Resume
Lucas Rangel - Senior Software Engineer
Lucas Rangel
São Paulo, São Paulo, Brazil
Work Experience
Senior Software Engineer
Yellowpad 05/2025 - Present Remote
The main area of focus is building an agentic in-house document editor with a focus on human-in-the-loop for contract reviewing and drafting.
This project is guided by the following principles: The document should be modifiable by both an agent and a human, through predefined workflows in the UI and direct text manipulation, all while maintaining a single source of truth.
What I've worked on so far:
- Engineered state-driven agent architecture using LangGraph with advanced state channels, reducers for message concatenation, and deterministic execution flows.
- Designed tool execution framework with automatic state synchronization between LangChain tools and document editor so users can do manual edits alongside LLM agents.
- Built Next.js 15 App Router applications with React 19, implementing real-time document collaboration UI with shadcn/ui components.
- Developed type-safe database layer using Drizzle ORM with PostgreSQL/AlloyDB, implementing multi-tenant data isolation patterns and SOC 2 compliance.
- Architected GCP infrastructure with Terraform, including Cloud Run auto-scaling, Pub/Sub message queuing.
- Built bidirectional data transformation layer between Slate editor JSON format and Word Docx, preserving formatting and metadata.
- Developed WebSocket protocol for real-time document collaboration and supporting streaming of LLM responses.
- Developed custom Slate plugins for paragraph-level operations, maintaining synchronization between Plate editor state and Docx document structure.
Founding Engineer
Plaza 07/2023 - 05/2025 São Paulo, São Paulo, Brazil
- Developed and maintained robust, scalable applications using Ruby on Rails, Hotwire, Stimulus Reflex, Phlex and Sidekiq.
- Played a key role in the successful launch of a new product, driving user adoption.
- Led the full lifecycle development of a successful LLM-based product, from initial design and implementation through testing and ongoing monitoring.
- Contributed significantly to product development and roadmap, influencing key decisions and features.
- Continuously gathered and analyzed customer feedback to identify and validate product-market fit.
- Managed infrastructure across Azure and AWS using Terraform, Docker, and Kubernetes.
- Implemented logging and audit trails.
- Implemented sorbet type checking to improve codebase reliability and maintainability.
- Set up CI/CD pipeline for seamless development and deployment processes.
Senior Software Engineer
Remoov 09/2020 - 07/2023 San Francisco Bay Area - Remote
- Implemented new features end to end, utilizing Node.js, React, and PostgreSQL for full-stack web applications.
- Developed internal tools using Rust to enhance efficiency and productivity.
- Built code mods to aid in large refactoring projects.
- Troubleshot and resolved technical issues, ensuring smooth operation of systems.
- Participated in code reviews, providing valuable feedback for continuous improvement.
- Built CI/CD pipelines.
- Solved Node.js performance and scaling issues.
Data Engineer and Data Scientist
Nextel Brasil 06/2018 - 09/2020 São Paulo, São Paulo, Brazil
- Developed a credit score model using machine learning algorithms to assess customer debt repayment likelihood.
- Effectively collaborated with cross-functional stakeholders (e.g., business analysts, risk managers, product managers) to interpret model outputs, translate findings into actionable insights, and devise data-driven strategic plans to optimize portfolio performance and minimize credit risk.
- Designed and implemented robust and scalable data pipelines on a Hadoop cluster leveraging Apache Airflow for orchestration, Hive for data warehousing, and Python, Scala, and Docker for efficient data processing and containerization.
- Maintained and optimized custom data ingestion pipelines to ensure efficient and timely data processing, maximizing operational efficiency and minimizing data latency.
Education
Federal University of ABC - UFABC
2014 - 2019
- B.S Computer Science
- B.S Science and Technology
Additional coursework:
- Parallel computing, Machine learning and Statistical inference
- Computational neuroscience and Bioinformatics
- Functional and logic programming
"UFABC is the only federal university in Brazil with 100% of its professors holding PhDs and, for the second consecutive year in 2011, emerged as the only university in Brazil with impact factor in scientific publications above the world average according to SCImago Institutions Rankings." — from the Henry Cary literal translation of 1897