1 min lesson
The artifact is neutral ground
Use "Is that the number we disagree on?" to describe the practical rule.
Step 1 of 2
The artifact is neutral groundargue the doc, not the people
Spirited debate is part of the culture here and it goes better against a shared document than across a table. A written cost model with stated assumptions turns “I think we're overspending on the big model” into “line 14 assumes a 40% routing rate to the small model - is that the number we disagree on?” The disagreement gets specific and specific disagreements get resolved.
Say it like this
“I don't need you to agree with my conclusion yet - I need us to agree on the assumptions. Here's the model. If you think the routing rate or the GPU price is wrong, change that cell and we'll see what falls out. I'd rather be wrong on paper now than expensive in production later.”