Sr. Staff Engineer, Applied AI (Customer Agent)

About the Team

Our Engineering team builds the AI systems that power how brands run their businesses on Klaviyo. We move fast, ship in production, and hold a high bar for what "AI-native" actually means: systems that make real judgment calls, not demos.

The Customer Agent team is one of the newest and most ambitious groups in that org, based in Boston and working in-office: we're building a conversational AI system that lets brands serve their own customers at a scale no human support team could match. We're past the demo stage: the team ships changes against live customer traffic, measures quality with real evaluation frameworks, and treats reliability as a product feature, not an afterthought.

About the Role

As Senior Staff Engineer, you'll set technical and product direction for Customer Agent end to end, building a 0-to-1 agentic product with the speed and ownership of a startup, backed by the scale and resources of Klaviyo, while staying hands-on with the hardest problems yourself. This is a principal-caliber individual contributor role for an engineer who has personally architected, built, scaled, and supported a production agentic system.

How You'll Make an Impact

• Set the technical and product direction for Customer Agent's core platform, from architecture through production.
• Take on the platform's hardest technical problems personally: orchestration, evaluation, guardrails, memory & context, self-healing/improving and failure handling for non-deterministic systems.
• Write and ship code, review designs, and make critical engineering decisions.
• Build architecture and frameworks that other engineers and teams adopt, and mentor through design reviews.
• Partner with product, design, data science, and go-to-market leaders to shape the roadmap.
• Evaluate emerging AI technologies and bring viable ones into production.

What We're Looking For

• Experience architecting, building, scaling, and supporting a production agentic system end to end (orchestration, evals, guardrails, non-deterministic failure handling) through launch, scale, and operational realities.
• Practical experience securing agents against misuse/abuse and maintaining reliability for non-deterministic systems.
• Experience setting technical and product direction across an entire product area.
• Hands-on engineering discipline: writing code, reviewing architecture decisions, and debugging production issues.
• Proven ability to build reusable frameworks and unblock multiple engineering teams.
• Ability to communicate complex technical trade-offs across engineering, product, and executive audiences.

Nice to Haves

• Experience running a multi-tenant agent platform at production scale with externally configured behaviors on shared infrastructure.
• Experience building 0-to-1 products or working in startup environments.
• A track record with production evaluation systems, AI observability, or human-in-the-loop workflows for LLM-powered products.

Additional Details

• Role is based in-office in Boston, MA.
• May require up to 10% travel for onboarding, team meetings, or industry events.