilter
-        {
-            DefinitionHandle = handle
-        };
+        var filter = handle.ToFilter();
         return await workflowDefinitionStore.FindAsync(filter, cancellationToken);
     }
 
@@ -87,12 +77,12 @@ public class WorkflowDefinitionService(
     /// <inheritdoc />
     public async Task<WorkflowGraph?> FindWorkflowGraphAsync(WorkflowDefinitionHandle definitionHandle, CancellationToken cancellationToken = default)
     {
-        var filter = new WorkflowDefinitionFilter
-        {
-            DefinitionHandle = definitionHandle
-        };
+        var definition = await FindWorkflowDefinitionAsync(definitionHandle, cancellationToken);
 
-        return await FindWorkflowGraphAsync(filter, cancellationToken);
+        if (definition == null)
+            return null;
+
+        return await MaterializeWorkflowAsync(definition, cancellationToken);
     }
 
     /// <inheritdoc />
diff --git a/src/modules/Elsa.Workflows.Runtime/Entities/StoredTrigger.cs b/src/modules/Elsa.Workflows.Runtime/Entities/StoredTrigger.cs
index 75fe494d6..d404fbfb9 100644
--- a/src/modules/Elsa.Workflows.Runtime/Entities/StoredTrigger.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Entities/StoredTrigger.cs
@@ -10,22 +10,22 @@ public class StoredTrigger : Entity
     /// <summary>
     /// The ID of the workflow definition.
     /// </summary>
-    public string WorkflowDefinitionId { get; set; } = default!;
+    public string WorkflowDefinitionId { get; set; } = null!;
     
     /// <summary>
     /// The version ID of the workflow definition.
     /// </summary>
-    public string WorkflowDefinitionVersionId { get; set; } = default!;
+    public string WorkflowDefinitionVersionId { get; set; } = null!;
     
     /// <summary>
     /// The name of the trigger.
     /// </summary>
-    public string Name { get; set; } = default!;
+    public string Name { get; set; } = null!;
     
     /// <summary>
     /// The ID of the activity associated with the trigger.
     /// </summary>
-    public string ActivityId { get; set; } = default!;
+    public string ActivityId { get; set; } = null!;
     
     /// <summary>
     /// The hash of the trigger.
diff --git a/src/modules/Elsa.Workflows.Runtime/Entities/WorkflowExecutionLogRecord.cs b/src/modules/Elsa.Workflows.Runtime/Entities/WorkflowExecutionLogRecord.cs
index 87460d6b6..54c412db1 100644
--- a/src/modules/Elsa.Workflows.Runtime/Entities/WorkflowExecutionLogRecord.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Entities/WorkflowExecutionLogRecord.cs
@@ -11,17 +11,17 @@ public class WorkflowExecutionLogRecord : Entity, ILogRecord
     /// <summary>
     /// The ID of the workflow definition.
     /// </summary>
-    public string WorkflowDefinitionId { get; set; } = default!;
+    public string WorkflowDefinitionId { get; set; } = null!;
     
     /// <summary>
     /// The version ID of the workflow definition.
     /// </summary>
-    public string WorkflowDefinitionVersionId { get; set; } = default!;
+    public string WorkflowDefinitionVersionId { get; set; } = null!;
     
     /// <summary>
     /// The ID of the workflow instance.
     /// </summary>
-    public string WorkflowInstanceId { get; set; } = default!;
+    public string WorkflowInstanceId { get; set; } = null!;
     
     /// <summary>
     /// The version of the workflow definition.
@@ -31,7 +31,7 @@ public class WorkflowExecutionLogRecord : Entity, ILogRecord
     /// <summary>
     /// The ID of the activity instance.
     /// </summary>
-    public string ActivityInstanceId { get; set; } = default!;
+    public string ActivityInstanceId { get; set; } = null!;
     
     /// <summary>
     /// The ID of the parent activity instance.
@@ -41,12 +41,12 @@ public class WorkflowExecutionLogRecord : Entity, ILogRecord
     /// <summary>
     /// The ID of the activity.
     /// </summary>
-    public string ActivityId { get; set; } = default!;
+    public string ActivityId { get; set; } = null!;
     
     /// <summary>
     /// The type of the activity.
     /// </summary>
-    public string ActivityType { get; set; } = default!;
+    public string ActivityType { get; set; } = null!;
 
     /// <summary>
     /// The version of the activity type.
@@ -61,7 +61,7 @@ public class WorkflowExecutionLogRecord : Entity, ILogRecord
     /// <summary>
     /// The unique ID of the node within the workflow graph.
     /// </summary>
-    public string ActivityNodeId { get; set; } = default!;
+    public string ActivityNodeId { get; set; } = null!;
 
     /// <summary>
     /// The time stamp of the log entry.
diff --git a/src/modules/Elsa.Workflows.Runtime/Services/TaskReporter.cs b/src/modules/Elsa.Workflows.Runtime/Services/TaskReporter.cs
index 560276b7e..54f86614f 100644
--- a/src/modules/Elsa.Workflows.Runtime/Services/TaskReporter.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Services/TaskReporter.cs
@@ -11,9 +11,9 @@ public class TaskReporter(IBookmarkQueue bookmarkQueue, IStimulusHasher stimulus
     private static readonly string ActivityTypeName = ActivityTypeNameHelper.GenerateTypeName<RunTask>();
     
     /// <inheritdoc />
-    public async Task ReportCompletionAsync(string taskId, object? result = default, CancellationToken cancellationToken = default)
+    public async Task ReportCompletionAsync(string taskId, object? result = null, CancellationToken cancellationToken = default)
     {
-        var stimulus = new RunTaskStimulus(taskId, default!);
+        var stimulus = new RunTaskStimulus(taskId, null!);
 
         var input = new Dictionary<string, object>
         {
@@ -24,7 +24,7 @@ public class TaskReporter(IBookmarkQueue bookmarkQueue, IStimulusHasher stimulus
         {
             ActivityTypeName = ActivityTypeName,
             StimulusHash = stimulusHasher.Hash(ActivityTypeName, stimulus),
-            Options = new ResumeBookmarkOptions
+            Options = new()
             {
                 Input = input
             }
diff --git a/src/modules/Elsa/Extensions/DependencyInjectionExtensions.cs b/src/modules/Elsa/Extensions/DependencyInjectionExtensions.cs
index 51805f5a2..53b363962 100644
--- a/src/modules/Elsa/Extensions/DependencyInjectionExtensions.cs
+++ b/src/modules/Elsa/Extensions/DependencyInjectionExtensions.cs
@@ -15,10 +15,10 @@ public static class ModuleExtensions
     /// <summary>
     /// Creates a new Elsa module and adds the <see cref="ElsaFeature"/> to it.
     /// </summary>
-    public static IModule AddElsa(this IServiceCollection services, Action<IModule>? configure = default)
+    public static IModule AddElsa(this IServiceCollection services, Action<IModule>? configure = null)
     {
         var module = services.GetOrCreateModule();
-        module.Configure<AppFeature>(app => app.Configurator = configure);
+        module.Configure<AppFeature>(app => app.Configurator += configure);
         module.Apply();
         
         return module;
@@ -27,7 +27,7 @@ public static class ModuleExtensions
     /// <summary>
     /// Configures the Elsa module.
     /// </summary>
-    public static IModule ConfigureElsa(this IServiceCollection services, Action<IModule>? configure = default)
+    public static IModule ConfigureElsa(this IServiceCollection services, Action<IModule>? configure = null)
     {
         var module = services.GetOrCreateModule();
         
diff --git a/src/modules/Elsa/Features/AppFeature.cs b/src/modules/Elsa/Features/AppFeature.cs
index 0a72a3396..775b19981 100644
--- a/src/modules/Elsa/Features/AppFeature.cs
+++ b/src/modules/Elsa/Features/AppFeature.cs
@@ -8,13 +8,8 @@ namespace Elsa.Features;
 /// A wrapper for invoking application-specific configuration, ensuring it is invoked lastly.
 /// </summary>
 [DependsOn(typeof(ElsaFeature))]
-public class AppFeature : FeatureBase
+public class AppFeature(IModule module) : FeatureBase(module)
 {
-    /// <inheritdoc />
-    public AppFeature(IModule module) : base(module)
-    {
-    }
-    
     /// <summary>
     /// The configurator to invoke.
     /// </summary>