refactor: Change Toolset getTools method to Flowable instead of Single

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

@@ -16,7 +16,6 @@
 
 package com.google.adk.agents;
 
-import static com.google.common.collect.ImmutableList.toImmutableList;
 import static java.util.stream.Collectors.joining;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
@@ -698,31 +697,29 @@ public Single<String> canonicalGlobalInstruction(ReadonlyContext context) {
    * @param context The context to retrieve the session state.
    * @return The resolved list of tools as a {@link Single} wrapped list of {@link BaseTool}.
    */
-  public Single<List<BaseTool>> canonicalTools(Optional<ReadonlyContext> context) {
-    List<Single<List<BaseTool>>> toolSingles = new ArrayList<>();
+  public Flowable<List<BaseTool>> canonicalTools(Optional<ReadonlyContext> context) {
+    List<Flowable<List<BaseTool>>> toolFlowables = new ArrayList<>();
     for (Object toolOrToolset : toolsUnion) {
       if (toolOrToolset instanceof BaseTool baseTool) {
-        toolSingles.add(Single.just(ImmutableList.of(baseTool)));
+        toolFlowables.add(Flowable.just(ImmutableList.of(baseTool)));
       } else if (toolOrToolset instanceof BaseToolset baseToolset) {
-        toolSingles.add(baseToolset.getTools(context.orElse(null)));
+        toolFlowables.add(baseToolset.getTools(context.orElse(null)));
       } else {
         throw new IllegalArgumentException(
             "Object in tools list is not of a supported type: "
                 + toolOrToolset.getClass().getName());
       }
     }
-    return Single.concat(toolSingles)
-        .toList()
-        .map(listOfLists -> listOfLists.stream().flatMap(List::stream).collect(toImmutableList()));
+    return Flowable.concat(toolFlowables).flatMap(Flowable::fromIterable).toList().toFlowable();
   }
 
   /** Overload of canonicalTools that defaults to an empty context. */
-  public Single<List<BaseTool>> canonicalTools() {
+  public Flowable<List<BaseTool>> canonicalTools() {
     return canonicalTools(Optional.empty());
   }
 
   /** Convenience overload of canonicalTools that accepts a non-optional ReadonlyContext. */
-  public Single<List<BaseTool>> canonicalTools(ReadonlyContext context) {
+  public Flowable<List<BaseTool>> canonicalTools(ReadonlyContext context) {
     return canonicalTools(Optional.ofNullable(context));
   }
 

core/src/main/java/com/google/adk/tools/BaseToolset.java

@@ -1,7 +1,7 @@
 package com.google.adk.tools;
 
 import com.google.adk.agents.ReadonlyContext;
-import io.reactivex.rxjava3.core.Single;
+import io.reactivex.rxjava3.core.Flowable;
 import java.util.List;
 import java.util.Optional;
 
@@ -12,9 +12,9 @@ public interface BaseToolset extends AutoCloseable {
    * Return all tools in the toolset based on the provided context.
    *
    * @param readonlyContext Context used to filter tools available to the agent.
-   * @return A Single emitting a list of tools available under the specified context.
+   * @return A Flowable emitting a list of tools available under the specified context.
    */
-  Single<List<BaseTool>> getTools(ReadonlyContext readonlyContext);
+  Flowable<List<BaseTool>> getTools(ReadonlyContext readonlyContext);
 
   /**
    * Performs cleanup and releases resources held by the toolset.

core/src/main/java/com/google/adk/tools/mcp/McpToolset.java

@@ -26,7 +26,7 @@
 import io.modelcontextprotocol.client.McpSyncClient;
 import io.modelcontextprotocol.client.transport.ServerParameters;
 import io.modelcontextprotocol.spec.McpSchema.ListToolsResult;
-import io.reactivex.rxjava3.core.Single;
+import io.reactivex.rxjava3.core.Flowable;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
@@ -151,8 +151,8 @@ public McpToolset(ServerParameters connectionParams) {
   }
 
   @Override
-  public Single<List<BaseTool>> getTools(ReadonlyContext readonlyContext) {
-    return Single.fromCallable(
+  public Flowable<List<BaseTool>> getTools(ReadonlyContext readonlyContext) {
+    return Flowable.fromCallable(
         () -> {
           for (int i = 0; i < MAX_RETRIES; i++) {
             try {

core/src/test/java/com/google/adk/tools/BaseToolsetTest.java

@@ -5,7 +5,7 @@
 
 import com.google.adk.agents.ReadonlyContext;
 import com.google.common.collect.ImmutableList;
-import io.reactivex.rxjava3.core.Single;
+import io.reactivex.rxjava3.core.Flowable;
 import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -23,15 +23,15 @@ public void testGetTools() {
     BaseToolset toolset =
         new BaseToolset() {
           @Override
-          public Single<List<BaseTool>> getTools(ReadonlyContext readonlyContext) {
-            return Single.just(ImmutableList.of(mockTool1, mockTool2));
+          public Flowable<List<BaseTool>> getTools(ReadonlyContext readonlyContext) {
+            return Flowable.just(ImmutableList.of(mockTool1, mockTool2));
           }
 
           @Override
           public void close() throws Exception {}
         };
 
-    List<BaseTool> tools = toolset.getTools(mockContext).blockingGet();
+    List<BaseTool> tools = toolset.getTools(mockContext).blockingFirst();
     assertThat(tools).containsExactly(mockTool1, mockTool2);
   }
 }

dev/src/main/java/com/google/adk/web/AgentGraphGenerator.java

@@ -105,7 +105,7 @@ private static void buildGraphRecursive(
 
     if (agent instanceof LlmAgent) {
       LlmAgent llmAgent = (LlmAgent) agent;
-      List<BaseTool> tools = llmAgent.canonicalTools().blockingGet();
+      List<BaseTool> tools = llmAgent.canonicalTools().blockingFirst();
       if (tools != null) {
         for (BaseTool tool : tools) {
           if (tool != null) {