Claude Code Plugin

The Archgate Claude Code plugin gives AI agents working in Claude Code a structured governance workflow. Instead of relying on prompt instructions that drift over time, agents read your ADRs directly through the MCP server and validate their own code against your rules.

What the plugin provides

The plugin adds role-based skills to Claude Code. Each skill encapsulates a specific part of the governance workflow, so agents follow the same process every time — read decisions before coding, validate after, and capture new patterns for the team.

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

Installation

Beta access required

The Claude Code 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 in your project. If you are already logged in, the plugin is installed automatically:

archgate init

To explicitly request plugin installation:

archgate init --install-plugin

If the claude CLI is on your PATH, the plugin is installed automatically via:

1. claude plugin marketplace add (registers the Archgate marketplace)
2. claude plugin install archgate@archgate (installs the plugin)

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

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.

The agent does not write code until it has read the applicable ADRs. This is enforced by the archgate:developer skill.

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 — the agent references them while coding.

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. The architect skill reviews the full context of the changes against all applicable ADRs.

5. Capture learnings

The agent invokes archgate:quality-manager to review the work and identify patterns worth capturing. The quality manager may propose new ADRs or updates to existing ones when recurring conventions emerge.

ADR-driven refusal

When the agent encounters a task that would require violating an ADR, it refuses and explains which ADR would be violated. It then suggests how to achieve the same goal while staying compliant.

For example, if a developer asks the agent to add chalk as a dependency in a project governed by ARCH-006 (dependency policy), the agent will:

1. Refuse, citing ARCH-006 and the approved dependency list
2. Suggest using styleText() from node:util instead
3. Offer to implement the task using the compliant alternative

This behavior is consistent regardless of how the developer phrases the request. ADRs are treated as mandatory constraints, not suggestions.

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.

When to use each skill

Scenario	Skill to use
Starting a new project with Archgate	archgate:onboard
Day-to-day coding tasks	archgate:developer
Reviewing a PR for ADR compliance	archgate:architect
Noticing a recurring pattern worth codifying	archgate:quality-manager
Creating or editing an ADR	archgate:adr-author

The archgate:developer skill orchestrates the others automatically — it invokes archgate:architect and archgate:quality-manager as part of its workflow. Most of the time, you only need to interact with the developer skill directly.