r2dbclisted

# R2DBC Reactive non-blocking DB access. Pairs with WebFlux. ## Quick start ```java @Table("users") public record User( @Id UUID id, String email, String name, @CreatedDate Instant createdAt, @LastModifiedDate Instant updatedAt, @Version Long version ) {} @Repository public interface UserRepository extends R2dbcRepository<User, UUID> { Mono<User> findByEmail(String email); Mono<Boolean> existsByEmail(String email); @Query("SELECT * FROM users WHERE active = true ORDER BY created_at DESC") Flux<User> findAllActive(); } ``` Detailed: `references/repository-patterns.md`, `references/reactive-transactions.md`, `references/converters.md`. ## Assets - `assets/templates/ReactiveRepository.java.tmpl` - `assets/templates/R2dbcConfig.java.tmpl` ## Hard rules - NEVER use JPA annotations (`@Entity`, `@JoinColumn`, `@OneToMany`) in R2DBC entities. R2DBC ≠ JPA. - NEVER fetch related entities via field reference — manual join queries or N+1 via `flatMap`. - ALWAYS use `TransactionalOperator` or `@Transactional` (reactive variant) for multi-statement transactions. - USE `R2dbcEntityTemplate` when query DSL is needed beyond repository derivation. - POOL config: r2dbc-pool with explicit `initial-size`, `max-size`, `acquire-timeout`. ## Exit criteria - [ ] Entity uses R2DBC `@Table`, `@Id`, `@Column` (not JPA) - [ ] No JPA-style relations (`@OneToMany`) - [ ] Transactions via `TransactionalOperator` - [ ] Connection pool tuned