GitHub Copilot CLI

The Archgate plugin for GitHub Copilot CLI gives Copilot’s agent a structured governance workflow: it reads the ADRs that apply to your change before writing code, validates the result with archgate check, and captures new patterns for the team. It is the same read-validate-capture loop available in every Archgate editor integration.

Authoritative CLI reference

This page covers Copilot CLI setup. For the exact syntax of archgate init, archgate login, archgate plugin install, and archgate plugin url, see the CLI reference at cli.archgate.dev.

How it works

Copilot CLI installs plugins from git repositories using copilot plugin install. Archgate serves its plugin from the distribution service at plugins.archgate.dev. The plugin uses the same .claude-plugin/plugin.json manifest format that Claude Code uses, which Copilot CLI recognizes natively — so a single packaged plugin works for both editors. The plugin’s settings.json sets archgate:developer as the default agent.

Requirements

• Archgate CLI — install via the CLI install guide.
• GitHub Copilot CLI on your PATH for automatic installation. If it is not found, archgate init prints the manual install command for you to run.
• A GitHub login — the plugin is in closed beta and downloads require an authenticated token from archgate login.

Installation

1. Log in to obtain a plugin token:

   archgate login

   This runs a GitHub Device Flow and stores credentials securely in your OS credential manager.

2. Initialize your project with the Copilot editor target:

   archgate init --editor copilot

   When you are logged in and the copilot CLI is on your PATH, the plugin is installed automatically. This also creates the .github/copilot/ directory for plugin configuration.

3. Start coding with the archgate:developer agent, which the plugin sets as the default.

Manual installation

If the copilot CLI is not detected during archgate init, install the plugin yourself. Retrieve your authenticated URL with archgate plugin url copilot, then:

copilot plugin install https://<github-user>:<token>@plugins.archgate.dev/archgate.git

To reinstall on an already-initialized project, use archgate plugin install --editor copilot. Both flows are documented in the CLI guide.

What the plugin provides

The plugin adds an agent and a set of governance skills. The agent orchestrates the workflow and invokes the skills as needed.

archgate:developer

The default development agent. It reads applicable ADRs before coding and validates after — the orchestrator for the whole workflow.

Governance skills

Skills for authoring ADRs, reviewing changes against all applicable ADRs, one-time project onboarding, and capturing lessons learned.

These map to the roles documented in Skills and Agents.

The workflow in practice

For every coding task, the archgate:developer agent follows a structured loop:

1. Read applicable ADRs — the agent runs archgate review-context to get a condensed briefing (Decision + Do’s and Don’ts) for every ADR that applies to the files being changed. It does not write code until it has read them.
2. Write code following the constraints — the Do’s and Don’ts serve as concrete guardrails.
3. Validate — the agent runs archgate check to execute automated rules and fixes any violations before proceeding.
4. Review — a review skill validates structural compliance beyond what automated rules catch.
5. Capture learnings — a lessons-learned skill reviews the work and proposes new ADRs when patterns emerge.

If a task would require violating an ADR, the agent refuses, names the ADR, and suggests a compliant alternative. ADRs are treated as mandatory constraints, not suggestions.

First-time setup

After installing, run the onboarding skill once in your project. It explores your codebase, interviews you about your conventions and constraints, and creates an initial set of ADRs in .archgate/. After that, the other skills handle day-to-day work. See Onboarding for details.

Next steps

All editor plugins Compare the six supported editors and what each one provides.

Skills The governance skills the agent invokes during the workflow.

CLI: Copilot CLI plugin Authoritative setup, flags, and manual installation.