01 / The Model
Harness
Everything wrapped around the model that turns it into something useful: its instructions, its tools, its permissions, how it manages what it can see. When a product feels good or bad, the harness is usually why, not the model.
How you’ll hear it
“Why is their assistant so much better on the same model?”
“Better harness. Better instructions, better tools, better handling of what it sees.”
Avoid
Crediting or blaming the model for what the surrounding product does.
The longer version
The harness is all the software around a model: instructions, tools, permissions, memory and the rules for what the model sees. Two products on the same model can feel completely different because of it, which makes the harness where most product and design decisions actually live.