initial commit

.agents/skills/vercel-react-native-skills/rules/design-system-compound-components.md

@@ -0,0 +1,66 @@
+---
+title: Use Compound Components Over Polymorphic Children
+impact: MEDIUM
+impactDescription: flexible composition, clearer API
+tags: design-system, components, composition
+---
+
+## Use Compound Components Over Polymorphic Children
+
+Don't create components that can accept a string if they aren't a text node. If
+a component can receive a string child, it must be a dedicated `*Text`
+component. For components like buttons, which can have both a View (or
+Pressable) together with text, use compound components, such a `Button`,
+`ButtonText`, and `ButtonIcon`.
+
+**Incorrect (polymorphic children):**
+
+```tsx
+import { Pressable, Text } from 'react-native'
+
+type ButtonProps = {
+  children: string | React.ReactNode
+  icon?: React.ReactNode
+}
+
+function Button({ children, icon }: ButtonProps) {
+  return (
+    <Pressable>
+      {icon}
+      {typeof children === 'string' ? <Text>{children}</Text> : children}
+    </Pressable>
+  )
+}
+
+// Usage is ambiguous
+<Button icon={<Icon />}>Save</Button>
+<Button><CustomText>Save</CustomText></Button>
+```
+
+**Correct (compound components):**
+
+```tsx
+import { Pressable, Text } from 'react-native'
+
+function Button({ children }: { children: React.ReactNode }) {
+  return <Pressable>{children}</Pressable>
+}
+
+function ButtonText({ children }: { children: React.ReactNode }) {
+  return <Text>{children}</Text>
+}
+
+function ButtonIcon({ children }: { children: React.ReactNode }) {
+  return <>{children}</>
+}
+
+// Usage is explicit and composable
+<Button>
+  <ButtonIcon><SaveIcon /></ButtonIcon>
+  <ButtonText>Save</ButtonText>
+</Button>
+
+<Button>
+  <ButtonText>Cancel</ButtonText>
+</Button>
+```