Claude Code for TanStack Form — Workflow Guide

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The Setup

You are building forms with TanStack Form, the headless, type-safe form library that works across React, Vue, Angular, and Solid. TanStack Form provides fine-grained reactivity and first-class TypeScript support without any UI opinions. Claude Code can generate form code, but it defaults to React Hook Form or Formik patterns.

What Claude Code Gets Wrong By Default

  1. Uses React Hook Form’s register API. Claude writes {...register('email')} spread patterns. TanStack Form uses a Field component with render props: <form.Field name="email" children={(field) => <input {...field.api.getInputProps()} />}.

  2. Manages form state with useState. Claude creates controlled inputs with useState for each field. TanStack Form manages all form state internally — you subscribe to it through field APIs, not React state.

  3. Uses Yup or Zod resolvers. Claude configures form validation through resolver middleware. TanStack Form has built-in validator adapters and supports Standard Schema — validation is configured per-field or at the form level with validatorAdapter.

  4. Wraps forms in context providers. Claude adds <FormProvider> wrappers from React Hook Form. TanStack Form’s useForm() hook returns a form instance that is passed directly to components, no context provider needed.

The CLAUDE.md Configuration

# TanStack Form Project

## Forms
- Library: TanStack Form (@tanstack/react-form)
- Validation: Built-in validators or Zod via @tanstack/zod-form-adapter
- Headless: no UI components — bring your own inputs
- Type-safe: full TypeScript inference from default values

## TanStack Form Rules
- Create form: const form = useForm({ defaultValues: { ... } })
- Fields: <form.Field name="email" children={(field) => ...} />
- Get value: field.state.value
- Set value: field.handleChange(newValue)
- Validation: validators prop on Field or form level
- Submit: <form onSubmit={form.handleSubmit}>
- Field errors: field.state.meta.errors
- Async validation: validators: { onChangeAsync: async (value) => ... }

## Conventions
- Form definitions in component files (colocated)
- Shared validators in lib/validators/
- Default values define the TypeScript form shape
- Use field.state.meta.isTouched for UX-friendly error display
- Async validation for server-side checks (email uniqueness, etc.)
- Use form.Subscribe for form-level state (isSubmitting, canSubmit)

Workflow Example

You want to create a registration form with async email validation. Prompt Claude Code:

“Create a registration form with TanStack Form that has email, password, and confirmPassword fields. Add synchronous validation for required fields and password strength, and async validation to check if the email is already registered.”

Claude Code should use useForm with default values defining the types, create form.Field components for each field with validators props, add synchronous validators for required and password rules, an onChangeAsyncDebounceMs with async email check, password confirmation matching via a form-level validator, and error display using field.state.meta.errors.

Common Pitfalls

  1. Field name type mismatches. Claude passes string field names that do not match the defaultValues keys. TanStack Form infers field names from defaultValues — a typo in the field name causes a TypeScript error and runtime undefined values.

  2. Missing onSubmit on the form element. Claude puts the submit handler on a button click. TanStack Form requires <form onSubmit={(e) => { e.preventDefault(); form.handleSubmit(); }}> on the form element for proper validation triggering and prevent-default behavior.

  3. Rendering errors before touch. Claude displays field.state.meta.errors immediately on mount. For good UX, check field.state.meta.isTouched before showing errors so users are not confronted with errors before they have interacted with the field.