From 86252d2ae6a860c96e8dd61505601d8d2128d63b Mon Sep 17 00:00:00 2001
From: Mason Daugherty <github@mdrxy.com>
Date: Fri, 15 Aug 2025 15:39:36 -0400
Subject: [PATCH] refactor: move ID prefixes

---
 libs/core/langchain_core/messages/ai.py        | 18 +++---------------
 .../langchain_core/messages/content_blocks.py  | 14 +++++++++++++-
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/libs/core/langchain_core/messages/ai.py b/libs/core/langchain_core/messages/ai.py
index 207ab6c1133..76bc8d980a1 100644
--- a/libs/core/langchain_core/messages/ai.py
+++ b/libs/core/langchain_core/messages/ai.py
@@ -26,18 +26,6 @@ from langchain_core.utils.usage import _dict_int_op
 
 logger = logging.getLogger(__name__)
 
-_LC_AUTO_PREFIX = "lc_"
-"""LangChain auto-generated ID prefix for messages and content blocks."""
-
-_LC_ID_PREFIX = f"{_LC_AUTO_PREFIX}run-"
-"""Internal tracing/callback system identifier.
-
-Used for:
-- Tracing. Every LangChain operation (LLM call, chain execution, tool use, etc.)
-  gets a unique run_id (UUID)
-- Enables tracking parent-child relationships between operations
-"""
-
 
 class InputTokenDetails(TypedDict, total=False):
     """Breakdown of input token counts.
@@ -523,15 +511,15 @@ def add_ai_message_chunks(
     for id_ in candidates:
         if (
             id_
-            and not id_.startswith(_LC_ID_PREFIX)
-            and not id_.startswith(_LC_AUTO_PREFIX)
+            and not id_.startswith(types.LC_ID_PREFIX)
+            and not id_.startswith(types.LC_AUTO_PREFIX)
         ):
             chunk_id = id_
             break
     else:
         # second pass: prefer lc_run-* ids over lc_* ids
         for id_ in candidates:
-            if id_ and id_.startswith(_LC_ID_PREFIX):
+            if id_ and id_.startswith(types.LC_ID_PREFIX):
                 chunk_id = id_
                 break
         else:
diff --git a/libs/core/langchain_core/messages/content_blocks.py b/libs/core/langchain_core/messages/content_blocks.py
index 1448d37086b..32673f1d3cc 100644
--- a/libs/core/langchain_core/messages/content_blocks.py
+++ b/libs/core/langchain_core/messages/content_blocks.py
@@ -135,6 +135,18 @@ from uuid import uuid4
 
 from typing_extensions import NotRequired, TypedDict, TypeGuard
 
+LC_AUTO_PREFIX = "lc_"
+"""LangChain auto-generated ID prefix for messages and content blocks."""
+
+LC_ID_PREFIX = f"{LC_AUTO_PREFIX}run-"
+"""Internal tracing/callback system identifier.
+
+Used for:
+- Tracing. Every LangChain operation (LLM call, chain execution, tool use, etc.)
+  gets a unique run_id (UUID)
+- Enables tracking parent-child relationships between operations
+"""
+
 
 def _ensure_id(id_val: Optional[str]) -> str:
     """Ensure the ID is a valid string, generating a new UUID if not provided.
@@ -148,7 +160,7 @@ def _ensure_id(id_val: Optional[str]) -> str:
     Returns:
         A string ID, either the validated provided value or a newly generated UUID4.
     """
-    return id_val or str(f"lc_{uuid4()}")
+    return id_val or str(f"{LC_AUTO_PREFIX}{uuid4()}")
 
 
 class Citation(TypedDict):