Merge pull request #38855 from BerriAI/litellm_/backport-38251-rc-1-99-0

[Backport rc/1.99.0] fix(anthropic): translate tool_result document blocks in the /v1/messages bridge

litellm/llms/anthropic/experimental_pass_through/adapters/transformation.py

@@ -433,7 +433,7 @@ class LiteLLMAnthropicMessagesAdapter:
                                 content_items = list(content.get("content", []))
 
                                 # Single-item text keeps the backward-compatible string format; a single
-                                # image becomes a structured image_url part
+                                # image or document becomes a structured image_url part
                                 if len(content_items) == 1:
                                     c = content_items[0]
                                     if isinstance(c, str):
@@ -453,7 +453,7 @@ class LiteLLMAnthropicMessagesAdapter:
                                             )
                                             self._add_cache_control_if_applicable(content, tool_result, model)
                                             tool_message_list.append(tool_result)
-                                        elif c.get("type") == "image":
+                                        elif c.get("type") in ("image", "document"):
                                             image_part = self._tool_result_image_part(c.get("source"))
                                             tool_result = ChatCompletionToolMessage(
                                                 role="tool",
@@ -481,7 +481,7 @@ class LiteLLMAnthropicMessagesAdapter:
                                                         text=c.get("text", ""),
                                                     )
                                                 )
-                                            elif c.get("type") == "image":
+                                            elif c.get("type") in ("image", "document"):
                                                 image_part = self._tool_result_image_part(c.get("source"))
                                                 if image_part:
                                                     combined_content_parts.append(image_part)

tests/test_litellm/llms/anthropic/experimental_pass_through/adapters/test_anthropic_experimental_pass_through_adapters_transformation.py

@@ -1,3 +1,4 @@
+import base64
 from typing import Any, cast
 
 import pytest
@@ -11,6 +12,7 @@ from litellm.litellm_core_utils.prompt_templates.common_utils import (
 )
 from litellm.litellm_core_utils.prompt_templates.factory import (
     THOUGHT_SIGNATURE_SEPARATOR,
+    _bedrock_converse_messages_pt,
 )
 from litellm.llms.anthropic.experimental_pass_through.adapters.transformation import (
     OPENAI_MAX_TOOL_NAME_LENGTH,
@@ -3830,6 +3832,75 @@ def test_tool_result_plain_text_unchanged_by_openai_transform():
     assert _image_urls_in_user_messages(result) == []
 
 
+TOOL_RESULT_PDF_B64 = base64.b64encode(b"%PDF-1.4 minimal regression fixture").decode()
+
+
+def _base64_pdf_block():
+    return {
+        "type": "document",
+        "source": {"type": "base64", "media_type": "application/pdf", "data": TOOL_RESULT_PDF_B64},
+    }
+
+
+def test_tool_result_single_document_kept_as_pdf_data_url():
+    adapter = LiteLLMAnthropicMessagesAdapter()
+    translated = adapter.translate_anthropic_messages_to_openai(
+        messages=[
+            _anthropic_tool_use_turn("toolu_01"),
+            _anthropic_tool_result_turn({"toolu_01": [_base64_pdf_block()]}),
+        ]
+    )
+
+    tool_messages = [m for m in translated if m.get("role") == "tool"]
+    assert len(tool_messages) == 1
+    assert tool_messages[0]["content"] == [
+        {
+            "type": "image_url",
+            "image_url": {"url": f"data:application/pdf;base64,{TOOL_RESULT_PDF_B64}"},
+        }
+    ]
+
+
+def test_tool_result_text_and_document_reach_bedrock_converse_tool_result():
+    """Claude Code >= 2.1.245 sends Read-tool PDF output as a document block inside
+    tool_result; dropping it left bedrock converse models blind to the PDF content."""
+    adapter = LiteLLMAnthropicMessagesAdapter()
+    translated = adapter.translate_anthropic_messages_to_openai(
+        messages=[
+            AnthropicMessagesUserMessageParam(role="user", content="Read pong.pdf"),
+            _anthropic_tool_use_turn("toolu_01"),
+            _anthropic_tool_result_turn(
+                {
+                    "toolu_01": [
+                        {"type": "text", "text": "PDF file read: pong.pdf (579 bytes)"},
+                        _base64_pdf_block(),
+                    ]
+                }
+            ),
+        ]
+    )
+
+    converse_messages = _bedrock_converse_messages_pt(
+        messages=translated,
+        model="anthropic.claude-haiku-4-5-20251001-v1:0",
+        llm_provider="bedrock_converse",
+    )
+
+    tool_results = [
+        block["toolResult"]
+        for message in converse_messages
+        for block in message["content"]
+        if "toolResult" in block
+    ]
+    assert len(tool_results) == 1
+    documents = [part["document"] for part in tool_results[0]["content"] if "document" in part]
+    assert len(documents) == 1
+    assert documents[0]["format"] == "pdf"
+    assert documents[0]["source"]["bytes"] == TOOL_RESULT_PDF_B64
+    texts = [part["text"] for part in tool_results[0]["content"] if "text" in part]
+    assert texts == ["PDF file read: pong.pdf (579 bytes)"]
+
+
 def test_translate_anthropic_to_openai_carries_prompt_cache_breakpoint_on_system_and_user_blocks():
     explicit = {"mode": "explicit"}
     openai_request, _ = LiteLLMAnthropicMessagesAdapter().translate_anthropic_to_openai(