diff --git a/nanobot/providers/litellm_provider.py b/nanobot/providers/litellm_provider.py
index a9a0517..ebc8c9b 100644
--- a/nanobot/providers/litellm_provider.py
+++ b/nanobot/providers/litellm_provider.py
@@ -62,6 +62,8 @@ class LiteLLMProvider(LLMProvider):
         # Drop unsupported parameters for providers (e.g., gpt-5 rejects some params)
         litellm.drop_params = True
 
+        self._langsmith_enabled = bool(os.getenv("LANGSMITH_API_KEY"))
+
     def _setup_env(self, api_key: str, api_base: str | None, model: str) -> None:
         """Set environment variables based on detected provider."""
         spec = self._gateway or find_by_model(model)
@@ -250,10 +252,9 @@ class LiteLLMProvider(LLMProvider):
         # Apply model-specific overrides (e.g. kimi-k2.5 temperature)
         self._apply_model_overrides(model, kwargs)
 
-        # Use langsmith to view the conversation
-        if os.getenv("LANGSMITH_API_KEY"):
-            kwargs["callbacks"] = ["langsmith"]
-        
+        if self._langsmith_enabled:
+            kwargs.setdefault("callbacks", []).append("langsmith")
+
         # Pass api_key directly — more reliable than env vars alone
         if self.api_key:
             kwargs["api_key"] = self.api_key
diff --git a/pyproject.toml b/pyproject.toml
index 5eb77c3..dce9e26 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -56,6 +56,9 @@ matrix = [
     "mistune>=3.0.0,<4.0.0",
     "nh3>=0.2.17,<1.0.0",
 ]
+langsmith = [
+    "langsmith>=0.1.0",
+]
 dev = [
     "pytest>=9.0.0,<10.0.0",
     "pytest-asyncio>=1.3.0,<2.0.0",