403-frameworks-quarkus-validation

name: 403-frameworks-quarkus-validation description: Use when you need to design, review, or improve validation in Quarkus applications — including Bean Validation on JAX-RS resources, @Valid on parameters and CDI beans, constraint groups, @ConfigMapping validation, custom constraints, nested DTO validation, and ExceptionMapper-based error mapping. This should trigger for requests such as Add validation support in Quarkus; Review Quarkus validation rules; Improve request validation in Quarkus REST APIs; Add custom validation constraints in Quarkus; Validate Quarkus @ConfigMapping properties. Part of cursor-rules-java project license: Apache-2.0 metadata: author: Juan Antonio Breña Moral version: 0.16.0

Quarkus Validation Guidelines

Apply Quarkus validation best practices at REST boundaries.

What is covered in this Skill?

• Bean Validation annotations on DTOs and command models
• @Valid and boundary validation in Jakarta REST resources
• Validation groups and custom constraints
• Validation error mapping for client-safe responses
• Consistent handling of invalid inputs across endpoints

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

Constraints

Before applying validation changes, ensure the project compiles. After improvements, run full verification.

• MANDATORY: Run ./mvnw compile or mvn compile before applying any change
• SAFETY: If compilation fails, stop immediately
• VERIFY: Run ./mvnw clean verify or mvn clean verify after applying improvements
• BEFORE APPLYING: Read the reference for detailed rules and examples

When to use this skill

• Add validation support in Quarkus
• Review Quarkus validation rules
• Improve request validation in Quarkus REST APIs
• Add custom validation constraints in Quarkus
• Validate Quarkus @ConfigMapping properties
• Improve validation error mapping with ExceptionMapper in Quarkus

Workflow

1. Read reference and assess project context

Read references/403-frameworks-quarkus-validation.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 validation-related 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/403-frameworks-quarkus-validation.md.