feat(redis): Add Redis-based semantic caching and chat memory implementations

Add comprehensive Redis-backed features to enhance Spring AI:

* Add semantic caching for chat responses:
  - SemanticCache interface and Redis implementation using vector similarity
  - SemanticCacheAdvisor for intercepting and caching chat responses
  - Uses vector search to cache and retrieve responses based on query similarity
  - Support for TTL-based cache expiration
  - Improves response times and reduces API costs for similar questions

* Add Redis-based chat memory implementation:
  - RedisChatMemory using RedisJSON + RediSearch for conversation storage
  - Configurable RedisChatMemoryConfig with builder pattern support
  - Message TTL, ordering, multi-conversation and batch operations
  - Efficient conversation history retrieval using RediSearch indexes

* Add integration tests:
  - Comprehensive test coverage using TestContainers
  - Tests for semantic caching features and chat memory operations
  - Integration test for RedisVectorStore with VectorStoreChatMemoryAdvisor
  - Verify chat completion augmentation with vector store content

The Redis implementations enable efficient storage and retrieval of chat
responses and conversation history, with semantic search capabilities and
configurable persistence options.

Signed-off-by: Brian Sam-Bodden bsb@redis.com

Author: bsbodden

spring-ai-docs/src/main/antora/modules/ROOT/pages/api/vectordbs/redis.adoc

@@ -9,6 +9,8 @@ link:https://redis.io/docs/interact/search-and-query/[Redis Search and Query] ex
 * Store vectors and the associated metadata within hashes or JSON documents
 * Retrieve vectors
 * Perform vector searches
+* Cache chat responses based on semantic similarity
+* Store and query conversation history
 
 == Prerequisites
 
@@ -152,6 +154,69 @@ is converted into the proprietary Redis filter format:
 @country:{UK | NL} @year:[2020 inf]
 ----
 
+=== Semantic Cache Usage
+
+The semantic cache provides vector similarity-based caching for chat responses implemented as an advisor:
+
+[source,java]
+----
+// Create semantic cache
+SemanticCache semanticCache = DefaultSemanticCache.builder()
+    .embeddingModel(embeddingModel)
+    .jedisClient(jedisClient)
+    .similarityThreshold(0.95)  // Optional: defaults to 0.95
+    .build();
+
+// Create cache advisor
+SemanticCacheAdvisor cacheAdvisor = SemanticCacheAdvisor.builder()
+    .cache(semanticCache)
+    .build();
+
+// Use with chat client
+ChatResponse response = ChatClient.builder(chatModel)
+    .build()
+    .prompt("What is the capital of France?")
+    .advisors(cacheAdvisor)
+    .call()
+    .chatResponse();
+
+// Manually interact with cache
+semanticCache.set("query", chatResponse);
+semanticCache.set("query", chatResponse, Duration.ofHours(1)); // With TTL
+Optional<ChatResponse> cached = semanticCache.get("similar query");
+----
+
+=== Chat Memory Usage
+
+RedisChatMemory provides persistent storage for conversation history:
+
+[source,java]
+----
+// Create chat memory
+RedisChatMemory chatMemory = RedisChatMemory.builder()
+    .jedisClient(jedisClient)
+    .timeToLive(Duration.ofHours(24))  // Optional: message TTL
+    .indexName("custom-memory-index")   // Optional
+    .keyPrefix("custom-prefix")         // Optional
+    .build();
+
+// Add messages
+chatMemory.add("conversation-1", new UserMessage("Hello"));
+chatMemory.add("conversation-1", new AssistantMessage("Hi there!"));
+
+// Add multiple messages
+chatMemory.add("conversation-1", List.of(
+    new UserMessage("How are you?"),
+    new AssistantMessage("I'm doing well!")
+));
+
+// Retrieve messages
+List<Message> messages = chatMemory.get("conversation-1", 10); // Last 10 messages
+
+// Clear conversation
+chatMemory.clear("conversation-1");
+----
+
 == Manual Configuration
 
 Instead of using the Spring Boot auto-configuration, you can manually configure the Redis vector store. For this you need to add the `spring-ai-redis-store` to your project:

vector-stores/spring-ai-redis-store/pom.xml

@@ -101,6 +101,13 @@
 			<scope>test</scope>
 		</dependency>
 
+		<dependency>
+		  <groupId>org.springframework.ai</groupId>
+		  <artifactId>spring-ai-openai</artifactId>
+		  <version>${project.parent.version}</version>
+		  <scope>test</scope>
+		</dependency>
+
 	</dependencies>
 
 </project>

vector-stores/spring-ai-redis-store/src/main/java/org/springframework/ai/chat/cache/semantic/SemanticCacheAdvisor.java

@@ -0,0 +1,188 @@
+/*
+ * Copyright 2023-2025 the original author or authors.
+ *
+ * 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
+ *
+ *      https://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 org.springframework.ai.chat.cache.semantic;
+
+import org.springframework.ai.chat.client.advisor.api.*;
+import org.springframework.ai.chat.model.ChatResponse;
+import org.springframework.ai.vectorstore.redis.cache.semantic.SemanticCache;
+import reactor.core.publisher.Flux;
+
+import java.util.Optional;
+
+/**
+ * An advisor implementation that provides semantic caching capabilities for chat
+ * responses. This advisor intercepts chat requests and checks for semantically similar
+ * cached responses before allowing the request to proceed to the model.
+ *
+ * <p>
+ * This advisor implements both {@link CallAroundAdvisor} for synchronous operations and
+ * {@link StreamAroundAdvisor} for reactive streaming operations.
+ * </p>
+ *
+ * <p>
+ * Key features:
+ * <ul>
+ * <li>Semantic similarity based caching of responses</li>
+ * <li>Support for both synchronous and streaming chat operations</li>
+ * <li>Configurable execution order in the advisor chain</li>
+ * </ul>
+ *
+ * @author Brian Sam-Bodden
+ */
+public class SemanticCacheAdvisor implements CallAroundAdvisor, StreamAroundAdvisor {
+
+	/** The underlying semantic cache implementation */
+	private final SemanticCache cache;
+
+	/** The order of this advisor in the chain */
+	private final int order;
+
+	/**
+	 * Creates a new semantic cache advisor with default order.
+	 * @param cache The semantic cache implementation to use
+	 */
+	public SemanticCacheAdvisor(SemanticCache cache) {
+		this(cache, Advisor.DEFAULT_CHAT_MEMORY_PRECEDENCE_ORDER);
+	}
+
+	/**
+	 * Creates a new semantic cache advisor with specified order.
+	 * @param cache The semantic cache implementation to use
+	 * @param order The order of this advisor in the chain
+	 */
+	public SemanticCacheAdvisor(SemanticCache cache, int order) {
+		this.cache = cache;
+		this.order = order;
+	}
+
+	@Override
+	public String getName() {
+		return this.getClass().getSimpleName();
+	}
+
+	@Override
+	public int getOrder() {
+		return this.order;
+	}
+
+	/**
+	 * Handles synchronous chat requests by checking the cache before proceeding. If a
+	 * semantically similar response is found in the cache, it is returned immediately.
+	 * Otherwise, the request proceeds through the chain and the response is cached.
+	 * @param request The chat request to process
+	 * @param chain The advisor chain to continue processing if needed
+	 * @return The response, either from cache or from the model
+	 */
+	@Override
+	public AdvisedResponse aroundCall(AdvisedRequest request, CallAroundAdvisorChain chain) {
+		// Check cache first
+		Optional<ChatResponse> cached = cache.get(request.userText());
+
+		if (cached.isPresent()) {
+			return new AdvisedResponse(cached.get(), request.adviseContext());
+		}
+
+		// Cache miss - call the model
+		AdvisedResponse response = chain.nextAroundCall(request);
+
+		// Cache the response
+		if (response.response() != null) {
+			cache.set(request.userText(), response.response());
+		}
+
+		return response;
+	}
+
+	/**
+	 * Handles streaming chat requests by checking the cache before proceeding. If a
+	 * semantically similar response is found in the cache, it is returned as a single
+	 * item flux. Otherwise, the request proceeds through the chain and the final response
+	 * is cached.
+	 * @param request The chat request to process
+	 * @param chain The advisor chain to continue processing if needed
+	 * @return A Flux of responses, either from cache or from the model
+	 */
+	@Override
+	public Flux<AdvisedResponse> aroundStream(AdvisedRequest request, StreamAroundAdvisorChain chain) {
+		// Check cache first
+		Optional<ChatResponse> cached = cache.get(request.userText());
+
+		if (cached.isPresent()) {
+			return Flux.just(new AdvisedResponse(cached.get(), request.adviseContext()));
+		}
+
+		// Cache miss - stream from model
+		return chain.nextAroundStream(request).collectList().flatMapMany(responses -> {
+			// Cache the final aggregated response
+			if (!responses.isEmpty()) {
+				AdvisedResponse last = responses.get(responses.size() - 1);
+				if (last.response() != null) {
+					cache.set(request.userText(), last.response());
+				}
+			}
+			return Flux.fromIterable(responses);
+		});
+	}
+
+	/**
+	 * Creates a new builder for constructing SemanticCacheAdvisor instances.
+	 * @return A new builder instance
+	 */
+	public static Builder builder() {
+		return new Builder();
+	}
+
+	/**
+	 * Builder class for creating SemanticCacheAdvisor instances. Provides a fluent API
+	 * for configuration.
+	 */
+	public static class Builder {
+
+		private SemanticCache cache;
+
+		private int order = Advisor.DEFAULT_CHAT_MEMORY_PRECEDENCE_ORDER;
+
+		/**
+		 * Sets the semantic cache implementation.
+		 * @param cache The cache implementation to use
+		 * @return This builder instance
+		 */
+		public Builder cache(SemanticCache cache) {
+			this.cache = cache;
+			return this;
+		}
+
+		/**
+		 * Sets the advisor order.
+		 * @param order The order value for this advisor
+		 * @return This builder instance
+		 */
+		public Builder order(int order) {
+			this.order = order;
+			return this;
+		}
+
+		/**
+		 * Builds and returns a new SemanticCacheAdvisor instance.
+		 * @return A new SemanticCacheAdvisor configured with this builder's settings
+		 */
+		public SemanticCacheAdvisor build() {
+			return new SemanticCacheAdvisor(cache, order);
+		}
+
+	}
+
+}