Senior Software Architect - TypeScript Monorepo + LangGraph (Ongoing Advisory)

We are a two-person SaaS company building an AI agent product for accounting firms, with pilots starting in the next couple of months. We are looking for a senior engineer to advise on architecture, around four hours a week, ongoing. THE STACK - TypeScript throughout, built as a modular monolith in a monorepo, two deployed services - SvelteKit web application - LangGraph agent service - Postgres with row-level security Most of the implementation is done by AI coding agents working from written rules kept in the repository. Our developers direct the work, review it, and make the decisions. We want the codebase design optimised for maintainability and rules created so those agents cannot get it wrong: one obvious home for each kind of logic. WHAT YOU WILL DO - Work with to define the target architecture and reduce trial & error cycles - where each kind of logic belongs, how the two services relate, how the codebase should grow - Help turn those decisions into types, lint rules and boundaries that fail the build when crossed, rather than more written rules - Advise on architecture and design questions as they come up in delivery: where a new piece belongs, whether an approach fits, how to unpick something built the wrong way - Provide general technical technical guidance/support to junior devs for complex issues/bugs (primary focus will remain design/architecture guidance) REQUIREMENTS - 6+ years in backend or codebase-architecture focused engineering roles (Essential) - Deep TypeScript experience - using the type system to make wrong code fail to compile, not just to annotate it (Essential) - Monorepo experience, keeping module boundaries honest across a codebase several people are changing at once (Essential) - Production LangGraph Experience - shipped and running, not tutorials (Preferred, not essential) - SvelteKit and Postgres row-level security (Useful, not essential) ENGAGEMENT - Around 2-4 hours a week: Tuesdays or Thursdays - Material sent the day before each session, so the time is spent deciding rather than reading - We start with one paid 2-hour session before either side commits further - Advisory/Mentoring role - we are not looking to outsource development - Ongoing, hourly, no minimum commitment - Remote, with overlap on Australian business hours (flexible) - NDA before repository access