[Hub|tracing] Tag hub prompts (#14720)

If you're using the hub, you'll likely be interested in tracking the
commit/object when tracing. This PR adds it to the config

libs/langchain/langchain/hub.py

@@ -5,6 +5,7 @@ from typing import TYPE_CHECKING, Any, Optional
 
 from langchain_core.load.dump import dumps
 from langchain_core.load.load import loads
+from langchain_core.runnables import Runnable
 
 if TYPE_CHECKING:
     from langchainhub import Client
@@ -78,4 +79,7 @@ def pull(
     """
     client = _get_client(api_url=api_url, api_key=api_key)
     resp: str = client.pull(owner_repo_commit)
-    return loads(resp)
+    loaded = loads(resp)
+    if isinstance(loaded, Runnable):
+        return loaded.with_config(metadata={"hub_owner_repo_commit": owner_repo_commit})
+    return loaded

libs/langchain/tests/unit_tests/test_hub.py

@@ -0,0 +1,61 @@
+from typing import Any, List
+from unittest.mock import MagicMock, Mock, patch
+
+from langchain_core.load.dump import dumps
+from langchain_core.prompts import ChatPromptTemplate
+from langchain_core.runnables.base import RunnableBinding
+from langchain_core.tracers.base import BaseTracer
+from langchain_core.tracers.schemas import Run
+
+from langchain import hub
+
+
+class FakeTracer(BaseTracer):
+    """Fake tracer that records LangChain execution."""
+
+    def __init__(self) -> None:
+        """Initialize the tracer."""
+        super().__init__()
+        self.runs: List[Run] = []
+
+    def _persist_run(self, run: Run) -> None:
+        """Persist a run."""
+        self.runs.append(run)
+
+
+repo_dict = {
+    "wfh/my-prompt-1": ChatPromptTemplate.from_messages(
+        [("system", "a"), ("user", "1")]
+    ),
+    "wfh/my-random-object": {"Hi": "there"},
+}
+
+
+def repo_lookup(owner_repo_commit: str, **kwargs: Any) -> str:
+    return dumps(repo_dict[owner_repo_commit])
+
+
+@patch("langchain.hub._get_client")
+def test_hub_pull_metadata(mock_get_client: Mock) -> None:
+    mock_client = MagicMock()
+    mock_client.pull = repo_lookup
+    mock_get_client.return_value = mock_client
+    res = hub.pull("wfh/my-prompt-1")
+    assert isinstance(res, RunnableBinding)
+    tracer = FakeTracer()
+    result = res.invoke({}, {"callbacks": [tracer]})
+    assert result.messages[0].content == "a"
+    assert result.messages[1].content == "1"
+    assert len(tracer.runs) == 1
+    run = tracer.runs[0]
+    assert run.extra is not None
+    assert run.extra["metadata"]["hub_owner_repo_commit"] == "wfh/my-prompt-1"  # type: ignore
+
+
+@patch("langchain.hub._get_client")
+def test_hub_pull_random_object(mock_get_client: Mock) -> None:
+    mock_client = MagicMock()
+    mock_client.pull = repo_lookup
+    mock_get_client.return_value = mock_client
+    res = hub.pull("wfh/my-random-object")
+    assert res == {"Hi": "there"}