How the Agent Reach check-update Command Determines If a New Version Is Available

The check-update command reads the installed version from agent_reach/__init__.py, queries the PyPI JSON API at https://pypi.org/pypi/agent-reach/json, and uses packaging.version.Version to compare the local version against the latest published release.

The check-update command in Agent Reach provides users with immediate feedback on package updates without performing any installations. This CLI functionality, implemented in the open-source Agent Reach repository, helps developers stay current with the latest features and bug fixes. Understanding how the check-update command determines version availability reveals a lightweight, API-driven approach that relies solely on standard library modules and robust semantic versioning.

How the check-update Command Works

The version detection process follows a deterministic four-step pipeline implemented in the CLI module.

Step 1: Reading the Installed Version

The command first establishes the baseline version by importing __version__ from agent_reach/__init__.py. This value represents the currently installed package version in the user's environment.

# In agent_reach/cli.py

from agent_reach import __version__

current_version = __version__

Step 2: Querying the PyPI API

The implementation sends an HTTP GET request to the PyPI JSON API endpoint using urllib.request from the Python standard library. The endpoint https://pypi.org/pypi/agent-reach/json returns a comprehensive metadata payload for all published releases.

import json
import urllib.request

def get_latest_version():
    url = "https://pypi.org/pypi/agent-reach/json"
    with urllib.request.urlopen(url) as response:
        data = json.loads(response.read().decode("utf-8"))
        return data["info"]["version"]

Step 3: Parsing and Comparing Versions

Rather than performing naive string comparison, the command utilizes the packaging.version.Version class (falling back to distutils.version.LooseVersion in older implementations) to parse both version strings. This ensures accurate handling of pre-release tags, post-release segments, and developmental versions.

from packaging.version import Version

def is_update_available(current, latest):
    return Version(latest) > Version(current)

Step 4: Reporting Results to the User

The check_update function in agent_reach/cli.py formats the comparison result into user-facing messages. If the PyPI version exceeds the installed version, the CLI prints an upgrade prompt; otherwise, it confirms the user is up-to-date.

Source Code Implementation

The version detection architecture depends on three key files in the repository:

• agent_reach/cli.py — Contains the check_update function that orchestrates the version check and handles the check-update sub-command wiring in the argument parser.
• agent_reach/__init__.py — Exposes the __version__ attribute used as the local version baseline.
• pyproject.toml — Declares the package name agent-reach, which must match the PyPI endpoint queried by the CLI.
• tests/test_cli.py — Houses unit tests that mock the PyPI HTTP response to verify the comparison logic without network dependencies.

Practical Usage Examples

Execute the version check from the command line:

python -m agent_reach.cli check-update

Typical output when a newer version exists:

📦  Current version: 1.4.0
🚀  New version available: 1.5.0
Run: pip install -U agent-reach

Typical output when already up-to-date:

✅  You are already on the latest version (1.5.0)

Summary

• The check_update function in agent_reach/cli.py implements the complete version check logic
• Local version is imported from __version__ in agent_reach/__init__.py
• The PyPI JSON API endpoint https://pypi.org/pypi/agent-reach/json provides the latest release data
• packaging.version.Version handles robust semantic version comparison including pre-releases
• The command performs read-only operations; it never modifies the installed package

Frequently Asked Questions

Does the check-update command automatically upgrade the package?

No, the command strictly checks availability and reports status. According to the Agent-Reach source code, the CLI never modifies installed packages. It merely prints a message suggesting pip install -U agent-reach when a newer version exists on PyPI.

How does the command handle beta or release candidate versions?

The implementation uses packaging.version.Version to parse version strings, which properly recognizes development releases, alpha, beta, and release candidate tags (e.g., 1.2.0rc1). This ensures that 1.2.0 is correctly identified as newer than 1.2.0rc1, preventing false positive update prompts for pre-release installations.

What happens if the PyPI API is unreachable?

Since the command relies on urllib.request to fetch https://pypi.org/pypi/agent-reach/json, any network failure or HTTP error would raise an exception. The current implementation in agent_reach/cli.py does not catch these exceptions, meaning the CLI will display the Python traceback rather than a graceful error message.

Where is the check-update command defined in the codebase?

The sub-command is defined in agent_reach/cli.py and wired to the check_update function in the argument parser. This function imports the current version from agent_reach/__init__.py and compares it against the info.version field returned by the PyPI JSON API.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}