diff --git a/app/components/AppShell.tsx b/app/components/AppShell.tsx
index e40e709d..fec4a11a 100644
--- a/app/components/AppShell.tsx
+++ b/app/components/AppShell.tsx
@@ -14,6 +14,7 @@ import { demoLabel, demoBreadcrumb } from '../vibenet/demos/catalogue';
 
 import { trackNavClick } from '../analytics/events';
 import { navExitingHighlightPath, navSlideDirection, type NavPresenceCustom } from './nav-motion';
+import { DrawerSlotContext } from './DrawerSlot';
 import { NavScrollArea } from './NavScrollArea';
 import { AnimatedBaseLogo, BaseMark } from './ui/AnimatedBaseLogo';
 import { Breadcrumb } from './ui/Breadcrumb';
@@ -676,6 +677,7 @@ export function AppShell({ children }: PropsWithChildren) {
   const pathname = usePathname() || '/';
   const title = titleForPath(pathname);
   const [menuOpen, setMenuOpen] = useState(false);
+  const [drawerSlot, setDrawerSlot] = useState<HTMLElement | null>(null);
   // aria-checked only. The switch's look is CSS against html[data-theme],
   // which the pre-paint script already set — this state starts false so SSR
   // and the first client render match, then catches up after mount.
@@ -712,6 +714,7 @@ export function AppShell({ children }: PropsWithChildren) {
   };
 
   return (
+    <DrawerSlotContext.Provider value={drawerSlot}>
     <div className="flex min-h-dvh flex-col">
       <div style={styles.root}>
         {/* Desktop sidebar */}
@@ -741,6 +744,7 @@ export function AppShell({ children }: PropsWithChildren) {
           <Dialog.Portal>
             <Dialog.Popup className="drawer outline-none [transform:translate3d(0,0,0)] transition-transform duration-300 ease-out data-[ending-style]:[transform:translate3d(100%,0,0)] data-[starting-style]:[transform:translate3d(100%,0,0)] motion-reduce:transition-none">
               <Dialog.Title className="sr-only">Menu</Dialog.Title>
+              <div ref={setDrawerSlot} className="shrink-0 px-2 pt-3 empty:hidden" />
               <SidebarContent
                 dark={dark}
                 onToggleTheme={toggleTheme}
@@ -792,5 +796,6 @@ export function AppShell({ children }: PropsWithChildren) {
       </div>
       <Toaster position="top-center" style={{ '--width': '300px' } as React.CSSProperties} toastOptions={{ className: 'text-[13px] tracking-[0px]' }} />
     </div>
+    </DrawerSlotContext.Provider>
   );
 }
diff --git a/app/components/DrawerSlot.tsx b/app/components/DrawerSlot.tsx
new file mode 100644
index 00000000..43e433cc
--- /dev/null
+++ b/app/components/DrawerSlot.tsx
@@ -0,0 +1,11 @@
+'use client';
+
+import { createContext, useContext } from 'react';
+
+// The mobile menu drawer's actions slot. Null while the drawer is closed, since
+// the drawer only mounts its contents when open.
+export const DrawerSlotContext = createContext<HTMLElement | null>(null);
+
+export function useDrawerSlot() {
+  return useContext(DrawerSlotContext);
+}
diff --git a/app/components/ui/Breadcrumb.tsx b/app/components/ui/Breadcrumb.tsx
index fb536451..9702d142 100644
--- a/app/components/ui/Breadcrumb.tsx
+++ b/app/components/ui/Breadcrumb.tsx
@@ -17,7 +17,7 @@ type BreadcrumbProps = {
 export function Breadcrumb({ parentLabel, parentHref, childLabel, middle }: BreadcrumbProps) {
   const backHref = middle?.href ?? parentHref;
   return (
-    <span className="relative flex w-full items-center justify-center">
+    <span className="relative flex w-full min-w-0 items-center justify-center px-24">
       <Link
         href={backHref}
         className="group absolute left-0 flex h-8 w-8 items-center justify-center rounded-full text-bds-gray-40 no-underline transition-colors hover:text-foreground"
@@ -35,8 +35,8 @@ export function Breadcrumb({ parentLabel, parentHref, childLabel, middle }: Brea
           />
         </svg>
       </Link>
-      <span className="flex items-center gap-2">
-        <Link href={parentHref} className="no-underline">
+      <span data-breadcrumb-trail className="flex min-w-0 items-center gap-2 whitespace-nowrap">
+        <Link href={parentHref} className="min-w-0 truncate no-underline">
           <Text as="span" variant="headline" className="text-bds-gray-40">
             {parentLabel}
           </Text>
@@ -46,7 +46,7 @@ export function Breadcrumb({ parentLabel, parentHref, childLabel, middle }: Brea
         </Text>
         {middle ? (
           <>
-            <Link href={middle.href} className="no-underline">
+            <Link href={middle.href} className="min-w-0 truncate no-underline">
               <Text as="span" variant="headline" className="text-bds-gray-40">
                 {middle.label}
               </Text>
@@ -56,7 +56,7 @@ export function Breadcrumb({ parentLabel, parentHref, childLabel, middle }: Brea
             </Text>
           </>
         ) : null}
-        <Text as="span" variant="headline">
+        <Text as="span" variant="headline" className="shrink-0">
           {childLabel}
         </Text>
       </span>
diff --git a/app/vibenet/demos/_components/AccountDemoShell.tsx b/app/vibenet/demos/_components/AccountDemoShell.tsx
index 60fb7e38..506dbffa 100644
--- a/app/vibenet/demos/_components/AccountDemoShell.tsx
+++ b/app/vibenet/demos/_components/AccountDemoShell.tsx
@@ -12,9 +12,10 @@
 // Each demo renders this inside one AccountEngineProvider, avoiding duplicate
 // store instances and repeated account-settings wiring.
 
-import { useEffect, useState, type ReactNode } from 'react';
+import { useEffect, useLayoutEffect, useState, type ReactNode } from 'react';
 import { createPortal } from 'react-dom';
 
+import { useDrawerSlot } from '../../../components/DrawerSlot';
 import { cn } from '../../../components/ui/cn';
 import { AccountSwitcher } from '../_shared/AccountSwitcher';
 import { ActivityDrawer } from '../_shared/ActivityDrawer';
@@ -46,6 +47,8 @@ export function AccountDemoShell({
 }: AccountDemoShellProps) {
   const engine = useAccountEngine();
   const [topbarSlot, setTopbarSlot] = useState<HTMLElement | null>(null);
+  const drawerSlot = useDrawerSlot();
+  const [collapsed, setCollapsed] = useState(false);
   // The switcher and the empty-state gate both open the create-account drawer.
   const [createOpen, setCreateOpen] = useState(false);
   const onCreate = () => setCreateOpen(true);
@@ -53,21 +56,44 @@ export function AccountDemoShell({
     setTopbarSlot(document.getElementById('topbar-actions-slot'));
   }, []);
 
-  const switcher = (
-    <AccountSwitcher
-      accounts={engine.accounts}
-      activeAccountId={engine.activeAccountId}
-      onSelect={engine.setActiveAccountId}
-      onCreate={onCreate}
-      onDelete={engine.deleteAccount}
-      onDetails={(id) => {
-        const addr = engine.accounts.find((a) => a.id === id)?.address;
-        if (addr) window.open(`/vibenet/explorer/address/${addr}`, '_blank', 'noopener,noreferrer');
-      }}
-    />
-  );
-
   const hasAccounts = engine.accounts.length > 0;
+  const activeLabel = engine.accounts.find((a) => a.id === engine.activeAccountId)?.label;
+
+  // Collapse the topbar switcher to avatar + chevron only when the expanded
+  // control would run into the centered breadcrumb; otherwise show the label.
+  useLayoutEffect(() => {
+    const header = topbarSlot?.parentElement;
+    if (!topbarSlot || !header || !hasAccounts) return;
+    const measure = () => {
+      const trigger = topbarSlot.firstElementChild as HTMLElement | null;
+      const label = topbarSlot.querySelector<HTMLElement>('[data-account-label]');
+      const trail = header.querySelector<HTMLElement>('[data-breadcrumb-trail]');
+      if (!trigger || !label || !trail) return;
+      const naturalLabel = Math.min(label.scrollWidth, 180);
+      const expandedWidth = trigger.offsetWidth + (label.offsetWidth < naturalLabel ? 8 + naturalLabel : 0);
+      const parts = Array.from(trail.children) as HTMLElement[];
+      const trailWidth = parts.reduce((sum, el) => sum + Math.max(el.scrollWidth, el.offsetWidth), 0) + 8 * (parts.length - 1);
+      // Switcher sits 28px from the right edge; keep 16px clear of the trail.
+      const room = header.clientWidth / 2 - trailWidth / 2 - expandedWidth - 28 - 16;
+      setCollapsed(room < 0);
+    };
+    measure();
+    const observer = new ResizeObserver(measure);
+    observer.observe(header);
+    return () => observer.disconnect();
+  }, [topbarSlot, hasAccounts, activeLabel]);
+
+  const switcherProps = {
+    accounts: engine.accounts,
+    activeAccountId: engine.activeAccountId,
+    onSelect: engine.setActiveAccountId,
+    onCreate,
+    onDelete: engine.deleteAccount,
+    onDetails: (id: string) => {
+      const addr = engine.accounts.find((a) => a.id === id)?.address;
+      if (addr) window.open(`/vibenet/explorer/address/${addr}`, '_blank', 'noopener,noreferrer');
+    },
+  };
 
   return (
     <>
@@ -77,7 +103,11 @@ export function AccountDemoShell({
       <div className={cn('relative -mb-20 flex min-w-0 flex-1 flex-col text-foreground', className)}>
         {/* Desktop: the switcher lives in the app top bar. Hidden until an account
             exists so the gate reads as a clean full-page empty state. */}
-        {hasAccounts && topbarSlot ? createPortal(switcher, topbarSlot) : null}
+        {hasAccounts && topbarSlot ? createPortal(<AccountSwitcher {...switcherProps} collapsed={collapsed} />, topbarSlot) : null}
+        {/* Mobile: the top bar is hidden, so the switcher lives in the hamburger menu. */}
+        {hasAccounts && drawerSlot
+          ? createPortal(<AccountSwitcher {...switcherProps} triggerClassName="w-full" />, drawerSlot)
+          : null}
 
         <DemoGate
           accounts={engine.accounts}
@@ -86,8 +116,6 @@ export function AccountDemoShell({
           title={gateTitle}
           description={gateDescription}
         >
-          {/* Mobile only — desktop uses the top-bar switcher. */}
-          <div className="shrink-0 md:hidden">{switcher}</div>
           {children}
           {activity ? (
             <ActivityDrawer count={activityCount} emptyMessage={activityEmptyMessage}>
diff --git a/app/vibenet/demos/_shared/AccountSwitcher.tsx b/app/vibenet/demos/_shared/AccountSwitcher.tsx
index a3f17931..7ab2b5d0 100644
--- a/app/vibenet/demos/_shared/AccountSwitcher.tsx
+++ b/app/vibenet/demos/_shared/AccountSwitcher.tsx
@@ -75,6 +75,8 @@ type AccountSwitcherProps = {
   onCreate?: () => void;
   /** Extra classes for the trigger button (e.g. `w-full` inside a form). */
   triggerClassName?: string;
+  /** Hide the label, leaving the avatar and chevron (for tight spaces like the topbar). */
+  collapsed?: boolean;
 };
 
 export function AccountSwitcher({
@@ -85,6 +87,7 @@ export function AccountSwitcher({
   onDelete,
   onCreate,
   triggerClassName,
+  collapsed = false,
 }: AccountSwitcherProps) {
   const [open, setOpen] = useState(false);
 
@@ -151,6 +154,7 @@ export function AccountSwitcher({
       }}
     >
       <Popover.Trigger
+        aria-label={collapsed && active ? `Account: ${active.label}` : undefined}
         className={cn(
           'group flex h-10 items-center justify-between gap-2 rounded-lg bg-transparent px-2.5 outline-none',
           'ring-1 ring-inset ring-bds-gray-10',
@@ -163,7 +167,12 @@ export function AccountSwitcher({
         {active ? (
           <span className="flex min-w-0 items-center gap-2">
             <AccountAvatar variant="default" size={22} />
-            <span className="max-w-[180px] truncate text-[13px] font-medium">{active.label}</span>
+            <span
+              data-account-label
+              className={cn('max-w-[180px] truncate text-[13px] font-medium', collapsed && '-ml-2 w-0 overflow-hidden')}
+            >
+              {active.label}
+            </span>
           </span>
         ) : (
           <Text as="span" variant="label.medium" tone="muted">