Upgrade an artisan's cart?

[t3hchri5]

What does this actually need? I've given them all every diagram and still have nothing. A few of them are maxed out and it hasn't popped. Is it bugged?

[Tornadoawe]

If you mean the achievement [Wainwright], in the vendor merchant's menu should be an [Upgrade] tab. If that vendor is levelled enough and you have the materials, you can obtain up to 4 Upgrades that either give discounts, or a passive effect (one of Rhys' Upgrades gives you a bonus to Essence drop from enemies, for example).

[flushfire]

You mean the tent upgrade? It's a separate click, it doesn't happen automatically.