Senior Backend Engineer

The core is deliberately domain-agnostic: it does not know what a row is, only that something must be authenticated, metered, quota-checked, audited and resumable. Everything an actor does, it does through that spine.

You would own it.

What you would work on

• The wrapper chain every route and every MCP tool passes through.
• Cursor semantics — the guarantee that a retry resumes rather than re-bills.
• The metering path, which has to be exact rather than eventually correct.
• The boundary lint rules that stop a domain leaking into the core, and the fixtures that prove each rule still fires.

What we look for

• You have run something in production that had to be correct about money or about counts, and you know why that is different from being mostly right.
• You are comfortable with Postgres beyond the ORM — you have reached for an advisory lock or read an execution plan and known what to do about it.
• You treat a 100% coverage threshold on a small core as a reasonable idea rather than a religious one.

What we do not look for

Years of experience with a specific framework. The core is a few thousand lines of TypeScript; the hard part is the thinking, not the API surface.