backend-module-structure

Development

Rules for the SkillHub backend Maven multi-module clean architecture. Ensures agents place new code in the correct module and respect dependency direction.

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Backend Module Structure Skill

Trigger

Use this skill when:

Adding or modifying Java backend code
Creating new services, controllers, repositories, or entities
Refactoring backend code across files
Reviewing backend code placement

Rules

Dependency Direction

The design-doc dependency direction:

app → domain, auth, search, storage, infra, notification
infra → domain          # implements domain repository interfaces
auth → domain
search → domain
notification → domain
storage → (independent) # pure SPI

Design intent: skillhub-domain should be the innermost layer, defining entities, repository interfaces, and domain services without depending on infra, auth, search, or storage.

Code reality: skillhub-domain declares a Maven dependency on skillhub-storage (via pom.xml), and several domain services (SkillHardDeleteService, SkillDownloadService, SkillPublishService, SkillGovernanceService, SkillQueryService, SkillStorageDeletionCompensationService) import com.iflytek.skillhub.storage.ObjectStorageService. This is an existing deviation from the ideal clean architecture. New code should avoid adding further cross-module dependencies from domain.

Where to Place Code

Code Type	Module	Java Package
Entity / Value Object	skillhub-domain	`com.iflytek.skillhub.domain.{submodule}/`
Repository Interface	skillhub-domain	`com.iflytek.skillhub.domain.{submodule}/`
Domain Service	skillhub-domain	`com.iflytek.skillhub.domain.{submodule}/service/`
Domain Event	skillhub-domain	`com.iflytek.skillhub.domain/event/`
Domain Exception	skillhub-domain	`com.iflytek.skillhub.domain/shared/exception/`
JPA Repository Impl	skillhub-infra	`com.iflytek.skillhub.infra.repository/`
Controller	skillhub-app	`com.iflytek.skillhub.controller/`
App Service	skillhub-app	`com.iflytek.skillhub.service/`
Query Repository	skillhub-app	`com.iflytek.skillhub.repository/`
DTO / Response	skillhub-app	`com.iflytek.skillhub.dto/`
OAuth2 / Auth Config	skillhub-auth	`com.iflytek.skillhub.auth/`
Search SPI / Impl	skillhub-search	`com.iflytek.skillhub.search/`
Storage SPI / Impl	skillhub-storage	`com.iflytek.skillhub.storage/`
Notification Service	skillhub-notification	`com.iflytek.skillhub.notification/`

Maven Modules

The parent POM (server/pom.xml) defines 7 modules with spring-boot-starter-parent:3.2.3:

skillhub-app | skillhub-domain | skillhub-auth | skillhub-search
skillhub-storage | skillhub-infra | skillhub-notification

Repository vs Query Repository

Domain Repository (skillhub-domain): Aggregate reads, state transitions, rule evaluation. Returns domain objects. Defined as interfaces, implemented in skillhub-infra via Spring Data JPA.
Query Repository (com.iflytek.skillhub.repository): Read-model assembly, joins multiple sources, presentation projection. Returns DTOs. Implemented directly in skillhub-app.

Current query repositories:

GovernanceQueryRepository / JpaGovernanceQueryRepository
MySkillQueryRepository / JpaMySkillQueryRepository
ProfileReviewQueryRepository / JpaProfileReviewQueryRepository
AdminSkillReportQueryRepository / JpaAdminSkillReportQueryRepository

When a new read use case arrives:

If it's for state transition or domain rule → domain repository port
If it's for page/list/detail response assembly with joins → app query repository
If it's a thin single-aggregate read → direct domain repository call from app service
If direct SQL/EntityManager is needed → add class-level comment explaining why

Building Backend Tests

Never run ./mvnw -pl skillhub-app clean test directly under server/. Use:

make test-backend-app   # skillhub-app + dependencies (includes -am)
make test-backend       # all backend modules

Running clean test on skillhub-app alone can fall back to stale artifacts from the local Maven repository, surfacing misleading cannot find symbol and signature-mismatch errors.

User Identity Type

User identity is always String throughout the codebase. This covers:

Authentication, API params, permissions, audit
Resource owner, creator, reviewer, actor, submittedBy
All user-associated fields

The UserAccount entity uses @Column(length = 128) for its ID. The platform needs to support external SSO/OIDC/SCIM identity sources whose UIDs are typically stable strings.