zush 0.2.0

Zush is a CLI framework for building nested CLI applications.

zush

zush is a Python CLI framework for discovering and serving nested command trees from plugin packages.

It is useful when you want one entry point that can load commands from multiple environments without hard-coding every command into a single application.

What zush does

• Discovers plugin packages from configured directories or site-packages.
• Exposes plugin commands as nested Click subcommands.
• Provides built-in commands for inspecting the active command tree.
• Supports lightweight plugin hooks and shared runtime context.
• Can be used as a standalone CLI or mounted inside another Click app.

Requirements

• Python 3.12+
• Click 8+

Installation

From the repository:

uv sync
uv run zush --help

Or install it as a package and use the zush console script.

Quick Start

Show the active command tree:

zush self map

Run a discovered plugin command:

zush <group> <command> ...

Use the bundled playground without touching your config:

uv run zush --mock-path ./playground self map
uv run zush --mock-path ./playground demo greet

--mock-path and -m scan only the given directory and disable cache usage for that run.

Configuration

zush reads its config from ~/.zush/config.toml.

If the file does not exist yet, zush creates a bootstrap config on first run.

Supported keys:

Key	Meaning
envs	Directories to scan for plugin packages.
env_prefix	Allowed package name prefixes. Default: ["zush_"].
playground	Optional directory scanned first for local development overrides.
include_current_env	When true, also scan the current Python environment's site-packages.

Example:

envs = ["/path/to/plugins", "/another/path"]
env_prefix = ["zush_", "my_"]
playground = "/path/to/zush/playground"
include_current_env = true

zush stores config, cache, and other runtime files under ~/.zush/ by default.

Plugin Layout

zush discovers directories whose names match one of the configured prefixes and that contain __zush__.py at the package root.

Inside __zush__.py, export a plugin instance with a .commands dictionary.

Minimal example:

import click


class Plugin:
    def __init__(self) -> None:
        self.commands = {
            "hello": click.Command("hello", callback=lambda: click.echo("Hello")),
        }


ZushPlugin = Plugin()

Command keys may use dotted paths to build nested subcommands:

• demo.greet
• tools.convert.json

Plugin Helper API

If you do not want to manage dotted command paths by hand, use zush.plugin.Plugin:

import click
from zush.plugin import Plugin


p = Plugin()
p.group("hello", help="Greeting commands").command(
    "say",
    callback=lambda: click.echo("Hi"),
    help="Say hi",
)

ZushPlugin = p

Plugin Hooks

Plugins may optionally expose these attributes on the exported instance:

• before_cmd
• after_cmd
• on_error
• on_ctx_match

These are lifecycle hooks for command execution and shared context changes. They are not exposed as CLI commands.

Runtime Globals

zush also provides a process-local runtime object store at zush.runtime.g.

This is useful for sharing live objects during a single zush process, for example:

• schedulers
• clients
• registries
• in-memory service handles

Helper-based plugins can register objects into that store:

from zush.plugin import Plugin


p = Plugin()
p.provide("scheduler", object())
ZushPlugin = p

If the object should be created lazily, use provide_factory(...) instead. The value is materialized on first access through zush.runtime.g and then cached for the rest of the process:

from zush.plugin import Plugin


def build_scheduler():
    return object()


p = Plugin()
p.provide_factory("scheduler", build_scheduler)
ZushPlugin = p

Factories may also accept a plugin runtime object as their first argument. That runtime can start, stop, restart, or ensure readiness for services declared by the same plugin.

When the provider depends on a service, declare that dependency directly so zush can ensure readiness before construction and invalidate the cached provider when the service changes:

from zush.plugin import Plugin


def build_client(runtime):
    return MyClient(runtime)


def close_client(client):
    client.close()


p = Plugin()
p.provide_factory(
    "client",
    build_client,
    service="web",
    recreate_on_restart=True,
    teardown=close_client,
)
ZushPlugin = p

With that setup:

• zush ensures web is ready before the provider is first created
• the provider is rebuilt after web restarts or stops
• the previous provider instance is passed to teardown before replacement

Objects in zush.runtime.g are not persisted to disk and are only available for the current process.

Persisted Plugin State

Helper-based plugins can persist state with persistedCtx():

import click
from zush.plugin import Plugin


@click.command("save")
def save_cmd() -> None:
    with ZushPlugin.persistedCtx() as state:
        state["count"] = state.get("count", 0) + 1
    click.echo("saved")


p = Plugin()
p.group("persist").command("save", callback=save_cmd.callback)
ZushPlugin = p

Supported payload types:

• persistedCtx() for JSON
• persistedCtx("notes.txt") for plain text
• persistedCtx("settings.toml") for TOML
• persistedCtx("settings.yaml") for YAML

Detached Services

Plugins can also declare detached subprocess-backed services for zush to manage.

Helper-based example:

import sys

from zush.plugin import Plugin


p = Plugin()
p.service(
    "web",
    [sys.executable, "-m", "flask", "run"],
    auto_restart=True,
)

ZushPlugin = p

zush persists service registration and state in user data and exposes a built-in control surface:

zush self services web --start
zush self services web --status
zush self services web --restart
zush self services web --stop

If a service is marked auto_restart=True, zush can restart it when it is missing or when its health check reports unhealthy.

Services may also supply a custom control interface when subprocess spawning is not the only or best lifecycle mechanism. A control interface can implement start(runtime), stop(runtime), restart(runtime), and status(runtime). When present, zush uses those methods first and falls back to OS-level termination only when terminate_fallback=True.

Example:

from zush.plugin import Plugin


class Control:
    def start(self, runtime):
        runtime.state["running"] = True
        runtime.save()
        return "started web"

    def stop(self, runtime):
        runtime.state["running"] = False
        runtime.save()
        return "stopped web"

    def status(self, runtime):
        return "healthy" if runtime.state.get("running") else "stopped"


p = Plugin()
p.service(
    "web",
    ["python", "app.py"],
    control=Control(),
    terminate_fallback=True,
)
ZushPlugin = p

This makes it possible for one plugin package to own both a provider object and the server/service it depends on.

The playground contains a concrete example in playground/README.md under zush_provider_service_demo.

Health checks can be provided as callbacks that return either:

• True or False
• (True, "message") or (False, "message")

Example:

import httpx
import sys

from zush.plugin import Plugin


def healthcheck(_state):
    try:
        response = httpx.get("http://127.0.0.1:5000/health", timeout=0.5)
        return response.status_code == 200, f"status={response.status_code}"
    except Exception as exc:
        return False, str(exc)


p = Plugin()
p.service(
    "web",
    [sys.executable, "-m", "flask", "run", "--no-reload"],
    auto_restart=True,
    healthcheck=healthcheck,
)

The test suite includes end-to-end service coverage with a real Flask subprocess and httpx clients, including restart behavior for unhealthy services.

Built-in Commands

The self group is reserved for zush itself.

• zush self map prints the active command tree.
• zush self config opens the active zush config directory.
• zush self services ... manages plugin-declared detached services.

Plugins cannot register commands under self.

Embedding

zush can be mounted as a subcommand group inside another Click application:

from pathlib import Path

import click

from zush import create_zush_group
from zush.config import Config
from zush.paths import DirectoryStorage, temporary_storage


app = click.Group("myapp")

app.add_command(create_zush_group(), "zush")

storage = DirectoryStorage(Path("/myapp/data/zush"))
config = Config(envs=[Path("/my/envs")], env_prefix=["zush_"])
app.add_command(create_zush_group(config=config, storage=storage), "zush")

with temporary_storage() as temp_storage:
    app.add_command(create_zush_group(config=config, storage=temp_storage), "temp-zush")

Factory signature:

create_zush_group(name="zush", config=None, storage=None, mock_path=None)

Playground

The playground/ directory contains sample plugins for local testing and exploration.

See playground/README.md for examples.

Development

Install dev dependencies and run tests:

uv sync --extra dev
uv run pytest