Senior Platform Engineer

You’ll build and own the core execution engine (agent runtime) that manages session state, tool calls, and long-running processes - the backbone that lets AI agents operate reliably over extended sessions.

• Production experience building and operating stateful backend systems - work that outlasts the initial request
• Professional experience writing production backend code in TypeScript
• Based in the San Francisco Bay Area, or willing to relocate, * Experience building an agent runtime or agent harness
• Production experience with Cloudflare Workers, Durable Objects, or other actor-based runtimes
• Experience deploying long-running processes that persist across code releases
• Background at next-gen AI/agentic companies or design-first product orgs

Y Combinator-backed, early-stage AI startup (~15 people) building a hybrid AI and software platform centered on a shared context engine.