Copilot CLI Plugin

The Archgate Copilot CLI plugin gives AI agents working in GitHub Copilot CLI a structured governance workflow. Agents read your ADRs before writing code, validate after, and capture new patterns for the team — the same workflow available in the Claude Code plugin.

How it works

Copilot CLI supports plugin installation from git repositories using copilot plugin install. The Archgate plugin is served from a git repository at plugins.archgate.dev/archgate.git, which Copilot CLI recognizes natively — the same .claude-plugin/plugin.json manifest format works for both Claude Code and Copilot CLI.

Installation

Beta access required

The Copilot CLI plugin is currently in beta. Sign up at plugins.archgate.dev to get access before following the steps below.

1. Log in with GitHub

Authenticate with your GitHub account to obtain a plugin token:

archgate login

This starts a GitHub Device Flow. The CLI displays a one-time code and URL — open the URL in your browser, enter the code, and authorize. Once complete, credentials are stored in ~/.archgate/credentials.

2. Initialize your project with the plugin

Run archgate init with the --editor copilot flag:

archgate init --editor copilot

If you are already logged in and the copilot CLI is on your PATH, the plugin is installed automatically via:

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

If the copilot CLI is not found, the command prints the manual command for you to run.

To explicitly request plugin installation:

archgate init --editor copilot --install-plugin

To install or reinstall the plugin on an already-initialized project:

archgate plugin install --editor copilot

Generated files

The command creates the following configuration:

File	Purpose
.github/copilot/mcp.json	MCP server connection so Copilot CLI can access ADRs

If .github/copilot/mcp.json already exists, Archgate merges its configuration additively — existing MCP server entries are preserved.

The MCP configuration:

{
  "mcpServers": {
    "archgate": {
      "command": "archgate",
      "args": ["mcp"]
    }
  }
}

Manual installation

If the copilot CLI is not found during archgate init, you can install the plugin manually:

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

You can find your authenticated URL by running archgate login and checking ~/.archgate/credentials.

What the plugin provides

The plugin adds role-based skills to Copilot CLI. Each skill encapsulates a specific part of the governance workflow, so agents follow the same process every time.

Skills included

Skill	Purpose
archgate:developer	General development agent that reads ADRs before coding and validates after
archgate:architect	Validates code changes against all project ADRs for structural compliance
archgate:quality-manager	Reviews rule coverage and proposes new ADRs when patterns emerge
archgate:adr-author	Creates and edits ADRs following project conventions
archgate:onboard	One-time setup: explores the codebase, interviews the developer, creates initial ADRs

Initial setup with onboard

After installation, run the archgate:onboard skill in your project once. This skill:

1. Explores your codebase structure (directories, key files, package configuration)
2. Interviews you about your team’s conventions, constraints, and architectural decisions
3. Creates an initial set of ADRs based on your responses
4. Sets up the .archgate/ directory with your first rules

The onboard skill is designed to run once per project. After onboarding, the other skills handle day-to-day development.

How it works in practice

The plugin follows a structured workflow for every coding task:

1. Read applicable ADRs

When the developer gives a coding task, the agent reads all ADRs that apply to the files being changed. The MCP server provides a condensed briefing with the Decision and Do’s and Don’ts sections from each relevant ADR.

2. Write code following ADR constraints

The agent writes code that complies with the constraints from the ADRs. The Do’s and Don’ts sections serve as concrete guardrails.

3. Validate changes

After writing code, the agent runs archgate check to execute automated rules against the changes. Any violations are fixed before proceeding.

4. Architect review

The agent invokes archgate:architect to validate structural ADR compliance beyond what automated rules catch.

5. Capture learnings

The agent invokes archgate:quality-manager to review the work and identify patterns worth capturing as new ADRs.

MCP server integration

The plugin communicates with your project’s ADRs through the Archgate MCP server. The server provides:

• ADR content — full text of any ADR, accessible by ID
• Review context — condensed briefings of all ADRs applicable to a set of changed files
• Rule checking — execution of automated rules with violation reporting
• ADR listing — inventory of all ADRs in the project with metadata

The MCP server runs locally and reads directly from your .archgate/adrs/ directory. No data leaves your machine.

Tips

• Commit .github/copilot/mcp.json to share the MCP configuration with your team.
• Run onboard once per project to generate your initial ADRs from your actual codebase.
• Keep ADR rule files up to date — the agent enforces what the rules check for.