Founding Engineer, Agent Systems — London (Equity)

Cross Border Talents; Stevenage; On-site; GBP 130,000 - 170,000; Full time

Benefits offered by this job

Equity

London office with on-site facilities

Job summary

Cross Border Talents is seeking a Founding Engineer to own the agent platform and orchestration for AI-native risk infrastructure. You will design multi-step workflows, tool-calling systems, and AI reliability layers in a seed-stage startup environment.

The role emphasizes ownership, production-grade systems, and hands-on leadership across backend, AI evaluation, and reliability work, with strong autonomy and London-on-site expectation.

Qualifications

• Proven backend engineering experience with production systems.
• 1–2+ years shipping production LLM-powered features.
• Strong TypeScript or Node.js experience.
• Experience building customer-facing production AI systems.
• Hands-on experience with agent frameworks.
• Experience with tool calling and multi-step orchestration.
• Production experience building AI evaluations.
• Experience with dataset curation and regression testing.
• Understanding of LLM-as-judge approaches and failure modes.
• Strong systems-thinking ability.
• Experience with asynchronous systems and queues.
• Understanding of idempotency and reliability patterns.
• Strong product-engineering mindset.
• Ability to own features from customer problem through production deployment.
• High level of autonomy and accountability.
• Based in London or able to commute regularly for an on-site-first role.

Responsibilities

• Build and evolve the core agent orchestration platform.
• Design multi-step agent workflows and tool-calling systems.
• Build context-management and agent-scaffolding infrastructure.
• Develop secure sandboxing for agent execution.
• Implement prompt-injection defenses and other agent-security controls.
• Build production evaluation frameworks for fuzzy, high-stakes outputs.
• Curate evaluation datasets and regression suites.
• Design and improve LLM-as-judge systems.
• Evaluate model performance across upgrades and provider changes.
• Build retries, fallbacks, and circuit-breaker mechanisms.
• Own prompt versioning and AI-quality infrastructure.
• Design systems around async processing, queues, and idempotency.
• Define the internal standard for production AI quality.
• Own AI reliability and make ship/no-ship decisions when necessary.

Skills

Backend engineering

Production LLM features

TypeScript/Node.js

Customer-facing AI systems

Agent frameworks

Tool calling/orchestration

AI evaluations

Dataset curation

LLM-as-judge concepts

Systems thinking

Asynchronous systems/queues

Idempotency/reliability

Product-engineering mindset

Ownership & accountability

On-site in London

Tools

Agent frameworks

Tool calling

Multi-step orchestration

Express

Azure

Postgres

Terraform

GitHub Actions

Docker

Job description

Cross Border Talents is seeking a Founding Engineer to own the agent platform and orchestration for AI-native risk infrastructure. You will design multi-step workflows, tool-calling systems, and AI reliability layers in a seed-stage startup environment.

The role emphasizes ownership, production-grade systems, and hands-on leadership across backend, AI evaluation, and reliability work, with strong autonomy and London-on-site expectation.