Unattended shadcn init runs now get Base UI unless they pass -b radix

The default bites at one moment: a fresh checkout running init with no human at the keyboard. The guide's author says to add the flag to any CI or script that calls init non-interactively and expects Radix ^[5]. Existing projects are untouched ^[3], so a repo that already has its components in place sees no change.

The failure that follows is likely to show up later than init does. The guide's first difference is that asChild becomes render, which it calls the one everyone meets first ^[8]. Radix code wraps a Button in `<DialogTrigger asChild>`. Base UI code writes `<DialogTrigger render={<Button />}>` ^[8]. A scaffold script or template that writes the first form into a Base UI project is writing an API the new primitives do not use.

The quieter differences are the ones a green build will not catch. The guide sorts changes by how they fail: some break the build, others compile and change behavior silently ^[12]. Open-state variants move from `data-[state=open]:` to `data-open:`. The author says they hide in className strings and cva variants, so grep for `data-[state=` before calling a migration done ^[9]. Tabs no longer activate on arrow keys. The user presses Enter or Space unless `activateOnFocus` is set on the list ^[10]. An end-to-end test that arrows across tabs and expects the panel to switch would fail on that alone. Navigation menus open after a 50ms hover delay, against Radix's 200ms default ^[11], which is 150ms sooner ^[14].

The stated reason for the flip is adoption. By then Base UI was stable at version 1.6.0 and pulling more than six million downloads a week, and new projects made with shadcn/create already favored it over Radix by about two to one ^[16]. That ratio describes people starting new projects in one scaffolding tool. It transfers to your repo only if your team is also starting fresh and has no Radix-specific components to carry.

Two cautions on the source. The guide relays the shadcn team's statements secondhand, and its author maintains HextaUI, a registry built on Base UI ^[7]. Even so, its advice on migrating is conservative. Asked whether to move, it answers "Probably not this quarter, and not all at once" ^[13]. It says to stay on Radix if the app is stable and nobody is blocked on a missing primitive, and to move if you need Combobox or Number Field without a second library ^[13].