{
  "context": "This criteria evaluates proficiency in using io-ts Codec module for bidirectional transformations with round-trip guarantees. The focus is on proper use of codec composition, custom codec creation, and leveraging the Codec type's encode/decode methods to ensure decode(encode(x)) === x.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "Codec module import",
      "description": "Uses io-ts Codec module (e.g., import * as C from 'io-ts/Codec' or similar) rather than the legacy Type interface",
      "max_score": 10
    },
    {
      "name": "Date codec implementation",
      "description": "Creates a custom codec for Date/ISO string transformation using C.make or similar, with proper encode (Date → string) and decode (string → Date) implementations",
      "max_score": 20
    },
    {
      "name": "Boolean/literal codec",
      "description": "Creates codec for boolean to/from 'active'/'inactive' literals using C.make or similar, correctly mapping true→'active' and false→'inactive'",
      "max_score": 20
    },
    {
      "name": "Struct codec composition",
      "description": "Uses C.struct or C.type to compose the configuration codec from individual field codecs",
      "max_score": 15
    },
    {
      "name": "Codec type annotation",
      "description": "Properly types the ConfigCodec export using Codec.Codec<InternalConfig, ExternalConfig> or equivalent from io-ts",
      "max_score": 10
    },
    {
      "name": "Decode method usage",
      "description": "Uses the codec's decode method to validate and transform external data, returning Either<DecodeError, InternalConfig>",
      "max_score": 10
    },
    {
      "name": "Encode method usage",
      "description": "Uses the codec's encode method to transform internal data to external representation",
      "max_score": 10
    },
    {
      "name": "Validation error handling",
      "description": "Properly handles validation errors from decode using Either (e.g., fold, isLeft, isRight) from fp-ts",
      "max_score": 5
    }
  ]
}