From 607921dcb0dd9bcc3063ba4e2213cc8ee938992e Mon Sep 17 00:00:00 2001
From: Dan Siwiec <dan@cleric.io>
Date: Wed, 17 Sep 2025 14:47:09 -0700
Subject: [PATCH] feat: expose parent_tool_use_id to support subagent tracking
 #138 (#166)

---
 .../_internal/message_parser.py               | 15 +++++++--
 src/claude_code_sdk/types.py                  |  2 ++
 tests/test_message_parser.py                  | 33 +++++++++++++++++++
 3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/src/claude_code_sdk/_internal/message_parser.py b/src/claude_code_sdk/_internal/message_parser.py
index 6b39a02..23269ef 100644
--- a/src/claude_code_sdk/_internal/message_parser.py
+++ b/src/claude_code_sdk/_internal/message_parser.py
@@ -46,6 +46,7 @@ def parse_message(data: dict[str, Any]) -> Message:
     match message_type:
         case "user":
             try:
+                parent_tool_use_id = data.get("parent_tool_use_id")
                 if isinstance(data["message"]["content"], list):
                     user_content_blocks: list[ContentBlock] = []
                     for block in data["message"]["content"]:
@@ -70,8 +71,14 @@ def parse_message(data: dict[str, Any]) -> Message:
                                         is_error=block.get("is_error"),
                                     )
                                 )
-                    return UserMessage(content=user_content_blocks)
-                return UserMessage(content=data["message"]["content"])
+                    return UserMessage(
+                        content=user_content_blocks,
+                        parent_tool_use_id=parent_tool_use_id,
+                    )
+                return UserMessage(
+                    content=data["message"]["content"],
+                    parent_tool_use_id=parent_tool_use_id,
+                )
             except KeyError as e:
                 raise MessageParseError(
                     f"Missing required field in user message: {e}", data
@@ -109,7 +116,9 @@ def parse_message(data: dict[str, Any]) -> Message:
                             )
 
                 return AssistantMessage(
-                    content=content_blocks, model=data["message"]["model"]
+                    content=content_blocks,
+                    model=data["message"]["model"],
+                    parent_tool_use_id=data.get("parent_tool_use_id"),
                 )
             except KeyError as e:
                 raise MessageParseError(
diff --git a/src/claude_code_sdk/types.py b/src/claude_code_sdk/types.py
index 14be39d..7fc9402 100644
--- a/src/claude_code_sdk/types.py
+++ b/src/claude_code_sdk/types.py
@@ -230,6 +230,7 @@ class UserMessage:
     """User message."""
 
     content: str | list[ContentBlock]
+    parent_tool_use_id: str | None = None
 
 
 @dataclass
@@ -238,6 +239,7 @@ class AssistantMessage:
 
     content: list[ContentBlock]
     model: str
+    parent_tool_use_id: str | None = None
 
 
 @dataclass
diff --git a/tests/test_message_parser.py b/tests/test_message_parser.py
index 60dea98..58e5851 100644
--- a/tests/test_message_parser.py
+++ b/tests/test_message_parser.py
@@ -130,6 +130,17 @@ class TestMessageParser:
         assert isinstance(message.content[2], ToolResultBlock)
         assert isinstance(message.content[3], TextBlock)
 
+    def test_parse_user_message_inside_subagent(self):
+        """Test parsing a valid user message."""
+        data = {
+            "type": "user",
+            "message": {"content": [{"type": "text", "text": "Hello"}]},
+            "parent_tool_use_id": "toolu_01Xrwd5Y13sEHtzScxR77So8",
+        }
+        message = parse_message(data)
+        assert isinstance(message, UserMessage)
+        assert message.parent_tool_use_id == "toolu_01Xrwd5Y13sEHtzScxR77So8"
+
     def test_parse_valid_assistant_message(self):
         """Test parsing a valid assistant message."""
         data = {
@@ -185,6 +196,28 @@ class TestMessageParser:
         assert isinstance(message, SystemMessage)
         assert message.subtype == "start"
 
+    def test_parse_assistant_message_inside_subagent(self):
+        """Test parsing a valid assistant message."""
+        data = {
+            "type": "assistant",
+            "message": {
+                "content": [
+                    {"type": "text", "text": "Hello"},
+                    {
+                        "type": "tool_use",
+                        "id": "tool_123",
+                        "name": "Read",
+                        "input": {"file_path": "/test.txt"},
+                    },
+                ],
+                "model": "claude-opus-4-1-20250805",
+            },
+            "parent_tool_use_id": "toolu_01Xrwd5Y13sEHtzScxR77So8",
+        }
+        message = parse_message(data)
+        assert isinstance(message, AssistantMessage)
+        assert message.parent_tool_use_id == "toolu_01Xrwd5Y13sEHtzScxR77So8"
+
     def test_parse_valid_result_message(self):
         """Test parsing a valid result message."""
         data = {