pyselfupdate

Self-update and update notification for Python CLIs installed with uv tool.

Two things, used independently: tell the user once a day that a newer release exists, and install it when they ask. No runtime dependencies.

from pyselfupdate import Config, notify, update

config = Config(tool='mytool', owner='you')

notify(config)  # once a day, one line if behind. Never raises.
update(config)  # install the latest release. Raises on failure.

Install

uv add pyselfupdate

# with the ready-made typer command
uv add "pyselfupdate[typer]"

Requires Python 3.11+.

Why

A CLI distributed with uv tool install has no way to tell its user a newer version exists, so it silently drifts. The usual fix drags an HTTP client, a TOML parser and a version library into a tool that had none of them.

This package has zero runtime dependencies — urllib for the network, tomllib for uv's receipt, and its own semver implementation — and CI enforces that by importing every module into a virtual environment containing nothing else.

notify

Put it in your CLI's root callback and ignore the result:

import typer
from pyselfupdate import Config, notify

app = typer.Typer()
CONFIG = Config(tool='mytool', owner='you')


@app.callback()
def main() -> None:
    notify(CONFIG)

Once per 24 hours, if a newer release exists, one line goes to stderr after your command's own output:

mytool v1.4.0 available (running v1.3.2) — run `mytool update`

It never raises, never installs anything, and never prints an error. A failed check is recorded in the state file and swallowed, because an update notice must not be able to break the command the user actually typed.

Nothing is printed when any of these hold:

Presence-only, any value: NO_AUTO_UPDATE=0 disables it, the same way NO_COLOR works. Set the interval separately with AUTO_UPDATE_INTERVAL=6h or MYTOOL_AUTO_UPDATE_INTERVAL=30m.

update

from pyselfupdate import Config, check, update

result = check(config)  # no filesystem, no install
if result.update_available:
    print(result.current, '->', result.latest)

result = update(config)  # installs, raises on failure

Or take the whole command:

from pyselfupdate.typercmd import add_update_command

add_update_command(app, CONFIG)  # gives you `mytool update [--check]`

update runs uv tool install --force, which rebuilds the virtual environment the running interpreter lives in. Unlike replacing a Unix binary — where the process holds an inode and is untouched — this pulls modules out from under a live process, so anything imported afterwards may fail in ways that are hard to read. Make it the last thing your process does, then call exit_now — or use update_and_reexec to replace the process with the new version immediately.

That cuts both ways: anything you want to print after the install has to be fetched before it. run_update resolves its changelog first for exactly this reason, and a caller that needs its own steps in between composes the three pieces update is made of rather than working around it:

installation = require_updatable(config)  # refuses a checkout, costs nothing
result = check(config)                    # network, environment still intact
notes = changelog(config, result.current, result.latest)
install_release(config, result, installation)
print(notes)
exit_now()

What will not be updated

Read from uv's own receipt, written at install time, rather than guessed at runtime:

A tool that cannot be identified at all is treated as local and left alone.

Configuration

Config(
    tool='mytool',  # required: uv tool name, state dir, env prefix
    owner='you',  # GitHub owner
    repo='mytool',  # defaults to tool
    package='mytool',  # distribution name, defaults to tool
    version='1.2.3',  # defaults to the installed distribution's metadata
    token='',  # defaults to $GITHUB_TOKEN, then $GH_TOKEN, then token_func
    token_func=None,  # called only when a request is made; for a credential that costs a subprocess
    tag_prefix='',  # e.g. 'cli/' for tags like cli/v1.2.3
    allow_prerelease=False,
    source=None,  # a custom Source; anything with latest_release()
)

Without a token, GitHub allows 60 API requests per hour per IP and rejects private repositories outright. One check per day per tool is far inside that; a shared egress address is not.

A private repository therefore needs a real token, and the usual source is the gh CLI. Pass it as token_func, not token:

def gh_token() -> str:
    result = subprocess.run(['gh', 'auth', 'token'], capture_output=True, text=True)
    return result.stdout.strip() if result.returncode == 0 else ''


Config(tool='mytool', owner='you', token_func=gh_token)

token_func is called only when a request is actually about to be made. Resolving the token eagerly into token instead puts that subprocess in front of every invocation of your CLI — including the overwhelming majority where the notify gate declines to check at all, which is otherwise free.

State

${XDG_STATE_HOME:-~/.local/state}/<tool>/autoupdate.json, written atomically:

{
  "schema": 1,
  "tool": "mytool",
  "checked_at": "2026-07-26T15:07:15Z",
  "checked_at_epoch": 1785078435,
  "current_version": "v1.3.2",
  "latest_version": "v1.4.0",
  "last_error": ""
}

State, not config and not cache: it persists across runs, it is not authored by the user, and deleting it changes behaviour rather than merely costing a recompute. That is XDG_STATE_HOME by the Base Directory specification, and it is where gh puts the same thing.

The timestamp is written before the network call. gh stamps only on success, so a rate-limited or offline user re-hits the API on every invocation until the window resets; an interval exists to bound the request rate, and only this ordering actually does that.

Siblings

The same two-layer design in other languages. update exists in all three; the notify layer, the shared autoupdate.json schema and the NO_AUTO_UPDATE contract are implemented in this library and in its bash sibling, and are still to be added to goselfupdate — until then goselfupdate provides the update half only.

• goselfupdate — replaces a Go binary
• bashselfupdate — moves a git checkout to its newest tag

Version precedence is deliberately identical across all three, so a tool and its siblings never disagree about which release is newer.

Licence

MIT