301-frameworks-spring-boot-core - Claude MCP Skill

# Spring Boot Core Guidelines

Apply Spring Boot Core guidelines for annotations, bean management, configuration, and dependency injection.

**What is covered in this Skill?**

- @SpringBootApplication and main application class
- Component annotations: @RestController, @Service, @Repository
- Bean definition, scoping, lifecycle
- Configuration classes and @ConfigurationProperties (with @Validated for fail-fast startup)
- Component scanning and package organization
- Conditional configuration and profiles (@Profile, @ConditionalOn*)
- Constructor dependency injection
- @Primary and @Qualifier for disambiguation when multiple beans share a type
- Bean minimization and composition
- Graceful shutdown for in-flight work
- Virtual threads on supported stacks for concurrency-bound workloads
- Jakarta EE namespace consistency (jakarta.* preferred; avoid mixing legacy javax.annotation / javax.validation)
- Scheduled tasks and background processing

**Scope:** Apply recommendations based on the reference rules and good/bad code examples.

## Constraints

Before applying any Spring Boot changes, ensure the project compiles. If compilation fails, stop immediately. After applying improvements, run full verification.

- **MANDATORY**: Run `./mvnw compile` or `mvn compile` before applying any change
- **SAFETY**: If compilation fails, stop immediately — compilation failure is a blocking condition
- **VERIFY**: Run `./mvnw clean verify` or `mvn clean verify` after applying improvements
- **BEFORE APPLYING**: Read the reference for detailed rules, good/bad patterns, and constraints
- **EDGE CASE**: If request scope is ambiguous, stop and ask a clarifying question before applying changes
- **EDGE CASE**: If required inputs, files, or tooling are missing, report what is missing and ask whether to proceed with setup guidance

## When to use this skill

- Review Java code for Spring Boot application
- Apply best practices for Spring Boot application in Java code
- Improve Spring Boot configuration properties and beans
- Review Spring Boot component scanning and profiles
- Tune Spring Boot graceful shutdown or virtual threads

## Workflow

1. **Read reference and assess project context**

Read `references/301-frameworks-spring-boot-core.md` and inspect the current project setup before proposing changes.

2. **Gather scope and decide target improvements**

Identify requested outcomes, constraints, and the minimum safe set of changes to apply.

3. **Apply framework-aligned changes**

Implement or refactor configuration/code following the reference patterns and project conventions.

4. **Run verification and report results**

Execute appropriate build/tests and summarize what changed, what was verified, and any follow-up actions.

## Reference

For detailed guidance, examples, and constraints, see [references/301-frameworks-spring-boot-core.md](references/301-frameworks-spring-boot-core.md).