We are looking for a Senior Rails Engineer (Applied AI) to help build the next generation of AI capabilities into our platform and engineering workflows.

This is a hybrid position: part senior Rails developer, part applied AI engineer, and part internal AI advisor. You will ship production features while helping our team adopt AI thoughtfully—with the evaluation harnesses, guardrails, and operational controls required for systems that affect physical inventory.

What You’ll Do
Rails Platform Engineering: Build and ship features across a mature Ruby on Rails backend (Heroku) and two React frontends (Vercel). Support real-world logistics, state machines, and warehouse workflows.
AI Platform & Guardrails: Design shared AI infrastructure, evaluation harnesses, confidence thresholds, and fail-safe mechanisms to ensure reliable production use.
Device Data & Grading: Build workflows using serial numbers and device identifiers to normalize data, enrich specs, and automate device grading (A–D framework).
AI-Assisted Workflows & Agents: Implement semantic support triage,



automated Linear issue creation, and controlled agents capable of executing safe domain actions (lookups, record updates, draft communications).
Enablement & Workflows: Help the engineering team adopt AI in QA, code reviews, and DevOps, raising overall team capabilities through practical implementation.

What We’re Looking For
5+ years of production Ruby on Rails experience, with deep architectural knowledge of large monolithic applications.
Hands-on experience shipping LLMs/ML to production, using patterns like retrieval (RAG), structured outputs, tool use, or agentic workflows.
Experience building AI Evaluation Harnesses, measuring model performance against real data before going to production.
Pragmatic AI Judgment: Ability to design guardrails, identify failure modes, and know when a deterministic or non-AI solution is better.
Full-Stack Comfort: Strong backend focus with enough React knowledge to troubl

📌 Senior Rails (Ciudad de México)
🏢 onephase
📍 Ciudad de México