typescript-zod

Development

Apply when validating external data (API inputs, form data, environment variables) with TypeScript type inference.

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How to use this skill

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Review the proposed files and risks before you approve installation.

Prompt to paste

I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/majiayu000/claude-skill-registry/blob/HEAD/skills/data/typescript-zod/SKILL.md

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First, summarize what it does, its dependencies, license status if identifiable, and any risks. Show the exact files you propose to add under .agents/skills/typescript-zod/. Do not write files or run scripts until I approve.

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Copying this prompt does not install or run the skill. Review third-party files before use. Codex skill guide

When to Use

Apply when validating external data (API inputs, form data, environment variables) with TypeScript type inference.

Patterns

Pattern 1: Basic Schema

// Source: https://zod.dev/
import { z } from 'zod';

const UserSchema = z.object({
  id: z.string().uuid(),
  name: z.string().min(2).max(100),
  email: z.string().email(),
  age: z.number().int().positive().optional(),
});

type User = z.infer<typeof UserSchema>; // Auto-infer TS type

Pattern 2: Parse vs SafeParse

// Source: https://zod.dev/
// Throws on error
const user = UserSchema.parse(data);

// Returns result object (safer)
const result = UserSchema.safeParse(data);
if (result.success) {
  console.log(result.data); // User type
} else {
  console.log(result.error.issues); // Validation errors
}

Pattern 3: API Request Validation

// Source: https://zod.dev/
const CreateUserSchema = z.object({
  name: z.string().min(1, 'Name is required'),
  email: z.string().email('Invalid email format'),
  password: z.string().min(8, 'Password must be at least 8 characters'),
});

// In API handler
export async function POST(req: Request) {
  const body = await req.json();
  const result = CreateUserSchema.safeParse(body);

  if (!result.success) {
    return Response.json({ errors: result.error.flatten() }, { status: 400 });
  }

  // result.data is typed as { name: string; email: string; password: string }
  const user = await createUser(result.data);
  return Response.json(user, { status: 201 });
}

Pattern 4: Environment Variables

// Source: https://zod.dev/
const EnvSchema = z.object({
  DATABASE_URL: z.string().url(),
  API_KEY: z.string().min(1),
  PORT: z.coerce.number().default(3000),
  NODE_ENV: z.enum(['development', 'production', 'test']),
});

export const env = EnvSchema.parse(process.env);

Pattern 5: Transform & Refinements

// Source: https://zod.dev/
const DateSchema = z.string().transform(s => new Date(s));

const PasswordSchema = z.string()
  .min(8)
  .refine(p => /[A-Z]/.test(p), 'Must contain uppercase')
  .refine(p => /[0-9]/.test(p), 'Must contain number');

Anti-Patterns

No validation on boundaries - Always validate external data
Using parse in user flows - Use safeParse to handle errors gracefully
Duplicating types - Use z.infer<> instead of manual types
Ignoring error messages - Provide user-friendly messages

Verification Checklist

All API inputs validated with Zod
Types inferred with z.infer<>
safeParse used for user-facing validation
Custom error messages for UX
Environment variables validated at startup