Use when you need to design, review, or improve validation in Micronaut applications — including Bean Validation on @Controller methods, @Body @Valid, query/path parameter validation, @ConfigurationProperties validation, custom constraints, nested DTO validation, and ExceptionHandler mapping for constraint violations. This should trigger for requests such as Add validation support in Micronaut; Review Micronaut validation rules; Improve request validation in Micronaut REST APIs; Add custom valid
SkillScore73Maintained
Automatic
◆Coding pack
Last verified 8/20/2026
What it changes
Passed 13 of 18 test cases with the skill, and 12 of 18 without it.
Without skill68%
With skill73%
Checks it passed that the model alone missed
Halts further modifications if compilation produces build errors.
Executes `./mvnw compile` or `mvn compile` before editing source files.
Passes the target validation group class to the endpoint validation annotation.
2 fixed14 passed either way5 still failing1 broke
Pass-rate lift
+5 pp
Tokens
-8%
Agent turns
0%
Response time
-29%
Model gemini-3.6-flashMeasured 8/20/2026v116 of 22 cases passed with skill · 18 comparable
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 2 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 2
Prompt
We need to refactor constraint annotations on a Micronaut DTO in a Maven repository where previous commit steps might have left broken code. Developers usually jump straight into editing source code files. What build command must be executed before making any code modifications?
What was checked, without and with the skill
Checked
Without skill
With skill
Executes `./mvnw compile` or `mvn compile` before editing source files.
Missed
Passed
Halts further modifications if compilation produces build errors.
Missed
Passed
case-05 · gemini-3.6-flash · 8/20/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md53 lines2 files
Micronaut Validation Guidelines
Apply Micronaut validation best practices at HTTP API boundaries.
What is covered in this Skill?
Bean Validation annotations on DTOs and command models
@Valid / @Validated usage in Micronaut controllers
Validation groups and custom validators
Consistent mapping of validation failures to 400 responses
Safe and predictable validation error payloads
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 Micronaut
Review Micronaut validation rules
Improve request validation in Micronaut REST APIs
Add custom validation constraints in Micronaut
Validate Micronaut configuration properties
Improve constraint violation handling in Micronaut
Workflow
Read reference and assess project context
Read references/503-frameworks-micronaut-validation.md and inspect the current project setup before proposing changes.
Use when you need data access with Micronaut Data — @MappedEntity, CrudRepository/PageableRepository, @Query with parameters, @Transactional services, projections, @Version, and @MicronautTest with TestPropertyProvider and Testcontainers. For raw java.sql access without generated repositories, use @511-frameworks-micronaut-jdbc. This should trigger for requests such as Review or implement Micronaut Data repositories and entities; Add transactions, pagination, or projections in Micronaut persiste