diff --git a/src/Grpc/orchestrator_service.proto b/src/Grpc/orchestrator_service.proto
index 1a86c0a27..196c88da6 100644
--- a/src/Grpc/orchestrator_service.proto
+++ b/src/Grpc/orchestrator_service.proto
@@ -276,6 +276,7 @@ message CreateSubOrchestrationAction {
     google.protobuf.StringValue version = 3;
     google.protobuf.StringValue input = 4;
     TraceContext parentTraceContext = 5;
+    map<string, string> tags = 6;
 }
 
 message CreateTimerAction {
@@ -356,6 +357,13 @@ message OrchestratorResponse {
 
     // Whether or not a history is required to complete the original OrchestratorRequest and none was provided.
     bool requiresHistory = 7;
+
+    // True if this is a partial (chunked) completion. The backend must keep the work item open until the final chunk (isPartial=false).
+    bool isPartial = 8;
+
+    // Zero-based position of the current chunk within a chunked completion sequence.
+    // This field is omitted for non-chunked completions.
+    google.protobuf.Int32Value chunkIndex = 9;
 }
 
 message CreateInstanceRequest {
diff --git a/src/Grpc/versions.txt b/src/Grpc/versions.txt
index 69b075cd3..3b7d51216 100644
--- a/src/Grpc/versions.txt
+++ b/src/Grpc/versions.txt
@@ -1,2 +1,2 @@
-# The following files were downloaded from branch main at 2025-11-14 16:36:47 UTC
-https://raw.githubusercontent.com/microsoft/durabletask-protobuf/9f762f1301b91e3e7c736b9c5a29c2e09f2a850e/protos/orchestrator_service.proto
+# The following files were downloaded from branch main at 2025-12-12 01:49:06 UTC
+https://raw.githubusercontent.com/microsoft/durabletask-protobuf/b03c06dea21952dcf2a86551fd761b6b78c64d15/protos/orchestrator_service.proto
diff --git a/src/InProcessTestHost/Sidecar/Grpc/ProtobufUtils.cs b/src/InProcessTestHost/Sidecar/Grpc/ProtobufUtils.cs
index fe4e093cb..8289574b6 100644
--- a/src/InProcessTestHost/Sidecar/Grpc/ProtobufUtils.cs
+++ b/src/InProcessTestHost/Sidecar/Grpc/ProtobufUtils.cs
@@ -288,7 +288,7 @@ public static OrchestratorAction ToOrchestratorAction(Proto.OrchestratorAction a
                     ParentTraceContext = a.CreateSubOrchestration.ParentTraceContext is not null
                         ? new DistributedTraceContext(a.CreateSubOrchestration.ParentTraceContext.TraceParent, a.CreateSubOrchestration.ParentTraceContext.TraceState)
                         : null,
-                    Tags = null, // TODO
+                    Tags = a.CreateSubOrchestration.Tags,
                     Version = a.CreateSubOrchestration.Version,
                 };
             case Proto.OrchestratorAction.OrchestratorActionTypeOneofCase.CreateTimer:
diff --git a/src/Shared/Grpc/ProtoUtils.cs b/src/Shared/Grpc/ProtoUtils.cs
index ab5551d45..2412fac37 100644
--- a/src/Shared/Grpc/ProtoUtils.cs
+++ b/src/Shared/Grpc/ProtoUtils.cs
@@ -373,7 +373,16 @@ internal static P.OrchestratorResponse ConstructOrchestratorResponse(
                         Name = subOrchestrationAction.Name,
                         Version = subOrchestrationAction.Version,
                         ParentTraceContext = CreateTraceContext(),
-                    };
+                    };
+
+                    if (subOrchestrationAction.Tags != null)
+                    {
+                        foreach (KeyValuePair<string, string> tag in subOrchestrationAction.Tags)
+                        {
+                            protoAction.CreateSubOrchestration.Tags[tag.Key] = tag.Value;
+                        }
+                    }
+
                     break;
                 case OrchestratorActionType.CreateTimer:
                     var createTimerAction = (CreateTimerOrchestratorAction)action;
diff --git a/src/Worker/Core/Shims/TaskOrchestrationContextWrapper.cs b/src/Worker/Core/Shims/TaskOrchestrationContextWrapper.cs
index 44430610e..945d6ac5b 100644
--- a/src/Worker/Core/Shims/TaskOrchestrationContextWrapper.cs
+++ b/src/Worker/Core/Shims/TaskOrchestrationContextWrapper.cs
@@ -235,7 +235,8 @@ public override async Task<TResult> CallSubOrchestratorAsync<TResult>(
                         orchestratorName.Name,
                         version,
                         instanceId,
-                        input),
+                        input,
+                        options?.Tags),
                     orchestratorName.Name,
                     handler,
                     default);
@@ -246,7 +247,8 @@ public override async Task<TResult> CallSubOrchestratorAsync<TResult>(
                     orchestratorName.Name,
                     version,
                     instanceId,
-                    input);
+                    input,
+                    options?.Tags);
             }
         }
         catch (global::DurableTask.Core.Exceptions.SubOrchestrationFailedException e)
diff --git a/test/Grpc.IntegrationTests/OrchestrationPatterns.cs b/test/Grpc.IntegrationTests/OrchestrationPatterns.cs
index 72c286f38..be7c0d1dc 100644
--- a/test/Grpc.IntegrationTests/OrchestrationPatterns.cs
+++ b/test/Grpc.IntegrationTests/OrchestrationPatterns.cs
@@ -36,7 +36,7 @@ public async Task EmptyOrchestration()
     }
 
     [Fact]
-    public async Task ScheduleOrchesrationWithTags()
+    public async Task ScheduleOrchestrationWithTags()
     {
         TaskName orchestratorName = nameof(EmptyOrchestration);
         await using HostTestLifetime server = await this.StartWorkerAsync(b =>
@@ -67,6 +67,52 @@ public async Task ScheduleOrchesrationWithTags()
         Assert.Equal("value2", metadata.Tags["tag2"]);
     }
 
+    [Fact]
+    public async Task ScheduleSubOrchestrationWithTags()
+    {
+        TaskName orchestratorName = nameof(ScheduleSubOrchestrationWithTags);
+
+        // Schedule a new orchestration instance with tags
+        SubOrchestrationOptions subOrchestrationOptions = new()
+        {
+            InstanceId = "instance_id",
+            Tags = new Dictionary<string, string>
+            {
+                { "tag1", "value1" },
+                { "tag2", "value2" }
+            }
+        };
+
+        await using HostTestLifetime server = await this.StartWorkerAsync(b =>
+        {
+            b.AddTasks(tasks => tasks.AddOrchestratorFunc<int, int>(orchestratorName, async (ctx, input) =>
+            {
+                int result = 1;
+                if (input < 2)
+                {
+                    // recursively call this same orchestrator
+                    result += await ctx.CallSubOrchestratorAsync<int>(orchestratorName, input: input + 1, subOrchestrationOptions);
+                }
+
+                return result;
+            }));
+        });
+
+
+        await server.Client.ScheduleNewOrchestrationInstanceAsync(orchestratorName, input: 1);
+
+        OrchestrationMetadata metadata = await server.Client.WaitForInstanceCompletionAsync(
+            subOrchestrationOptions.InstanceId, this.TimeoutToken);
+
+        Assert.NotNull(metadata);
+        Assert.Equal(subOrchestrationOptions.InstanceId, metadata.InstanceId);
+        Assert.Equal(OrchestrationRuntimeStatus.Completed, metadata.RuntimeStatus);
+        Assert.NotNull(metadata.Tags);
+        Assert.Equal(2, metadata.Tags.Count);
+        Assert.Equal("value1", metadata.Tags["tag1"]);
+        Assert.Equal("value2", metadata.Tags["tag2"]);
+    }
+
     [Fact]
     public async Task SingleTimer()
     {