AI-Powered Principal Engineer: Legacy Modernization

RedRock Resourcing; Reading; On-site; GBP 70,000 - 120,000; Full time

Job summary

RedRock Resourcing seeks three experienced Software Engineers to join a brand-new agentic engineering team. You will modernise legacy software using AI and agentic techniques, going beyond traditional ticket-based work.

You'll operate at the intersection of software engineering, architecture, AI, and developer experience to design systems, standards and guardrails that enable engineers to deliver better software safely.

Qualifications

• Serious for a strong software engineering foundation and experience with complex legacy systems.
• Deep experience in C#/.NET or Java; depth in one stack preferred over breadth across many stacks.
• Willingness to work on AI-assisted software engineering and agentic development; knowledge of automated testing is a plus.

Responsibilities

• Use AI coding agents to investigate, refactor and modernise legacy codebases.
• Design the engineering harness that gives AI agents the right context, rules and constraints.
• Build repository-level instructions, agent skills, prompts and dynamic context.
• Work with agentic development tools like Claude Code, MCP and related tooling.
• Establish automated testing and AI evaluation frameworks to balance speed and quality.
• Build guardrails, sandboxes and CI/CD controls around AI-driven development.

Skills

Strong software engineering foundation

C#/.NET or Java

Experience with large/legacy systems

Depth in one stack

Tools

Claude Code

Cursor

GitHub Copilot

Codex

Job description

RedRock Resourcing seeks three experienced Software Engineers to join a brand-new agentic engineering team. You will modernise legacy software using AI and agentic techniques, going beyond traditional ticket-based work.

You'll operate at the intersection of software engineering, architecture, AI, and developer experience to design systems, standards and guardrails that enable engineers to deliver better software safely.