Senior Software Engineer – Agentic Engineering x4

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

Senior Software Engineer – Agentic Engineering x4

Using AI and agentic engineering to modernise complex legacy software, and fundamentally change how engineering teams build software.

What will you actually be doing?

• 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

What background are we looking for?

We're looking for someone who has built a seriously strong software engineering foundation.

You’ll ideally have deep experience in C#/.NET, alongside experience working with large, complex or legacy systems.

You might have worked with:

• Claude Code, Cursor, GitHub Copilot, Codex or similar coding agents
• Agentic development or AI-assisted software engineering
• Automated testing, evals and quality frameworks
• Legacy modernisation, major refactoring or framework migrations

We're particularly interested if you've also been working with:

• Claude Code, Cursor, GitHub Copilot, Codex or similar coding agents
• Agentic development or AI-assisted software engineering
• Automated testing, evals and quality frameworks
• Legacy modernisation, major refactoring or framework migrations

Investment areas

You'll be joining during a major transformation across Technology, with significant investment in:

• Public cloud migration
• AI-enabled software engineering