diff --git a/packages/sunpeak/src/mcp/production-server.ts b/packages/sunpeak/src/mcp/production-server.ts
index c4f3298..63b93f4 100644
--- a/packages/sunpeak/src/mcp/production-server.ts
+++ b/packages/sunpeak/src/mcp/production-server.ts
@@ -143,6 +143,17 @@ export interface ProductionServerConfig {
    * where holding open SSE connections is unreliable. Defaults to `true`.
    */
   enableJsonResponse?: boolean;
+  /**
+   * Override the client name used for domain resolution (e.g. `'chatgpt'`).
+   *
+   * Normally, client name is detected from the MCP initialization handshake.
+   * In stateless/serverless environments where each request creates a fresh
+   * server instance, the client name won't be available for non-initialize
+   * requests. Set this to ensure proper domain resolution for resources.
+   *
+   * Common values: `'chatgpt'`, `'openai-mcp'`, `'claude'`
+   */
+  clientName?: string;
 }
 
 /**
@@ -194,6 +205,7 @@ export function createProductionMcpServer(config: ProductionServerConfig): McpSe
     tools,
     resources,
     serverUrl,
+    clientName: configClientName,
   } = config;
 
   const mcpServer = new McpServer(
@@ -218,9 +230,11 @@ export function createProductionMcpServer(config: ProductionServerConfig): McpSe
   // Read callbacks close over this variable to resolve host-specific domain maps.
   // Also update listing-level _meta on all resources so that `resources/list`
   // returns the resolved domain (hosts like ChatGPT check domain from the listing).
-  let clientName: string | undefined;
+  // In stateless/serverless mode, use configClientName as the default since
+  // oninitialized won't fire for non-initialize requests.
+  let clientName: string | undefined = configClientName;
   mcpServer.server.oninitialized = () => {
-    clientName = mcpServer.server.getClientVersion()?.name;
+    clientName = mcpServer.server.getClientVersion()?.name ?? configClientName;
 
     for (const handle of resourceHandles) {
       const currentMeta = handle.metadata?._meta as Record<string, unknown> | undefined;
@@ -269,6 +283,7 @@ export function createProductionMcpServer(config: ProductionServerConfig): McpSe
         if (typeof result === 'string') {
           return { content: [{ type: 'text' as const, text: result }] };
         }
+
         return result;
       };
     };