diff --git a/.changeset/avatar-use-client.md b/.changeset/avatar-use-client.md
new file mode 100644
index 0000000..ba43095
--- /dev/null
+++ b/.changeset/avatar-use-client.md
@@ -0,0 +1,20 @@
+---
+'@code-sherpas/pharos-react': patch
+---
+
+Mark the published ESM bundle as client-only via a `"use client"` banner.
+
+Avatar (D14) calls `createContext(...)` three times at module top level
+(shape / loading / group). Without the banner, Next.js evaluates the
+Pharos module during its RSC build-time analysis pass and fails with
+`TypeError: (0 , c.createContext) is not a function` while collecting
+page data for any route whose layout transitively imports an Avatar.
+
+The banner is the same convention every React DS ships with
+(MUI / Chakra / Radix / shadcn). The atoms that have no hooks
+(Card / Separator) lose server-render-ability as a side effect; this is
+acceptable since they were never advertised as server-safe and React DS
+libraries are universally client-only today.
+
+The Avatar source file also carries its own `"use client"` directive so
+the intent is visible to anyone reading the source.
diff --git a/src/components/Avatar.tsx b/src/components/Avatar.tsx
index 0a39103..55f93ad 100644
--- a/src/components/Avatar.tsx
+++ b/src/components/Avatar.tsx
@@ -1,3 +1,20 @@
+'use client';
+
+/* The `'use client'` directive at the top of this file is load-bearing.
+ * Avatar runs `createContext(...)` three times at module top level (shape /
+ * loading / group). Without the directive, Next.js evaluates the module in
+ * its build-time RSC analysis pass, where React is wired in a way that
+ * makes `createContext` blow up with
+ * `TypeError: (0 , c.createContext) is not a function` during page-data
+ * collection. The directive marks the module as client-only in the
+ * published bundle (esbuild / Vite preserve the banner verbatim) and the
+ * RSC analysis stops at the import boundary.
+ *
+ * The other Pharos atoms (Button / Spinner / etc.) do not need this
+ * because their hook calls happen inside the component body, not at module
+ * scope — module evaluation is side-effect free for them.
+ */
+
 import {
   createContext,
   useCallback,
diff --git a/vite.config.ts b/vite.config.ts
index 7527dc5..5e8d4b8 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -33,6 +33,19 @@ export default defineConfig({
         '@base-ui/react',
         /^@base-ui\/react\//,
       ],
+      output: {
+        // Bundle banner that marks the published ESM module as client-only.
+        // Avatar (D14) calls `createContext` at module top level; without
+        // this directive, Next.js evaluates the module during RSC
+        // build-time analysis and fails with
+        // `TypeError: (0 , c.createContext) is not a function` while
+        // collecting page data. The whole library shipping as client-only
+        // matches what every React DS does (MUI, Chakra, Radix, shadcn).
+        // The atoms that have no hooks (Card / Separator) lose
+        // server-render-ability as a side effect — acceptable; consumers
+        // were never asked to render them as Server Components anyway.
+        banner: "'use client';",
+      },
     },
     cssCodeSplit: false,
     sourcemap: true,