AddThisFeature

Compound Component Pattern

Let related parts of a component share state while the caller keeps control of the arrangement.

involved Components & Primitives

What it adds

Groups of subcomponents that coordinate shared state internally while leaving structure and ordering to the call site.

What your agent is told to do

5
  1. 1

    Identify the components currently configured through long lists of props for their internal parts — a tabs component taking an array of labels, a dialog taking title, body, and footer as strings — and let the caller compose those parts instead.

  2. 2

    Keep the shared state inside the group. Selection, open state, active index, and registration of the parts are the group's responsibility, and callers should not have to wire them together to get correct behaviour.

  3. 3

    Support both a self-managing mode and a caller-controlled mode for the shared state, and make them mutually exclusive rather than allowing a half-controlled configuration that fights itself.

  4. 4

    Give each subcomponent a clear error when it renders outside its group, naming the parent it requires. A part that silently renders inert because it found no shared state is very hard to diagnose from a screenshot.

  5. 5

    Do not couple the parts by inspecting children, cloning them, or reaching for a particular position in the child list. That breaks the moment someone wraps a part in a conditional, a layout element, or a component of their own — which is exactly the flexibility this pattern exists to allow.

Edge cases it handles

7
  • A subcomponent rendered outside its required parent must fail with a message naming that parent rather than rendering as an inert element. Silence here produces a control that looks right and does nothing.
  • Reordering or wrapping the parts must not break accessibility. The relationships that assistive technology relies on — which label belongs to which panel, which trigger controls which region — must be established through explicit association rather than through the order the parts happen to appear in.
  • Shared state passed implicitly is easy to depend on by accident. Keep what the group provides deliberately small and documented, so a caller cannot end up relying on internals that change in the next release.
  • Both a self-managing and a caller-controlled mode must be supported, and switching between them mid-life must be refused or handled explicitly rather than leaving two sources of truth disagreeing about which item is selected.
  • Parts rendered conditionally, in a loop, or through an intermediate wrapper must still register with the group, so keyboard navigation and roving focus cover exactly the parts that are present.
  • Nesting one group inside another — a menu within a menu, tabs within a panel — must resolve to the nearest enclosing group, not the outermost one.
  • Duplicated or missing required parts, such as two panels claiming the same identifier or a trigger with no matching panel, need a development-time warning.

Definition of done

9
  • Related components are composed at the call site rather than configured through arrays or slot-shaped prop lists.
  • Shared state is owned by the group, and callers get correct behaviour without wiring it themselves.
  • A subcomponent used outside its parent raises an error naming the required parent.
  • Self-managing and caller-controlled modes are both supported and cannot be mixed.
  • Wrapping, reordering, or conditionally rendering the parts leaves accessibility relationships intact.
  • The group's implementation never inspects, clones, or indexes into its children.
  • Nested groups resolve to the nearest enclosing parent.
  • The feature matches the existing design system.
  • No existing functionality is broken.

Related features

How it works

  1. 1

    Copy the link

    Grab the Markdown instruction URL for this feature.

  2. 2

    Give it to your AI

    Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.

  3. 3

    It inspects, then implements

    Your agent reads your existing app first, then adds the feature to fit it.

Works with your stack

These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.

Need it tighter than that? Customize the feature and tell it exactly what you're running.