Phase 2 实战：使用 Spring AI VectorStore + pgvector 构建 PSLE 题库 RAG 检索，融入多 Agent 解题链，搭配 Redis 缓存实现秒级响应。

本文复盘一次集成测试在 make coverage 阶段卡死的问题：先是连接池超时，再是 Lettuce SharedLock 自旋。重点分享排查路径、错误假设、最终根因与可复用修复策略。

A seemingly harmless removal of publishOn(Schedulers.boundedElastic()) led to cascading Redis timeouts in production. This post explains how Spring’s @Cacheable blocks the Netty event loop when used with RedisCacheManager, and why BlockHound failed to catch it.