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Engineering notes, research and playbooks from the team building Spark.

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Engineering

Why our refund playbook never asks the model for permission

Language models are good at conversation and bad at policy. Here is how we split the two, and what it did to our error rate.

By Tomasz Wrona

Cardboard parcels stacked inside a delivery van

Engineering

Why our refund playbook never asks the model for permission

Language models are good at conversation and bad at policy. Here is how we split the two, and what it did to our error rate.

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Research

Grading every conversation: what changed when we stopped sampling

Reviewing fifty tickets a week felt rigorous. Scoring all of them showed us how much the sample was hiding.

A smiling woman talking on her phone against a white wall

Engineering

Sub-second voice: where the 800 milliseconds go

People notice a pause on the phone at around a second. This is the latency budget we work to, stage by stage.

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Guides

A five-week launch plan for your first support agent

The plan we run with every new customer, week by week, including what we check before real traffic arrives.

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Research

Writing rubrics a reviewer model can actually apply

Most quality rubrics are written for people who already know what good looks like. Here is how to write one for a model.

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Product

Routing each step to a different model

One model per agent is simple and expensive. One model per step is cheaper, faster and easier to change. Here is how routing works.

Two support agents with headsets working through a case together at a desk

Product

Hand-offs are a feature, not a failure

An agent that never hands over is either doing very easy work or doing hard work badly. How we design the moment it passes to a person.