fix(tokt): don't fail on grounding metadata without image search queries

tokt/src/main/kotlin/com/google/adk/tokt/codecs/GroundingMetadataCodec.kt

@@ -49,7 +49,7 @@ internal object GroundingMetadataCodec {
   /** Returns the Kotlin [KtGroundingMetadata] view of the genai [metadata]. */
   fun fromJava(metadata: GenaiGroundingMetadata): KtGroundingMetadata =
     KtGroundingMetadata(
-      imageSearchQueries = metadata.imageSearchQueries().getOrNull().orEmpty(),
+      imageSearchQueries = metadata.imageSearchQueries().getOrNull(),
       groundingChunks = metadata.groundingChunks().getOrNull()?.map { chunkFromJava(it) },
       groundingSupports = metadata.groundingSupports().getOrNull()?.map { supportFromJava(it) },
       webSearchQueries = metadata.webSearchQueries().getOrNull(),
@@ -62,7 +62,8 @@ internal object GroundingMetadataCodec {
 
   /** Returns the genai [GenaiGroundingMetadata] view of the Kotlin [metadata]. */
   fun toJava(metadata: KtGroundingMetadata): GenaiGroundingMetadata {
-    val builder = GenaiGroundingMetadata.builder().imageSearchQueries(metadata.imageSearchQueries)
+    val builder = GenaiGroundingMetadata.builder()
+    metadata.imageSearchQueries?.let { builder.imageSearchQueries(it) }
     metadata.groundingChunks?.let { builder.groundingChunks(it.map { c -> chunkToJava(c) }) }
     metadata.groundingSupports?.let { builder.groundingSupports(it.map { s -> supportToJava(s) }) }
     metadata.webSearchQueries?.let { builder.webSearchQueries(it) }

tokt/src/test/kotlin/com/google/adk/tokt/KtRunnerInteropTest.kt

@@ -60,6 +60,7 @@ import com.google.adk.kt.types.GenerationConfigRoutingConfig as KtRoutingConfig
 import com.google.adk.kt.types.GenerationConfigRoutingConfigManualRoutingMode as KtManualRoutingMode
 import com.google.adk.kt.types.GoogleMaps as KtGoogleMaps
 import com.google.adk.kt.types.GoogleSearch as KtGoogleSearch
+import com.google.adk.kt.types.GroundingMetadata as KtGroundingMetadata
 import com.google.adk.kt.types.HarmBlockMethod as KtHarmBlockMethod
 import com.google.adk.kt.types.HarmBlockThreshold as KtHarmBlockThreshold
 import com.google.adk.kt.types.HarmCategory as KtHarmCategory
@@ -506,6 +507,19 @@ class KtRunnerInteropTest {
     }
   }
 
+  /** A native Kotlin agent emitting grounding metadata that has no image search queries. */
+  private class GroundedKtAgent : KtBaseAgent(name = "grounded") {
+    override fun runAsyncImpl(context: KtInvocationContext): Flow<KtEvent> = flow {
+      emit(
+        KtEvent(
+          invocationId = context.invocationId,
+          author = name,
+          groundingMetadata = KtGroundingMetadata(webSearchQueries = listOf("q")),
+        )
+      )
+    }
+  }
+
   /** A Java plugin that requests an auth config the engine cannot represent, from before-agent. */
   private class AuthConfigRequestingJavaPlugin : JavaBasePlugin("auth_config_plugin") {
     override fun beforeAgentCallback(
@@ -4134,6 +4148,42 @@ class KtRunnerInteropTest {
     assertEquals("the forecast", response.description().getOrNull(), "response description")
   }
 
+  @Test
+  fun groundingMetadataCodec_withoutImageSearchQueries_leavesThemUnset() {
+    // The Kotlin list is nullable, but the genai builder's setter rejects a null argument.
+    val kt =
+      GroundingMetadataCodec.fromJava(
+        GenaiGroundingMetadata.builder().webSearchQueries(listOf("q")).build()
+      )
+    val java = GroundingMetadataCodec.toJava(KtGroundingMetadata(webSearchQueries = listOf("q")))
+
+    assertNull(kt.imageSearchQueries)
+    assertEquals(Optional.of(listOf("q")), java.webSearchQueries())
+    assertEquals(Optional.empty(), java.imageSearchQueries())
+  }
+
+  @Test
+  fun asJavaRunner_groundingMetadataWithoutImageSearchQueries_streamsTheEvent() {
+    // The same metadata through the Java runAsync API, which converts every engine event.
+    val javaRunner =
+      KotlinAdkToJava.asJavaRunner(KtInMemoryRunner(agent = GroundedKtAgent(), appName = "app"))
+
+    val events =
+      javaRunner
+        .runAsync(
+          "u",
+          "s",
+          GenaiContent.builder().role("user").parts(GenaiPart.fromText("hi")).build(),
+          JavaRunConfig.builder().autoCreateSession(true).build(),
+        )
+        .toList()
+        .blockingGet()
+
+    val metadata = assertNotNull(events.firstNotNullOfOrNull { it.groundingMetadata().getOrNull() })
+    assertEquals(Optional.of(listOf("q")), metadata.webSearchQueries())
+    assertEquals(Optional.empty(), metadata.imageSearchQueries())
+  }
+
   @Test
   fun groundingMetadataCodec_carriesMapsChunkText_roundTrip() {
     // A maps grounding chunk's text (the place answer) must survive Java -> Kotlin -> Java; the