Merge main into planner

.github/workflows/validation.yml

@@ -23,13 +23,13 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Set up Java ${{ matrix.java-version }}
-        uses: actions/setup-java@v4
+        uses: actions/setup-java@v5
         with:
           distribution: temurin
           java-version: ${{ matrix.java-version }}
 
       - name: Cache Maven packages
-        uses: actions/cache@v3
+        uses: actions/cache@v5
         with:
           path: ~/.m2/repository
           key: ${{ runner.os }}-maven-${{ matrix.java-version }}-${{ hashFiles('**/pom.xml') }}

.release-please-manifest.json

@@ -1,4 +1,3 @@
 {
     ".": "0.9.0"
 }
-

AGENTS.md

@@ -0,0 +1,3 @@
+# AGENTS.md
+
+Validate changes by running `./mvnw test`.

a2a/src/main/java/com/google/adk/a2a/agent/RemoteA2AAgent.java

@@ -117,7 +117,7 @@ private RemoteA2AAgent(Builder builder) {
     if (this.description.isEmpty() && this.agentCard.description() != null) {
       this.description = this.agentCard.description();
     }
-    this.streaming = this.agentCard.capabilities().streaming();
+    this.streaming = builder.streaming && this.agentCard.capabilities().streaming();
   }
 
   public static Builder builder() {
@@ -133,6 +133,13 @@ public static class Builder {
     private List<? extends BaseAgent> subAgents;
     private List<Callbacks.BeforeAgentCallback> beforeAgentCallback;
     private List<Callbacks.AfterAgentCallback> afterAgentCallback;
+    private boolean streaming;
+
+    @CanIgnoreReturnValue
+    public Builder streaming(boolean streaming) {
+      this.streaming = streaming;
+      return this;
+    }
 
     @CanIgnoreReturnValue
     public Builder name(String name) {
@@ -181,6 +188,10 @@ public RemoteA2AAgent build() {
     }
   }
 
+  public boolean isStreaming() {
+    return streaming;
+  }
+
   private Message.Builder newA2AMessage(Message.Role role, List<io.a2a.spec.Part<?>> parts) {
     return new Message.Builder().messageId(UUID.randomUUID().toString()).role(role).parts(parts);
   }

a2a/src/main/java/com/google/adk/a2a/converters/A2AMetadataKey.java

@@ -0,0 +1,40 @@
+/*
+ * 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.a2a.converters;
+
+/**
+ * Enum for the type of A2A metadata. Adds a prefix used to differentiage ADK-related values stored
+ * in Metadata an A2A event.
+ */
+public enum A2AMetadataKey {
+  TYPE("type"),
+  IS_LONG_RUNNING("is_long_running"),
+  PARTIAL("partial"),
+  GROUNDING_METADATA("grounding_metadata"),
+  USAGE_METADATA("usage_metadata"),
+  CUSTOM_METADATA("custom_metadata"),
+  ERROR_CODE("error_code");
+
+  private final String type;
+
+  private A2AMetadataKey(String type) {
+    this.type = "adk_" + type;
+  }
+
+  public String getType() {
+    return type;
+  }
+}

a2a/src/main/java/com/google/adk/a2a/converters/AdkMetadataKey.java

@@ -0,0 +1,35 @@
+/*
+ * 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.a2a.converters;
+
+/**
+ * Enum for the type of ADK metadata. Adds a prefix used to differentiate A2A-related values stored
+ * in custom metadata of an ADK session event.
+ */
+public enum AdkMetadataKey {
+  TASK_ID("task_id"),
+  CONTEXT_ID("context_id");
+
+  private final String type;
+
+  private AdkMetadataKey(String type) {
+    this.type = "a2a:" + type;
+  }
+
+  public String getType() {
+    return type;
+  }
+}

a2a/src/main/java/com/google/adk/a2a/converters/PartConverter.java

@@ -52,11 +52,7 @@ public final class PartConverter {
 
   private static final Logger logger = LoggerFactory.getLogger(PartConverter.class);
   private static final ObjectMapper objectMapper = new ObjectMapper();
-  // Constants for metadata types. By convention metadata keys are prefixed with "adk_" to align
-  // with the Python and Golang libraries.
-  public static final String A2A_DATA_PART_METADATA_TYPE_KEY = "adk_type";
-  public static final String A2A_DATA_PART_METADATA_IS_LONG_RUNNING_KEY = "adk_is_long_running";
-  public static final String A2A_DATA_PART_METADATA_IS_PARTIAL_KEY = "adk_partial";
+  // Constants for metadata types.
   public static final String LANGUAGE_KEY = "language";
   public static final String OUTCOME_KEY = "outcome";
   public static final String CODE_KEY = "code";
@@ -135,7 +131,7 @@ private static com.google.genai.types.Part convertDataPartToGenAiPart(DataPart d
     Map<String, Object> metadata =
         Optional.ofNullable(dataPart.getMetadata()).map(HashMap::new).orElseGet(HashMap::new);
 
-    String metadataType = metadata.getOrDefault(A2A_DATA_PART_METADATA_TYPE_KEY, "").toString();
+    String metadataType = metadata.getOrDefault(A2AMetadataKey.TYPE.getType(), "").toString();
 
     if ((data.containsKey(NAME_KEY) && data.containsKey(ARGS_KEY))
         || metadataType.equals(A2ADataPartMetadataType.FUNCTION_CALL.getType())) {
@@ -218,7 +214,7 @@ private static DataPart createDataPartFromFunctionCall(
     addValueIfPresent(data, WILL_CONTINUE_KEY, functionCall.willContinue());
     addValueIfPresent(data, PARTIAL_ARGS_KEY, functionCall.partialArgs());
 
-    metadata.put(A2A_DATA_PART_METADATA_TYPE_KEY, A2ADataPartMetadataType.FUNCTION_CALL.getType());
+    metadata.put(A2AMetadataKey.TYPE.getType(), A2ADataPartMetadataType.FUNCTION_CALL.getType());
 
     return new DataPart(data.buildOrThrow(), metadata.buildOrThrow());
   }
@@ -245,7 +241,7 @@ private static DataPart createDataPartFromFunctionResponse(
     addValueIfPresent(data, PARTS_KEY, functionResponse.parts());
 
     metadata.put(
-        A2A_DATA_PART_METADATA_TYPE_KEY, A2ADataPartMetadataType.FUNCTION_RESPONSE.getType());
+        A2AMetadataKey.TYPE.getType(), A2ADataPartMetadataType.FUNCTION_RESPONSE.getType());
 
     return new DataPart(data.buildOrThrow(), metadata.buildOrThrow());
   }
@@ -268,7 +264,7 @@ private static DataPart createDataPartFromCodeExecutionResult(
     addValueIfPresent(data, OUTPUT_KEY, codeExecutionResult.output());
 
     metadata.put(
-        A2A_DATA_PART_METADATA_TYPE_KEY, A2ADataPartMetadataType.CODE_EXECUTION_RESULT.getType());
+        A2AMetadataKey.TYPE.getType(), A2ADataPartMetadataType.CODE_EXECUTION_RESULT.getType());
 
     return new DataPart(data.buildOrThrow(), metadata.buildOrThrow());
   }
@@ -290,8 +286,7 @@ private static DataPart createDataPartFromExecutableCode(
             .orElse(Language.Known.LANGUAGE_UNSPECIFIED.toString()));
     addValueIfPresent(data, CODE_KEY, executableCode.code());
 
-    metadata.put(
-        A2A_DATA_PART_METADATA_TYPE_KEY, A2ADataPartMetadataType.EXECUTABLE_CODE.getType());
+    metadata.put(A2AMetadataKey.TYPE.getType(), A2ADataPartMetadataType.EXECUTABLE_CODE.getType());
 
     return new DataPart(data.buildOrThrow(), metadata.buildOrThrow());
   }
@@ -305,7 +300,7 @@ public static io.a2a.spec.Part<?> fromGenaiPart(Part part, boolean isPartial) {
     }
     ImmutableMap.Builder<String, Object> metadata = ImmutableMap.builder();
     if (isPartial) {
-      metadata.put(A2A_DATA_PART_METADATA_IS_PARTIAL_KEY, true);
+      metadata.put(A2AMetadataKey.PARTIAL.getType(), true);
     }
 
     if (part.text().isPresent()) {