From cb8e35df83383d70bba4a616b724603d11a0255b Mon Sep 17 00:00:00 2001
From: Erick Friis <erick@langchain.dev>
Date: Fri, 24 Jan 2025 16:23:37 -0800
Subject: [PATCH] core: allow merging metadata in tracing

---
 libs/core/langchain_core/tracers/core.py      | 25 +++++++++++++++----
 libs/core/langchain_core/tracers/langchain.py |  5 +++-
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/libs/core/langchain_core/tracers/core.py b/libs/core/langchain_core/tracers/core.py
index d3544df04e3..1e4df5d9503 100644
--- a/libs/core/langchain_core/tracers/core.py
+++ b/libs/core/langchain_core/tracers/core.py
@@ -178,7 +178,10 @@ class _TracerCore(ABC):
             raise NotImplementedError(msg)
         start_time = datetime.now(timezone.utc)
         if metadata:
-            kwargs.update({"metadata": metadata})
+            if isinstance(kwargs.get("metadata"), dict):
+                kwargs["metadata"].update(metadata)
+            else:
+                kwargs.update({"metadata": metadata})
         return Run(
             id=run_id,
             parent_run_id=parent_run_id,
@@ -209,7 +212,10 @@ class _TracerCore(ABC):
         """Create a llm run."""
         start_time = datetime.now(timezone.utc)
         if metadata:
-            kwargs.update({"metadata": metadata})
+            if isinstance(kwargs.get("metadata"), dict):
+                kwargs["metadata"].update(metadata)
+            else:
+                kwargs.update({"metadata": metadata})
         return Run(
             id=run_id,
             parent_run_id=parent_run_id,
@@ -314,7 +320,10 @@ class _TracerCore(ABC):
         """Create a chain Run."""
         start_time = datetime.now(timezone.utc)
         if metadata:
-            kwargs.update({"metadata": metadata})
+            if isinstance(kwargs.get("metadata"), dict):
+                kwargs["metadata"].update(metadata)
+            else:
+                kwargs.update({"metadata": metadata})
         return Run(
             id=run_id,
             parent_run_id=parent_run_id,
@@ -399,7 +408,10 @@ class _TracerCore(ABC):
         """Create a tool run."""
         start_time = datetime.now(timezone.utc)
         if metadata:
-            kwargs.update({"metadata": metadata})
+            if isinstance(kwargs.get("metadata"), dict):
+                kwargs["metadata"].update(metadata)
+            else:
+                kwargs.update({"metadata": metadata})
 
         if self._schema_format in ("original", "original+chat"):
             inputs = {"input": input_str}
@@ -464,7 +476,10 @@ class _TracerCore(ABC):
         """Create a retrieval run."""
         start_time = datetime.now(timezone.utc)
         if metadata:
-            kwargs.update({"metadata": metadata})
+            if isinstance(kwargs.get("metadata"), dict):
+                kwargs["metadata"].update(metadata)
+            else:
+                kwargs.update({"metadata": metadata})
         return Run(
             id=run_id,
             name=name or "Retriever",
diff --git a/libs/core/langchain_core/tracers/langchain.py b/libs/core/langchain_core/tracers/langchain.py
index d125494af9a..fdf9a133074 100644
--- a/libs/core/langchain_core/tracers/langchain.py
+++ b/libs/core/langchain_core/tracers/langchain.py
@@ -154,7 +154,10 @@ class LangChainTracer(BaseTracer):
         """
         start_time = datetime.now(timezone.utc)
         if metadata:
-            kwargs.update({"metadata": metadata})
+            if isinstance(kwargs.get("metadata"), dict):
+                kwargs["metadata"].update(metadata)
+            else:
+                kwargs.update({"metadata": metadata})
         chat_model_run = Run(
             id=run_id,
             parent_run_id=parent_run_id,