402-frameworks-quarkus-rest

# Quarkus REST API Guidelines Apply REST API design principles on Quarkus using Jakarta REST (JAX-RS). **What is covered in this Skill?** - Resource classes, @Path, HTTP method mapping, and resource URI design - Status codes, Location headers, and Response building - DTOs and Bean Validation at the boundary; ISO-8601 for date/time fields - ExceptionMapper for consistent error JSON (RFC 7807 Problem Details) - API versioning strategies (URI path, Accept header) - Idempotency with Idempotency-Key header - Optimistic concurrency: ETag, If-Match, If-None-Match - HTTP caching with Cache-Control headers - API deprecation: Sunset and Deprecation headers - Pagination, sorting, and filtering query parameters - Optional `/openapi` via SmallRye; API-first contract maintained in `openapi.yaml` (codegen) - Reactive vs blocking considerations; @RunOnVirtualThread - Security integration at the filter layer **Scope:** Apply recommendations based on the reference rules and good/bad code examples. ## Constraints Before applying REST changes, ensure the project compiles. After applying improvements, run full verification. - **MANDATORY**: Run `./mvnw compile` or `mvn compile` before applying any change - **PREREQUISITE**: Project must compile before applying REST API improvements - **SAFETY**: If compilation fails, stop immediately - **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 and examples ## When to use this skill - Review or improve JAX-RS resources in a Quarkus project - Design HTTP APIs with validation and error handling on Quarkus - Add API versioning, idempotency, ETag concurrency, or deprecation headers - Implement pagination, sorting, or RFC 7807 Problem Details error responses ## Workflow 1. **Read reference and assess project context** Read `references/402-frameworks-quarkus-rest.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/402-frameworks-quarkus-rest.md](references/402-frameworks-quarkus-rest.md).