Automatic registration of workflows and activities

src/Dapr.Workflow.Abstractions/AssemblyInfo.cs

@@ -0,0 +1,20 @@
+// ------------------------------------------------------------------------
+// Copyright 2026 The Dapr Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//     http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// ------------------------------------------------------------------------
+
+using System.Runtime.CompilerServices;
+
+// Allow Dapr.Workflow to call internal members (e.g. WorkflowAutoRegistry.Apply).
+[assembly: InternalsVisibleTo("Dapr.Workflow, PublicKey=0024000004800000940000000602000000240000525341310004000001000100b1f597635c44597fcecb493e2b1327033b29b1a98ac956a1a538664b68f87d45fbaada0438a15a6265e62864947cc067d8da3a7d93c5eb2fcbb850e396c8684dba74ea477d82a1bbb18932c0efb30b64ff1677f85ae833818707ac8b49ad8062ca01d2c89d8ab1843ae73e8ba9649cd28666b539444dcdee3639f95e2a099bb2")]
+
+// Allow test projects to call internal members.
+[assembly: InternalsVisibleTo("Dapr.Workflow.Abstractions.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100b1f597635c44597fcecb493e2b1327033b29b1a98ac956a1a538664b68f87d45fbaada0438a15a6265e62864947cc067d8da3a7d93c5eb2fcbb850e396c8684dba74ea477d82a1bbb18932c0efb30b64ff1677f85ae833818707ac8b49ad8062ca01d2c89d8ab1843ae73e8ba9649cd28666b539444dcdee3639f95e2a099bb2")]

src/Dapr.Workflow.Abstractions/WorkflowAutoRegistry.cs

@@ -0,0 +1,88 @@
+// ------------------------------------------------------------------------
+// Copyright 2026 The Dapr Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//     http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// ------------------------------------------------------------------------
+
+using System.Runtime.CompilerServices;
+
+namespace Dapr.Workflow;
+
+/// <summary>
+/// Static registration point for source-generated workflow and activity auto-registrations.
+/// The Dapr Workflow source generator emits a <c>[ModuleInitializer]</c> that calls
+/// <see cref="Register"/> at process startup. <c>AddDaprWorkflow()</c> then calls
+/// <see cref="Apply"/> to push all discovered types into <see cref="WorkflowRuntimeOptions"/>
+/// before the workflow factory is built — meaning application code never has to call
+/// <c>RegisterWorkflow</c> or <c>RegisterActivity</c> manually.
+/// </summary>
+/// <remarks>
+/// Registrations stored here use first-write-wins semantics (via
+/// <see cref="System.Collections.Concurrent.ConcurrentDictionary{TKey,TValue}.TryAdd"/>
+/// inside <c>WorkflowsFactory</c>), so any explicit registrations made by
+/// the application in its <c>AddDaprWorkflow(configure)</c> callback take precedence over
+/// the auto-discovered ones without conflict.
+/// </remarks>
+public static class WorkflowAutoRegistry
+{
+    private static readonly object SyncLock = new();
+    private static readonly List<Action<WorkflowRuntimeOptions>> Registrations = [];
+    private static readonly HashSet<WorkflowRuntimeOptions> AppliedOptions = new(ReferenceEqualityComparer.Instance);
+
+    /// <summary>
+    /// Registers a source-generated auto-registration callback.
+    /// Called from <c>[ModuleInitializer]</c> code emitted by the Dapr Workflow source generator.
+    /// Safe to call from multiple assemblies; duplicate delegates are silently ignored.
+    /// </summary>
+    /// <param name="registration">
+    /// An action that registers discovered workflows and activities with the provided
+    /// <see cref="WorkflowRuntimeOptions"/>.
+    /// </param>
+    public static void Register(Action<WorkflowRuntimeOptions> registration)
+    {
+        ArgumentNullException.ThrowIfNull(registration);
+
+        lock (SyncLock)
+        {
+            if (!Registrations.Contains(registration))
+                Registrations.Add(registration);
+        }
+    }
+
+    /// <summary>
+    /// Applies all source-generated auto-registrations to <paramref name="options"/>.
+    /// Called once per <see cref="WorkflowRuntimeOptions"/> instance (idempotent on repeated calls).
+    /// </summary>
+    internal static void Apply(WorkflowRuntimeOptions options)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+
+        List<Action<WorkflowRuntimeOptions>> snapshot;
+
+        lock (SyncLock)
+        {
+            // Guard against multiple AddDaprWorkflow() calls that share the same options instance.
+            if (!AppliedOptions.Add(options))
+                return;
+
+            snapshot = [.. Registrations];
+        }
+
+        foreach (var registration in snapshot)
+            registration(options);
+    }
+
+    private sealed class ReferenceEqualityComparer : IEqualityComparer<WorkflowRuntimeOptions>
+    {
+        public static readonly ReferenceEqualityComparer Instance = new();
+        public bool Equals(WorkflowRuntimeOptions? x, WorkflowRuntimeOptions? y) => ReferenceEquals(x, y);
+        public int GetHashCode(WorkflowRuntimeOptions obj) => RuntimeHelpers.GetHashCode(obj);
+    }
+}

src/Dapr.Workflow.Versioning.Generators/KnownSymbols.cs

@@ -15,4 +15,7 @@
 
 namespace Dapr.Workflow.Versioning;
 
-internal sealed record KnownSymbols(INamedTypeSymbol? WorkflowBase, INamedTypeSymbol? WorkflowVersionAttribute);
+internal sealed record KnownSymbols(
+    INamedTypeSymbol? WorkflowBase,
+    INamedTypeSymbol? WorkflowVersionAttribute,
+    INamedTypeSymbol? ActivityBase);