Senior Developer [Magalog]

Description

***About Us*** Magalu is one of Brazil's largest retail companies, recognized for its innovation and digital presence. The Magalu technology team consists of innovative professionals passionate about transforming digital retail. Focused on agile and scalable solutions, they develop projects that impact millions of customers. In a collaborative environment, they constantly pursue excellence in technology and innovation. **Job Description** **Who We Are and Our Current Moment** At Luizalabs, our mission is to deliver intelligent, integrated solutions that revolutionize ultra-fast delivery and last-mile logistics. We are building a new generation of software engineering grounded in **Specification-Driven Development (SDD)** and **Agentic Engineering**. Under this model, the role of the Senior Engineer evolves from manually writing code to designing high-performance systems. You will serve as the technical lead responsible for translating complex business and logistics challenges into executable specifications, defining robust guardrails, and orchestrating AI agents (specialized in architecture, development, and testing) to evolve our large-scale **Ruby on Rails** platform. We seek professionals who understand that code is no longer the primary asset but rather a byproduct of an impeccable specification—blending mature traditional software engineering with the pinnacle of AI-assisted development. **Responsibilities and Duties** * **AI-Native Development and Orchestration:** Execute and orchestrate workflows daily using multiple AI agents to accelerate and ensure delivery quality. * **Technical Specification and SDD:** Translate logistics and high-concurrency challenges into clear, complete, and executable specifications via SDDs (*System Design Documents*). * **Guardrail & Harness Construction:** Create and evolve automated validation mechanisms (*harnesses*) and technical safeguards to ensure AI-generated code meets security, business, and performance criteria. * **Reverse Engineering and Critical Review:** Audit, test, and refactor AI-generated software within the Ruby on Rails ecosystem with a critical eye, ensuring Clean Code standards, resilience, and scalability. * **Large-Scale Platform Evolution:** Write and refine efficient code for high-availability scenarios, resolving complex production issues, performance bottlenecks, and infrastructure optimization challenges. * **Mentorship and Culture Dissemination:** Guide mid-level and junior developers on best practices in software engineering, TDD, and the advanced/efficient use of generative AI tools. **Essential Requirements: Applied AI in Engineering & GenAI Symbiosis** * Consistent hands-on experience using generative AI tools for software development (**GitHub Copilot, Claude Code, Cursor, OpenHands, Devin**, or similar). * Strong proficiency in *Prompt Engineering*, *Context Engineering*, and understanding of *Agentic Workflows*, enabling delegation of raw code generation while focusing on governance and logical refinement. * Strong abstraction ability, capacity to decompose complex problems, and systemic reasoning. **Software Engineering & Backend Ecosystem** * Proven, solid industry experience developing with **Ruby on Rails** in high-scale production environments. * Deep expertise in backend architecture patterns (modular monoliths, microservices, RESTful APIs, object-oriented design/SOLID). * Advanced experience optimizing Rails performance (avoiding N+1 queries, strategic caching, large-scale background jobs with **Sidekiq** or Resque). * Mastery of relational databases (**PostgreSQL/MySQL**), including data modeling and optimization of complex queries. * Practical familiarity with event-driven architectures and messaging systems (**Kafka, RabbitMQ, or AWS SQS**). **Quality, Reliability, and Observability** * Deep-rooted culture of automated testing: mastery of **TDD**, testing frameworks (**RSpec**, mocks, stubs, factory_bot), and integration/contract testing. * Hands-on experience with CI/CD pipelines, containerization (**Docker**), and cloud platforms (**AWS, GCP, or Azure**). * Experience with monitoring and observability tools (**New Relic, Datadog, Prometheus/Grafana**). **Nice-to-Have** * Prior experience or strong familiarity with *Specification-Driven Development* (SDD). * Experience creating or customizing specialized AI agents for engineering tasks. * Practical knowledge of DevOps (**Terraform**, **Kubernetes**). * Experience in logistics, e-commerce, or marketplace platforms. **How We Measure Success for This Senior Role** Success in this role is measured less by the raw volume of manually written lines of code and more by your ability to: * Structure highly precise technical specifications and guardrails that enable AIs to produce correct software on the first attempt. * Ensure the security, maintainability, and performance of the Ruby on Rails ecosystem, mitigating risks associated with automation-generated code. * Increase the squad’s delivery throughput (*throughput*) through intelligent use of agentic tools. * Multiply technical knowledge across the team, helping lead the cultural shift toward AI-Native development. **Work Model** We operate under a fully remote model, offering flexibility while maintaining virtual interaction with the team to ensure effective collaboration and continuous growth. ‘’If you seek an environment of growth and challenge, come be happy!’’ Our values unite us, and our differences empower us as a group. More than equality, we strive for equity: Here, there is space to be authentic—regardless of gender, ethnicity, race, sexual orientation, religion, or disability.