{
  "context": "Evaluates whether the solution uses @babel/parser with the correct plugin flags to parse modern syntax and produce the specified AST summary. Emphasis is on turning feature flags into parser options and handling plugin-dependent failures clearly.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "Parser setup",
      "description": "Uses @babel/parser's `parse` (or `parseExpression` when appropriate) with a `plugins` array and `sourceType` derived from options instead of ad hoc parsing.",
      "max_score": 15
    },
    {
      "name": "Optional chains",
      "description": "Maps the `optional-chains` flag to @babel/parser plugins `optionalChaining` and `nullishCoalescingOperator` so the optional chaining test input parses and surfaces the expected node types/identifiers.",
      "max_score": 25
    },
    {
      "name": "JSX gating",
      "description": "Enables the `jsx` plugin only when the `jsx` feature is present, ensuring JSX parsing succeeds with the flag and fails cleanly without it (no `jsx` plugin always-on).",
      "max_score": 20
    },
    {
      "name": "TypeScript handling",
      "description": "Adds the `typescript` plugin when the flag is provided and omits it otherwise; type-only constructs are ignored when collecting identifiers so they do not appear in the summary.",
      "max_score": 25
    },
    {
      "name": "Feature errors",
      "description": "When parsing fails because a required feature flag is missing, surfaces a descriptive error that names the missing feature instead of a generic syntax error (e.g., wraps @babel/parser errors to mention the absent flag).",
      "max_score": 15
    }
  ]
}