VRefine adds JSON Schema constraints to a primitive type. It's globally available - no import needed.

VRefine<number, { minimum: 1000, maximum: 1_000_000 }>

The first argument is the base type, the second is any valid JSON Schema validation keyword:

• Strings: minLength, maxLength, pattern, format
• Numbers: minimum, maximum, exclusiveMinimum, exclusiveMaximum, multipleOf
• Arrays: minItems, maxItems, uniqueItems

One common gotcha: number alone allows decimals. If you need a true integer, use multipleOf: 1 - it means the value must be evenly divisible by 1:

// allows 1000.5 - probably not what you want
VRefine<number, { minimum: 1000, maximum: 1_000_000 }>

// integers only
VRefine<number, { minimum: 1000, maximum: 1_000_000, multipleOf: 1 }>

This matters especially for database IDs, where a float would pass validation but get rejected at the query level - turning a clear validation error into a confusing DB error.