lightrace-python

Lightweight LLM tracing SDK for Python with remote tool invocation.

Install

pip install lightrace

Quick Start

from lightrace import Lightrace, trace

lt = Lightrace(
    public_key="pk-lt-demo",
    secret_key="sk-lt-demo",
    host="http://localhost:3002",
)

# Root trace
@trace()
def run_agent(query: str):
    return search(query)

# Span
@trace(type="span")
def search(query: str) -> list:
    return ["result1", "result2"]

# Generation (LLM call)
@trace(type="generation", model="gpt-4o")
def generate(prompt: str) -> str:
    return "LLM response"

# Tool — remotely invocable from the Lightrace UI
@trace(type="tool")
def weather_lookup(city: str) -> dict:
    return {"temp": 72, "unit": "F"}

# Tool — traced but NOT remotely invocable
@trace(type="tool", invoke=False)
def read_file(path: str) -> str:
    return open(path).read()

run_agent("hello")
lt.flush()
lt.shutdown()

@trace API

@trace()                                    # Root trace
@trace(type="span")                         # Span observation
@trace(type="generation", model="gpt-4o")   # LLM generation
@trace(type="tool")                         # Tool (remotely invocable)
@trace(type="tool", invoke=False)           # Tool (trace only)

Parameters

Parameter	Type	Default	Description
type	str	None	"span", "generation", "tool", "chain", "event"
name	str	None	Override name (defaults to function name)
invoke	bool	True	For type="tool": register for remote invocation
model	str	None	For type="generation": LLM model name
metadata	dict	None	Static metadata attached to every call

Compatibility

Lightrace server also accepts traces from Langfuse Python/JS SDKs.

Development

uv sync --extra dev
uv run pre-commit install
uv run pytest -s -v tests/
uv run ruff check .
uv run mypy src/lightrace

License

MIT