diff --git a/apps/app/src/layouts/components/AppShell.vue b/apps/app/src/layouts/components/AppShell.vue
index 9761e1d2..6ca7f231 100644
--- a/apps/app/src/layouts/components/AppShell.vue
+++ b/apps/app/src/layouts/components/AppShell.vue
@@ -94,10 +94,8 @@ function toggleUserMenu(event: Event) {
 <template>
   <div class="crewli-app-shell flex min-h-screen">
     <!-- Desktop sidebar (lg+) -->
-    <aside class="hidden lg:flex w-64 flex-col border-r border-surface-200 bg-surface-0">
-      <div class="flex h-16 items-center justify-center border-b border-surface-200">
-        <span class="text-xl font-semibold text-primary-500">{{ title }}</span>
-      </div>
+    <aside class="hidden lg:flex w-72 flex-col border-r border-surface-200 bg-surface-0">
+      <SidebarHeader :title="title" />
       <nav class="flex-1 overflow-y-auto p-3">
         <template
           v-for="(item, idx) in navItems"
@@ -130,12 +128,12 @@ function toggleUserMenu(event: Event) {
       v-model:visible="mobileNavOpen"
       position="left"
       class="lg:hidden"
-      :pt="{ root: { style: { width: '16rem' } } }"
+      :pt="{ root: { style: { width: '18rem' } }, header: { class: 'p-0' } }"
     >
       <template #header>
-        <span class="text-lg font-semibold text-primary-500">{{ title }}</span>
+        <SidebarHeader :title="title" />
       </template>
-      <nav class="flex flex-col">
+      <nav class="flex flex-col p-3">
         <template
           v-for="(item, idx) in navItems"
           :key="idx"
diff --git a/apps/app/src/layouts/components/SidebarHeader.vue b/apps/app/src/layouts/components/SidebarHeader.vue
new file mode 100644
index 00000000..37cb3361
--- /dev/null
+++ b/apps/app/src/layouts/components/SidebarHeader.vue
@@ -0,0 +1,104 @@
+<script setup lang="ts">
+// SidebarHeader — top-of-sidebar org-switcher card introduced in F3.5
+// per the AppShell mockup-parity sprint. PrimeVue-only rewrite of the
+// legacy Vuetify OrganisationSwitcher (apps/app/src/components/layout/
+// OrganisationSwitcher.vue), which cannot be reused inside AppShell
+// per the R-10 layout-shell-isolation invariant.
+//
+// When the auth store has no active organisation (e.g. portal users,
+// or a fresh super_admin without an org), the component degrades to a
+// plain title block — the same visual the F3 AppShell shipped with.
+
+import { computed, ref } from 'vue'
+import Menu from 'primevue/menu'
+import Avatar from 'primevue/avatar'
+import Icon from '@/components/Icon.vue'
+import { useAuthStore } from '@/stores/useAuthStore'
+
+interface Props {
+  title?: string
+}
+
+withDefaults(defineProps<Props>(), {
+  title: 'Crewli',
+})
+
+const authStore = useAuthStore()
+const menuRef = ref<InstanceType<typeof Menu> | null>(null)
+
+const currentOrg = computed(() => authStore.currentOrganisation)
+const organisations = computed(() => authStore.organisations)
+const hasSwitcher = computed(() => !!currentOrg.value)
+const hasMultiple = computed(() => organisations.value.length > 1)
+
+const orgInitials = computed(() => {
+  const name = currentOrg.value?.name ?? ''
+  const parts = name.split(/\s+/).filter(Boolean).slice(0, 2)
+  const initials = parts.map(w => w[0]?.toUpperCase() ?? '').join('')
+
+  return initials || '?'
+})
+
+// Plan tier placeholder. Backend `Organisation` resource does not yet
+// expose a plan field (see types/auth.ts:17-27); 'Pro' is hardcoded
+// per Bert's A6.1 decision until that field lands.
+const planLabel = 'Pro'
+
+const menuItems = computed(() =>
+  organisations.value.map(org => ({
+    label: org.name,
+    command: () => authStore.setActiveOrganisation(org.id),
+  })),
+)
+
+function toggleMenu(event: Event) {
+  if (!hasMultiple.value)
+    return
+  menuRef.value?.toggle(event)
+}
+</script>
+
+<template>
+  <div class="border-b border-surface-200">
+    <button
+      v-if="hasSwitcher"
+      type="button"
+      class="flex w-full items-center gap-3 px-3 py-3 text-left transition enabled:hover:bg-surface-100 disabled:cursor-default"
+      :disabled="!hasMultiple"
+      :aria-label="hasMultiple ? 'Organisatie wisselen' : currentOrg?.name"
+      :aria-haspopup="hasMultiple ? 'menu' : undefined"
+      @click="toggleMenu"
+    >
+      <Avatar
+        :label="orgInitials"
+        shape="circle"
+        class="shrink-0 bg-primary-500 text-white"
+      />
+      <div class="flex min-w-0 flex-1 flex-col">
+        <span class="truncate text-sm font-semibold text-surface-900">
+          {{ currentOrg?.name }}
+        </span>
+        <span class="text-xs text-surface-500">{{ planLabel }}</span>
+      </div>
+      <Icon
+        v-if="hasMultiple"
+        name="tabler-chevron-down"
+        size="18"
+        class="shrink-0 text-surface-500"
+      />
+    </button>
+
+    <div
+      v-else
+      class="flex h-16 items-center justify-center px-3"
+    >
+      <span class="text-xl font-semibold text-primary-500">{{ title }}</span>
+    </div>
+
+    <Menu
+      ref="menuRef"
+      :model="menuItems"
+      :popup="true"
+    />
+  </div>
+</template>