From c511e3ea06ab87b0edd70aa5ab56b1e758c77c2b Mon Sep 17 00:00:00 2001
From: er-s-an <er-s-an@users.noreply.github.com>
Date: Fri, 9 Oct 2026 09:35:37 +0800
Subject: [PATCH] fix(anthropic): preserve assistant text order around tool_use
 in Responses adapter

Fixes #45470. translate_messages_to_responses_input previously deferred
all assistant text into one trailing message after function_call items,
replaying text that appeared before the tool. Emit text blocks in group
order and stop collecting them at the end.
---
 .../responses_adapters/transformation.py      | 23 +++++-----
 .../test_responses_adapters_transformation.py | 45 +++++++++++++++++++
 2 files changed, 55 insertions(+), 13 deletions(-)

diff --git a/litellm/llms/anthropic/messages/responses_adapters/transformation.py b/litellm/llms/anthropic/messages/responses_adapters/transformation.py
index d7b8592f45c..3ea53d7aec6 100644
--- a/litellm/llms/anthropic/messages/responses_adapters/transformation.py
+++ b/litellm/llms/anthropic/messages/responses_adapters/transformation.py
@@ -294,6 +294,16 @@ class LiteLLMAnthropicToResponsesAPIAdapter:
                     "arguments": json.dumps(first.get("input", {})),
                 },
             )
+        if btype == "text":
+            # Emit text in block order so text before/after tool_use is not
+            # replayed as one trailing assistant message (#45470).
+            return (
+                {
+                    "type": "message",
+                    "role": "assistant",
+                    "content": [{"type": "output_text", "text": first.get("text", "")}],
+                },
+            )
         return ()
 
     def translate_messages_to_responses_input(
@@ -447,19 +457,6 @@ class LiteLLMAnthropicToResponsesAPIAdapter:
                         for _, group in groupby(enumerate(blocks), key=self._assistant_block_group_key)
                         for item in self._assistant_group_to_input_items(tuple(block for _, block in group))
                     )
-                    asst_parts: list[dict[str, object]] = [  # mutable-ok: API message payload
-                        {"type": "output_text", "text": block.get("text", "")}
-                        for block in blocks
-                        if block.get("type") == "text"
-                    ]
-                    if asst_parts:
-                        input_items.append(
-                            {
-                                "type": "message",
-                                "role": "assistant",
-                                "content": asst_parts,
-                            }
-                        )
 
         return input_items
 
diff --git a/tests/unit/llms/anthropic/messages/responses_adapters/test_responses_adapters_transformation.py b/tests/unit/llms/anthropic/messages/responses_adapters/test_responses_adapters_transformation.py
index 660f00cd722..77792ab6806 100644
--- a/tests/unit/llms/anthropic/messages/responses_adapters/test_responses_adapters_transformation.py
+++ b/tests/unit/llms/anthropic/messages/responses_adapters/test_responses_adapters_transformation.py
@@ -696,6 +696,51 @@ class TestTranslateMessagesToResponsesInput:
         assert result[0]["summary"] == [{"type": "summary_text", "text": "Before the call."}]
         assert result[2]["summary"] == [{"type": "summary_text", "text": "After the call."}]
 
+    def test_assistant_text_before_and_after_tool_use_preserves_order(self):
+        """Text around tool_use stays in block order, not replayed after (#45470)."""
+        messages = [
+            {"role": "user", "content": "weather in Paris?"},
+            {
+                "role": "assistant",
+                "content": [
+                    {"type": "text", "text": "Let me check."},
+                    {
+                        "type": "tool_use",
+                        "id": "toolu_1",
+                        "name": "get_weather",
+                        "input": {"city": "Paris"},
+                    },
+                    {"type": "text", "text": "(after)"},
+                ],
+            },
+            {
+                "role": "user",
+                "content": [
+                    {"type": "tool_result", "tool_use_id": "toolu_1", "content": "sunny"}
+                ],
+            },
+        ]
+        result = _translate_messages(messages)
+        assert [item["type"] for item in result] == [
+            "message",
+            "message",
+            "function_call",
+            "message",
+            "function_call_output",
+        ]
+        assert result[1] == {
+            "type": "message",
+            "role": "assistant",
+            "content": [{"type": "output_text", "text": "Let me check."}],
+        }
+        assert result[2]["type"] == "function_call"
+        assert result[2]["call_id"] == "toolu_1"
+        assert result[3] == {
+            "type": "message",
+            "role": "assistant",
+            "content": [{"type": "output_text", "text": "(after)"}],
+        }
+
     def test_thinking_and_text_stay_separate(self):
         """The visible answer stays the only thing in the assistant message."""
         messages = [