`fromTypes()` generates invalid `{"type":"Date"}` in OpenAPI schema

[0-don]

The fromTypes() function generates invalid OpenAPI schemas when TypeScript types contain Date objects. The generated schema shows {"type":"Date"} instead of {"type":"string","format":"date-time"}.

Reproduction

openapi({
  references: fromTypes('src/index.ts')
})

// TypeScript return type: { createdAt: Date }
// Generated schema: { "createdAt": { "type": "Date" } }
// Expected: { "createdAt": { "type": "string", "format": "date-time" } }

Root Cause

Underlying @sinclair/typemap library doesn't parse Date correctly from declaration strings.

Suggested Fix

Add post-processing in declarationToJSONSchema() to transform {"type":"Date"} → {"type":"string","format":"date-time"} until upstream fix is available.

Implementation

function transformDateTypes(schema: any): any {
  if (!schema || typeof schema !== 'object') return schema

  if (schema.type === 'Date') {
    return { type: 'string', format: 'date-time' }
  }

  if (schema.properties) {
    const transformed: any = { ...schema }
    transformed.properties = Object.fromEntries(
      Object.entries(schema.properties).map(([key, value]) => [
        key,
        transformDateTypes(value)
      ])
    )
    return transformed
  }

  if (schema.items) {
    return { ...schema, items: transformDateTypes(schema.items) }
  }

  if (schema.anyOf || schema.oneOf || schema.allOf) {
    const key = schema.anyOf ? 'anyOf' : schema.oneOf ? 'oneOf' : 'allOf'
    return {
      ...schema,
      [key]: schema[key].map(transformDateTypes)
    }
  }

  return schema
}

export function declarationToJSONSchema(declaration: string) {
  const schema = TypeBox(declaration)
  return transformDateTypes(schema)
}