shadcn ui : Popover vs Tooltip vs HoverCard

Three Radix-backed floating-panel primitives ship in shadcn ui new-york-v4. They look similar (a panel anchored to a trigger) but solve three disjoint UX problems. Picking the wrong one breaks keyboard navigation, touch users, screen readers, or all three at once. This skill is a decision tree, not three API surfaces stacked together. The full prop tables live in references/methods.md; the working recipes live in references/examples.md; the failure modes live in references/anti-patterns.md.

The single decision

Is the panel content interactive (inputs, links, buttons, anything
keyboard-focusable)?
├─ NO  -> Is the hint a short, plain-text label (one sentence max)?
│         ├─ YES -> Tooltip
│         └─ NO  -> Popover (open it on click, even for read-only content)
└─ YES -> Should the panel appear on hover, or on click?
          ├─ HOVER (and the trigger is keyboard-reachable too) -> HoverCard
          └─ CLICK                                              -> Popover

Three additional gates ALWAYS override the table above :