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.agents/skills/vercel-composition-patterns/SKILL.md

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+---
+name: vercel-composition-patterns
+description:
+  React composition patterns that scale. Use when refactoring components with
+  boolean prop proliferation, building flexible component libraries, or
+  designing reusable APIs. Triggers on tasks involving compound components,
+  render props, context providers, or component architecture. Includes React 19
+  API changes.
+license: MIT
+metadata:
+  author: vercel
+  version: '1.0.0'
+---
+
+# React Composition Patterns
+
+Composition patterns for building flexible, maintainable React components. Avoid
+boolean prop proliferation by using compound components, lifting state, and
+composing internals. These patterns make codebases easier for both humans and AI
+agents to work with as they scale.
+
+## When to Apply
+
+Reference these guidelines when:
+
+- Refactoring components with many boolean props
+- Building reusable component libraries
+- Designing flexible component APIs
+- Reviewing component architecture
+- Working with compound components or context providers
+
+## Rule Categories by Priority
+
+| Priority | Category                | Impact | Prefix          |
+| -------- | ----------------------- | ------ | --------------- |
+| 1        | Component Architecture  | HIGH   | `architecture-` |
+| 2        | State Management        | MEDIUM | `state-`        |
+| 3        | Implementation Patterns | MEDIUM | `patterns-`     |
+| 4        | React 19 APIs           | MEDIUM | `react19-`      |
+
+## Quick Reference
+
+### 1. Component Architecture (HIGH)
+
+- `architecture-avoid-boolean-props` - Don't add boolean props to customize
+  behavior; use composition
+- `architecture-compound-components` - Structure complex components with shared
+  context
+
+### 2. State Management (MEDIUM)
+
+- `state-decouple-implementation` - Provider is the only place that knows how
+  state is managed
+- `state-context-interface` - Define generic interface with state, actions, meta
+  for dependency injection
+- `state-lift-state` - Move state into provider components for sibling access
+
+### 3. Implementation Patterns (MEDIUM)
+
+- `patterns-explicit-variants` - Create explicit variant components instead of
+  boolean modes
+- `patterns-children-over-render-props` - Use children for composition instead
+  of renderX props
+
+### 4. React 19 APIs (MEDIUM)
+
+> **⚠️ React 19+ only.** Skip this section if using React 18 or earlier.
+
+- `react19-no-forwardref` - Don't use `forwardRef`; use `use()` instead of `useContext()`
+
+## How to Use
+
+Read individual rule files for detailed explanations and code examples:
+
+```
+rules/architecture-avoid-boolean-props.md
+rules/state-context-interface.md
+```
+
+Each rule file contains:
+
+- Brief explanation of why it matters
+- Incorrect code example with explanation
+- Correct code example with explanation
+- Additional context and references
+
+## Full Compiled Document
+
+For the complete guide with all rules expanded: `AGENTS.md`

.agents/skills/vercel-composition-patterns/rules/architecture-avoid-boolean-props.md

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+---
+title: Avoid Boolean Prop Proliferation
+impact: CRITICAL
+impactDescription: prevents unmaintainable component variants
+tags: composition, props, architecture
+---
+
+## Avoid Boolean Prop Proliferation
+
+Don't add boolean props like `isThread`, `isEditing`, `isDMThread` to customize
+component behavior. Each boolean doubles possible states and creates
+unmaintainable conditional logic. Use composition instead.
+
+**Incorrect (boolean props create exponential complexity):**
+
+```tsx
+function Composer({
+  onSubmit,
+  isThread,
+  channelId,
+  isDMThread,
+  dmId,
+  isEditing,
+  isForwarding,
+}: Props) {
+  return (
+    <form>
+      <Header />
+      <Input />
+      {isDMThread ? (
+        <AlsoSendToDMField id={dmId} />
+      ) : isThread ? (
+        <AlsoSendToChannelField id={channelId} />
+      ) : null}
+      {isEditing ? (
+        <EditActions />
+      ) : isForwarding ? (
+        <ForwardActions />
+      ) : (
+        <DefaultActions />
+      )}
+      <Footer onSubmit={onSubmit} />
+    </form>
+  )
+}
+```
+
+**Correct (composition eliminates conditionals):**
+
+```tsx
+// Channel composer
+function ChannelComposer() {
+  return (
+    <Composer.Frame>
+      <Composer.Header />
+      <Composer.Input />
+      <Composer.Footer>
+        <Composer.Attachments />
+        <Composer.Formatting />
+        <Composer.Emojis />
+        <Composer.Submit />
+      </Composer.Footer>
+    </Composer.Frame>
+  )
+}
+
+// Thread composer - adds "also send to channel" field
+function ThreadComposer({ channelId }: { channelId: string }) {
+  return (
+    <Composer.Frame>
+      <Composer.Header />
+      <Composer.Input />
+      <AlsoSendToChannelField id={channelId} />
+      <Composer.Footer>
+        <Composer.Formatting />
+        <Composer.Emojis />
+        <Composer.Submit />
+      </Composer.Footer>
+    </Composer.Frame>
+  )
+}
+
+// Edit composer - different footer actions
+function EditComposer() {
+  return (
+    <Composer.Frame>
+      <Composer.Input />
+      <Composer.Footer>
+        <Composer.Formatting />
+        <Composer.Emojis />
+        <Composer.CancelEdit />
+        <Composer.SaveEdit />
+      </Composer.Footer>
+    </Composer.Frame>
+  )
+}
+```
+
+Each variant is explicit about what it renders. We can share internals without
+sharing a single monolithic parent.

.agents/skills/vercel-composition-patterns/rules/architecture-compound-components.md

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+---
+title: Use Compound Components
+impact: HIGH
+impactDescription: enables flexible composition without prop drilling
+tags: composition, compound-components, architecture
+---
+
+## Use Compound Components
+
+Structure complex components as compound components with a shared context. Each
+subcomponent accesses shared state via context, not props. Consumers compose the
+pieces they need.
+
+**Incorrect (monolithic component with render props):**
+
+```tsx
+function Composer({
+  renderHeader,
+  renderFooter,
+  renderActions,
+  showAttachments,
+  showFormatting,
+  showEmojis,
+}: Props) {
+  return (
+    <form>
+      {renderHeader?.()}
+      <Input />
+      {showAttachments && <Attachments />}
+      {renderFooter ? (
+        renderFooter()
+      ) : (
+        <Footer>
+          {showFormatting && <Formatting />}
+          {showEmojis && <Emojis />}
+          {renderActions?.()}
+        </Footer>
+      )}
+    </form>
+  )
+}
+```
+
+**Correct (compound components with shared context):**
+
+```tsx
+const ComposerContext = createContext<ComposerContextValue | null>(null)
+
+function ComposerProvider({ children, state, actions, meta }: ProviderProps) {
+  return (
+    <ComposerContext value={{ state, actions, meta }}>
+      {children}
+    </ComposerContext>
+  )
+}
+
+function ComposerFrame({ children }: { children: React.ReactNode }) {
+  return <form>{children}</form>
+}
+
+function ComposerInput() {
+  const {
+    state,
+    actions: { update },
+    meta: { inputRef },
+  } = use(ComposerContext)
+  return (
+    <TextInput
+      ref={inputRef}
+      value={state.input}
+      onChangeText={(text) => update((s) => ({ ...s, input: text }))}
+    />
+  )
+}
+
+function ComposerSubmit() {
+  const {
+    actions: { submit },
+  } = use(ComposerContext)
+  return <Button onPress={submit}>Send</Button>
+}
+
+// Export as compound component
+const Composer = {
+  Provider: ComposerProvider,
+  Frame: ComposerFrame,
+  Input: ComposerInput,
+  Submit: ComposerSubmit,
+  Header: ComposerHeader,
+  Footer: ComposerFooter,
+  Attachments: ComposerAttachments,
+  Formatting: ComposerFormatting,
+  Emojis: ComposerEmojis,
+}
+```
+
+**Usage:**
+
+```tsx
+<Composer.Provider state={state} actions={actions} meta={meta}>
+  <Composer.Frame>
+    <Composer.Header />
+    <Composer.Input />
+    <Composer.Footer>
+      <Composer.Formatting />
+      <Composer.Submit />
+    </Composer.Footer>
+  </Composer.Frame>
+</Composer.Provider>
+```
+
+Consumers explicitly compose exactly what they need. No hidden conditionals. And the state, actions and meta are dependency-injected by a parent provider, allowing multiple usages of the same component structure.

.agents/skills/vercel-composition-patterns/rules/patterns-children-over-render-props.md

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+---
+title: Prefer Composing Children Over Render Props
+impact: MEDIUM
+impactDescription: cleaner composition, better readability
+tags: composition, children, render-props
+---
+
+## Prefer Children Over Render Props
+
+Use `children` for composition instead of `renderX` props. Children are more
+readable, compose naturally, and don't require understanding callback
+signatures.
+
+**Incorrect (render props):**
+
+```tsx
+function Composer({
+  renderHeader,
+  renderFooter,
+  renderActions,
+}: {
+  renderHeader?: () => React.ReactNode
+  renderFooter?: () => React.ReactNode
+  renderActions?: () => React.ReactNode
+}) {
+  return (
+    <form>
+      {renderHeader?.()}
+      <Input />
+      {renderFooter ? renderFooter() : <DefaultFooter />}
+      {renderActions?.()}
+    </form>
+  )
+}
+
+// Usage is awkward and inflexible
+return (
+  <Composer
+    renderHeader={() => <CustomHeader />}
+    renderFooter={() => (
+      <>
+        <Formatting />
+        <Emojis />
+      </>
+    )}
+    renderActions={() => <SubmitButton />}
+  />
+)
+```
+
+**Correct (compound components with children):**
+
+```tsx
+function ComposerFrame({ children }: { children: React.ReactNode }) {
+  return <form>{children}</form>
+}
+
+function ComposerFooter({ children }: { children: React.ReactNode }) {
+  return <footer className='flex'>{children}</footer>
+}
+
+// Usage is flexible
+return (
+  <Composer.Frame>
+    <CustomHeader />
+    <Composer.Input />
+    <Composer.Footer>
+      <Composer.Formatting />
+      <Composer.Emojis />
+      <SubmitButton />
+    </Composer.Footer>
+  </Composer.Frame>
+)
+```
+
+**When render props are appropriate:**
+
+```tsx
+// Render props work well when you need to pass data back
+<List
+  data={items}
+  renderItem={({ item, index }) => <Item item={item} index={index} />}
+/>
+```
+
+Use render props when the parent needs to provide data or state to the child.
+Use children when composing static structure.