Senior Software Engineer: AI-Driven Legacy Modernisation

RedRock Resourcing; Reading; On-site; GBP 70,000 - 110,000; Full time

Job summary

RedRock Resourcing in Reading, United Kingdom, seeks a Senior Software Engineer to join Agentic Engineering initiatives. You will leverage AI coding agents to refactor and modernise complex legacy systems, building the engineering harness and governance needed for safe AI-driven development.

The role emphasizes a strong C#/.NET foundation, working with large or legacy codebases, and collaborating across teams to implement automated tests, evals and quality controls.

Qualifications

• Strong software engineering foundation.
• Deep experience in C#/.NET with large/legacy systems.
• Familiarity with AI-assisted software engineering and automated testing.

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 to work effectively.
• Build repository-level instructions, agent skills, prompts and dynamic context.
• Work with technologies such as Claude Code, MCP and other agentic development tools.
• Establish automated testing and AI evaluation frameworks (evals) to make sure speed doesn't come at the expense of quality.
• Build guardrails, sandboxes and CI/CD controls around AI-driven development.

Skills

C#/.NET

Legacy systems

AI-assisted development

Software engineering fundamentals

Tools

Claude Code

Cursor

GitHub Copilot

Codex

Job description

RedRock Resourcing in Reading, United Kingdom, seeks a Senior Software Engineer to join Agentic Engineering initiatives. You will leverage AI coding agents to refactor and modernise complex legacy systems, building the engineering harness and governance needed for safe AI-driven development.

The role emphasizes a strong C#/.NET foundation, working with large or legacy codebases, and collaborating across teams to implement automated tests, evals and quality controls.