Senior Platform Engineer

Responsibilities

• Build and improve the runtime that starts agent work, carries session state through tool calls, and resumes interrupted runs.
• Choose between actors and jobs for different kinds of work. Implement the choice and check how it behaves when sessions overlap.
• Design how long-running processes drain or resume when code changes, keeping in-flight work accounted for across releases.
• Handle retries and timeouts around tool calls, including cases where an external action succeeded but the response never came back.
• Make runtime failures traceable. Find why a run stopped or stalled, fix the execution path, and see the change through to production.

Requirements

• You've built and operated stateful backend systems in production, including work that outlasts the request that started it.
• You can explain a decision you made between an actor, a background job, or a simpler service, and show what you shipped.
• You've debugged concurrency, retries, or recovery in code you've owned.
• You're productive in TypeScript and want to keep writing code as your scope grows.

About the Role

Sauna's agent runtime has to keep track of work when a tool fails or new code ships mid-task. One session might start with a message, check Calendar, draft a Slack reply, and update Linear after the first response. A tool call can time out after the action succeeds; the runtime needs to know what happened before retrying.

You'll build the execution engine behind those sessions, choosing when work belongs in an actor and when a job is enough. You'll also design how long-running processes deploy while other tasks are in flight. This is a senior, hands-on engineering role. You'll make those calls with the team, write the code, and own it in production. We'll teach you our agent harness.

Stack

TypeScript, Cloudflare Workers, Durable Objects, Postgres, Docker. Experience with comparable runtimes counts.

Bonus

• You've worked on an agent runtime or agent harness.
• You've worked with Cloudflare Workers, Durable Objects, or another actor-based runtime.
• You've deployed long-running processes that persist or resume work across a code release.

Base salary

• $180K-$240K
• + meaningful early-stage equity + health, dental, 401(k), considerable PTO, gym budget, lunch.

The Process

We keep our process simple. Exceptional candidates go from first touch to offer within 2 weeks.

Application

Submit your resume and answer a few short questions.

15-minute intro call

Quick check to align on location, motivation, and logistics. If it's a go, we move fast from here.

45-minute technical interview

You'll work through a real backend problem. We're looking for fluency, depth, and how you think about systems.

System design interview

We'll walk through a real Wordware architecture problem together.

Final conversation

We answer your questions and scope out the work trial.

Work trial

Paid trial to work on a real project in person with us, usually a few days to two weeks. See how we work and whether this feels like the right fit on both sides.