{
  "context": "Tests whether the agent implements nominal/brand types using the phantom property pattern and correctly distinguishes between type predicates and assertion functions, including the function-keyword requirement for assertions.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "Opaque pattern",
      "description": "Defines an Opaque or Brand generic helper type using intersection with a phantom brand property (e.g., `TValue & { __brand: TBrand }` or similar)",
      "max_score": 12
    },
    {
      "name": "Multiple opaque types",
      "description": "Defines at least two distinct opaque types using the helper (e.g., UserId and PostId, or ValidEmail and ValidPassword)",
      "max_score": 8
    },
    {
      "name": "Assertion function syntax",
      "description": "Assertion functions (those with `asserts value is T` return type) are declared using the `function` keyword, NOT as arrow function constants",
      "max_score": 15
    },
    {
      "name": "Type predicate syntax",
      "description": "Type guard predicates (those returning `value is T`) correctly annotate the return type — not just `boolean`",
      "max_score": 10
    },
    {
      "name": "Both predicate and assertion present",
      "description": "At least one type predicate function AND at least one assertion function are implemented",
      "max_score": 10
    },
    {
      "name": "Async utility types",
      "description": "When extracting the return type of an async function, uses `Awaited<ReturnType<typeof fn>>` (not bare `ReturnType<typeof fn>`)",
      "max_score": 10
    },
    {
      "name": "typeof with utility types",
      "description": "Uses `typeof` before runtime function names when passing them to utility types like `Parameters<>` or `ReturnType<>`",
      "max_score": 8
    },
    {
      "name": "Type theory explanation",
      "description": "Written explanation distinguishes structural typing from nominal typing and explains why the phantom brand property creates incompatibility",
      "max_score": 10
    },
    {
      "name": "Before/after comparison",
      "description": "Shows a before/after code comparison illustrating how the unbranded version allowed unsafe assignments and the branded version prevents them",
      "max_score": 10
    },
    {
      "name": "Type tests",
      "description": "Includes at least two type-level tests (using `// @ts-expect-error` or explicit type assertions) verifying that incompatible opaque types are rejected",
      "max_score": 7
    }
  ]
}