Address PR review feedback

- Add Schema.Task.EntityOperationName constant for entity operation tag
- Replace magic string 'durabletask.entity.operation' with constant
- Combine nested if statements for ParentTraceContext null check
- Extract entity name from TargetInstanceId (format '@name@key')
- Add comment explaining Server span trace context for entity batches

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: cgillum

src/Shared/Grpc/Tracing/Schema.cs

@@ -60,5 +60,10 @@ public static class Task
         /// The time at which the timer is scheduled to fire.
         /// </summary>
         public const string FireAt = "durabletask.fire_at";
+
+        /// <summary>
+        /// The name of the entity operation being executed.
+        /// </summary>
+        public const string EntityOperationName = "durabletask.entity.operation";
     }
 }

src/Shared/Grpc/Tracing/TraceHelper.cs

@@ -202,7 +202,7 @@ static class TraceHelper
 
         if (!string.IsNullOrEmpty(operationName))
         {
-            newActivity.SetTag("durabletask.entity.operation", operationName);
+            newActivity.SetTag(Schema.Task.EntityOperationName, operationName);
         }
 
         return newActivity;
@@ -526,7 +526,18 @@ static string CreateSpanName(string spanDescription, string? taskName, string? t
             return null;
         }
 
-        string entityName = historyEvent?.EntityOperationCalled?.TargetInstanceId ?? string.Empty;
+        string targetInstanceId = historyEvent?.EntityOperationCalled?.TargetInstanceId ?? string.Empty;
+
+        // Extract entity name from instance ID (format: "@name@key")
+        string entityName = targetInstanceId;
+        if (targetInstanceId.Length > 1 && targetInstanceId[0] == '@')
+        {
+            int secondAt = targetInstanceId.IndexOf('@', 1);
+            if (secondAt > 1)
+            {
+                entityName = targetInstanceId.Substring(1, secondAt - 1);
+            }
+        }
         string spanName = string.IsNullOrEmpty(calledEvent.Operation)
             ? $"{TraceActivityConstants.EntityOperation}:{entityName}"
             : $"{TraceActivityConstants.EntityOperation}:{entityName}:{calledEvent.Operation}";
@@ -542,15 +553,13 @@ static string CreateSpanName(string spanDescription, string? taskName, string? t
             return null;
         }
 
-        if (calledEvent.ParentTraceContext != null)
+        if (calledEvent.ParentTraceContext != null
+            && ActivityContext.TryParse(
+                calledEvent.ParentTraceContext.TraceParent,
+                calledEvent.ParentTraceContext?.TraceState,
+                out ActivityContext parentContext))
         {
-            if (ActivityContext.TryParse(
-                    calledEvent.ParentTraceContext.TraceParent,
-                    calledEvent.ParentTraceContext?.TraceState,
-                    out ActivityContext parentContext))
-            {
-                newActivity.SetSpanId(parentContext.SpanId.ToString());
-            }
+            newActivity.SetSpanId(parentContext.SpanId.ToString());
         }
 
         newActivity.AddTag(Schema.Task.Type, TraceActivityConstants.EntityOperation);
@@ -559,7 +568,7 @@ static string CreateSpanName(string spanDescription, string? taskName, string? t
 
         if (!string.IsNullOrEmpty(calledEvent.Operation))
         {
-            newActivity.AddTag("durabletask.entity.operation", calledEvent.Operation);
+            newActivity.AddTag(Schema.Task.EntityOperationName, calledEvent.Operation);
         }
 
         return newActivity;

src/Worker/Grpc/GrpcDurableTaskWorker.Processor.cs

@@ -900,7 +900,10 @@ async Task OnRunEntityBatchAsync(
             var coreEntityId = DTCore.Entities.EntityId.FromString(batchRequest.InstanceId!);
             EntityId entityId = new(coreEntityId.Name, coreEntityId.Key);
 
-            // Start a trace span for entity operation execution using the first operation's trace context.
+            // Start a Server trace span for entity operation execution using the first operation's
+            // trace context. In multi-operation batches, only the first operation's trace context is
+            // used as the parent. This is acceptable because entity batches are typically single-operation,
+            // and individual Client spans are emitted per-operation in the orchestrator replay path.
             OperationRequest? firstOp = batchRequest.Operations?.FirstOrDefault();
             using Activity? traceActivity = TraceHelper.StartTraceActivityForEntityOperation(
                 entityId.Name,