refactor: Move ReasoningBank from core to contrib module

Move the ReasoningBank feature into contrib/reasoning-bank/ as it is
specific to ADK Java and not available across all language runtimes.
Revert reasoning-specific changes from InvocationContext and ToolContext
in core. Refactor LoadReasoningStrategyTool to be self-contained via a
handler pattern, accepting the service and appName in its constructor.

Author: nebrass

contrib/reasoning-bank/pom.xml

@@ -0,0 +1,92 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ Copyright 2025 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.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>com.google.adk</groupId>
+        <artifactId>google-adk-parent</artifactId>
+        <version>0.5.1-SNAPSHOT</version><!-- {x-version-update:google-adk:current} -->
+        <relativePath>../../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>google-adk-reasoning-bank</artifactId>
+    <name>Agent Development Kit - Reasoning Bank</name>
+    <description>Reasoning Bank integration with Agent Development Kit for reusable reasoning strategies</description>
+
+    <dependencies>
+
+        <dependency>
+            <groupId>com.google.adk</groupId>
+            <artifactId>google-adk</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.auto.value</groupId>
+            <artifactId>auto-value-annotations</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.reactivex.rxjava3</groupId>
+            <artifactId>rxjava</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>33.0.0-jre</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.truth</groupId>
+            <artifactId>truth</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.vintage</groupId>
+            <artifactId>junit-vintage-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <groupId>org.jacoco</groupId>
+                <artifactId>jacoco-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+</project>

…/reasoning/BaseReasoningBankService.java …/reasoning/BaseReasoningBankService.javacore/src/main/java/com/google/adk/reasoning/BaseReasoningBankService.java renamed to contrib/reasoning-bank/src/main/java/com/google/adk/reasoning/BaseReasoningBankService.java core/src/main/java/com/google/adk/reasoning/BaseReasoningBankService.java renamed to contrib/reasoning-bank/src/main/java/com/google/adk/reasoning/BaseReasoningBankService.java

@@ -17,6 +17,7 @@
 package com.google.adk.tools;
 
 import com.google.adk.models.LlmRequest;
+import com.google.adk.reasoning.BaseReasoningBankService;
 import com.google.common.collect.ImmutableList;
 import io.reactivex.rxjava3.core.Completable;
 import io.reactivex.rxjava3.core.Single;
@@ -33,39 +34,56 @@
  */
 public class LoadReasoningStrategyTool extends FunctionTool {
 
+  /** Handler that holds the service reference and implements the tool method. */
+  public static class ReasoningBankHandler {
+    private final BaseReasoningBankService reasoningBankService;
+    private final String appName;
+
+    ReasoningBankHandler(BaseReasoningBankService reasoningBankService, String appName) {
+      this.reasoningBankService = reasoningBankService;
+      this.appName = appName;
+    }
+
+    /**
+     * Loads reasoning strategies that match the given query.
+     *
+     * @param query A description of the task or problem to find strategies for.
+     * @param toolContext The tool context (required by FunctionTool contract).
+     * @return A response containing matching reasoning strategies.
+     */
+    public Single<LoadReasoningStrategyResponse> loadReasoningStrategy(
+        @Annotations.Schema(name = "query", description = "A description of the task or problem")
+            String query,
+        ToolContext toolContext) {
+      return reasoningBankService
+          .searchStrategies(appName, query)
+          .map(response -> new LoadReasoningStrategyResponse(response.strategies()));
+    }
+  }
+
   private static Method getLoadReasoningStrategyMethod() {
     try {
-      return LoadReasoningStrategyTool.class.getMethod(
+      return ReasoningBankHandler.class.getMethod(
           "loadReasoningStrategy", String.class, ToolContext.class);
     } catch (NoSuchMethodException e) {
       throw new IllegalStateException("Failed to find loadReasoningStrategy method.", e);
     }
   }
 
-  public LoadReasoningStrategyTool() {
+  /**
+   * Creates a new LoadReasoningStrategyTool.
+   *
+   * @param reasoningBankService The reasoning bank service to search for strategies.
+   * @param appName The application name used to scope strategy storage and retrieval.
+   */
+  public LoadReasoningStrategyTool(BaseReasoningBankService reasoningBankService, String appName) {
     super(
-        /* instance= */ null,
+        new ReasoningBankHandler(reasoningBankService, appName),
         getLoadReasoningStrategyMethod(),
         /* isLongRunning= */ false,
         /* requireConfirmation= */ false);
   }
 
-  /**
-   * Loads reasoning strategies that match the given query.
-   *
-   * @param query A description of the task or problem to find strategies for.
-   * @param toolContext The tool context providing access to the reasoning bank service.
-   * @return A response containing matching reasoning strategies.
-   */
-  public static Single<LoadReasoningStrategyResponse> loadReasoningStrategy(
-      @Annotations.Schema(name = "query", description = "A description of the task or problem")
-          String query,
-      ToolContext toolContext) {
-    return toolContext
-        .searchReasoningStrategies(query)
-        .map(response -> new LoadReasoningStrategyResponse(response.strategies()));
-  }
-
   @Override
   public Completable processLlmRequest(
       LlmRequest.Builder llmRequestBuilder, ToolContext toolContext) {