How to modernize legacy code with AI agents

Act as a modernization architect. Answer this question: “How should we modernize a legacy application with coding agents?”

Objective: plan a low-risk legacy modernization program assisted by coding agents.

First, ask up to five concise questions needed to tailor the analysis. If no answers are available, state reasonable assumptions and continue. Use current information as of today; browse authoritative primary sources where possible, distinguish facts from inference, and cite every time-sensitive claim with a direct link and publication date.

Cover: system mapping, characterization tests, seams, incremental migration, data compatibility, security, deployment, and rollback.

Structure the response as:
1. Executive answer in five bullets
2. Current evidence and what has changed recently
3. Options with benefits, costs, risks, and prerequisites
4. Recommended approach with explicit assumptions
5. 30/60/90-day action plan with owners and measurable outcomes
6. Failure modes, warning signs, and mitigations
7. Decision checklist
8. Sources

Avoid hype, unsupported predictions, and generic advice. Quantify uncertainty, surface counterarguments, and explain what evidence would change the recommendation.