Senior Backend Engineer (Ruby), Plan: Spec-Driven Development

Overview

Senior Backend Engineer on GitLab’s Plan: Spec-Driven Development team, building an intent-to-code loop that turns stated intent into work items, plans, and verified mergeable code.

What you'll do

• Lead backend features from early product discussions through design, implementation, rollout, and post-launch learning.
• Build flows, APIs, and data models behind agent-generated work items, implementation plans, and durable specifications.
• Develop evaluation and benchmarking systems to measure workflow quality, token cost, and success rate.
• Use Ruby on Rails and Python with PostgreSQL, GraphQL, and REST/RS... to implement production systems.
• Collaborate with product, design, engineers, design partners, and users to shape scope and trade-offs.
• Mentor engineers and influence technical decisions across agent workflows and evaluation methods.

What you'll need

• Strong Ruby on Rails experience in a large production codebase.
• Production experience with Python.
• Experience driving substantial multi-engine projects over multiple months with user or business outcomes.
• Product mindset with end-to-end feature ownership and post-launch learning.
• Backend-focused full-stack background, including ability to read modern frontend code and design APIs.
• Strong API design and structured query language fundamentals.
• Ability to work independently and collaborate across functions and regions.

Details

• Job location/eligibility: Remote, Poland.
• Team is described as all-remote, async-first with weekly sync calls, retrospectives, demos, and short iterations.