diff --git a/packages/super-editor/src/document-api-adapters/tables-adapter.regressions.test.ts b/packages/super-editor/src/document-api-adapters/tables-adapter.regressions.test.ts
index e224b4b909..fd376dddef 100644
--- a/packages/super-editor/src/document-api-adapters/tables-adapter.regressions.test.ts
+++ b/packages/super-editor/src/document-api-adapters/tables-adapter.regressions.test.ts
@@ -7,6 +7,7 @@ import {
   tablesClearShadingAdapter,
   tablesDeleteCellAdapter,
   tablesDistributeColumnsAdapter,
+  tablesInsertColumnAdapter,
   tablesInsertCellAdapter,
   tablesSetBorderAdapter,
   tablesSetShadingAdapter,
@@ -42,8 +43,11 @@ type NodeOptions = {
 type TableEditorOptions = {
   firstRowAsHeaders?: boolean;
   firstRowBorders?: Record<string, unknown> | null;
+  lastColumnAsHeaders?: boolean;
 };
 
+const mockSchema: { nodes: Record<string, unknown> } = { nodes: {} };
+
 function createNode(typeName: string, children: ProseMirrorNode[] = [], options: NodeOptions = {}): ProseMirrorNode {
   const attrs = options.attrs ?? {};
   const text = options.text ?? '';
@@ -59,6 +63,7 @@ function createNode(typeName: string, children: ProseMirrorNode[] = [], options:
   const node = {
     type: {
       name: typeName,
+      schema: mockSchema,
       create(newAttrs: Record<string, unknown>) {
         return createNode(typeName, [], { attrs: newAttrs, isBlock, inlineContent });
       },
@@ -125,12 +130,17 @@ function createNode(typeName: string, children: ProseMirrorNode[] = [], options:
     },
   };
 
+  mockSchema.nodes[typeName] = node.type;
+
   return node as unknown as ProseMirrorNode;
 }
 
 function makeTableEditor(options: TableEditorOptions = {}): Editor {
   const firstRowAsHeaders = options.firstRowAsHeaders ?? false;
+  const lastColumnAsHeaders = options.lastColumnAsHeaders ?? false;
   const firstRowType = firstRowAsHeaders ? 'tableHeader' : 'tableCell';
+  const secondColumnType = lastColumnAsHeaders ? 'tableHeader' : firstRowType;
+  const lastCellType = lastColumnAsHeaders ? 'tableHeader' : 'tableCell';
   const firstRowAttrs =
     options.firstRowBorders === undefined
       ? {}
@@ -163,7 +173,7 @@ function makeTableEditor(options: TableEditorOptions = {}): Editor {
     isBlock: true,
     inlineContent: false,
   });
-  const cell2 = createNode(firstRowType, [paragraph2], {
+  const cell2 = createNode(secondColumnType, [paragraph2], {
     attrs: { sdBlockId: 'cell-2', colspan: 1, rowspan: 1, colwidth: [200], ...firstRowAttrs },
     isBlock: true,
     inlineContent: false,
@@ -173,7 +183,7 @@ function makeTableEditor(options: TableEditorOptions = {}): Editor {
     isBlock: true,
     inlineContent: false,
   });
-  const cell4 = createNode('tableCell', [paragraph4], {
+  const cell4 = createNode(lastCellType, [paragraph4], {
     attrs: { sdBlockId: 'cell-4', colspan: 1, rowspan: 1, colwidth: [200] },
     isBlock: true,
     inlineContent: false,
@@ -383,6 +393,37 @@ describe('tables-adapter regressions', () => {
     expect(insertedTable.type.name).toBe('table');
   });
 
+  it('SD-2127: inserts a new cell in every row when appending a column to the right of the last column', () => {
+    const editor = makeTableEditor();
+    const tr = editor.state.tr as unknown as { insert: ReturnType<typeof vi.fn> };
+
+    const result = tablesInsertColumnAdapter(
+      editor,
+      { tableNodeId: 'table-1', columnIndex: 1, position: 'right' },
+      { changeMode: 'direct' },
+    );
+
+    expect(result.success).toBe(true);
+    expect(tr.insert).toHaveBeenCalledTimes(2);
+  });
+
+  it('SD-2127: appending right of a header edge inserts body cells, not cloned header cells', () => {
+    const editor = makeTableEditor({ lastColumnAsHeaders: true });
+    const tr = editor.state.tr as unknown as { insert: ReturnType<typeof vi.fn> };
+
+    const result = tablesInsertColumnAdapter(
+      editor,
+      { tableNodeId: 'table-1', columnIndex: 1, position: 'right' },
+      { changeMode: 'direct' },
+    );
+
+    expect(result.success).toBe(true);
+    expect(tr.insert).toHaveBeenCalledTimes(2);
+
+    const insertedTypeNames = tr.insert.mock.calls.map(([, node]) => (node as ProseMirrorNode).type.name);
+    expect(insertedTypeNames).toEqual(['tableCell', 'tableCell']);
+  });
+
   it('deletes shiftLeft cells without appending a trailing replacement cell', () => {
     const editor = makeTableEditor();
     const tr = editor.state.tr as unknown as {
diff --git a/packages/super-editor/src/document-api-adapters/tables-adapter.ts b/packages/super-editor/src/document-api-adapters/tables-adapter.ts
index 3c59a0eee1..b5657ba647 100644
--- a/packages/super-editor/src/document-api-adapters/tables-adapter.ts
+++ b/packages/super-editor/src/document-api-adapters/tables-adapter.ts
@@ -1,3 +1,4 @@
+import type { Node as ProseMirrorNode, NodeType } from 'prosemirror-model';
 import type { Editor } from '../core/Editor.js';
 import { v4 as uuidv4 } from 'uuid';
 import type {
@@ -541,6 +542,33 @@ function addColSpan(attrs: Record<string, unknown>, pos: number, n = 1): Record<
   return result;
 }
 
+function isHeaderColumn(tableNode: ProseMirrorNode, map: ReturnType<(typeof TableMap)['get']>, col: number): boolean {
+  for (let row = 0; row < map.height; row++) {
+    const cell = tableNode.nodeAt(map.map[col + row * map.width]);
+    if (!cell || cell.type.name !== 'tableHeader') return false;
+  }
+  return true;
+}
+
+function resolveInsertedColumnCellType(
+  tableNode: ProseMirrorNode,
+  map: ReturnType<(typeof TableMap)['get']>,
+  index: number,
+  col: number,
+): NodeType | null {
+  let refColumn: number | null = col > 0 ? -1 : 0;
+  if (isHeaderColumn(tableNode, map, col + refColumn)) {
+    refColumn = col === 0 || col === map.width ? null : 0;
+  }
+
+  if (refColumn == null) {
+    return tableNode.type.schema.nodes.tableCell ?? null;
+  }
+
+  const refPos = map.map[index + refColumn];
+  return refPos != null ? (tableNode.nodeAt(refPos)?.type ?? null) : null;
+}
+
 /** Inserts a column at `col` in the table (before that column index). Follows prosemirror-tables addColumn pattern. */
 function addColumnToTable(tr: Transaction, tablePos: number, col: number): void {
   const tableNode = tr.doc.nodeAt(tablePos);
@@ -551,12 +579,11 @@ function addColumnToTable(tr: Transaction, tablePos: number, col: number): void
 
   for (let row = 0; row < map.height; row++) {
     const index = row * map.width + col;
-    const pos = map.map[index];
-    const cell = tableNode.nodeAt(pos);
-    if (!cell) continue;
-
-    if (col > 0 && map.map[index - 1] === pos) {
+    if (col > 0 && col < map.width && map.map[index - 1] === map.map[index]) {
       // Cell spans from the left — expand colspan
+      const pos = map.map[index];
+      const cell = tableNode.nodeAt(pos);
+      if (!cell) continue;
       tr.setNodeMarkup(
         tr.mapping.slice(mapStart).map(tableStart + pos),
         null,
@@ -565,10 +592,10 @@ function addColumnToTable(tr: Transaction, tablePos: number, col: number): void
       row += (((cell.attrs as Record<string, unknown>).rowspan as number) || 1) - 1;
     } else {
       // Insert a new empty cell
-      const refType = col > 0 ? (tableNode.nodeAt(map.map[index - 1])?.type ?? cell.type) : cell.type;
+      const refType = resolveInsertedColumnCellType(tableNode, map, index, col);
+      if (!refType) continue;
       const cellPos = map.positionAt(row, col, tableNode);
       tr.insert(tr.mapping.slice(mapStart).map(tableStart + cellPos), refType.createAndFill()!);
-      row += ((cell.attrs?.rowspan as number) || 1) - 1;
     }
   }
 }