FastAPI

Name: z4j for FastAPI
Author: z4j

v1.6.8 Apache-2.0

Lifespan-hook integration for async stacks.

FastAPI lifespan-aware. Most commonly paired with arq or taskiq (both async-native) but works with Celery or RQ when your sync stack calls for them. Dependency-injection friendly.

Docs PyPI: z4j-fastapi Source Upstream

Latest: v1.6.8
Released: 2026-06-08
License: Apache-2.0

Install

bash

pip install z4j-fastapi

Pick an engine

FastAPI + any task engine

Every extra pulls the engine adapter AND its companion scheduler in one shot, so a fresh install never needs a second command.

Engine	Install command	Bundled scheduler
Celery	`pip install z4j-fastapi[celery]`	celery-beat
RQ	`pip install z4j-fastapi[rq]`	rq-scheduler
Dramatiq	`pip install z4j-fastapi[dramatiq]`	APScheduler
Huey	`pip install z4j-fastapi[huey]`	huey-periodic
arq recommended	`pip install z4j-fastapi[arq]`	arq-cron
TaskIQ	`pip install z4j-fastapi[taskiq]`	taskiq-scheduler
Every engine (CI / kitchen sink)	`pip install z4j-fastapi[all]`	all of the above

  pip install z4j-fastapi
with no extra installs only the framework adapter. Pick an engine extra
      for the normal case.

Wire it in

python

from fastapi import FastAPI
from z4j_fastapi import install

app = FastAPI(lifespan=install)

Verify

Confirm the agent reaches the brain

Run the doctor as the same user the service runs under. It probes brain DNS / TCP / TLS / WebSocket upgrade, the on-disk buffer path, and reports auto-detected engines - exits 0 on all-green, 1 on any failure.

bash

python -m z4j_fastapi doctor

Catches the gunicorn-under-www-data silent startup failure (the agent now auto-relocates the buffer to $TMPDIR/z4j-{uid} when $HOME is unwritable), NAT / firewall / cert mismatches, and wrong-token / wrong-project_id problems with a specific failure reason. Add --no-websocket to skip the WS round-trip, --json for scripts. Reference.

What you get