feat: add avatar stack component

components/motion/avatar-stack.tsx

@@ -0,0 +1,151 @@
+"use client";
+
+import { motion, useReducedMotion } from "motion/react";
+import type { ReactNode } from "react";
+import { SPRING_LAYOUT, SPRING_PRESS } from "@/lib/ease";
+import { useHoverCapable } from "@/lib/hooks/use-hover-capable";
+import { cn } from "@/lib/utils";
+
+export type AvatarStackItem = {
+  id: string;
+  name: string;
+  src?: string;
+  fallback?: ReactNode;
+  className?: string;
+};
+
+export interface AvatarStackProps {
+  items: AvatarStackItem[];
+  className?: string;
+  itemClassName?: string;
+  size?: number;
+  max?: number;
+  overlap?: number;
+  spreadOnHover?: boolean;
+}
+
+export function AvatarStack({
+  items,
+  className,
+  itemClassName,
+  size = 44,
+  max = 5,
+  overlap = 14,
+  spreadOnHover = true,
+}: AvatarStackProps) {
+  const reduce = useReducedMotion();
+  const canHover = useHoverCapable();
+  const visibleItems = items.slice(0, max);
+  const remaining = Math.max(items.length - visibleItems.length, 0);
+  const shouldSpread = spreadOnHover && canHover && !reduce;
+  const step = Math.max(size - overlap, 10);
+  const expandedStep = size + 6;
+  const width = visibleItems.length
+    ? size + Math.max(visibleItems.length - 1, 0) * step + (remaining ? step : 0)
+    : 0;
+
+  return (
+    <ul
+      className={cn("group relative inline-flex items-center", className)}
+      style={{ minHeight: size, width }}
+      aria-label={`${items.length} people`}
+    >
+      {visibleItems.map((item, index) => {
+        const x = index * step;
+        const hoverX = index * expandedStep;
+
+        return (
+          <motion.li
+            key={item.id}
+            initial={false}
+            animate={{
+              x,
+              scale: 1,
+            }}
+            whileHover={
+              shouldSpread
+                ? {
+                    x: hoverX,
+                    y: -4,
+                    scale: 1.04,
+                  }
+                : undefined
+            }
+            whileTap={reduce ? undefined : { scale: 0.96 }}
+            transition={reduce ? { duration: 0 } : index === 0 ? SPRING_LAYOUT : SPRING_PRESS}
+            className="absolute top-0 list-none"
+            style={{ zIndex: visibleItems.length - index }}
+          >
+            <AvatarStackItemView
+              item={item}
+              size={size}
+              className={cn(itemClassName, item.className)}
+            />
+          </motion.li>
+        );
+      })}
+
+      {remaining ? (
+        <motion.li
+          initial={false}
+          animate={{ x: visibleItems.length * step }}
+          whileHover={shouldSpread ? { x: visibleItems.length * expandedStep, y: -2 } : undefined}
+          transition={reduce ? { duration: 0 } : SPRING_LAYOUT}
+          className="absolute top-0 list-none"
+          style={{ zIndex: 0 }}
+        >
+          <span
+            className={cn(
+              "flex items-center justify-center rounded-full border border-background/80 bg-muted text-xs font-semibold text-muted-foreground shadow-sm ring-2 ring-background",
+              itemClassName,
+            )}
+            style={{ width: size, height: size }}
+            title={`${remaining} more`}
+          >
+            +{remaining}
+          </span>
+        </motion.li>
+      ) : null}
+    </ul>
+  );
+}
+
+function AvatarStackItemView({
+  item,
+  size,
+  className,
+}: {
+  item: AvatarStackItem;
+  size: number;
+  className?: string;
+}) {
+  const fallback =
+    item.fallback ??
+    item.name
+      .split(" ")
+      .map((part) => part[0])
+      .join("")
+      .slice(0, 2)
+      .toUpperCase();
+
+  return (
+    <span
+      title={item.name}
+      className={cn(
+        "flex shrink-0 items-center justify-center overflow-hidden rounded-full border border-background/80 bg-card text-sm font-medium text-foreground shadow-sm ring-2 ring-background",
+        className,
+      )}
+      style={{ width: size, height: size }}
+    >
+      {item.src ? (
+        <span
+          aria-hidden
+          className="h-full w-full bg-cover bg-center"
+          style={{ backgroundImage: `url(${item.src})` }}
+        />
+      ) : (
+        <span>{fallback}</span>
+      )}
+    </span>
+  );
+}

components/previews/index.tsx

@@ -62,6 +62,9 @@ export const previews: Record<string, ComponentType> = {
   "motion/animated-badge": dynamic(() =>
     import("./motion/animated-badge.preview").then((m) => m.AnimatedBadgePreview),
   ),
+  "motion/avatar-stack": dynamic(() =>
+    import("./motion/avatar-stack.preview").then((m) => m.AvatarStackPreview),
+  ),
   "motion/animated-toast-stack": dynamic(() =>
     import("./motion/animated-toast-stack.preview").then((m) => m.AnimatedToastStackPreview),
   ),

components/previews/motion/avatar-stack.preview.tsx

@@ -0,0 +1,23 @@
+"use client";
+
+import { AvatarStack } from "@/components/motion/avatar-stack";
+
+const TEAM = [
+  { id: "maya", name: "Maya Patel", fallback: "MP", className: "bg-violet-500/15 text-violet-700 dark:text-violet-300" },
+  { id: "alex", name: "Alex Kim", fallback: "AK", className: "bg-sky-500/15 text-sky-700 dark:text-sky-300" },
+  { id: "nina", name: "Nina Chen", fallback: "NC", className: "bg-emerald-500/15 text-emerald-700 dark:text-emerald-300" },
+  { id: "omar", name: "Omar Diaz", fallback: "OD", className: "bg-amber-500/15 text-amber-700 dark:text-amber-300" },
+  { id: "zoe", name: "Zoe Hart", fallback: "ZH", className: "bg-rose-500/15 text-rose-700 dark:text-rose-300" },
+  { id: "liam", name: "Liam Scott", fallback: "LS", className: "bg-fuchsia-500/15 text-fuchsia-700 dark:text-fuchsia-300" },
+];
+
+export function AvatarStackPreview() {
+  return (
+    <div className="flex flex-col items-center gap-3">
+      <AvatarStack items={TEAM} />
+      <p className="text-center text-xs text-muted-foreground">
+        6 collaborators live in this thread
+      </p>
+    </div>
+  );
+}

lib/registry.ts

@@ -205,6 +205,13 @@ export const registry: CategoryEntry[] = [
         description: "Status badge with animated state icons, pulse feedback and compact size variants.",
         file: "components/motion/animated-badge.tsx",
       },
+      {
+        slug: "avatar-stack",
+        name: "Avatar Stack",
+        description: "Overlapping avatar group that fans out on hover with spring-driven spacing and a trailing +N counter.",
+        file: "components/motion/avatar-stack.tsx",
+        badge: "new",
+      },
       {
         slug: "action-swap",
         name: "Action Swap",