301-frameworks-spring-boot-core

# 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 ## 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).