Add or Update Domain

VerifiedSafe

Use this skill when adding or updating a domain in a bounded context. It enforces conventions for command and query classes in the domain/model directory, using sealed interfaces for commands and paginated queries.

Sby Skills Guide Bot
DevelopmentIntermediate
506/2/2026
Claude Code
#domain-driven-design#bounded-context#command-query#kotlin#pagination

Recommended for

Our review

Adds or updates a domain in a bounded context following a command and query model structure with pagination.

Strengths

  • Clean and consistent structure for commands and queries
  • Supports both cursor and offset pagination
  • Uses sealed classes for type safety

Limitations

  • Kotlin-specific, not language-agnostic
  • Requires strict naming conventions
  • Does not cover advanced use cases like events
When to use it

When adding or modifying a domain in a DDD architecture with a bounded context.

When not to use it

For simple projects without DDD, or if you're using a language other than Kotlin.

Security analysis

Safe
Quality score85/100

This skill is a coding style guide and does not contain any executable commands, destructive actions, or data exfiltration instructions. It is purely informational and poses no security risk.

No concerns found

Examples

Add a new Task domain
Add a new domain model for Task with CreateTask, UpdateTask, and DeleteTask commands, and queries for listing tasks by member and week with cursor pagination.
Add query for user by email
Add a query for finding users by email with offset pagination following the pattern in SKILL.md.

name: add-or-update-domain description: Bounded Context에 새로운 도메인을 추가하거나 수정할 때 사용하세요.

Add or Update Domain

Instructions

새로운 도메인을 추가하거나 기존 도메인을 수정할 때 다음 규칙을 따르세요:

1. model 디렉토리

├── domain/
│   ├── model/
│   │   ├── command/
│   │   └── query/

command 에는 생성/수정/삭제를 위한 조건이나 데이터를 표현하는 클래스가 위치합니다.

command 클래스는 마커 인터페이스로 정의하고, 필요한 속성들을 구현체에 정의합니다. 예를 들어:

sealed interface TaskCommand {
    data class CreateTask(
        val title: TaskTitle,
        val description: TaskDescription?,
        val state: TaskState,
        val step: TaskStep,
        val memberId: MemberId,
        val weekId: WeekId,
    ): TaskCommand

    data class UpdateTask(
        val taskId: TaskId,
        val title: TaskTitle,
        val description: TaskDescription?,
    ) : TaskCommand

    data class DeleteTask(
        val taskId: TaskId,
    ) : TaskCommand
}

query 에는 조회를 위한 조건을 표현하는 클래스가 위치합니다.

query 클래스는 반드시 xyz.robinjoon.growweek.common.PageQuery 인터페이스를 구현한 sealed class로 정의하고, 이를 다시 구체적인 클래스가 상속하도록 합니다. 예를 들어:

sealed class TaskQuery(
    override val pageInfo: PageInfo
) : PageQuery {

    object Cursor {
        fun byMemberAndWeek(
            memberId: MemberId,
            weekId: WeekId,
            cursor: String? = null,
            size: Int = 20,
            orderBy: String? = "createdAt"
        ): CursorByMemberAndWeek {
            return CursorByMemberAndWeek(
                memberId = memberId,
                weekId = weekId,
                pageInfo = CursorPageInfo(
                    cursor = cursor,
                    size = size,
                    orderBy = orderBy
                )
            )
        }

        fun byTaskIds(
            taskIds: List<TaskId>,
            cursor: String? = null,
            size: Int = 20,
            orderBy: String? = "createdAt"
        ): CursorByTaskIds {
            return CursorByTaskIds(
                taskIds = taskIds,
                pageInfo = CursorPageInfo(
                    cursor = cursor,
                    size = size,
                    orderBy = orderBy
                )
            )
        }
    }

    object Offset {
        fun byMemberAndWeek(
            memberId: MemberId,
            weekId: WeekId,
            page: Int = 0,
            size: Int = 20,
            orderBy: String? = "createdAt"
        ): OffsetByMemberAndWeek {
            return OffsetByMemberAndWeek(
                memberId = memberId,
                weekId = weekId,
                pageInfo = OffsetPageInfo(
                    page = page,
                    size = size,
                    orderBy = orderBy
                )
            )
        }

        fun byTaskIds(
            taskIds: List<TaskId>,
            page: Int = 0,
            size: Int = 20,
            orderBy: String? = "createdAt"
        ): OffsetByTaskIds {
            return OffsetByTaskIds(
                taskIds = taskIds,
                pageInfo = OffsetPageInfo(
                    page = page,
                    size = size,
                    orderBy = orderBy
                )
            )
        }
    }

    data class CursorByMemberAndWeek(
        val memberId: MemberId,
        val weekId: WeekId,
        override val pageInfo: CursorPageInfo
    ) : TaskQuery(pageInfo) {
        val cursor get() = pageInfo.cursor
        val size get() = pageInfo.size
        val orderBy: String? get() = pageInfo.orderBy
    }

    data class CursorByTaskIds(
        val taskIds: List<TaskId>,
        override val pageInfo: CursorPageInfo
    ) : TaskQuery(pageInfo) {
        val cursor get() = pageInfo.cursor
        val size get() = pageInfo.size
        val orderBy: String? get() = pageInfo.orderBy
    }

    data class OffsetByMemberAndWeek(
        val memberId: MemberId,
        val weekId: WeekId,
        override val pageInfo: OffsetPageInfo
    ) : TaskQuery(pageInfo) {
        val page get() = pageInfo.page
        val size get() = pageInfo.size
        val orderBy: String? get() = pageInfo.orderBy
    }

    data class OffsetByTaskIds(
        val taskIds: List<TaskId>,
        override val pageInfo: OffsetPageInfo
    ) : TaskQuery(pageInfo) {
        val page get() = pageInfo.page
        val size get() = pageInfo.size
        val orderBy: String? get() = pageInfo.orderBy
    }
}

그 외 도메인의 엔티티나 VO 등은 model 디렉토리에 함께 위치시키며 다음 조건을 따릅니다.

  1. 다른 바운디드 컨텍스트에서 사용해야 하는 것들은 common 에 추가합니다.

        @JvmInline
        value class MemberId(val value: Long) {
            init {
                require(value >= 0) { "MemberId must be greater than or equal to 0" }
            }
        }
    
       ├── common /
       │   ├── domain/
       │   │   ├── MemberId.kt/
       {bounded-context}/
       ├── domain/
       │   ├── model/
       │   │   ├── command/
       │   │   └── query/
       │   ├── repository/
       │   └── service/
    
  2. common 을 제외한 다른 바운디드 컨텍스트의 도메인 모델은 참조하지 않도록 합니다.

2. repository 디렉토리

├── domain/
│   ├── model/
│   │   ├── command/
│   │   └── query/
│   ├── repository/

repository 디렉토리에는 도메인 모델에 대한 영속성 인터페이스를 정의합니다. 이때, 반드시 saveAll(List<command>) : List<Domain> , findAll(query) : Page<Domain> 메서드만을 포함합니다. 예를 들어:

interface TaskRepository {
    fun saveAll(commands: List<TaskCommand>): List<Task>
    fun findAll(query: TaskQuery): Page<Task>
}

3. service 디렉토리

├── domain/
│   ├── model/
│   │   ├── command/
│   │   └── query/
│   ├── repository/
│   └── service/

service 디렉토리는 도메인 서비스가 위치합니다. 단, 도메인 서비스는 도메인 서비스 추가 필요성 결정 기준 문서에 따라 신중하게 설계하고 구현해야 합니다.

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