diff --git a/src/lib/smartsheet.ts b/src/lib/smartsheet.ts
index f973095..02d2c55 100644
--- a/src/lib/smartsheet.ts
+++ b/src/lib/smartsheet.ts
@@ -297,16 +297,22 @@ export async function addRow(
     "POST",
     `/2.0/sheets/${encodeURIComponent(sheetId)}/rows`,
     token,
-    {
-      rows: [
-        {
-          cells: cells.map((c) => ({
-            columnId: Number(c.columnId),
-            value: toCellValue(c.value),
-          })),
-        },
-      ],
-    },
+    // Body MUST be a top-level array (or single Row object), NOT wrapped
+    // in { rows: [...] }. When wrapped, Smartsheet returns HTTP 200 +
+    // resultCode 0 + "SUCCESS" but silently drops every cell value —
+    // creates empty rows. (Verified by direct probe: POSTing with
+    // { rows: [...] } returns 200 with no values persisted; POSTing with
+    // [...] returns 200 with values persisted.) This was the root cause
+    // of "rows created but data not inserted" — see the Smartsheet docs
+    // cURL example for POST /sheets/{id}/rows.
+    [
+      {
+        cells: cells.map((c) => ({
+          columnId: Number(c.columnId),
+          value: toCellValue(c.value),
+        })),
+      },
+    ],
   );
 
   const result = data?.result;