Micronaut REST API Guidelines

Apply REST design principles for Micronaut HTTP applications.

What is covered in this Skill?

• Semantic HTTP with @Get/@Post/@Put/@Patch/@Delete and HttpResponse status control
• Resource-oriented paths and stable DTO contracts
• @Valid on request bodies with Bean Validation
• Centralized error mapping (ExceptionHandler / problem JSON when applicable)
• Pagination with Pageable and bounded sizes
• OpenAPI contract file (API-first) and OpenAPI Generator for server stubs
• Security annotations (@Secured) on sensitive routes
• Idempotency-Key for retried writes
• ETag / If-Match for optimistic concurrency
• Cache-Control discipline
• API versioning patterns
• ISO-8601 time types in DTOs

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

Constraints

Compile before REST refactors; verify after.

• 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
• 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 or improve Micronaut @Controller REST APIs
• Add validation, error handling, or align controllers with the OpenAPI contract on Micronaut HTTP layer

Workflow

1. Read reference and assess project context

Read references/502-frameworks-micronaut-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/502-frameworks-micronaut-rest.md.