CrewAI¶

Install (the SDK declares crewai>=0.80,<2.0; the guide targets CrewAI 1.15+, which exposes the EventBus subsystem used for lifecycle event tracking):

shell

pip install nullrun crewai

The patch subscribes to the crewai EventBus and translates each lifecycle event into a nullrun.get_runtime().track(...) call. The runtime and the crewai EventBus hook are attached lazily on the first @protect call:

crewai_crew.py

import nullrun
from crewai import Agent, Crew, Task
from nullrun import protect

researcher = Agent(
    role="Researcher",
    goal="Answer the question",
    backstory="Concise and accurate.",
)

task = Task(
    description="What does NullRun do?",
    agent=researcher,
    expected_output="Two sentences.",
)

crew = Crew(agents=[researcher], tasks=[task])


@protect
def run_crew() -> str:
    return str(crew.kickoff())


print(run_crew())

The CrewAI integration automatically tracks crew / agent / task / tool lifecycle events. Token totals still come from the crew's usage metrics after kickoff — the SDK reports the canonical (model, prompt_tokens, completion_tokens) tuple on every billable row.

When crewai's events module is not importable (a stripped-down third-party build), only the per-event span bridge is skipped; the post-run cost attribution still works.

CrewAI¶

See also¶