diff --git a/experimental/fluent/agentic/src/main/java/io/serverlessworkflow/fluent/agentic/AgentWorkflowBuilder.java b/experimental/fluent/agentic/src/main/java/io/serverlessworkflow/fluent/agentic/AgentWorkflowBuilder.java
index d09af6da..5472904f 100644
--- a/experimental/fluent/agentic/src/main/java/io/serverlessworkflow/fluent/agentic/AgentWorkflowBuilder.java
+++ b/experimental/fluent/agentic/src/main/java/io/serverlessworkflow/fluent/agentic/AgentWorkflowBuilder.java
@@ -16,8 +16,13 @@
 package io.serverlessworkflow.fluent.agentic;
 
 import dev.langchain4j.agentic.scope.AgenticScope;
+import io.serverlessworkflow.api.types.TaskItem;
+import io.serverlessworkflow.api.types.Workflow;
 import io.serverlessworkflow.fluent.func.spi.FuncTransformations;
 import io.serverlessworkflow.fluent.spec.BaseWorkflowBuilder;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 import java.util.UUID;
 import java.util.function.Predicate;
 
@@ -25,8 +30,11 @@ public class AgentWorkflowBuilder
     extends BaseWorkflowBuilder<AgentWorkflowBuilder, AgentDoTaskBuilder, AgentTaskItemListBuilder>
     implements FuncTransformations<AgentWorkflowBuilder> {
 
+  private final List<AgentDoTaskBuilder> agentDoTaskBuilders;
+
   AgentWorkflowBuilder(final String name, final String namespace, final String version) {
     super(name, namespace, version);
+    agentDoTaskBuilders = new ArrayList<>();
   }
 
   public static AgentWorkflowBuilder workflow() {
@@ -49,7 +57,7 @@ public AgentWorkflowBuilder agent(Object agent) {
   public AgentWorkflowBuilder agent(String name, Object agent) {
     final AgentDoTaskBuilder doTaskBuilder = this.newDo();
     doTaskBuilder.agent(name, agent);
-    this.workflow.setDo(doTaskBuilder.build().getDo());
+    agentDoTaskBuilders.add(doTaskBuilder);
     return this;
   }
 
@@ -60,7 +68,7 @@ public AgentWorkflowBuilder sequence(Object... agents) {
   public AgentWorkflowBuilder sequence(String name, Object... agents) {
     final AgentDoTaskBuilder doTaskBuilder = this.newDo();
     doTaskBuilder.sequence(name, agents);
-    this.workflow.setDo(doTaskBuilder.build().getDo());
+    agentDoTaskBuilders.add(doTaskBuilder);
     return this;
   }
 
@@ -71,7 +79,7 @@ public AgentWorkflowBuilder parallel(Object... agents) {
   public AgentWorkflowBuilder parallel(String name, Object... agents) {
     final AgentDoTaskBuilder doTaskBuilder = this.newDo();
     doTaskBuilder.parallel(name, agents);
-    this.workflow.setDo(doTaskBuilder.build().getDo());
+    agentDoTaskBuilders.add(doTaskBuilder);
     return this;
   }
 
@@ -83,7 +91,7 @@ public AgentWorkflowBuilder loop(
       String name, Predicate<AgenticScope> exitCondition, Object... agents) {
     final AgentDoTaskBuilder doTaskBuilder = this.newDo();
     doTaskBuilder.loop(name, loop -> loop.subAgents(agents).exitCondition(exitCondition));
-    this.workflow.setDo(doTaskBuilder.build().getDo());
+    agentDoTaskBuilders.add(doTaskBuilder);
     return this;
   }
 
@@ -96,4 +104,15 @@ protected AgentDoTaskBuilder newDo() {
   protected AgentWorkflowBuilder self() {
     return this;
   }
+
+  @Override
+  public Workflow build() {
+    List<TaskItem> items = new ArrayList<>(workflow.getDo());
+    this.agentDoTaskBuilders.stream()
+        .map(AgentDoTaskBuilder::build)
+        .forEach(b -> items.addAll(b.getDo()));
+    this.workflow.setDo(Collections.unmodifiableList(items));
+    this.agentDoTaskBuilders.clear();
+    return this.workflow;
+  }
 }
diff --git a/fluent/spec/src/main/java/io/serverlessworkflow/fluent/spec/BaseWorkflowBuilder.java b/fluent/spec/src/main/java/io/serverlessworkflow/fluent/spec/BaseWorkflowBuilder.java
index c3127a30..993f325f 100644
--- a/fluent/spec/src/main/java/io/serverlessworkflow/fluent/spec/BaseWorkflowBuilder.java
+++ b/fluent/spec/src/main/java/io/serverlessworkflow/fluent/spec/BaseWorkflowBuilder.java
@@ -19,8 +19,12 @@
 import io.serverlessworkflow.api.types.Export;
 import io.serverlessworkflow.api.types.Input;
 import io.serverlessworkflow.api.types.Output;
+import io.serverlessworkflow.api.types.TaskItem;
 import io.serverlessworkflow.api.types.Workflow;
 import io.serverlessworkflow.fluent.spec.spi.TransformationHandlers;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 import java.util.UUID;
 import java.util.function.Consumer;
 
@@ -90,7 +94,9 @@ public SELF tasks(Consumer<DBuilder> doTaskConsumer) {
     if (this.workflow.getDo() == null) {
       this.workflow.setDo(doTaskBuilder.build().getDo());
     } else {
-      this.workflow.getDo().addAll(doTaskBuilder.build().getDo());
+      List<TaskItem> existingTasks = new ArrayList<>(this.workflow.getDo());
+      existingTasks.addAll(doTaskBuilder.build().getDo());
+      this.workflow.setDo(Collections.unmodifiableList(existingTasks));
     }
     return self();
   }