sysdesign-challenges

Scaffold a new domain feature with TDD order (entity -> test -> service -> test -> controller -> test)

새 Spring Boot 멀티모듈 프로젝트의 기초 세팅(common shared kernel + Gradle/Docker/CI 골격)을 깔아주는 스킬. 시스템 설계 문서 기반 구현 시작 시 가장 먼저 발동. 핵심 골격만 포함 — `BusinessException`/`ErrorCodeBase`/`ApiResponse`/`GlobalExceptionHandler`/`BaseEntity` + JPA/CORS/OpenAPI configs. Kafka/Outbox/QueryDSL 같은 도메인 특화 패턴은 별도 llm-wiki에서 끌어다 쓴다.

Design partner mode for system design practice. Activated when the user wants to design a new system (chat, notification, news feed, URL shortener, etc.). Sets up topic directory, copies the mock-interview template, loads the matching problem from sysdesign-question-bank, marks the topic as active in .omx/state/, and conducts a back-and-forth Clarifying → High Level → Drill Down conversation, updating <topic>/System-Design-Document/mock-interview.md immediately as each decision lands. Uses Alex Xu Vol.1's canned numbers as the starting point (book-first), user adjusts. NOT an interview — the user drives, this skill is a design collaborator with a calculator (back-of- envelope, latency estimation via auto-injected sysdesign-frameworks) and a reference book (sysdesign-question-bank).

Scaffold a minimum-viable implementation of a designed system. Activated when the user is ready to write code. Reads sdd.md (or falls back to mock-interview.md), determines the smallest component subset that lets the design's NFRs be testable (NOT a full production build — single-region, in-memory or single-container infra, no CDN, no multi-region), asks the user for the language/framework stack (default Spring Boot + PostgreSQL + Kafka per project's existing skill set), then scaffolds <topic>/source/ with per-service directories, a docker-compose.yml that brings everything up locally, and test-results/ scaffolding for functional / load / failure tests. The point is verification of design assumptions, not production.

Promote a filled mock-interview.md into a formal Software Design Document (sdd.md) following the IEEE 1016 / Atlassian / Google design-doc style. Activated when the user says they are ready to write the SDD. Reads the topic's mock-interview.md AND the topic's conversation log files (which capture the back-and-forth detail not preserved in the structured mock-interview), then asks the user the SDD-specific questions that mock-interview doesn't cover (Constraints, ADRs, Risk Register, Rollout, Testing strategy). Writes sdd.md incrementally as decisions land.

TDD workflow, per-layer test types, naming conventions, and test fixture patterns for Spring Boot. Use when writing or reviewing tests.

Applies Eric Evans' Domain-Driven Design patterns to design and review domain model classes. Covers tactical patterns (Entity, Value Object, Aggregate, Service, Repository, Factory, Domain Event) and strategic patterns (Bounded Context, Context Map, Anti-Corruption Layer, Core Domain, Distillation). Use when designing JPA entities, defining aggregate boundaries, identifying value objects, mapping bounded contexts, creating domain events, or reviewing domain model code. Also use when asked about ubiquitous language, context maps, or anti-corruption layers.

E2E/QA testing with agent-browser CLI for token-efficient browser automation

Kafka topic naming, producer/consumer configuration, outbox pattern, and idempotency strategies. Use when implementing event-driven messaging with Kafka.

Layered architecture conventions for service types, transaction boundaries, REST API design, DTO patterns, and error handling. Use when implementing or reviewing service/controller layer code.

Scaffold a new domain feature with TDD order (entity -> test -> service -> test -> controller -> test)

SAGA orchestration pattern, state machine, compensation transactions, and error handling for distributed transactions. Use when implementing order processing across services.

새 Spring Boot 멀티모듈 프로젝트의 기초 세팅(common shared kernel + Gradle/Docker/CI 골격)을 깔아주는 스킬. 시스템 설계 문서 기반 구현 시작 시 가장 먼저 발동. 핵심 골격만 포함 — `BusinessException`/`ErrorCodeBase`/`ApiResponse`/`GlobalExceptionHandler`/`BaseEntity` + JPA/CORS/OpenAPI configs. Kafka/Outbox/QueryDSL 같은 도메인 특화 패턴은 별도 llm-wiki에서 끌어다 쓴다.

Spring Boot 예외 처리 규칙 — try-catch 남용 방지, GlobalExceptionHandler + BusinessException 패턴 강제. spring-boot-expert agent가 부재한 메인 스레드 작업에서도 자동 주입되는 안전망.

Design partner mode for system design practice. Activated when the user wants to design a new system (chat, notification, news feed, URL shortener, etc.). Sets up topic directory, copies the mock-interview template, loads the matching problem from sysdesign-question-bank, marks the topic as active in .omc/state/, and conducts a back-and-forth Clarifying → High Level → Drill Down conversation, updating <topic>/System-Design-Document/mock-interview.md immediately as each decision lands. Uses Alex Xu Vol.1's canned numbers as the starting point (book-first), user adjusts. NOT an interview — the user drives, this skill is a design collaborator with a calculator (back-of- envelope, latency estimation via auto-injected sysdesign-frameworks) and a reference book (sysdesign-question-bank).

Reusable system design frameworks and reference data. Capacity estimation formulas (QPS, storage, bandwidth), Jeff Dean / Colin Scott latency numbers, building blocks (load balancer, replication, sharding, cache, CDN, message queue), CAP theorem and consistency models, rate limiting algorithms, Snowflake ID generation, consistent hashing, fan-out strategies (push/pull/ hybrid), Hello Interview delivery framework. Loaded by sysdesign-design / sysdesign-sdd / sysdesign-impl when their respective triggers fire, OR auto-injected when the user asks about a specific framework.

Scaffold a minimum-viable implementation of a designed system. Activated when the user is ready to write code. Reads sdd.md (or falls back to mock-interview.md), determines the smallest component subset that lets the design's NFRs be testable (NOT a full production build — single-region, in-memory or single-container infra, no CDN, no multi-region), asks the user for the language/framework stack (default Spring Boot + PostgreSQL + Kafka per project's existing skill set), then scaffolds <topic>/source/ with per-service directories, a docker-compose.yml that brings everything up locally, and test-results/ scaffolding for functional / load / failure tests. The point is verification of design assumptions, not production.

Catalog of 12 canonical system design problems from Alex Xu Vol.1 with the book's canned numbers (DAU/QPS/storage), key decisions, common traps, and expected rubric categories per problem. Loaded explicitly by sysdesign-design when a topic is chosen — not auto-injected. Each problem has its own file under problems/. Vol.2 problems (proximity service, distributed message queue, etc.) are NOT in this catalog — see _vol2-gap.md.

Promote a filled mock-interview.md into a formal Software Design Document (sdd.md) following the IEEE 1016 / Atlassian / Google design-doc style. Activated when the user says they are ready to write the SDD. Reads the topic's mock-interview.md AND the topic's conversation log files (which capture the back-and-forth detail not preserved in the structured mock-interview), then asks the user the SDD-specific questions that mock-interview doesn't cover (Constraints, ADRs, Risk Register, Rollout, Testing strategy). Writes sdd.md incrementally as decisions land.

TDD workflow, per-layer test types, naming conventions, and test fixture patterns for Spring Boot. Use when writing or reviewing tests.