Fix: reject delete_pages page numbers below 1

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/documents/serialisers.py

@@ -2137,6 +2137,8 @@ class BulkEditSerializer(
             raise serializers.ValidationError("pages must be a list")
         if not all(isinstance(i, int) for i in parameters["pages"]):
             raise serializers.ValidationError("pages must be a list of integers")
+        if any(i < 1 for i in parameters["pages"]):
+            raise serializers.ValidationError("pages must be positive integers")
 
     def _validate_parameters_merge(self, parameters) -> None:
         if "delete_originals" in parameters:

src/documents/tests/test_api_bulk_edit.py

@@ -1843,6 +1843,36 @@ class TestBulkEditAPI(DirectoriesMixin, APITestCase):
         m.assert_called_once()
         self.assertEqual(m.call_args.kwargs["pages"], [[1], [2, 3, 4], [5]])
 
+    @mock.patch("documents.serialisers.bulk_edit.delete_pages")
+    def test_bulk_edit_delete_pages_rejects_pages_below_one(self, m) -> None:
+        """
+        GIVEN:
+            - A legacy delete_pages bulk edit
+        WHEN:
+            - API to bulk edit is called with a page number below 1
+        THEN:
+            - API returns HTTP 400
+            - delete_pages is not called
+        """
+        self.setup_mock(m, "delete_pages")
+
+        for pages in ([0], [-1], [1, 0]):
+            with self.subTest(pages=pages):
+                response = self.client.post(
+                    "/api/documents/bulk_edit/",
+                    json.dumps(
+                        {
+                            "documents": [self.doc2.id],
+                            "method": "delete_pages",
+                            "parameters": {"pages": pages},
+                        },
+                    ),
+                    content_type="application/json",
+                )
+                self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+                self.assertIn(b"pages must be positive integers", response.content)
+        m.assert_not_called()
+
     @mock.patch("documents.views.bulk_edit.rotate")
     def test_rotate_insufficient_permissions(self, m) -> None:
         self.doc1.owner = User.objects.get(username="temp_admin")