<div id="readability-page-1" class="page"><div>
												
<h2>스킬이란?</h2>
<p>Claude 에서 만들어 공개한 기법입니다.<br>
다른 AI 에서도 사용가능하므로 <code>Claude Skill</code> 이 아니라 <code>Agent Skill</code> 로 명명합니다.<br>
Agent Skills는 Claude의 기능을 확장하는 모듈입니다.<br>
패턴이나 가이드라인을 정리해 놓고, 그것에 맞게 AI 가 코딩하게 하는 기법입니다.</p>
<h2>샘플</h2>
<pre><code>---
name: my-skill-name
description: A clear description of what this skill does and when to use it
---

# My Skill Name

[Add your instructions here that Claude will follow when this skill is active]

## Examples
- Example usage 1
- Example usage 2

## Guidelines
- Guideline 1
- Guideline 2</code></pre>
<h2>실제코드 (오픈소스)</h2>
<p>문서가 깨지므로 따옴표를 물결무늬문자로 변경하였습니다.</p>
<pre><code>---
name: springboot-patterns
description: Spring Boot architecture patterns, REST API design, layered services, data access, caching, async processing, and logging. Use for Java Spring Boot backend work.
---

# Spring Boot Development Patterns

Spring Boot architecture and API patterns for scalable, production-grade services.

## REST API Structure

~~~java
@RestController
@RequestMapping("/api/markets")
@Validated
class MarketController {
  private final MarketService marketService;

  MarketController(MarketService marketService) {
    this.marketService = marketService;
  }

  @GetMapping
  ResponseEntity&lt;Page&lt;MarketResponse&gt;&gt; list(
      @RequestParam(defaultValue = "0") int page,
      @RequestParam(defaultValue = "20") int size) {
    Page&lt;Market&gt; markets = marketService.list(PageRequest.of(page, size));
    return ResponseEntity.ok(markets.map(MarketResponse::from));
  }

  @PostMapping
  ResponseEntity&lt;MarketResponse&gt; create(@Valid @RequestBody CreateMarketRequest request) {
    Market market = marketService.create(request);
    return ResponseEntity.status(HttpStatus.CREATED).body(MarketResponse.from(market));
  }
}
~~~

## Repository Pattern (Spring Data JPA)

~~~java
public interface MarketRepository extends JpaRepository&lt;MarketEntity, Long&gt; {
  @Query("select m from MarketEntity m where m.status = :status order by m.volume desc")
  List&lt;MarketEntity&gt; findActive(@Param("status") MarketStatus status, Pageable pageable);
}
~~~

## Service Layer with Transactions

~~~java
@Service
public class MarketService {
  private final MarketRepository repo;

  public MarketService(MarketRepository repo) {
    this.repo = repo;
  }

  @Transactional
  public Market create(CreateMarketRequest request) {
    MarketEntity entity = MarketEntity.from(request);
    MarketEntity saved = repo.save(entity);
    return Market.from(saved);
  }
}
~~~

## DTOs and Validation

~~~java
public record CreateMarketRequest(
    @NotBlank @Size(max = 200) String name,
    @NotBlank @Size(max = 2000) String description,
    @NotNull @FutureOrPresent Instant endDate,
    @NotEmpty List&lt;@NotBlank String&gt; categories) {}

public record MarketResponse(Long id, String name, MarketStatus status) {
  static MarketResponse from(Market market) {
    return new MarketResponse(market.id(), market.name(), market.status());
  }
}
~~~

## Exception Handling

~~~java
@ControllerAdvice
class GlobalExceptionHandler {
  @ExceptionHandler(MethodArgumentNotValidException.class)
  ResponseEntity&lt;ApiError&gt; handleValidation(MethodArgumentNotValidException ex) {
    String message = ex.getBindingResult().getFieldErrors().stream()
        .map(e -&gt; e.getField() + ": " + e.getDefaultMessage())
        .collect(Collectors.joining(", "));
    return ResponseEntity.badRequest().body(ApiError.validation(message));
  }

  @ExceptionHandler(AccessDeniedException.class)
  ResponseEntity&lt;ApiError&gt; handleAccessDenied() {
    return ResponseEntity.status(HttpStatus.FORBIDDEN).body(ApiError.of("Forbidden"));
  }

  @ExceptionHandler(Exception.class)
  ResponseEntity&lt;ApiError&gt; handleGeneric(Exception ex) {
    // Log unexpected errors with stack traces
    return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
        .body(ApiError.of("Internal server error"));
  }
}
~~~

## Caching

Requires `@EnableCaching` on a configuration class.

~~~java
@Service
public class MarketCacheService {
  private final MarketRepository repo;

  public MarketCacheService(MarketRepository repo) {
    this.repo = repo;
  }

  @Cacheable(value = "market", key = "#id")
  public Market getById(Long id) {
    return repo.findById(id)
        .map(Market::from)
        .orElseThrow(() -&gt; new EntityNotFoundException("Market not found"));
  }

  @CacheEvict(value = "market", key = "#id")
  public void evict(Long id) {}
}
~~~

## Async Processing

Requires `@EnableAsync` on a configuration class.

~~~java
@Service
public class NotificationService {
  @Async
  public CompletableFuture&lt;Void&gt; sendAsync(Notification notification) {
    // send email/SMS
    return CompletableFuture.completedFuture(null);
  }
}
~~~

## Logging (SLF4J)

~~~java
@Service
public class ReportService {
  private static final Logger log = LoggerFactory.getLogger(ReportService.class);

  public Report generate(Long marketId) {
    log.info("generate_report marketId={}", marketId);
    try {
      // logic
    } catch (Exception ex) {
      log.error("generate_report_failed marketId={}", marketId, ex);
      throw ex;
    }
    return new Report();
  }
}
~~~

## Middleware / Filters

~~~java
@Component
public class RequestLoggingFilter extends OncePerRequestFilter {
  private static final Logger log = LoggerFactory.getLogger(RequestLoggingFilter.class);

  @Override
  protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
      FilterChain filterChain) throws ServletException, IOException {
    long start = System.currentTimeMillis();
    try {
      filterChain.doFilter(request, response);
    } finally {
      long duration = System.currentTimeMillis() - start;
      log.info("req method={} uri={} status={} durationMs={}",
          request.getMethod(), request.getRequestURI(), response.getStatus(), duration);
    }
  }
}
~~~

## Pagination and Sorting

~~~java
PageRequest page = PageRequest.of(pageNumber, pageSize, Sort.by("createdAt").descending());
Page&lt;Market&gt; results = marketService.list(page);
~~~

## Error-Resilient External Calls

~~~java
public &lt;T&gt; T withRetry(Supplier&lt;T&gt; supplier, int maxRetries) {
  int attempts = 0;
  while (true) {
    try {
      return supplier.get();
    } catch (Exception ex) {
      attempts++;
      if (attempts &gt;= maxRetries) {
        throw ex;
      }
      try {
        Thread.sleep((long) Math.pow(2, attempts) * 100L);
      } catch (InterruptedException ie) {
        Thread.currentThread().interrupt();
        throw ex;
      }
    }
  }
}
~~~

## Rate Limiting (Filter + Bucket4j)

**Security Note**: The `X-Forwarded-For` header is untrusted by default because clients can spoof it.
Only use forwarded headers when:
1. Your app is behind a trusted reverse proxy (nginx, AWS ALB, etc.)
2. You have registered `ForwardedHeaderFilter` as a bean
3. You have configured `server.forward-headers-strategy=NATIVE` or `FRAMEWORK` in application properties
4. Your proxy is configured to overwrite (not append to) the `X-Forwarded-For` header

When `ForwardedHeaderFilter` is properly configured, `request.getRemoteAddr()` will automatically
return the correct client IP from the forwarded headers. Without this configuration, use
`request.getRemoteAddr()` directly—it returns the immediate connection IP, which is the only
trustworthy value.

~~~java
@Component
public class RateLimitFilter extends OncePerRequestFilter {
  private final Map&lt;String, Bucket&gt; buckets = new ConcurrentHashMap&lt;&gt;();

  /*
   * SECURITY: This filter uses request.getRemoteAddr() to identify clients for rate limiting.
   *
   * If your application is behind a reverse proxy (nginx, AWS ALB, etc.), you MUST configure
   * Spring to handle forwarded headers properly for accurate client IP detection:
   *
   * 1. Set server.forward-headers-strategy=NATIVE (for cloud platforms) or FRAMEWORK in
   *    application.properties/yaml
   * 2. If using FRAMEWORK strategy, register ForwardedHeaderFilter:
   *
   *    @Bean
   *    ForwardedHeaderFilter forwardedHeaderFilter() {
   *        return new ForwardedHeaderFilter();
   *    }
   *
   * 3. Ensure your proxy overwrites (not appends) the X-Forwarded-For header to prevent spoofing
   * 4. Configure server.tomcat.remoteip.trusted-proxies or equivalent for your container
   *
   * Without this configuration, request.getRemoteAddr() returns the proxy IP, not the client IP.
   * Do NOT read X-Forwarded-For directly—it is trivially spoofable without trusted proxy handling.
   */
  @Override
  protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
      FilterChain filterChain) throws ServletException, IOException {
    // Use getRemoteAddr() which returns the correct client IP when ForwardedHeaderFilter
    // is configured, or the direct connection IP otherwise. Never trust X-Forwarded-For
    // headers directly without proper proxy configuration.
    String clientIp = request.getRemoteAddr();

    Bucket bucket = buckets.computeIfAbsent(clientIp,
        k -&gt; Bucket.builder()
            .addLimit(Bandwidth.classic(100, Refill.greedy(100, Duration.ofMinutes(1))))
            .build());

    if (bucket.tryConsume(1)) {
      filterChain.doFilter(request, response);
    } else {
      response.setStatus(HttpStatus.TOO_MANY_REQUESTS.value());
    }
  }
}
~~~

## Background Jobs

Use Spring’s `@Scheduled` or integrate with queues (e.g., Kafka, SQS, RabbitMQ). Keep handlers idempotent and observable.

## Observability

- Structured logging (JSON) via Logback encoder
- Metrics: Micrometer + Prometheus/OTel
- Tracing: Micrometer Tracing with OpenTelemetry or Brave backend

## Production Defaults

- Prefer constructor injection, avoid field injection
- Enable `spring.mvc.problemdetails.enabled=true` for RFC 7807 errors (Spring Boot 3+)
- Configure HikariCP pool sizes for workload, set timeouts
- Use `@Transactional(readOnly = true)` for queries
- Enforce null-safety via `@NonNull` and `Optional` where appropriate

**Remember**: Keep controllers thin, services focused, repositories simple, and errors handled centrally. Optimize for maintainability and testability.
</code></pre>
<h2>설치방법</h2>
<p>전역 Skills 위치: ~/.claude/skills/{skill-name}/SKILL.md<br>
프로젝트 Skills 위치: .claude/skills/{skill-name}/SKILL.md</p>
<h2>사용법</h2>
<p>기본적으로는 클로드가 알아서 필요한 스킬을 찾아서 참조합니다.</p>
<p>하지만, 아래와 같이 특정 스킬을 사용하도록 강제할 수 있습니다.</p>
<pre><code>/{skill-name} 프롬프트 입력</code></pre>
<p><span></span> <span>Post Views:</span> <span>12</span>
			</p>											</div></div>

상구리의 기술 블로그

Claude Code – 스킬 생성 및 사용법
스킬이란?
Claude 에서 만들어 공개한 기법입니다.
Claude Skill 이 아니라 Agent Skill 로 명명합니다.
샘플
---
name: my-skill-name
description: A clear description of what this skill does and when to use it
---
# My Skill Name
[Add your instructions here that Claude will follow when this skill is active]
## Examples
- Example usage 1
- Example usage 2
## Guidelines
- Guideline 1
- Guideline 2
실제코드 (오픈소스)
문서가 깨지므로 따옴표를 물결무늬문자로 변경하였습니다.
---
name: springboot-patterns
description: Spring Boot architecture patterns, REST API design, layered services, data access, caching, async processing, and logging. Use for Java Spring Boot backend work.
---
# Spring Boot Development Patterns
Spring Boot architecture and API patterns for scalable, production-grade services.
## REST API Structure
~~~java
@RestController
@RequestMapping("/api/markets")
@Validated
class MarketController {
  private final MarketService marketService;
  MarketController(MarketService marketService) {
    this.marketService = marketService;
  }
  @GetMapping
  ResponseEntity<Page<MarketResponse>> list(
      @RequestParam(defaultValue = "0") int page,
      @RequestParam(defaultValue = "20") int size) {
    Page<Market> markets = marketService.list(PageRequest.of(page, size));
    return ResponseEntity.ok(markets.map(MarketResponse::from));
  }
  @PostMapping
  ResponseEntity<MarketResponse> create(@Valid @RequestBody CreateMarketRequest request) {
    Market market = marketService.create(request);
    return ResponseEntity.status(HttpStatus.CREATED).body(MarketResponse.from(market));
  }
}
~~~
## Repository Pattern (Spring Data JPA)
~~~java
public interface MarketRepository extends JpaRepository<MarketEntity, Long> {
  @Query("select m from MarketEntity m where m.status = :status order by m.volume desc")
  List<MarketEntity> findActive(@Param("status") MarketStatus status, Pageable pageable);
}
~~~
## Service Layer with Transactions
~~~java
@Service
public class MarketService {
  private final MarketRepository repo;
  public MarketService(MarketRepository repo) {
    this.repo = repo;
  }
  @Transactional
  public Market create(CreateMarketRequest request) {
    MarketEntity entity = MarketEntity.from(request);
    MarketEntity saved = repo.save(entity);
    return Market.from(saved);
  }
}
~~~
## DTOs and Validation
~~~java
public record CreateMarketRequest(
    @NotBlank @Size(max = 200) String name,
    @NotBlank @Size(max = 2000) String description,
    @NotNull @FutureOrPresent Instant endDate,
    @NotEmpty List<@NotBlank String> categories) {}
public record MarketResponse(Long id, String name, MarketStatus status) {
  static MarketResponse from(Market market) {
    return new MarketResponse(market.id(), market.name(), market.status());
  }
}
~~~
## Exception Handling
~~~java
@ControllerAdvice
class GlobalExceptionHandler {
  @ExceptionHandler(MethodArgumentNotValidException.class)
  ResponseEntity<ApiError> handleValidation(MethodArgumentNotValidException ex) {
    String message = ex.getBindingResult().getFieldErrors().stream()
        .map(e -> e.getField() + ": " + e.getDefaultMessage())
        .collect(Collectors.joining(", "));
    return ResponseEntity.badRequest().body(ApiError.validation(message));
  }
  @ExceptionHandler(AccessDeniedException.class)
  ResponseEntity<ApiError> handleAccessDenied() {
    return ResponseEntity.status(HttpStatus.FORBIDDEN).body(ApiError.of("Forbidden"));
  }
  @ExceptionHandler(Exception.class)
  ResponseEntity<ApiError> handleGeneric(Exception ex) {
    // Log unexpected errors with stack traces
    return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
        .body(ApiError.of("Internal server error"));
  }
}
~~~
## Caching
Requires `@EnableCaching` on a configuration class.
~~~java
@Service
public class MarketCacheService {
  private final MarketRepository repo;
  public MarketCacheService(MarketRepository repo) {
    this.repo = repo;
  }
  @Cacheable(value = "market", key = "#id")
  public Market getById(Long id) {
    return repo.findById(id)
        .map(Market::from)
        .orElseThrow(() -> new EntityNotFoundException("Market not found"));
  }
  @CacheEvict(value = "market", key = "#id")
  public void evict(Long id) {}
}
~~~
## Async Processing
Requires `@EnableAsync` on a configuration class.
~~~java
@Service
public class NotificationService {
  @Async
  public CompletableFuture<Void> sendAsync(Notification notification) {
    // send email/SMS
    return CompletableFuture.completedFuture(null);
  }
}
~~~
## Logging (SLF4J)
~~~java
@Service
public class ReportService {
  private static final Logger log = LoggerFactory.getLogger(ReportService.class);
  public Report generate(Long marketId) {
    log.info("generate_report marketId={}", marketId);
    try {
      // logic
    } catch (Exception ex) {
      log.error("generate_report_failed marketId={}", marketId, ex);
      throw ex;
    }
    return new Report();
  }
}
~~~
## Middleware / Filters
~~~java
@Component
public class RequestLoggingFilter extends OncePerRequestFilter {
  private static final Logger log = LoggerFactory.getLogger(RequestLoggingFilter.class);
  @Override
  protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
      FilterChain filterChain) throws ServletException, IOException {
    long start = System.currentTimeMillis();
    try {
      filterChain.doFilter(request, response);
    } finally {
      long duration = System.currentTimeMillis() - start;
      log.info("req method={} uri={} status={} durationMs={}",
          request.getMethod(), request.getRequestURI(), response.getStatus(), duration);
    }
  }
}
~~~
## Pagination and Sorting
~~~java
PageRequest page = PageRequest.of(pageNumber, pageSize, Sort.by("createdAt").descending());
Page<Market> results = marketService.list(page);
~~~
## Error-Resilient External Calls
~~~java
public <T> T withRetry(Supplier<T> supplier, int maxRetries) {
  int attempts = 0;
  while (true) {
    try {
      return supplier.get();
    } catch (Exception ex) {
      attempts++;
      if (attempts >= maxRetries) {
        throw ex;
      }
      try {
        Thread.sleep((long) Math.pow(2, attempts) * 100L);
      } catch (InterruptedException ie) {
        Thread.currentThread().interrupt();
        throw ex;
      }
    }
  }
}
~~~
## Rate Limiting (Filter + Bucket4j)
**Security Note**: The `X-Forwarded-For` header is untrusted by default because clients can spoof it.
Only use forwarded headers when:
1. Your app is behind a trusted reverse proxy (nginx, AWS ALB, etc.)
2. You have registered `ForwardedHeaderFilter` as a bean
3. You have configured `server.forward-headers-strategy=NATIVE` or `FRAMEWORK` in application properties
4. Your proxy is configured to overwrite (not append to) the `X-Forwarded-For` header
When `ForwardedHeaderFilter` is properly configured, `request.getRemoteAddr()` will automatically
return the correct client IP from the forwarded headers. Without this configuration, use
`request.getRemoteAddr()` directly—it returns the immediate connection IP, which is the only
trustworthy value.
~~~java
@Component
public class RateLimitFilter extends OncePerRequestFilter {
  private final Map<String, Bucket> buckets = new ConcurrentHashMap<>();
  /*
   * SECURITY: This filter uses request.getRemoteAddr() to identify clients for rate limiting.
   *
   * If your application is behind a reverse proxy (nginx, AWS ALB, etc.), you MUST configure
   * Spring to handle forwarded headers properly for accurate client IP detection:
   *
   * 1. Set server.forward-headers-strategy=NATIVE (for cloud platforms) or FRAMEWORK in
   *    application.properties/yaml
   * 2. If using FRAMEWORK strategy, register ForwardedHeaderFilter:
   *
   *    @Bean
   *    ForwardedHeaderFilter forwardedHeaderFilter() {
   *        return new ForwardedHeaderFilter();
   *    }
   *
   * 3. Ensure your proxy overwrites (not appends) the X-Forwarded-For header to prevent spoofing
   * 4. Configure server.tomcat.remoteip.trusted-proxies or equivalent for your container
   *
   * Without this configuration, request.getRemoteAddr() returns the proxy IP, not the client IP.
   * Do NOT read X-Forwarded-For directly—it is trivially spoofable without trusted proxy handling.
   */
  @Override
  protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
      FilterChain filterChain) throws ServletException, IOException {
    // Use getRemoteAddr() which returns the correct client IP when ForwardedHeaderFilter
    // is configured, or the direct connection IP otherwise. Never trust X-Forwarded-For
    // headers directly without proper proxy configuration.
    String clientIp = request.getRemoteAddr();
    Bucket bucket = buckets.computeIfAbsent(clientIp,
        k -> Bucket.builder()
            .addLimit(Bandwidth.classic(100, Refill.greedy(100, Duration.ofMinutes(1))))
            .build());
    if (bucket.tryConsume(1)) {
      filterChain.doFilter(request, response);
    } else {
      response.setStatus(HttpStatus.TOO_MANY_REQUESTS.value());
    }
  }
}
~~~
## Background Jobs
Use Spring’s `@Scheduled` or integrate with queues (e.g., Kafka, SQS, RabbitMQ). Keep handlers idempotent and observable.
## Observability
- Structured logging (JSON) via Logback encoder
- Metrics: Micrometer + Prometheus/OTel
- Tracing: Micrometer Tracing with OpenTelemetry or Brave backend
## Production Defaults
- Prefer constructor injection, avoid field injection
- Enable `spring.mvc.problemdetails.enabled=true` for RFC 7807 errors (Spring Boot 3+)
- Configure HikariCP pool sizes for workload, set timeouts
- Use `@Transactional(readOnly = true)` for queries
- Enforce null-safety via `@NonNull` and `Optional` where appropriate
**Remember**: Keep controllers thin, services focused, repositories simple, and errors handled centrally. Optimize for maintainability and testability.
설치방법
전역 Skills 위치: ~/.claude/skills/{skill-name}/SKILL.md
사용법
기본적으로는 클로드가 알아서 필요한 스킬을 찾아서 참조합니다.
하지만, 아래와 같이 특정 스킬을 사용하도록 강제할 수 있습니다.
/{skill-name} 프롬프트 입력

Claude Code – 스킬 생성 및 사용법

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