fix: Exclude model thoughts when saving LLM output to state

PiperOrigin-RevId: 839890911

Author: google-genai-bot

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

@@ -53,6 +53,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.genai.types.Content;
 import com.google.genai.types.GenerateContentConfig;
+import com.google.genai.types.Part;
 import com.google.genai.types.Schema;
 import io.reactivex.rxjava3.core.Flowable;
 import io.reactivex.rxjava3.core.Maybe;
@@ -567,10 +568,11 @@ protected BaseLlmFlow determineLlmFlow() {
 
   private void maybeSaveOutputToState(Event event) {
     if (outputKey().isPresent() && event.finalResponse() && event.content().isPresent()) {
-      // Concatenate text from all parts.
+      // Concatenate text from all parts, excluding thoughts.
       Object output;
       String rawResult =
           event.content().flatMap(Content::parts).orElse(ImmutableList.of()).stream()
+              .filter(part -> !isThought(part))
               .map(part -> part.text().orElse(""))
               .collect(joining());
 
@@ -602,6 +604,10 @@ private void maybeSaveOutputToState(Event event) {
     }
   }
 
+  private static boolean isThought(Part part) {
+    return part.thought().isPresent() && part.thought().get();
+  }
+
   @Override
   protected Flowable<Event> runAsyncImpl(InvocationContext invocationContext) {
     return llmFlow

core/src/test/java/com/google/adk/agents/LlmAgentTest.java

@@ -96,6 +96,25 @@ public void testRun_withOutputKey_savesMultiPartState() {
         .containsEntry("myMultiPartOutput", "Part 1. Part 2.");
   }
 
+  @Test
+  public void testRun_withOutputKey_savesState_ignoresThoughts() {
+    Content modelContent =
+        Content.fromParts(
+            Part.fromText("Saved output"),
+            Part.fromText("Ignored thought").toBuilder().thought(true).build());
+    TestLlm testLlm = createTestLlm(createLlmResponse(modelContent));
+    LlmAgent agent = createTestAgentBuilder(testLlm).outputKey("myOutput").build();
+    InvocationContext invocationContext = createInvocationContext(agent);
+
+    List<Event> events = agent.runAsync(invocationContext).toList().blockingGet();
+
+    assertThat(events).hasSize(1);
+    assertThat(events.get(0).content()).hasValue(modelContent);
+    assertThat(events.get(0).finalResponse()).isTrue();
+
+    assertThat(events.get(0).actions().stateDelta()).containsEntry("myOutput", "Saved output");
+  }
+
   @Test
   public void testRun_withoutOutputKey_doesNotSaveState() {
     Content modelContent = Content.fromParts(Part.fromText("Some output"));