java-architecture-standards

Layer 1 (Architecture) for Java backend. Daily decisions you can make WITHOUT opening SKILL.md: - Red Lines: NO @PathVariable (use query string / request body); NO hard delete (is_deleted=1); NO I prefix on interfaces; every list query filters by tenant_id. - Service writes: throw DomainException + AbstractErrorCode (never RuntimeException) — guarantees @Transactional rollback. - Cross-domain reads: Anti-JOIN — query main table, extract FK ids, query related table, assemble in memory. - DI: @RequiredArgsConstructor on the class, NEVER @Autowired on fields. Lombok: @Getter+@Setter, NOT @Data. - Null checks: Objects.isNull() / Objects.nonNull(), not == null. Open SKILL.md when deciding: POJO directory layout, audit field set, endpoint naming verbs, @ResourceLock usage.