Some changes for PR comments

Author: Evanthx

temporal-sdk/src/main/java/io/temporal/internal/client/RootWorkflowClientInvoker.java

@@ -103,7 +103,9 @@ public WorkflowStartOutput start(WorkflowStartInput input) {
         }
       }
       if (CurrentNexusOperationContext.isNexusContext()) {
-        CurrentNexusOperationContext.get().setStartWorkflowResponseLink(response.getLink());
+        // Auto-capture the start-workflow backlink so the task handler drains it onto the
+        // StartOperationResponse, the same path used for signal/signalWithStart responses.
+        CurrentNexusOperationContext.get().addBacklink(response.getLink());
       }
       return new WorkflowStartOutput(execution);
     }
@@ -125,12 +127,6 @@ public WorkflowSignalOutput signal(WorkflowSignalInput input) {
     boolean inNexusContext = CurrentNexusOperationContext.isNexusContext();
     if (inNexusContext) {
       request.addAllLinks(CurrentNexusOperationContext.get().getNexusOperationLinks());
-    } else {
-      // Most signal calls (from a regular client or workflow) won't be in a Nexus context — this
-      // is normal. The log helps a debugger when a Nexus operation handler "mysteriously" lacks
-      // link propagation because it spawned a thread to issue the signal (the thread-local
-      // CurrentNexusOperationContext is invisible from that thread).
-      log.debug("signal RPC issued outside a Nexus operation context; no link propagation");
     }
 
     DataConverter dataConverterWitSignalContext =

temporal-sdk/src/main/java/io/temporal/internal/nexus/InternalNexusOperationContext.java

@@ -17,7 +17,6 @@ public class InternalNexusOperationContext {
   private final Scope metricScope;
   private final WorkflowClient client;
   NexusOperationOutboundCallsInterceptor outboundCalls;
-  Link startWorkflowResponseLink;
   // Links extracted from the inbound Nexus task. Stored once at the task-handler boundary so the
   // workflow client (signal, signalWithStart) can attach them to outgoing requests via
   // SignalWorkflowExecutionRequest.links.
@@ -50,17 +49,6 @@ public InternalNexusOperationContext(
     this.ownerThread = Thread.currentThread();
   }
 
-  private void assertOwnerThread() {
-    if (Thread.currentThread() != ownerThread) {
-      throw new IllegalStateException(
-          "InternalNexusOperationContext mutated from thread '"
-              + Thread.currentThread().getName()
-              + "' but is owned by '"
-              + ownerThread.getName()
-              + "'. Operation handlers must not spawn threads to issue link-propagating RPCs.");
-    }
-  }
-
   public Scope getMetricsScope() {
     return metricScope;
   }
@@ -92,20 +80,11 @@ public NexusOperationContext getUserFacingContext() {
     return new NexusOperationContextImpl();
   }
 
-  public void setStartWorkflowResponseLink(Link link) {
-    this.startWorkflowResponseLink = link;
-  }
-
-  public Link getStartWorkflowResponseLink() {
-    return startWorkflowResponseLink;
-  }
-
   /**
    * Set the {@code common.v1.Link}s extracted from the inbound Nexus task so they can be attached
    * to RPCs issued by the operation handler.
    */
   public void setNexusOperationLinks(List<Link> links) {
-    assertOwnerThread();
     this.nexusOperationLinks = links == null ? Collections.emptyList() : links;
   }
 
@@ -120,7 +99,6 @@ public List<Link> getNexusOperationLinks() {
    * StartOperationResponse.
    */
   public void addBacklink(Link link) {
-    assertOwnerThread();
     if (link != null) {
       this.responseBacklinks.add(link);
     }

temporal-sdk/src/main/java/io/temporal/nexus/WorkflowRunOperationImpl.java

@@ -1,20 +1,13 @@
 package io.temporal.nexus;
 
-import static io.temporal.internal.common.LinkConverter.workflowEventToNexusLink;
-import static io.temporal.internal.common.NexusUtil.nexusProtoLinkToLink;
-
 import io.nexusrpc.handler.*;
 import io.nexusrpc.handler.OperationHandler;
-import io.temporal.api.common.v1.Link;
-import io.temporal.api.common.v1.WorkflowExecution;
-import io.temporal.api.enums.v1.EventType;
 import io.temporal.client.WorkflowClient;
 import io.temporal.internal.client.NexusStartWorkflowRequest;
 import io.temporal.internal.client.NexusStartWorkflowResponse;
 import io.temporal.internal.nexus.CurrentNexusOperationContext;
 import io.temporal.internal.nexus.InternalNexusOperationContext;
 import io.temporal.internal.nexus.OperationTokenUtil;
-import java.net.URISyntaxException;
 
 class WorkflowRunOperationImpl<T, R> implements OperationHandler<T, R> {
   private final WorkflowHandleFactory<T, R> handleFactory;
@@ -40,38 +33,9 @@ public OperationStartResult<R> start(
 
     NexusStartWorkflowResponse nexusStartWorkflowResponse =
         handle.getInvoker().invoke(nexusRequest);
-    WorkflowExecution workflowExec = nexusStartWorkflowResponse.getWorkflowExecution();
 
-    // If the start workflow response returned a link use it, otherwise
-    // create the link information about the new workflow and return to the caller.
-    Link.WorkflowEvent workflowEventLink =
-        nexusCtx.getStartWorkflowResponseLink().hasWorkflowEvent()
-            ? nexusCtx.getStartWorkflowResponseLink().getWorkflowEvent()
-            : null;
-    if (workflowEventLink == null) {
-      workflowEventLink =
-          Link.WorkflowEvent.newBuilder()
-              .setNamespace(nexusCtx.getNamespace())
-              .setWorkflowId(workflowExec.getWorkflowId())
-              .setRunId(workflowExec.getRunId())
-              .setEventRef(
-                  Link.WorkflowEvent.EventReference.newBuilder()
-                      .setEventType(EventType.EVENT_TYPE_WORKFLOW_EXECUTION_STARTED))
-              .build();
-    }
-    io.temporal.api.nexus.v1.Link nexusLink = workflowEventToNexusLink(workflowEventLink);
-    // Attach the link to the operation result.
-    OperationStartResult.Builder<R> result =
-        OperationStartResult.newAsyncBuilder(nexusStartWorkflowResponse.getOperationToken());
-    if (nexusLink != null) {
-      try {
-        ctx.addLinks(nexusProtoLinkToLink(nexusLink));
-      } catch (URISyntaxException e) {
-        // Not expected as the link is constructed by the SDK.
-        throw new HandlerException(HandlerException.ErrorType.INTERNAL, "failed to parse URI", e);
-      }
-    }
-    return result.build();
+    return OperationStartResult.<R>newAsyncBuilder(nexusStartWorkflowResponse.getOperationToken())
+        .build();
   }
 
   @Override