Salem Cobalt#

Principal Frontend Engineer, Design Systems Expert#

Boston-based frontend engineer with 14+ years specializing in design systems used at scale — component API architecture, design token pipelines, and theming systems — with deep expertise in React, TypeScript, headless UI primitives, web components, accessibility, and AI-assisted (agentic) development workflows.

Work Experience#

Independent Software Consultant, Midnight Mansion (April 2026 – May 2026)

• Frontend architecture consulting, plus agent-driven refactoring and migration workflows (Claude Code) across the client's full-stack codebase
• Designed and shipped a highly interactive physical mini-game for Edge of Elsewhere, their upcoming immersive venue — MCU programming, a centralized SSE-based control system, WebSockets, and a collection of fully playable levels

VP of Engineering – Frontend Architecture, Pypestream (January 2023 – March 2026)

• Architected and helped build Pypestream's cross-platform (Lit + React-wrapped) design system — built on headless UI primitives (Base UI, Floating UI, TanStack Table) and adopted company-wide across 5+ next-gen products
• Baked WCAG 2.1 AA accessibility — keyboard navigation, focus management, ARIA patterns — directly into the design system, so every downstream product inherited it
• Owned the company-wide frontend re-platforming: unified 7+ disjointed product repos and shared UI libraries into a single TypeScript monorepo, centralizing how everything is built, tested, documented, deployed, and maintained
• Drove a 4x increase in frontend release frequency and 50%+ faster CI/CD — even as the number of centrally managed apps grew — saving thousands in infrastructure costs
• Led pragmatic AI coding-agent adoption across frontend teams (Cursor, Claude Code) and AI-assisted code review (CodeRabbit) — shipping production code with agents while raising, not lowering, the code-quality bar
• Led a distributed team of 9 full-stack / senior frontend engineers; technical lead on the greenfield rebuild of Pypestream's core management platform, which directly supported $1M+ in Fortune 500 contract renewals and expansions

Principal Frontend Engineer, Knapsack (May 2020 – January 2023)

• Rebuilt the entire frontend UI for Knapsack's flagship "design system as a platform" product — the tool enterprise design system teams use to build, document, theme, and ship their own design systems
• Co-developed the codemod systems powering the core product, including an inheritance-based UI theming system that lets customer brands customize the product's appearance without compromising accessibility or slowing product iteration
• Architected the end-to-end design token pipeline: Style Dictionary definitions consumed as CSS custom properties, Sass mixins, and auto-generated TypeScript typings
• Built, tested, and shipped major UI/UX-heavy iterations of the product's modular block-based editor — React, XState, GraphQL, and TypeScript throughout

Lead Frontend Architect, Pegasystems (July 2016 – May 2020)

• Frontend development lead and creator of the Bolt Design System, powering the UI across Pega's 5+ corporate sites and 7+ microsites
• Drove Pega's web frontend consolidation onto Bolt — the fragmentation → migration → adoption arc — through design system summits, cross-team component API workshops, and long-term maintainability practices later featured in my 2019 conference talks
• Planned, built, documented, tested, released, and maintained the system's frontend deliverables: highly accessible components, patterns, design tokens, docs & demos, CI/CD, and dev tooling
• Developed centrally maintained, shared Lit-based web components with deep CMS integration (Drupal 8 + custom Twig extensions), and authored the Sass-based CSS architecture and theming used by engineers, designers, and content authors

Frontend Architect, Genuine Interactive (March 2012 – March 2016)

• Built front-end websites & apps for clients including Angry Orchard, Samuel Adams, Panera Bread, and Akamai
• Consulted on, architected, and built best-in-class responsive, mobile, and desktop sites; early design system advocate