refactor: Fixing EventAction's artifaceDelta type

This type now matches with Vertex AI Session API and the python implementation.  The new implementation unblocks rewind functionality.

PiperOrigin-RevId: 868327356

Author: google-genai-bot

core/src/main/java/com/google/adk/agents/CallbackContext.java

@@ -134,7 +134,7 @@ public Completable saveArtifact(String filename, Part artifact) {
             invocationContext.session().id(),
             filename,
             artifact)
-        .doOnSuccess(unusedVersion -> this.eventActions.artifactDelta().put(filename, artifact))
+        .doOnSuccess(version -> this.eventActions.artifactDelta().put(filename, version))
         .ignoreElement();
   }
 }

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

@@ -22,7 +22,6 @@
 import com.google.adk.agents.BaseAgentState;
 import com.google.adk.sessions.State;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
-import com.google.genai.types.Part;
 import java.util.HashSet;
 import java.util.Objects;
 import java.util.Optional;
@@ -38,7 +37,7 @@ public class EventActions extends JsonBaseModel {
 
   private Optional<Boolean> skipSummarization;
   private ConcurrentMap<String, Object> stateDelta;
-  private ConcurrentMap<String, Part> artifactDelta;
+  private ConcurrentMap<String, Integer> artifactDelta;
   private Set<String> deletedArtifactIds;
   private Optional<String> transferToAgent;
   private Optional<Boolean> escalate;
@@ -120,11 +119,11 @@ public void removeStateByKey(String key) {
   }
 
   @JsonProperty("artifactDelta")
-  public ConcurrentMap<String, Part> artifactDelta() {
+  public ConcurrentMap<String, Integer> artifactDelta() {
     return artifactDelta;
   }
 
-  public void setArtifactDelta(ConcurrentMap<String, Part> artifactDelta) {
+  public void setArtifactDelta(ConcurrentMap<String, Integer> artifactDelta) {
     this.artifactDelta = artifactDelta;
   }
 
@@ -288,7 +287,7 @@ public int hashCode() {
   public static class Builder {
     private Optional<Boolean> skipSummarization;
     private ConcurrentMap<String, Object> stateDelta;
-    private ConcurrentMap<String, Part> artifactDelta;
+    private ConcurrentMap<String, Integer> artifactDelta;
     private Set<String> deletedArtifactIds;
     private Optional<String> transferToAgent;
     private Optional<Boolean> escalate;
@@ -348,7 +347,7 @@ public Builder stateDelta(ConcurrentMap<String, Object> value) {
 
     @CanIgnoreReturnValue
     @JsonProperty("artifactDelta")
-    public Builder artifactDelta(ConcurrentMap<String, Part> value) {
+    public Builder artifactDelta(ConcurrentMap<String, Integer> value) {
       this.artifactDelta = value;
       return this;
     }

core/src/main/java/com/google/adk/flows/llmflows/CodeExecution.java

@@ -448,11 +448,9 @@ private static Single<Event> postProcessCodeExecutionResult(
         .toList()
         .map(
             versions -> {
-              ConcurrentMap<String, Part> artifactDelta = new ConcurrentHashMap<>();
+              ConcurrentMap<String, Integer> artifactDelta = new ConcurrentHashMap<>();
               for (int i = 0; i < versions.size(); i++) {
-                artifactDelta.put(
-                    codeExecutionResult.outputFiles().get(i).name(),
-                    Part.fromText(String.valueOf(versions.get(i))));
+                artifactDelta.put(codeExecutionResult.outputFiles().get(i).name(), versions.get(i));
               }
               eventActionsBuilder.artifactDelta(artifactDelta);
               return Event.builder()

core/src/main/java/com/google/adk/sessions/SessionJsonConverter.java

@@ -298,18 +298,19 @@ private static Instant convertToInstant(Object timestampObj) {
    * @return A {@link ConcurrentMap} representing the artifact delta.
    */
   @SuppressWarnings("unchecked")
-  private static ConcurrentMap<String, Part> convertToArtifactDeltaMap(Object artifactDeltaObj) {
+  private static ConcurrentMap<String, Integer> convertToArtifactDeltaMap(Object artifactDeltaObj) {
     if (!(artifactDeltaObj instanceof Map)) {
       return new ConcurrentHashMap<>();
     }
-    ConcurrentMap<String, Part> artifactDeltaMap = new ConcurrentHashMap<>();
-    Map<String, Map<String, Object>> rawMap = (Map<String, Map<String, Object>>) artifactDeltaObj;
-    for (Map.Entry<String, Map<String, Object>> entry : rawMap.entrySet()) {
+    ConcurrentMap<String, Integer> artifactDeltaMap = new ConcurrentHashMap<>();
+    Map<String, Object> rawMap = (Map<String, Object>) artifactDeltaObj;
+    for (Map.Entry<String, Object> entry : rawMap.entrySet()) {
       try {
-        Part part = objectMapper.convertValue(entry.getValue(), Part.class);
-        artifactDeltaMap.put(entry.getKey(), part);
+        Integer value = objectMapper.convertValue(entry.getValue(), Integer.class);
+        artifactDeltaMap.put(entry.getKey(), value);
       } catch (IllegalArgumentException e) {
-        logger.warn("Error converting artifactDelta value to Part for key: {}", entry.getKey(), e);
+        logger.warn(
+            "Error converting artifactDelta value to Integer for key: {}", entry.getKey(), e);
       }
     }
     return artifactDeltaMap;

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

@@ -63,7 +63,7 @@ public void merge_mergesAllFields() {
         EventActions.builder()
             .skipSummarization(true)
             .stateDelta(new ConcurrentHashMap<>(ImmutableMap.of("key1", "value1")))
-            .artifactDelta(new ConcurrentHashMap<>(ImmutableMap.of("artifact1", PART)))
+            .artifactDelta(new ConcurrentHashMap<>(ImmutableMap.of("artifact1", 1)))
             .deletedArtifactIds(ImmutableSet.of("deleted1"))
             .requestedAuthConfigs(
                 new ConcurrentHashMap<>(
@@ -75,7 +75,7 @@ public void merge_mergesAllFields() {
     EventActions eventActions2 =
         EventActions.builder()
             .stateDelta(new ConcurrentHashMap<>(ImmutableMap.of("key2", "value2")))
-            .artifactDelta(new ConcurrentHashMap<>(ImmutableMap.of("artifact2", PART)))
+            .artifactDelta(new ConcurrentHashMap<>(ImmutableMap.of("artifact2", 2)))
             .deletedArtifactIds(ImmutableSet.of("deleted2"))
             .transferToAgent("agentId")
             .escalate(true)
@@ -91,7 +91,7 @@ public void merge_mergesAllFields() {
 
     assertThat(merged.skipSummarization()).hasValue(true);
     assertThat(merged.stateDelta()).containsExactly("key1", "value1", "key2", "value2");
-    assertThat(merged.artifactDelta()).containsExactly("artifact1", PART, "artifact2", PART);
+    assertThat(merged.artifactDelta()).containsExactly("artifact1", 1, "artifact2", 2);
     assertThat(merged.deletedArtifactIds()).containsExactly("deleted1", "deleted2");
     assertThat(merged.transferToAgent()).hasValue("agentId");
     assertThat(merged.escalate()).hasValue(true);

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

@@ -45,9 +45,7 @@ public final class EventTest {
       EventActions.builder()
           .skipSummarization(true)
           .stateDelta(new ConcurrentHashMap<>(ImmutableMap.of("key", "value")))
-          .artifactDelta(
-              new ConcurrentHashMap<>(
-                  ImmutableMap.of("artifact_key", Part.builder().text("artifact_value").build())))
+          .artifactDelta(new ConcurrentHashMap<>(ImmutableMap.of("artifact_key", 1)))
           .transferToAgent("agent_id")
           .escalate(true)
           .requestedAuthConfigs(

core/src/test/java/com/google/adk/sessions/SessionJsonConverterTest.java

@@ -39,9 +39,7 @@ public void convertEventToJson_fullEvent_success() throws JsonProcessingExceptio
         EventActions.builder()
             .skipSummarization(true)
             .stateDelta(new ConcurrentHashMap<>(ImmutableMap.of("key", "value")))
-            .artifactDelta(
-                new ConcurrentHashMap<>(
-                    ImmutableMap.of("artifact", Part.fromText("artifact_text"))))
+            .artifactDelta(new ConcurrentHashMap<>(ImmutableMap.of("artifact", 1)))
             .transferToAgent("agent")
             .escalate(true)
             .build();
@@ -80,8 +78,7 @@ public void convertEventToJson_fullEvent_success() throws JsonProcessingExceptio
     JsonNode actionsNode = jsonNode.get("actions");
     assertThat(actionsNode.get("skipSummarization").asBoolean()).isTrue();
     assertThat(actionsNode.get("stateDelta").get("key").asText()).isEqualTo("value");
-    assertThat(actionsNode.get("artifactDelta").get("artifact").get("text").asText())
-        .isEqualTo("artifact_text");
+    assertThat(actionsNode.get("artifactDelta").get("artifact").asInt()).isEqualTo(1);
     assertThat(actionsNode.get("transferAgent").asText()).isEqualTo("agent");
     assertThat(actionsNode.get("escalate").asBoolean()).isTrue();
   }
@@ -131,8 +128,7 @@ public void fromApiEvent_fullEvent_success() {
     Map<String, Object> actions = new HashMap<>();
     actions.put("skipSummarization", true);
     actions.put("stateDelta", ImmutableMap.of("key", "value"));
-    actions.put(
-        "artifactDelta", ImmutableMap.of("artifact", ImmutableMap.of("text", "artifact_text")));
+    actions.put("artifactDelta", ImmutableMap.of("artifact", 1));
     actions.put("transferAgent", "agent");
     actions.put("escalate", true);
     apiEvent.put("actions", actions);
@@ -154,7 +150,7 @@ public void fromApiEvent_fullEvent_success() {
     EventActions eventActions = event.actions();
     assertThat(eventActions.skipSummarization()).hasValue(true);
     assertThat(eventActions.stateDelta()).containsEntry("key", "value");
-    assertThat(eventActions.artifactDelta().get("artifact").text()).hasValue("artifact_text");
+    assertThat(eventActions.artifactDelta().get("artifact")).isEqualTo(1);
     assertThat(eventActions.transferToAgent()).hasValue("agent");
     assertThat(eventActions.escalate()).hasValue(true);
   }
@@ -383,7 +379,7 @@ public void fromApiEvent_withInvalidArtifactDelta_skipsInvalidEntries() {
     apiEvent.put("timestamp", "2023-01-01T00:00:00Z");
 
     Map<String, Object> artifactDelta = new HashMap<>();
-    artifactDelta.put("valid", ImmutableMap.of("text", "valid_text"));
+    artifactDelta.put("valid", 1);
     artifactDelta.put("invalid", "not-a-map");
 
     Map<String, Object> actions = new HashMap<>();