AI-Enabled Legacy Modernisation Playbook

Version 1.0.0

This playbook describes how Defra’s Legacy Application Programme (LAP) uses AI to reverse-engineer legacy applications and rebuild them. It covers the end-to-end process — from gathering source material through automated analysis to a signed-off PRD, feature specifications, and an autonomous build loop that implements the replacement application feature by feature.

flowchart LR
    A["Gather Inputs"] --> B["Content Curation"]
    B --> C["Review Curated Outputs"]
    C --> D["Analysis & PRD Generation"]
    D --> E["PRD Review & Sign-off"]
    E --> F["Feature Decomposition"]
    F --> G["Rebuild Setup"]
    G --> H["Autonomous Build"]

Sections

Overview — what this playbook covers, team structure, and stakeholder roles
Process — step-by-step guide through each phase of the reverse engineering process
Tooling — AI coding assistants, plugins, and project directory structure
Output Reference — detailed descriptions of each artefact the process produces
Considerations & Caveats — information governance, PII handling, AI quality, and costs
Glossary — key terms and definitions
Contributing — how to propose changes to this playbook

Start with the Overview for context, then follow the Process guide.

All content is available under the Open Government Licence v3.0, except where otherwise stated

AI-Enabled Legacy Modernisation Playbook

Sections

Support links