feat: add NodeInfo.name, runId, and parentRunId, and Event.nodeName

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

@@ -419,6 +419,21 @@ && functionResponses().isEmpty()
         && !hasTrailingCodeExecutionResult();
   }
 
+  /**
+   * Returns the name of the workflow node that emitted this event, from {@link NodeInfo#name()}.
+   * Empty outside a workflow and on an event that carries any agent state or ends an agent. ADK
+   * Python's {@code Event.node_name} returns an empty string instead and ignores an empty agent
+   * state.
+   */
+  @Experimental
+  @JsonIgnore
+  public final Optional<String> nodeName() {
+    if (actions().agentState().isPresent() || actions().endOfAgent()) {
+      return Optional.empty();
+    }
+    return nodeInfo().flatMap(NodeInfo::name);
+  }
+
   /**
    * Converts the event content into a readable string.
    *

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

@@ -17,6 +17,7 @@
 package com.google.adk.workflow;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonSetter;
@@ -27,6 +28,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.List;
+import java.util.Optional;
 
 /**
  * The identity of the workflow-node activation that emitted an {@link com.google.adk.events.Event}.
@@ -64,6 +66,53 @@ public abstract class NodeInfo {
   @JsonInclude(JsonInclude.Include.NON_DEFAULT)
   public abstract boolean messageAsOutput();
 
+  /**
+   * Returns the emitting node's name: the last segment of {@link #path()} without its run ID, such
+   * as {@code a} for {@code wf@1/a@2}, or empty when the path is empty. ADK Python's {@code
+   * NodeInfo.name} returns an empty string instead.
+   */
+  @JsonIgnore
+  public final Optional<String> name() {
+    if (path().isEmpty()) {
+      return Optional.empty();
+    }
+    String segment = lastSegment(path());
+    int at = segment.lastIndexOf('@');
+    return Optional.of(at < 0 ? segment : segment.substring(0, at));
+  }
+
+  /**
+   * Returns the emitting node's run ID: the part after {@code @} in the last segment of {@link
+   * #path()}, such as {@code 2} for {@code wf@1/a@2}, or empty when the segment has none. ADK
+   * Python's {@code NodeInfo.run_id} returns an empty string instead.
+   */
+  @JsonIgnore
+  public final Optional<String> runId() {
+    return runIdOf(lastSegment(path()));
+  }
+
+  /**
+   * Returns the run ID of the emitting node's parent: the part after {@code @} in the
+   * second-to-last segment of {@link #path()}, such as {@code 1} for {@code wf@1/a@2}. Empty when
+   * the path has no parent segment or that segment has no run ID, as in ADK Python's {@code
+   * NodeInfo.parent_run_id}.
+   */
+  @JsonIgnore
+  public final Optional<String> parentRunId() {
+    String path = path();
+    int lastSlash = path.lastIndexOf('/');
+    return lastSlash < 0 ? Optional.empty() : runIdOf(lastSegment(path.substring(0, lastSlash)));
+  }
+
+  private static String lastSegment(String path) {
+    return path.substring(path.lastIndexOf('/') + 1);
+  }
+
+  private static Optional<String> runIdOf(String segment) {
+    int at = segment.lastIndexOf('@');
+    return at < 0 ? Optional.empty() : Optional.of(segment.substring(at + 1));
+  }
+
   public static Builder builder() {
     return new AutoValue_NodeInfo.Builder()
         .path("")

core/src/test/java/com/google/adk/events/EventTest.java

@@ -275,6 +275,36 @@ public void json_roundTripsAnEmptyNodeInfo() {
     assertThat(Event.fromJson(event.toJson())).isEqualTo(event);
   }
 
+  @Test
+  public void nodeName_isTheEmittingNodesName() {
+    Event event = EVENT.toBuilder().nodeInfo(NodeInfo.builder().path("wf@1/a@2").build()).build();
+
+    assertThat(event.nodeName()).hasValue("a");
+  }
+
+  @Test
+  public void nodeName_emptyOutsideAWorkflow() {
+    assertThat(EVENT.nodeName()).isEmpty();
+    assertThat(EVENT.toBuilder().nodeInfo(NodeInfo.builder().build()).build().nodeName()).isEmpty();
+  }
+
+  @Test
+  public void nodeName_emptyForAgentStateAndEndOfAgentEvents() {
+    Event endOfAgent =
+        EVENT.toBuilder()
+            .nodeInfo(NODE_INFO)
+            .actions(EventActions.builder().endOfAgent(true).build())
+            .build();
+    Event agentState =
+        EVENT.toBuilder()
+            .nodeInfo(NODE_INFO)
+            .actions(EventActions.builder().agentState(ImmutableMap.of()).build())
+            .build();
+
+    assertThat(endOfAgent.nodeName()).isEmpty();
+    assertThat(agentState.nodeName()).isEmpty();
+  }
+
   @Test
   public void event_builder_with_transcriptions_works() {
     Transcription inputTranscription =

core/src/test/java/com/google/adk/workflow/NodeInfoTest.java

@@ -20,6 +20,7 @@
 
 import com.google.adk.JsonBaseModel;
 import com.google.common.collect.ImmutableList;
+import java.util.Map;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -63,4 +64,62 @@ public void json_omitsUnsetOutputForAndFalseMessageAsOutput() {
     assertThat(json).doesNotContain("outputFor");
     assertThat(json).doesNotContain("messageAsOutput");
   }
+
+  @Test
+  public void json_omitsPathHelpers() {
+    Map<?, ?> json = JsonBaseModel.getMapper().convertValue(NODE_INFO, Map.class);
+
+    assertThat(json.keySet()).containsExactly("path", "outputFor", "messageAsOutput");
+  }
+
+  @Test
+  public void name_isTheLastSegmentWithoutItsRunId() {
+    assertThat(nodeInfo("wf@1/a@2/b@3").name()).hasValue("b");
+    assertThat(nodeInfo("wf@1/b").name()).hasValue("b");
+    assertThat(nodeInfo("wf@1").name()).hasValue("wf");
+  }
+
+  @Test
+  public void runId_isTheLastSegmentsRunId() {
+    assertThat(nodeInfo("wf@1/a@2/b@3").runId()).hasValue("3");
+  }
+
+  @Test
+  public void runId_emptyWithoutARunId() {
+    assertThat(nodeInfo("wf@1/b").runId()).isEmpty();
+  }
+
+  @Test
+  public void parentRunId_isTheSecondToLastSegmentsRunId() {
+    assertThat(nodeInfo("wf@1/a@2/b@3").parentRunId()).hasValue("2");
+    assertThat(nodeInfo("wf@1/b").parentRunId()).hasValue("1");
+  }
+
+  @Test
+  public void parentRunId_emptyWithoutAParentRunId() {
+    assertThat(nodeInfo("wf@1").parentRunId()).isEmpty();
+    assertThat(nodeInfo("wf/b@1").parentRunId()).isEmpty();
+  }
+
+  @Test
+  public void pathHelpers_splitEachSegmentAtItsLastAt() {
+    NodeInfo nodeInfo = nodeInfo("w@f@1/a@b@2");
+
+    assertThat(nodeInfo.name()).hasValue("a@b");
+    assertThat(nodeInfo.runId()).hasValue("2");
+    assertThat(nodeInfo.parentRunId()).hasValue("1");
+  }
+
+  @Test
+  public void pathHelpers_emptyForAnEmptyPath() {
+    NodeInfo nodeInfo = NodeInfo.builder().build();
+
+    assertThat(nodeInfo.name()).isEmpty();
+    assertThat(nodeInfo.runId()).isEmpty();
+    assertThat(nodeInfo.parentRunId()).isEmpty();
+  }
+
+  private static NodeInfo nodeInfo(String path) {
+    return NodeInfo.builder().path(path).build();
+  }
 }