awesome-copilot/skills/eval-driven-dev/references/runnable-examples/standalone-function.md

Runnable Example: Standalone Function (No Server)

When the app is a plain Python function or module — no web framework, no server, no infrastructure.

Approach: Import and call the function directly from run(). This is the simplest case.

# pixie_qa/run_app.py
from pydantic import BaseModel
import pixie


class AppArgs(BaseModel):
    question: str


class AppRunnable(pixie.Runnable[AppArgs]):
    """Drives a standalone function for tracing and evaluation."""

    @classmethod
    def create(cls) -> "AppRunnable":
        return cls()

    async def run(self, args: AppArgs) -> None:
        from myapp.agent import answer_question
        await answer_question(args.question)

If the function is synchronous, wrap it with asyncio.to_thread:

import asyncio

async def run(self, args: AppArgs) -> None:
    from myapp.agent import answer_question
    await asyncio.to_thread(answer_question, args.question)

If the function depends on an external service (e.g., a vector store), the wrap(purpose="input") calls you added in Step 2a handle it automatically — the registry injects test data in eval mode.

When to use setup() / teardown()

Most standalone functions don't need lifecycle methods. Use them only when the function requires a shared resource (e.g., a pre-loaded embedding model, a database connection):

class AppRunnable(pixie.Runnable[AppArgs]):
    _model: SomeModel

    @classmethod
    def create(cls) -> "AppRunnable":
        return cls()

    async def setup(self) -> None:
        from myapp.models import load_model
        self._model = load_model()

    async def run(self, args: AppArgs) -> None:
        from myapp.agent import answer_question
        await answer_question(args.question, model=self._model)