diff --git a/src/Client/Core/PurgeInstancesFilter.cs b/src/Client/Core/PurgeInstancesFilter.cs
index 04c7f9c3f..4c20e2cde 100644
--- a/src/Client/Core/PurgeInstancesFilter.cs
+++ b/src/Client/Core/PurgeInstancesFilter.cs
@@ -14,4 +14,16 @@ public record PurgeInstancesFilter(
     DateTimeOffset? CreatedTo = null,
     IEnumerable<OrchestrationRuntimeStatus>? Statuses = null)
 {
+    /// <summary>
+    /// Gets or sets the maximum amount of time to spend purging instances in a single call.
+    /// If <c>null</c> (default), all matching instances are purged with no time limit.
+    /// When set, the purge operation stops deleting additional instances after this duration elapses
+    /// and returns a partial result. Callers can check <see cref="PurgeResult.IsComplete"/> and
+    /// re-invoke the purge to continue where it left off.
+    /// The value of <see cref="PurgeResult.IsComplete"/> depends on the backend implementation:
+    /// it may be <c>false</c> if the purge timed out, <c>true</c> if all instances were purged,
+    /// or <c>null</c> if the backend does not support reporting completion status.
+    /// Not all backends support this property; those that do not will ignore it.
+    /// </summary>
+    public TimeSpan? Timeout { get; init; }
 }
diff --git a/src/Client/Grpc/GrpcDurableTaskClient.cs b/src/Client/Grpc/GrpcDurableTaskClient.cs
index eba7b9bc0..46e4dd2ed 100644
--- a/src/Client/Grpc/GrpcDurableTaskClient.cs
+++ b/src/Client/Grpc/GrpcDurableTaskClient.cs
@@ -488,6 +488,19 @@ public override Task<PurgeResult> PurgeAllInstancesAsync(
             request.PurgeInstanceFilter.RuntimeStatus.AddRange(filter.Statuses.Select(x => x.ToGrpcStatus()));
         }
 
+        if (filter?.Timeout is not null)
+        {
+            if (filter.Timeout.Value <= TimeSpan.Zero)
+            {
+                throw new ArgumentOutOfRangeException(
+                    nameof(filter),
+                    filter.Timeout.Value,
+                    "PurgeInstancesFilter.Timeout must be a positive TimeSpan.");
+            }
+
+            request.PurgeInstanceFilter.Timeout = Google.Protobuf.WellKnownTypes.Duration.FromTimeSpan(filter.Timeout.Value);
+        }
+
         return this.PurgeInstancesCoreAsync(request, cancellation);
     }
 
diff --git a/src/Grpc/orchestrator_service.proto b/src/Grpc/orchestrator_service.proto
index 0c34d986d..3d7c8eb49 100644
--- a/src/Grpc/orchestrator_service.proto
+++ b/src/Grpc/orchestrator_service.proto
@@ -25,6 +25,7 @@ message ActivityRequest {
     OrchestrationInstance orchestrationInstance = 4;
     int32 taskId = 5;
     TraceContext parentTraceContext = 6;
+    map<string, string> tags = 7;
 }
 
 message ActivityResponse {
@@ -320,6 +321,10 @@ message SendEntityMessageAction {
     }
 }
 
+message RewindOrchestrationAction {
+    repeated HistoryEvent newHistory = 1;
+}
+
 message OrchestratorAction {
     int32 id = 1;
     oneof orchestratorActionType {
@@ -330,6 +335,7 @@ message OrchestratorAction {
         CompleteOrchestrationAction completeOrchestration = 6;
         TerminateOrchestrationAction terminateOrchestration = 7;
         SendEntityMessageAction sendEntityMessage = 8;
+        RewindOrchestrationAction rewindOrchestration = 9;
     }
 }
 
@@ -517,6 +523,7 @@ message PurgeInstanceFilter {
     google.protobuf.Timestamp createdTimeFrom = 1;
     google.protobuf.Timestamp createdTimeTo = 2;
     repeated OrchestrationStatus runtimeStatus = 3;
+    google.protobuf.Duration timeout = 4;
 }
 
 message PurgeInstancesResponse {
diff --git a/src/Grpc/versions.txt b/src/Grpc/versions.txt
index 743f3f8bd..b781a3903 100644
--- a/src/Grpc/versions.txt
+++ b/src/Grpc/versions.txt
@@ -1,2 +1,2 @@
-# The following files were downloaded from branch main at 2026-02-24 00:01:28 UTC
-https://raw.githubusercontent.com/microsoft/durabletask-protobuf/1caadbd7ecfdf5f2309acbeac28a3e36d16aa156/protos/orchestrator_service.proto
+# The following files were downloaded from branch main at 2026-04-06 16:10:08 UTC
+https://raw.githubusercontent.com/microsoft/durabletask-protobuf/bcf5af6a22caa70601bfc909918ba5937484279f/protos/orchestrator_service.proto
diff --git a/test/Client/Grpc.Tests/GrpcDurableTaskClientTests.cs b/test/Client/Grpc.Tests/GrpcDurableTaskClientTests.cs
index 8d098106c..f3da85ebf 100644
--- a/test/Client/Grpc.Tests/GrpcDurableTaskClientTests.cs
+++ b/test/Client/Grpc.Tests/GrpcDurableTaskClientTests.cs
@@ -127,5 +127,44 @@ public async Task ScheduleNewOrchestrationInstanceAsync_ValidDedupeStatus_DoesNo
         var exception = await act.Should().ThrowAsync<Exception>();
         exception.Which.Should().NotBeOfType<ArgumentException>();
     }
+
+    [Fact]
+    public async Task PurgeAllInstancesAsync_NegativeTimeout_ThrowsArgumentOutOfRangeException()
+    {
+        // Arrange
+        var client = this.CreateClient();
+        var filter = new PurgeInstancesFilter { Timeout = TimeSpan.FromSeconds(-1) };
+
+        // Act & Assert
+        Func<Task> act = async () => await client.PurgeAllInstancesAsync(filter);
+        var exception = await act.Should().ThrowAsync<ArgumentOutOfRangeException>();
+        exception.Which.Message.Should().Contain("Timeout must be a positive TimeSpan.");
+    }
+
+    [Fact]
+    public async Task PurgeAllInstancesAsync_ZeroTimeout_ThrowsArgumentOutOfRangeException()
+    {
+        // Arrange
+        var client = this.CreateClient();
+        var filter = new PurgeInstancesFilter { Timeout = TimeSpan.Zero };
+
+        // Act & Assert
+        Func<Task> act = async () => await client.PurgeAllInstancesAsync(filter);
+        var exception = await act.Should().ThrowAsync<ArgumentOutOfRangeException>();
+        exception.Which.Message.Should().Contain("Timeout must be a positive TimeSpan.");
+    }
+
+    [Fact]
+    public async Task PurgeAllInstancesAsync_PositiveTimeout_DoesNotThrowValidationError()
+    {
+        // Arrange
+        var client = this.CreateClient();
+        var filter = new PurgeInstancesFilter { Timeout = TimeSpan.FromSeconds(30) };
+
+        // Act & Assert - validation should pass; the call will fail at gRPC level, not validation
+        Func<Task> act = async () => await client.PurgeAllInstancesAsync(filter);
+        var exception = await act.Should().ThrowAsync<Exception>();
+        exception.Which.Should().NotBeOfType<ArgumentOutOfRangeException>();
+    }
 }