LangSmith Fetch

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0.3.1 verified Fri May 01 auth: no python

Minimal CLI and library for fetching LangSmith threads and traces. Version 0.3.1, regular releases on PyPI.

pip install langsmith-fetch

Common errors

error ModuleNotFoundError: No module named 'langsmith_fetch' ↓

cause Package not installed or installed under different name.

fix

Install with pip install langsmith-fetch and import with from langsmith_fetch import ....

error langsmith_fetch.exceptions.AuthenticationError: Invalid API key ↓

cause Missing or incorrect LangSmith API key.

fix

Set the LANGSMITH_API_KEY environment variable or pass api_key parameter.

error TypeError: fetch_thread() missing 1 required positional argument: 'api_key' ↓

cause API key not provided.

fix

Add api_key=os.environ.get('LANGSMITH_API_KEY') to the function call.

error AttributeError: 'Trace' object has no attribute 'items' ↓

cause Assuming returned object is a dict in version >=0.3.0.

fix

Access attributes directly, e.g., trace.id, trace.runs.

Warnings

gotcha The CLI and Python API have different parameter names. Use `--api-key` for CLI, `api_key` for Python. ↓

fix Be consistent with casing and dashes depending on usage.

deprecated Python 3.9 support dropped in 0.3.0, requires Python >=3.10. ↓

fix Use Python 3.10 or newer.

gotcha API key must be passed explicitly; reading from environment is not automatic. ↓

fix Always provide `api_key` parameter or use `--api-key` flag in CLI.

breaking In version 0.3.0, the return format of `fetch_trace` changed from dict to custom Trace object. ↓

fix Access attributes directly instead of dict keys, e.g., `trace.id` instead of `trace['id']`.

Imports

LangSmithFetch

wrong

from langsmith_fetch.fetch import LangSmithFetch

correct

from langsmith_fetch import LangSmithFetch

Incorrect submodule path

fetch_thread

wrong

from langsmith import fetch_thread

correct

from langsmith_fetch import fetch_thread

Function is not in the main langsmith package

fetch_trace
```
from langsmith_fetch import fetch_trace
```

main

wrong

from langsmith_fetch import main

correct

from langsmith_fetch.cli import main

main is in cli module, not top-level

Quickstart

Fetch a LangSmith thread by ID using environment variable for API key.

import os
from langsmith_fetch import fetch_thread

api_key = os.environ.get('LANGSMITH_API_KEY', '')
result = fetch_thread('thread_id_here', api_key=api_key)
print(result)