Fulya Lisa Neubert, writing for the Slack Design blog, starts with a familiar design handoff problem:

For most of my design career, Figma was where the real work happened. I’d design screens, build prototypes, then hand off the designs for someone else to build. If something felt slightly wrong in production, we’d go back and forth trying to articulate what “it should feel like” in words. This process worked well enough, but there was always a gap between what I could show in a static design tool and what someone would actually experience in the product.

The piece gets concrete when Neubert moves from screens to Slack search. She points to a kind of interaction where static prototypes can suggest the flow, but can’t prove whether the experience works under someone’s hands:

The search experience in Slack is a deeply keyboard-driven feature: typing states, focus management, the way content scrolls and reflows as you interact. These are things you can sketch in Figma and even prototype to a degree, but a Figma prototype can’t tell you whether the focus ring moves correctly between elements when you press tab, or whether a scrolling gradient feels right as content overflows. You need to actually use it.

I don’t read this as an argument that designers need to become frontend engineers. Neubert came in with the basics and figured it out:

I came into this with basic HTML and CSS — enough to roughly understand what I was looking at, but not enough to write it myself. That turned out to matter less than I expected. The first time I described a focus interaction in plain language and had a prototype working in minutes, I stopped thinking of code as someone else’s territory. […]

My setup is fairly straightforward. Cursor is my main environment. I use Figma’s MCP integration to pull in components I’ve already designed and Slack’s design tokens, so I don’t have to rebuild spacing, color, and type from scratch every time. I tried working directly in Slack’s codebase — years of accumulated complexity that made every small change feel like a bigger undertaking than it needed to be. […]

The Figma integration matters because the prototype isn’t starting from a blank toy environment. It pulls real components and tokens into a lighter workspace, which makes the thing shareable without pretending to be production. For Slack search, that means the team can review behavior instead of debating screenshots.

Neubert is also clear about the tax:

AI also doesn’t always preserve what you’ve already built. You prompt it to change one thing, and it quietly breaks something else. If you’re not testing after every turn, you won’t notice until you’re sharing the prototype with someone — or worse, presenting it — and that’s when you realize something’s broken.

That is the right caution. AI changes the distance between intent and working behavior, but it doesn’t remove verification. If anything, it makes the habit of testing after every small change part of the design process itself.