{
  "instruction": "Validate request bodies with class-validator DTOs and global ValidationPipe",
  "relevant_when": "Agent handles request validation in a NestJS application",
  "context": "NestJS uses class-validator decorators on DTO classes for declarative validation. The global ValidationPipe must be configured with whitelist: true and transform: true. Nested DTOs require both @ValidateNested({ each: true }) and @Type(() => NestedDto) from class-transformer.",
  "sources": [
    {
      "type": "file",
      "filename": "skills/nestjs-best-practices/SKILL.md",
      "tile": "tessl-labs/nestjs-best-practices@0.2.0"
    }
  ],
  "checklist": [
    {
      "name": "global-validation-pipe",
      "rule": "Agent enables ValidationPipe globally in main.ts with whitelist: true and transform: true",
      "relevant_when": "Agent configures validation in a NestJS application"
    },
    {
      "name": "class-validator-decorators",
      "rule": "Agent uses class-validator decorators (@IsString, @IsInt, @Min, @Max, @MinLength, etc.) on DTO class properties",
      "relevant_when": "Agent creates DTOs for NestJS request bodies"
    },
    {
      "name": "nested-dto-validation",
      "rule": "Agent uses BOTH @ValidateNested({ each: true }) AND @Type(() => NestedDto) from class-transformer on nested DTO arrays",
      "relevant_when": "Agent creates a DTO containing nested objects or arrays of objects"
    },
    {
      "name": "separate-dto-class",
      "rule": "Agent defines a separate DTO class for nested items rather than using inline object types",
      "relevant_when": "Agent creates DTOs with nested object structures"
    }
  ]
}