Quarkus Core Guidelines

Apply Quarkus core guidelines for CDI beans, configuration, profiles, and lifecycle.

What is covered in this Skill?

• @QuarkusMain and application entry (when custom main is needed)
• CDI scopes: @ApplicationScoped, @Singleton, @Dependent; bean disambiguation (@Default, @Alternative, @Named)
• Constructor injection with @Inject
• CDI interceptors (@Interceptor, @InterceptorBinding) for cross-cutting concerns
• CDI events: @Observes StartupEvent / ShutdownEvent, @ObservesAsync for async dispatch
• Programmatic injection with Instance<T> for dynamic bean selection
• @ConfigMapping and structured configuration with Bean Validation (@Valid)
• Profile-specific properties (%dev, %test, %prod) and @IfBuildProfile
• Startup and shutdown observers (@Startup, @PreDestroy)
• SmallRye Health probes (@Liveness, @Readiness)
• Virtual threads with @RunOnVirtualThread (Java 21+)
• Native-image safety: @RegisterForReflection, @DisabledOnNativeImage

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

Constraints

Before applying any Quarkus 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
• PREREQUISITE: Project must compile successfully before applying Quarkus core improvements
• SAFETY: If compilation fails, stop immediately — compilation failure is a blocking condition
• BLOCKING CONDITION: Compilation errors must be resolved by the user before proceeding
• 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

When to use this skill

• Review Java code for Quarkus application structure and CDI
• Apply best practices for Quarkus configuration and beans
• Improve CDI interceptors, events, or programmatic injection in Quarkus
• Add SmallRye Health probes or virtual-thread configuration

Reference

For detailed guidance, examples, and constraints, see references/401-frameworks-quarkus-core.md.