Software Development Engineer 3

The Sizer / Flow Designer is the heart of the Foundry customer experience: the tool that turns a customer's intent into their SKUs, throughput targets and site constraints into a validated bill of materials and a warehouse flow design. It is an agentic, AI-assisted experience that must feel as fluid as a modern spreadsheet while carrying the complexity of a constraint-solving engine underneath. As the senior frontend engineer on this squad, you own the interaction model, the data-grid and formula layer, the agentic-flow UX (step-by-step AI-guided configuration), the BOM visualisation and the traceability UI that shows users why the system recommended what it did. You will collaborate closely with the Applied AI squad to expose recommendation outputs through intuitive, trustworthy interfaces.

Responsibilities:

• Own the Sizer / Flow Designer interaction model: Design and build the core UX: grid-based input, formula references, dependent fields, validation feedback, and the step-by-step agentic flow.
• Build the agentic flow UX: Implement the guided configuration experience step cards, AI-surfaced suggestions, inline explanations, progress tracking and the ability to override any AI recommendation with a clear audit trail.
• Build the BOM generator UI: Design the bill-of-materials output: grouped line items, configurable views, export (PDF / CSV), comparison to previous versions and change highlights.
• Build the logic-traceability panel: Show users which inputs drove which outputs; implement expandable explanation trees, formula references and sensitivity indicators.
• Own versioning and locking: Implement solution versioning (save, compare, restore), collaborative locking and change-request workflows for multi-user scenarios.
• Partner with Applied AI: Work with the AI squad to design the API contract that surfaces recommendations into the UI; handle streamed responses (SSE / WebSocket) and partial-result rendering.
• Define and enforce frontend standards: Set code-quality patterns, component-library conventions and testing standards for the squad's frontend layer.
• Mentor and review: Code-review other engineers' frontend work; raise the skill ceiling of the squad through pairing and design critique.

Requirements:

• 7-10 years of professional frontend engineering experience.
• Deep React expertise: component architecture, performance optimisation, hooks, render lifecycle.
• TypeScript at scale: strong typing, generics, discriminated unions, utility types.
• Experience building data-grid, spreadsheet-like or form-heavy enterprise UIs.
• Familiarity with UX patterns for complex multi-step workflows or wizards.
• Experience designing or consuming RESTful and/or GraphQL APIs.
• Strong testing discipline: unit, integration and E2E tests.
• Experience owning a feature from discovery through production, including observability.

Good to Have:

• Experience building AI-assisted or LLM-integrated UIs (streaming responses, partial-result rendering, explainability surfaces).
• Exposure to CPQ, ERP, estimation or pricing tools.
• Familiarity with React Query / SWR or similar server-state libraries.
• Contributed to or owned a design system or shared component library.
• Experience with collaborative/real-time editing (OT, CRDTs, or similar).
• Warehousing, logistics or supply-chain domain experience.
• Prior experience at the SDE3 / senior level with mentoring responsibility.

Technical Qualifications:

We expect you to be proficient in or quickly learn the following. Senior roles (Band E+) are expected to be experts; Band C/D roles are expected to have working knowledge.

• Core: React 18+, TypeScript, Vite; strict ESLint / Prettier.
• Data-grid: AG Grid or TanStack Table with virtual scrolling, custom cell renderers and formula evaluation.
• State: TanStack Query for server state; Zustand or Jotai for local; optimistic updates and cache invalidation.
• AI integration: SSE / WebSocket streamed response handling, abort controllers, partial-state rendering.
• Testing: Vitest + Testing Library; Playwright for E2E; visual regression via Chromatic or similar.
• Design system: Radix UI primitives or shadcn/ui as a base; Tailwind CSS for layout and tokens.
• Tooling: GitHub monorepo, GitHub Actions CI, CODEOWNERS; Backstage for API / service discovery.
• Observability: product analytics instrumentation (e. g., Mixpanel); error tracking; reads own Grafana dashboard.
• Accessibility: WCAG 2.1 AA baseline for all interactive surfaces.