defra-legacy-reveng

Claude Legacy Reverse Engineering Plugin

A Claude Code plugin for Defra's Legacy Application Programme (LAP) to aid in the reverse engineering of legacy applications.

Purpose

This plugin extends Claude Code with specialised tooling and prompts to assist engineers in understanding, documenting, and modernising legacy systems within Defra's estate.

Data Classification

This plugin must only be used on source material classified as OFFICIAL. Do not use it with material at any higher classification. If you are unsure about the classification of your source material, seek guidance from your organisation before proceeding.

By default, Claude Code sends data to models hosted by Anthropic. Claude Code can also be configured to use Amazon Bedrock or Google Cloud Vertex AI — consult your organisation's guidance on approved platforms.

Permissions

Claude Code prompts for approval before executing tools such as shell commands and file writes. The --dangerously-skip-permissions flag bypasses these prompts, allowing fully unattended operation (e.g. in the batch curation script below).

If you use this flag, run Claude Code inside a containerised sandbox (Docker, Podman, or a devcontainer) so that any unintended actions are contained. If a sandbox is not available, omit the flag and approve each action manually instead.

Prerequisites

• Claude Code installed and authenticated
• Bash 4+
• jq (for parsing Claude output in the reveng CLI)
• For reveng sandbox only: Docker and the devcontainer CLI (npm install -g @devcontainers/cli)

Installation

The repository ships with a reveng CLI that wraps the plugin in a set of command-driven workflows. See specs/reveng-cli.md for the full specification.

git clone https://github.com/DEFRA/claude-legacy-reveng-plugin
cd claude-legacy-reveng-plugin
./install.sh

install.sh copies files to:

Source	Destination
reveng	~/.local/bin/reveng
skills/, agents/, hooks/, .claude-plugin/, CLAUDE.md	~/.config/reveng/plugin/
container/Dockerfile, container/devcontainer.json	~/.config/reveng/container/

Override the destinations with the REVENG_BIN_DIR and REVENG_CONFIG_DIR environment variables. install.sh refuses to overwrite an existing installation by default — pass --update to upgrade in place:

./install.sh --update

After installation, verify with:

reveng version    # prints: reveng 0.1.0

If ~/.local/bin is not already on your PATH, add it to your shell profile:

export PATH="$HOME/.local/bin:$PATH"

Uninstall

There is no dedicated uninstall command. Remove the installed files manually:

rm ~/.local/bin/reveng
rm -rf ~/.config/reveng

CLI Commands

All reveng commands run headlessly — they invoke Claude Code in --dangerously-skip-permissions mode with the plugin loaded from ~/.config/reveng/plugin/. When run outside a devcontainer, a safety warning is printed to stderr. Use reveng sandbox (below) to run commands inside an isolated container.

Command	Purpose
reveng init	Scaffold screenshots/, transcripts/, src/, output/ and add the intermediate-output entries to .gitignore
reveng curate	Run the digital-content-curator agent to prepare screenshots and transcripts for analysis (default model: sonnet)
reveng synthesise	Run the product-manager agent to produce output/PRD.md from curated content (default model: opus)
reveng decompose	Run the prd-to-features agent to decompose output/PRD.md into output/features/FT-*.md (default model: opus)
reveng sandbox	Start or attach to a devcontainer for the current project (supports --rebuild and clean subcommand)
reveng version	Print the CLI version and exit
reveng help	Print usage information

Global flags

These flags are accepted by the curate, synthesise, and decompose commands:

Flag	Default	Description
-m, --model MODEL	varies by command	Claude model to use
-v, --verbose	off	Show Claude commands and raw output
--dry-run	off	Print the claude command that would run without executing it
-h, --help		Show command-specific help

Prerequisites between stages

Each stage validates its inputs before invoking Claude and points the user at the preceding command if something is missing: