Schema Guard

isStandardSchema is a runtime guard that checks whether a value implements the Standard Schema interface.

Use it when schema values are dynamic, external, or typed as unknown.

Why It Exists

In static code, TypeScript types usually ensure you pass a schema to validation helpers. At runtime, you may still receive unknown values from plugins, shared registries, or configuration.

isStandardSchema helps you:

• prevent invalid values from being passed to validation helpers
• branch safely before validation
• keep runtime behavior predictable in dynamic systems

Basic Usage

import { isStandardSchema } from "@zap-studio/validation";

if (isStandardSchema(schemaLike)) {
  // schemaLike is now typed as StandardSchemaV1
}

Guard Before Validation

import { isStandardSchema, standardValidate } from "@zap-studio/validation";

export async function validateIfPossible(schemaLike: unknown, input: unknown) {
  if (!isStandardSchema(schemaLike)) {
    return { ok: false as const, reason: "not-a-schema" as const };
  }

  const result = await standardValidate(schemaLike, input, {
    throwOnError: false,
  });

  if (result.issues) {
    return { ok: false as const, reason: "invalid-input" as const, issues: result.issues };
  }

  return { ok: true as const, value: result.value };
}

When To Use It

• schema objects come from external modules or user configuration
• your API accepts flexible unknown inputs
• you build framework/package boundaries and want explicit runtime checks

If schema values are always strongly typed as StandardSchemaV1, you usually do not need this guard.