feat: add the workflow fields Event.output, Event.nodeInfo and EventActions.route

core/src/main/java/com/google/adk/events/Event.java

@@ -23,7 +23,9 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.google.adk.JsonBaseModel;
+import com.google.adk.annotations.Experimental;
 import com.google.adk.platform.UuidProvider;
+import com.google.adk.workflow.NodeInfo;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -66,6 +68,8 @@ public class Event extends JsonBaseModel {
   private @Nullable String modelVersion;
   private @Nullable Transcription inputTranscription;
   private @Nullable Transcription outputTranscription;
+  private @Nullable Object output;
+  private @Nullable NodeInfo nodeInfo;
 
   private long timestamp;
 
@@ -306,6 +310,38 @@ public void setOutputTranscription(@Nullable Transcription outputTranscription)
     this.outputTranscription = outputTranscription;
   }
 
+  /**
+   * For a workflow node, returns the value handed to successors, distinct from {@link #content()},
+   * or empty when the event carries no node output. Holds any value Jackson can serialize, such as
+   * a JSON-native value or a {@link Content}. An event read from JSON holds the JSON-native form (a
+   * map with string keys, a list, a string, a number, or a boolean).
+   */
+  @Experimental
+  @JsonProperty("output")
+  public Optional<Object> output() {
+    return Optional.ofNullable(output);
+  }
+
+  @Experimental
+  public void setOutput(@Nullable Object output) {
+    this.output = output;
+  }
+
+  /**
+   * Identifies the workflow-node activation that emitted this event; outside a workflow, this value
+   * is empty or has an empty path.
+   */
+  @Experimental
+  @JsonProperty("nodeInfo")
+  public Optional<NodeInfo> nodeInfo() {
+    return Optional.ofNullable(nodeInfo);
+  }
+
+  @Experimental
+  public void setNodeInfo(@Nullable NodeInfo nodeInfo) {
+    this.nodeInfo = nodeInfo;
+  }
+
   /** The timestamp of the event. */
   @JsonProperty("timestamp")
   public long timestamp() {
@@ -415,6 +451,8 @@ public static class Builder {
     private @Nullable String modelVersion;
     private @Nullable Transcription inputTranscription;
     private @Nullable Transcription outputTranscription;
+    private @Nullable Object output;
+    private @Nullable NodeInfo nodeInfo;
     private @Nullable Long timestamp;
 
     @JsonCreator
@@ -592,6 +630,22 @@ public Builder outputTranscription(@Nullable Transcription value) {
       return this;
     }
 
+    @Experimental
+    @CanIgnoreReturnValue
+    @JsonProperty("output")
+    public Builder output(@Nullable Object value) {
+      this.output = value;
+      return this;
+    }
+
+    @Experimental
+    @CanIgnoreReturnValue
+    @JsonProperty("nodeInfo")
+    public Builder nodeInfo(@Nullable NodeInfo value) {
+      this.nodeInfo = value;
+      return this;
+    }
+
     public Event build() {
       Event event = new Event();
       event.setId(id);
@@ -616,6 +670,8 @@ public Event build() {
           timestamp().orElseGet(() -> InstantSource.system().instant().toEpochMilli()));
       event.setInputTranscription(inputTranscription);
       event.setOutputTranscription(outputTranscription);
+      event.setOutput(output);
+      event.setNodeInfo(nodeInfo);
       return event;
     }
   }
@@ -631,30 +687,30 @@ public static Event fromJson(String json) {
 
   /** Creates a builder pre-filled with this event's values. */
   public Builder toBuilder() {
-    Builder builder =
-        new Builder()
-            .id(this.id)
-            .invocationId(this.invocationId)
-            .author(this.author)
-            .content(this.content)
-            .actions(this.actions)
-            .longRunningToolIds(this.longRunningToolIds)
-            .partial(this.partial)
-            .turnComplete(this.turnComplete)
-            .errorCode(this.errorCode)
-            .errorMessage(this.errorMessage)
-            .finishReason(this.finishReason)
-            .usageMetadata(this.usageMetadata)
-            .avgLogprobs(this.avgLogprobs)
-            .interrupted(this.interrupted)
-            .branch(this.branch)
-            .groundingMetadata(this.groundingMetadata)
-            .customMetadata(this.customMetadata)
-            .modelVersion(this.modelVersion)
-            .inputTranscription(this.inputTranscription)
-            .outputTranscription(this.outputTranscription)
-            .timestamp(this.timestamp);
-    return builder;
+    return new Builder()
+        .id(this.id)
+        .invocationId(this.invocationId)
+        .author(this.author)
+        .content(this.content)
+        .actions(this.actions)
+        .longRunningToolIds(this.longRunningToolIds)
+        .partial(this.partial)
+        .turnComplete(this.turnComplete)
+        .errorCode(this.errorCode)
+        .errorMessage(this.errorMessage)
+        .finishReason(this.finishReason)
+        .usageMetadata(this.usageMetadata)
+        .avgLogprobs(this.avgLogprobs)
+        .interrupted(this.interrupted)
+        .branch(this.branch)
+        .groundingMetadata(this.groundingMetadata)
+        .customMetadata(this.customMetadata)
+        .modelVersion(this.modelVersion)
+        .inputTranscription(this.inputTranscription)
+        .outputTranscription(this.outputTranscription)
+        .output(this.output)
+        .nodeInfo(this.nodeInfo)
+        .timestamp(this.timestamp);
   }
 
   @Override
@@ -685,7 +741,9 @@ public boolean equals(Object obj) {
         && Objects.equals(customMetadata, other.customMetadata)
         && Objects.equals(modelVersion, other.modelVersion)
         && Objects.equals(inputTranscription, other.inputTranscription)
-        && Objects.equals(outputTranscription, other.outputTranscription);
+        && Objects.equals(outputTranscription, other.outputTranscription)
+        && Objects.equals(output, other.output)
+        && Objects.equals(nodeInfo, other.nodeInfo);
   }
 
   @Override
@@ -716,6 +774,8 @@ public int hashCode() {
         modelVersion,
         inputTranscription,
         outputTranscription,
+        output,
+        nodeInfo,
         timestamp);
   }
 }

core/src/main/java/com/google/adk/events/EventActions.java

@@ -15,13 +15,18 @@
  */
 package com.google.adk.events;
 
+import com.fasterxml.jackson.annotation.JsonFormat;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.google.adk.JsonBaseModel;
+import com.google.adk.annotations.Experimental;
 import com.google.adk.sessions.State;
+import com.google.adk.workflow.Route;
+import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -47,6 +52,7 @@ public class EventActions extends JsonBaseModel {
   private @Nullable EventCompaction compaction;
   private @Nullable Object setModelResponse;
   private @Nullable String rewindBeforeInvocationId;
+  private @Nullable ImmutableList<Route> route;
 
   /** Default constructor for Jackson. */
   public EventActions() {
@@ -72,6 +78,7 @@ private EventActions(Builder builder) {
     this.compaction = builder.compaction;
     this.setModelResponse = builder.setModelResponse;
     this.rewindBeforeInvocationId = builder.rewindBeforeInvocationId;
+    this.route = builder.route;
   }
 
   @JsonProperty("skipSummarization")
@@ -252,6 +259,23 @@ public void setRewindBeforeInvocationId(@Nullable String rewindBeforeInvocationI
     this.rewindBeforeInvocationId = rewindBeforeInvocationId;
   }
 
+  /**
+   * For a workflow node, returns the routes this event selects; an edge is followed when it has one
+   * of these routes. The value is optional because an empty list is still a routing decision that
+   * selects no route, whereas an absent value means the event makes no routing decision. When
+   * merging, an empty list replaces the existing routes, while an absent value keeps them.
+   */
+  @Experimental
+  @JsonProperty("route")
+  public Optional<ImmutableList<Route>> route() {
+    return Optional.ofNullable(route);
+  }
+
+  @Experimental
+  public void setRoute(@Nullable List<Route> route) {
+    this.route = route == null ? null : ImmutableList.copyOf(route);
+  }
+
   public static Builder builder() {
     return new Builder();
   }
@@ -280,7 +304,8 @@ public boolean equals(Object o) {
         && Objects.equals(agentState, that.agentState)
         && Objects.equals(compaction, that.compaction)
         && Objects.equals(setModelResponse, that.setModelResponse)
-        && Objects.equals(rewindBeforeInvocationId, that.rewindBeforeInvocationId);
+        && Objects.equals(rewindBeforeInvocationId, that.rewindBeforeInvocationId)
+        && Objects.equals(route, that.route);
   }
 
   @Override
@@ -298,7 +323,8 @@ public int hashCode() {
         agentState,
         compaction,
         setModelResponse,
-        rewindBeforeInvocationId);
+        rewindBeforeInvocationId,
+        route);
   }
 
   /** Builder for {@link EventActions}. */
@@ -316,6 +342,7 @@ public static class Builder {
     private @Nullable EventCompaction compaction;
     private @Nullable Object setModelResponse;
     private @Nullable String rewindBeforeInvocationId;
+    private @Nullable ImmutableList<Route> route;
 
     public Builder() {
       this.stateDelta = new ConcurrentHashMap<>();
@@ -340,6 +367,7 @@ private Builder(EventActions eventActions) {
       this.compaction = eventActions.compaction;
       this.setModelResponse = eventActions.setModelResponse;
       this.rewindBeforeInvocationId = eventActions.rewindBeforeInvocationId;
+      this.route = eventActions.route;
     }
 
     @CanIgnoreReturnValue
@@ -467,6 +495,16 @@ public Builder rewindBeforeInvocationId(@Nullable String value) {
       return this;
     }
 
+    // ADK Python writes a single route as a bare value rather than a one-element list.
+    @Experimental
+    @CanIgnoreReturnValue
+    @JsonProperty("route")
+    @JsonFormat(with = JsonFormat.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY)
+    public Builder route(@Nullable List<Route> value) {
+      this.route = value == null ? null : ImmutableList.copyOf(value);
+      return this;
+    }
+
     @CanIgnoreReturnValue
     public Builder merge(EventActions other) {
       other.skipSummarization().ifPresent(this::skipSummarization);
@@ -482,6 +520,7 @@ public Builder merge(EventActions other) {
       other.compaction().ifPresent(this::compaction);
       other.setModelResponse().ifPresent(this::setModelResponse);
       other.rewindBeforeInvocationId().ifPresent(this::rewindBeforeInvocationId);
+      other.route().ifPresent(this::route);
       return this;
     }
 

core/src/main/java/com/google/adk/workflow/NodeInfo.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.adk.workflow;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonSetter;
+import com.fasterxml.jackson.annotation.Nulls;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.google.adk.annotations.Experimental;
+import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import java.util.List;
+
+/**
+ * The identity of the workflow-node activation that emitted an {@link com.google.adk.events.Event}.
+ */
+@Experimental
+@AutoValue
+@JsonDeserialize(builder = NodeInfo.Builder.class)
+public abstract class NodeInfo {
+
+  /**
+   * Returns the emitting node's path. Segments are {@code /}-separated and each is {@code
+   * name@runId}, so a node of workflow {@code wf} reads {@code wf@1/a@1}; an empty path means the
+   * event did not come from a workflow node.
+   */
+  @JsonProperty("path")
+  public abstract String path();
+
+  /**
+   * Returns the node paths this event's output counts for: the emitting node's path, followed by
+   * the paths of the ancestor workflows that use this event as their output. It is set on an event
+   * that carries the node's output, either in its {@code output} field or as a message-as-output
+   * event whose content is the output; an empty list means the output counts for no node.
+   */
+  @JsonProperty("outputFor")
+  @JsonInclude(JsonInclude.Include.NON_EMPTY)
+  public abstract ImmutableList<String> outputFor();
+
+  /**
+   * Returns {@code true} if this event's content is the node's output, so no separate output event
+   * follows.
+   */
+  @JsonProperty("messageAsOutput")
+  @JsonInclude(JsonInclude.Include.NON_DEFAULT)
+  public abstract boolean messageAsOutput();
+
+  public static Builder builder() {
+    return new AutoValue_NodeInfo.Builder()
+        .path("")
+        .outputFor(ImmutableList.of())
+        .messageAsOutput(false);
+  }
+
+  public abstract Builder toBuilder();
+
+  /** Builder for {@link NodeInfo}. */
+  @AutoValue.Builder
+  public abstract static class Builder {
+
+    @JsonCreator
+    static Builder create() {
+      return builder();
+    }
+
+    @CanIgnoreReturnValue
+    @JsonProperty("path")
+    public abstract Builder path(String path);
+
+    @CanIgnoreReturnValue
+    @JsonProperty("outputFor")
+    @JsonSetter(nulls = Nulls.AS_EMPTY)
+    public abstract Builder outputFor(List<String> outputFor);
+
+    @CanIgnoreReturnValue
+    @JsonProperty("messageAsOutput")
+    public abstract Builder messageAsOutput(boolean messageAsOutput);
+
+    public abstract NodeInfo build();
+  }
+}