AI Engineer

Modern Relay is the source of truth for enterprise AI. As AI moves from chat to action, companies need a shared view of what's real, the governance to change it, and the infrastructure they control.

We've built a graph engine where humans and agents share one governed context. The ontology models every entity and relationship in the customer's domain. Git-like branching and merging let agents work in parallel under human review, with the query layer operating directly on the graph.

Every change to the graph is versioned, reviewed, and reversible, with all of it running on the customer's infrastructure. We believe this is the future of enterprise AI, and we're building it.

You might thrive at Modern Relay if you:

• Have shipped production LLM systems and can walk the agent, retrieval, evaluation, and serving layers end to end
• Think in terms of state, not prompts. How a system learns over time, how humans intervene, how confidence is scored.
• Already use Claude and Codex as your default tooling
• Write Rust, or are ready to. The systems layer isn't something you hand off.
• Prefer open-ended problems over ones with established answers

You'll work across the agent layer and the Rust engine underneath. Ship features with customers, then generalize them back into the core. Your week might span an architecture call with the founders, pairing with a Forward Deployed Engineer on an enterprise deployment, and walking a customer's CIO through what you built.

• Build the Tasks layer: reactive agent workflows that propose governed changes to the context graph
• Extend the MCP server so Claude and OpenAI agents read and write through typed, branched proposals
• Own the human-in-the-loop review surface that turns those proposals into auditable commits
• Design evaluation frameworks for long-horizon tasks. Decide when to automate, when to escalate.
• Contribute to the open-source Rust engine: schema compiler for .pg files, .gq query parser, DataFusion-backed query planner, CSR/CSC graph indexes
• Ship what runs at on-prem customer sites, including the observability to debug it remotely

• 3+ years shipping production LLM systems you can explain end to end
• Depth in Python and/or TypeScript, with fluency in agent frameworks, RAG, and eval tooling
• Rust isn't required. Appetite to learn it is. You'll pair with engineers already writing it.
• Experience with human-in-the-loop feedback, reward shaping, or long-horizon task decomposition
• Comfort at a customer whiteboard, explaining a governance model to a non-technical stakeholder
• Direct communication. Problems surfaced early, solutions proposed in the same sentence.

• Founder-tier equity
• Competitive cash, weighted toward equity
• Unlimited token access to Claude, Codex, and every AI tool to bring your wildest ideas to reality
• Small, flat team
• Build alongside the founders
• San Francisco or Barcelona, in person
• Health, dental, and vision insurance
• Flexible time off

If this sounds like you, email careers@modernrelay.com with the subject line "Application: AI Engineer". Attach a resume, point us at work you're proud of, and tell us what you'd build first.

We read every application. We write back within a week.