Evolve to only make IServiceProvider accessible to InterceptActivity

src/Temporalio.Extensions.Hosting/ServiceProviderExtensions.cs

@@ -68,13 +68,7 @@ public static ActivityDefinition CreateTemporalActivityDefinition(
 #else
                 var scope = provider.CreateScope();
 #endif
-                IServiceProviderAccessor? serviceProviderAccessor =
-                    scope.ServiceProvider.GetService<IServiceProviderAccessor>();
-
-                if (serviceProviderAccessor is not null)
-                {
-                    serviceProviderAccessor.ServiceProvider = scope.ServiceProvider;
-                }
+                ActivityServiceProviderAccessor.AsyncLocalCurrent.Value = scope.ServiceProvider;
 
                 try
                 {
@@ -119,10 +113,7 @@ public static ActivityDefinition CreateTemporalActivityDefinition(
                 }
                 finally
                 {
-                    if (serviceProviderAccessor is not null)
-                    {
-                        serviceProviderAccessor.ServiceProvider = null;
-                    }
+                    ActivityServiceProviderAccessor.AsyncLocalCurrent.Value = null;
 #if NET6_0_OR_GREATER
                     await scope.DisposeAsync().ConfigureAwait(false);
 #else

src/Temporalio/Activities/ActivityServiceProviderAccessor.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Threading;
+
+namespace Temporalio.Activities
+{
+    /// <summary>
+    /// Provides access to the scoped <see cref="IServiceProvider" /> for the
+    /// current activity execution context.
+    /// </summary>
+    public static class ActivityServiceProviderAccessor
+    {
+        /// <summary>
+        /// Gets the async local current value.
+        /// </summary>
+        public static readonly AsyncLocal<IServiceProvider?> AsyncLocalCurrent = new();
+
+        /// <summary>
+        /// Gets a value indicating whether the current code is running in an
+        /// activity with a service provider.
+        /// </summary>
+        public static bool HasCurrent => AsyncLocalCurrent.Value is not null;
+
+        /// <summary>
+        /// Gets the current activity's scoped <see cref="IServiceProvider"/>.
+        /// </summary>
+        /// <exception cref="InvalidOperationException">If no <see
+        /// cref="IServiceProvider"/>  is available.</exception>
+        public static IServiceProvider Current => AsyncLocalCurrent.Value ??
+            throw new InvalidOperationException("No current service provider");
+    }
+}

src/Temporalio/Worker/Interceptors/IWorkerInterceptorWithServiceProvider.cs

@@ -0,0 +1,31 @@
+using System;
+#if NETCOREAPP3_0_OR_GREATER
+using Temporalio.Activities;
+#endif
+
+namespace Temporalio.Worker.Interceptors
+{
+    /// <summary>
+    /// Interceptor for intercepting activities and workflows providing activity
+    /// interceptors with access to the service provider.
+    /// </summary>
+    public interface IWorkerInterceptorWithServiceProvider : IWorkerInterceptor
+    {
+        /// <summary>
+        /// Create an activity inbound interceptor to intercept calls, with
+        /// access to the service provider for the current activity.
+        /// </summary>
+        /// <param name="serviceProvider">Service provider instance scoped to the current activity.</param>
+        /// <param name="nextInterceptor">The next interceptor in the chain to call.</param>
+        /// <returns>Created interceptor.</returns>
+#if NETCOREAPP3_0_OR_GREATER
+        ActivityInboundInterceptor InterceptActivity(IServiceProvider serviceProvider, ActivityInboundInterceptor nextInterceptor) =>
+            nextInterceptor;
+
+        ActivityInboundInterceptor InterceptActivity(ActivityInboundInterceptor nextInterceptor) =>
+            InterceptActivity(ActivityServiceProviderAccessor.Current, nextInterceptor);
+#else
+        ActivityInboundInterceptor InterceptActivity(IServiceProvider serviceProvider, ActivityInboundInterceptor nextInterceptor);
+#endif
+    }
+}