07
vertical slice
Ship one user-visible sliver at a time, instead of finishing a layer.
What is vertical slice?
A vertical slice is cut on user value, not on technical layers. Each slice contains the bit of UI, logic, and data that slice needs.
Why does vertical slice matter when vibe coding?
“Design the database first” is the model’s default. Slices give you something to accept every turn. Without them, a vibe-coding thread generates half a system at once.
How do you do vertical slice?
Write the feature as a list of user verbs. One verb per turn. Finish, test, merge, then take the next.
How do you ask a model for vertical slice?
This turn is one vertical slice: (user verb). No other verbs. Tests included. I must be able to click it.
What goes wrong with vertical slice?
Cutting a slice called “perfect auth.” Auth is platform, not the first user value — unless the product is auth.