From ae55098c2dd03da9515b110a8af4c7dd1a64e6b7 Mon Sep 17 00:00:00 2001
From: youdie006 <youdie006@users.noreply.github.com>
Date: Wed, 7 Oct 2026 10:35:51 +0900
Subject: [PATCH] Keep out-of-order table indices valid after a table is
 removed

OutOfOrderTableProxy maps each key to positions in self._tables, but
_remove_table took a table out of that list without shifting the later
positions, so a second delete through the same proxy indexed the wrong
table or ran past the end:

    tool = doc["tool"]; del tool["black"]; del tool["ruff"]  # IndexError

Remove the table by identity and shift the later positions down.
---
 tests/test_toml_document.py | 30 ++++++++++++++++++++++++++++++
 tomlkit/container.py        |  8 ++++++--
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/tests/test_toml_document.py b/tests/test_toml_document.py
index 116de352..3b4edf5c 100644
--- a/tests/test_toml_document.py
+++ b/tests/test_toml_document.py
@@ -1592,6 +1592,36 @@ def test_delete_key_from_out_of_order_table() -> None:
     )
 
 
+def test_delete_keys_through_the_same_out_of_order_table() -> None:
+    content = """\
+[tool.a]
+x = 1
+[project]
+name = "p"
+[tool.b]
+y = 2
+[other]
+[tool.c]
+z = 3
+"""
+    doc = parse(content)
+    tool = doc["tool"]
+    del tool["a"]
+    del tool["b"]
+    assert (
+        doc.as_string()
+        == """\
+[project]
+name = "p"
+[other]
+[tool.c]
+z = 3
+"""
+    )
+    tool["c"] = {"w": 4}
+    assert doc["tool"] == {"c": {"w": 4}}
+
+
 def test_parse_aot_without_ending_newline() -> None:
     content = '''\
 [[products]]
diff --git a/tomlkit/container.py b/tomlkit/container.py
index 2f0fc034..c930b3c2 100644
--- a/tomlkit/container.py
+++ b/tomlkit/container.py
@@ -1227,7 +1227,11 @@ def _is_table_or_aot(it: Any) -> bool:
 
     def _remove_table(self, table: Table) -> None:
         """Remove table from the parent container"""
-        self._tables.remove(table)
+        pos = next(i for i, t in enumerate(self._tables) if t is table)
+        del self._tables[pos]
+        # Later tables shift down by one; keep the key -> table index map valid.
+        for indices in self._tables_map.values():
+            indices[:] = [i - 1 if i > pos else i for i in indices if i != pos]
         for idx, body_item in enumerate(self._container._body):
             if body_item[1] is table:
                 self._container._remove_at(idx)
@@ -1238,7 +1242,7 @@ def __delitem__(self, key: Key | str) -> None:
         if _key not in self._tables_map:
             raise NonExistentKey(key)
 
-        for i in reversed(self._tables_map[_key]):
+        for i in reversed(list(self._tables_map[_key])):
             table = self._tables[i]
             del table[key]
             if not table and len(self._tables) > 1: