Added AI skills

.agents/skills/react-hook-form/references/formcfg-revalidate-mode.md

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+---
+title: Keep Default reValidateMode Unless Validation Is Expensive
+impact: MEDIUM
+impactDescription: maintains immediate corrective feedback after first submit
+tags: formcfg, revalidate-mode, validation, useForm
+---
+
+## Keep Default reValidateMode Unless Validation Is Expensive
+
+After the first submit, `reValidateMode` controls when fields re-validate. The default is `onChange`, which gives users immediate positive feedback the moment they fix an error — this is the recommended UX in most cases ("don't eagerly scold, but eagerly reward"). Only switch to `onBlur` or `onSubmit` when validation is genuinely expensive (async checks, large schemas, heavy regex on long inputs).
+
+**Incorrect (switching reValidateMode to onBlur for a cheap synchronous schema):**
+
+```typescript
+function CheckoutForm() {
+  const { register, handleSubmit } = useForm<CheckoutFormData>({
+    mode: 'onSubmit',
+    reValidateMode: 'onBlur',  // Hurts UX: user fixes a wrong CVV and gets no feedback until blur
+    resolver: zodResolver(cheapSyncSchema),
+  })
+
+  return (
+    <form onSubmit={handleSubmit(placeOrder)}>
+      <input {...register('cardNumber')} />
+      <input {...register('cvv')} />
+    </form>
+  )
+}
+```
+
+**Correct (default onChange revalidation; switch only when validation is genuinely expensive):**
+
+```typescript
+function CheckoutForm() {
+  const { register, handleSubmit } = useForm<CheckoutFormData>({
+    mode: 'onSubmit',
+    // reValidateMode: 'onChange' is the default — leave it for immediate feedback on correction.
+    // Switch to 'onBlur' only if you have an async check or >16ms-per-keystroke validation cost.
+    resolver: zodResolver(cheapSyncSchema),
+  })
+
+  return (
+    <form onSubmit={handleSubmit(placeOrder)}>
+      <input {...register('cardNumber')} />
+      <input {...register('cvv')} />
+    </form>
+  )
+}
+```
+
+**When to deviate from the default:**
+- Validation involves a network call or expensive computation (>16ms per keystroke)
+- The form has dozens of fields and post-submit re-render cost is measurable in profiling
+- The error message is purely informational, not correctable in real time
+
+Otherwise keep `onChange` — users who just fixed an error get instant validation success, which is the UX the RHF defaults are tuned for.
+
+Reference: [useForm - reValidateMode](https://react-hook-form.com/docs/useform)