feat: format and display full federated user handles across the application.

src/lib/utils/handle.ts

@@ -0,0 +1,21 @@
+export const NODE_DOMAIN = process.env.NEXT_PUBLIC_NODE_DOMAIN || 'localhost:3000';
+
+/**
+ * Formats a handle into its full federated form: @user@domain
+ * If the handle already contains a domain (e.g. user@other.com), it returns it as @user@other.com
+ * If it's a local handle (e.g. user), it appends the local node domain: @user@localnode.com
+ */
+export function formatFullHandle(handle: string): string {
+    if (!handle) return '';
+
+    // Remove leading @ if present for processing
+    const cleanHandle = handle.startsWith('@') ? handle.slice(1) : handle;
+
+    // Check if it already has a domain (contains @)
+    if (cleanHandle.includes('@')) {
+        return `@${cleanHandle}`;
+    }
+
+    // Append local node domain
+    return `@${cleanHandle}@${NODE_DOMAIN}`;
+}