fix(llm_response_utils): expand every hallucinated multi_tool_use.parallel call

_handle_invalid_parallel_tool_calls replaces one entry with len(replacement)
entries, so the offsets of everything after it shift by len(replacement) - 1.
Advancing by the full length skipped one entry per expansion: with two
multi_tool_use.parallel calls in one message the second stayed in
message.tool_calls (so agents tried to call a non-existent tool) and the call
after it was overwritten.

Adds a regression test that expands two such calls in one message.

litellm/litellm_core_utils/llm_response_utils/convert_dict_to_response.py

@@ -406,7 +406,11 @@ def _handle_invalid_parallel_tool_calls(
         shift = 0
         for i, replacement in replacements.items():
             tool_calls[:] = tool_calls[: i + shift] + replacement + tool_calls[i + shift + 1 :]
-            shift += len(replacement)
+            # One entry is replaced by ``len(replacement)`` entries, so the
+            # offsets of everything after it move by the difference - not by
+            # the full length, which would skip one entry per expansion and
+            # leave the next ``multi_tool_use.parallel`` call in place.
+            shift += len(replacement) - 1
 
         return tool_calls
     except json.JSONDecodeError:

tests/llm_translation/test_llm_response_utils/test_convert_dict_to_chat_completion.py

@@ -2486,3 +2486,79 @@ class TestConvertToModelResponseObjectCompletion:
                 },
                 model_response_object=None,
             )
+
+
+def test_convert_to_model_response_object_expands_every_parallel_tool_call():
+    """
+    Every hallucinated `multi_tool_use.parallel` entry in one message must be
+    expanded. Replacing one entry with its expansions moves the offsets of the
+    entries that follow it by `len(expansions) - 1`; advancing by the full
+    length skipped one entry per expansion, so with two such calls the second
+    one stayed in place and the call after it was overwritten.
+    """
+
+    def parallel(call_id, recipient_name, parameters):
+        return {
+            "id": call_id,
+            "type": "function",
+            "function": {
+                "name": "multi_tool_use.parallel",
+                "arguments": json.dumps(
+                    {
+                        "tool_uses": [
+                            {
+                                "recipient_name": recipient_name,
+                                "parameters": parameters,
+                            }
+                        ]
+                    }
+                ),
+            },
+        }
+
+    def plain(call_id, name):
+        return {
+            "id": call_id,
+            "type": "function",
+            "function": {"name": name, "arguments": "{}"},
+        }
+
+    response_object = {
+        "id": "chatcmpl-parallel",
+        "object": "chat.completion",
+        "created": 1728933352,
+        "model": "gpt-4o-2024-08-06",
+        "choices": [
+            {
+                "index": 0,
+                "finish_reason": "tool_calls",
+                "message": {
+                    "role": "assistant",
+                    "content": None,
+                    "tool_calls": [
+                        plain("0", "get_weather"),
+                        parallel("m1", "functions.get_time", {"tz": "UTC"}),
+                        plain("2", "get_news"),
+                        parallel("m2", "functions.get_quote", {"sym": "AAPL"}),
+                        plain("4", "get_forecast"),
+                    ],
+                },
+            }
+        ],
+    }
+
+    result = convert_to_model_response_object(
+        response_object=response_object,
+        model_response_object=ModelResponse(),
+        response_type="completion",
+    )
+
+    names = [tc.function.name for tc in result.choices[0].message.tool_calls]
+    assert names == [
+        "get_weather",
+        "get_time",
+        "get_news",
+        "get_quote",
+        "get_forecast",
+    ]
+    assert "multi_tool_use.parallel" not in names