RedisChatMemoryRepository auto-config backs off when any ChatMemory bean exists (ChatMemory.class in ConditionalOnMissingBean)

Bug description

RedisChatMemoryRepositoryAutoConfiguration refuses to register RedisChatMemoryRepository when any ChatMemory bean is already present:

@Bean
@ConditionalOnMissingBean({ RedisChatMemoryRepository.class, ChatMemory.class, ChatMemoryRepository.class })
public RedisChatMemoryRepository redisChatMemoryRepository(...) { ... }

That condition is too broad for a repository auto-configuration.

Spring AI separates responsibilities clearly:

• ChatMemoryRepository – persistence
• ChatMemory – retention strategy (e.g. MessageWindowChatMemory with maxMessages)

The docs encourage adding the Redis starter for auto-configured RedisChatMemoryRepository, and then customizing ChatMemory on top of that repository. Including ChatMemory.class in @ConditionalOnMissingBean breaks that pattern: defining a custom ChatMemory suppresses Redis repository auto-config entirely.

Even without a custom bean, ChatMemoryAutoConfiguration always provides a default ChatMemory, so any scenario where that bean is visible before Redis auto-config evaluates will also suppress RedisChatMemoryRepository.

Comparison with sibling store auto-configs

JdbcChatMemoryRepositoryAutoConfiguration and CassandraChatMemoryRepositoryAutoConfiguration only use @ConditionalOnMissingBean on the repository type itself — they do not back off because a ChatMemory exists. Redis should follow the same pattern.

Relation to #5623 / #5644 (please do not close as duplicate without checking main)

This is related to https://github.com/spring-projects/spring-ai/issues/5623, but it is not fully resolved on current main.

PR https://github.com/spring-projects/spring-ai/pull/5644 explicitly fixed the same root cause for the older RedisChatMemoryAutoConfiguration by:

1. ordering Redis auto-config before ChatMemoryAutoConfiguration
2. narrowing the missing-bean condition to ChatMemoryRepository only (removing ChatMemory.class)

Relevant change from that PR:

- @ConditionalOnMissingBean({ RedisChatMemoryRepository.class, ChatMemory.class, ChatMemoryRepository.class })
+ @ConditionalOnMissingBean(ChatMemoryRepository.class)

However, on current main, the successor module RedisChatMemoryRepositoryAutoConfiguration still has:

@ConditionalOnMissingBean({ RedisChatMemoryRepository.class, ChatMemory.class, ChatMemoryRepository.class })

Source (main):
https://github.com/spring-projects/spring-ai/blob/main/auto-configurations/models/chat/memory/repository/spring-ai-autoconfigure-model-chat-memory-repository-redis/src/main/java/org/springframework/ai/model/chat/memory/repository/redis/autoconfigure/RedisChatMemoryRepositoryAutoConfiguration.java

So the before = ChatMemoryAutoConfiguration.class ordering helps the default InMemory vs Redis race, but ChatMemory.class being part of the condition remains a regression / incomplete fix relative to what #5644 proposed.

Environment

• Spring AI main (verified against current RedisChatMemoryRepositoryAutoConfiguration)
• spring-ai-starter-model-chat-memory-repository-redis

Steps to reproduce

1. Add spring-ai-starter-model-chat-memory-repository-redis.
2. Declare a custom ChatMemory that depends on the auto-configured Redis repository, e.g.:

@Bean
public ChatMemory chatMemory(RedisChatMemoryRepository redisChatMemoryRepository) {
    return MessageWindowChatMemory.builder()
            .chatMemoryRepository(redisChatMemoryRepository)
            .maxMessages(20)
            .build();
}

3. Start the application.

Expected behavior

• RedisChatMemoryRepository is auto-configured when no ChatMemoryRepository (or Redis-specific repository) bean exists.
• A user-defined ChatMemory must not prevent Redis repository auto-configuration.
• Align Redis with JDBC/Cassandra: repository auto-config should not condition on ChatMemory.class.

Actual behavior

Because a ChatMemory bean is present, RedisChatMemoryRepository is not registered. The custom ChatMemory bean then fails to obtain RedisChatMemoryRepository, or the app falls back to in-memory storage depending on ordering / other beans.

Suggested fix

Narrow the condition back to repository types only, as in #5644, for example:

@ConditionalOnMissingBean(ChatMemoryRepository.class)
// or at most:
@ConditionalOnMissingBean({ RedisChatMemoryRepository.class, ChatMemoryRepository.class })

and add a regression test where a user-provided ChatMemory bean still receives an auto-configured RedisChatMemoryRepository.

Start with auto-configurations/models/chat/memory/repository/spring-ai-autoconfigure-model-chat-memory-repository-redis/src/main/java/org/springframework/ai/model/chat/memory/repository/redis/autoconfigure/RedisChatMemoryRepositoryAutoConfiguration.java and compare the JDBC and Cassandra conditions. Add a regression test for a user-provided ChatMemory receiving the Redis repository, then run the relevant Redis repository auto-configuration tests; done means ChatMemory no longer suppresses repository creation.