diff --git a/webui/README.md b/webui/README.md
index bdeaf3b..20b8fe7 100644
--- a/webui/README.md
+++ b/webui/README.md
@@ -71,11 +71,18 @@ npm run build     # what `make admin-ui` runs, plus webui/generate.mjs
   (Overview/Usage, 5s poll), `history` (Charts, fetch-on-selection + 30s
   refresh).
 - `src/components/` — `AuthGate`, `OverviewView`, `UsageView`,
-  `ChartsView`/`UsageChart`, `UsageTable`; `ui/` holds the shadcn-vue
-  primitives this panel actually uses (Card, Table, Tabs, Button, Input,
-  Alert, Select, Badge) — nothing installed and unused.
+  `ChartsView`/`UsageChart`, `UsageTable`, `DataTable` (the shared
+  sortable-table wrapper — shadcn-vue's DataTable pattern, `@tanstack/
+  vue-table`, generic over row type); `ui/` holds the shadcn-vue
+  primitives this panel actually uses (Accordion, Card, Table, Tabs,
+  Button, Input, Alert, Select, Badge) — nothing installed and unused.
+  Providers (Overview) and Groups (Usage) render as a real Accordion —
+  expanding a group shows its member users' own usage rows, a
+  client-side join on `AdminUsageEntryView.groupName`.
 - `src/lib/` — `api.ts` (the `/admin/api/*` fetch wrapper), `format.ts`,
-  `key-storage.ts`, `chart-setup.ts`.
+  `key-storage.ts`, `chart-setup.ts`, `provider-expand.ts` (search-aware
+  expand state, adapted to drive Accordion's v-model), `usage-columns.ts`
+  (shared `ColumnDef`s for every usage table).
 - `src/types/api.ts` — TypeScript mirrors of admin.go's JSON response
   shapes (`adminOverviewResponse`, `adminUsageResponse`,
   `usageHistoryResponse`).
diff --git a/webui/package-lock.json b/webui/package-lock.json
index c5faa42..b4322cb 100644
--- a/webui/package-lock.json
+++ b/webui/package-lock.json
@@ -11,6 +11,7 @@
         "@fortawesome/fontawesome-svg-core": "^7.3.1",
         "@fortawesome/free-solid-svg-icons": "^7.3.1",
         "@fortawesome/vue-fontawesome": "^3.3.3",
+        "@tanstack/vue-table": "^8.21.3",
         "@vueuse/core": "^14.4.0",
         "chart.js": "^4.5.1",
         "class-variance-authority": "^0.7.1",
@@ -1753,6 +1754,19 @@
         "vite": "^5.2.0 || ^6 || ^7 || ^8"
       }
     },
+    "node_modules/@tanstack/table-core": {
+      "version": "8.21.3",
+      "resolved": "https://registry.npmjs.org/@tanstack/table-core/-/table-core-8.21.3.tgz",
+      "integrity": "sha512-ldZXEhOBb8Is7xLs01fR3YEc3DERiz5silj8tnGkFZytt1abEvl/GhUmCE0PMLaMPTa3Jk4HbKmRlHmu+gCftg==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/tannerlinsley"
+      }
+    },
     "node_modules/@tanstack/virtual-core": {
       "version": "3.17.8",
       "resolved": "https://registry.npmjs.org/@tanstack/virtual-core/-/virtual-core-3.17.8.tgz",
@@ -1763,6 +1777,25 @@
         "url": "https://github.com/sponsors/tannerlinsley"
       }
     },
+    "node_modules/@tanstack/vue-table": {
+      "version": "8.21.3",
+      "resolved": "https://registry.npmjs.org/@tanstack/vue-table/-/vue-table-8.21.3.tgz",
+      "integrity": "sha512-rusRyd77c5tDPloPskctMyPLFEQUeBzxdQ+2Eow4F7gDPlPOB1UnnhzfpdvqZ8ZyX2rRNGmqNnQWm87OI2OQPw==",
+      "license": "MIT",
+      "dependencies": {
+        "@tanstack/table-core": "8.21.3"
+      },
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/tannerlinsley"
+      },
+      "peerDependencies": {
+        "vue": ">=3.2"
+      }
+    },
     "node_modules/@tanstack/vue-virtual": {
       "version": "3.13.36",
       "resolved": "https://registry.npmjs.org/@tanstack/vue-virtual/-/vue-virtual-3.13.36.tgz",
diff --git a/webui/package.json b/webui/package.json
index 96db079..11c489c 100644
--- a/webui/package.json
+++ b/webui/package.json
@@ -12,6 +12,7 @@
     "@fortawesome/fontawesome-svg-core": "^7.3.1",
     "@fortawesome/free-solid-svg-icons": "^7.3.1",
     "@fortawesome/vue-fontawesome": "^3.3.3",
+    "@tanstack/vue-table": "^8.21.3",
     "@vueuse/core": "^14.4.0",
     "chart.js": "^4.5.1",
     "class-variance-authority": "^0.7.1",
diff --git a/webui/src/App.vue b/webui/src/App.vue
index 6cf3666..bfd4e56 100644
--- a/webui/src/App.vue
+++ b/webui/src/App.vue
@@ -32,7 +32,7 @@ onMounted(() => {
 </script>
 
 <template>
-  <div class="mx-auto flex max-w-6xl flex-col gap-6 px-4 py-8">
+  <div class="flex w-full flex-col gap-6 px-4 py-8 sm:px-6 lg:px-8">
     <header class="flex flex-col gap-1">
       <h1 class="text-xl font-semibold tracking-tight">LLM Gateway &mdash; Admin</h1>
       <p class="flex items-center gap-1.5 text-sm text-muted-foreground">
diff --git a/webui/src/components/DataTable.vue b/webui/src/components/DataTable.vue
new file mode 100644
index 0000000..33735c1
--- /dev/null
+++ b/webui/src/components/DataTable.vue
@@ -0,0 +1,114 @@
+<script setup lang="ts" generic="TData">
+import type { ColumnDef, SortingState } from '@tanstack/vue-table'
+import { faSort, faSortDown, faSortUp } from '@fortawesome/free-solid-svg-icons'
+import { FlexRender, getCoreRowModel, getSortedRowModel, useVueTable } from '@tanstack/vue-table'
+import { ref } from 'vue'
+
+import {
+  Table,
+  TableBody,
+  TableCell,
+  TableEmpty,
+  TableHead,
+  TableHeader,
+  TableRow,
+  valueUpdater,
+} from '@/components/ui/table'
+
+/**
+ * DataTable is the shared sortable-table shape every real tabular surface
+ * in the panel uses (users usage, a group's nested member-user rows,
+ * aliases) — the shadcn-vue DataTable pattern
+ * (shadcn-vue.com/docs/components/data-table: useVueTable +
+ * getSortedRowModel + FlexRender), factored into one reusable component
+ * instead of re-writing the same table setup and sortable-header-button
+ * boilerplate at every call site (vue.md: "if you've written it twice,
+ * you owe an abstraction"). Each column stays a plain TanStack
+ * `ColumnDef` — a string `header` label plus an optional custom `cell`
+ * renderer — and this component supplies the uniform
+ * clickable-header-with-asc/desc-icon chrome for every column that does
+ * not explicitly set `enableSorting: false`. `meta: { align: 'right' }`
+ * (declared in ui/table/utils.ts) right-aligns a numeric column's header
+ * button and cell content with tabular-nums, matching this panel's
+ * existing numeric-column convention.
+ */
+const props = defineProps<{
+  columns: ColumnDef<TData, unknown>[]
+  data: TData[]
+  /** Extra classes for one row, keyed by its own data (e.g. a destructive tint for a storeDown entry). */
+  rowClass?: (row: TData) => string | undefined
+  /** Shown in the empty-state row when data is empty. */
+  emptyMessage?: string
+}>()
+
+const sorting = ref<SortingState>([])
+
+const table = useVueTable({
+  get data() {
+    return props.data
+  },
+  get columns() {
+    return props.columns
+  },
+  getCoreRowModel: getCoreRowModel(),
+  getSortedRowModel: getSortedRowModel(),
+  onSortingChange: (updater) => valueUpdater(updater, sorting),
+  state: {
+    get sorting() {
+      return sorting.value
+    },
+  },
+})
+
+/** ariaSort maps a column's current sort direction to the `aria-sort` value native to a real <th> — set only on the sorted column, per spec. */
+function ariaSort(dir: false | 'asc' | 'desc'): 'ascending' | 'descending' | undefined {
+  if (dir === 'asc') return 'ascending'
+  if (dir === 'desc') return 'descending'
+  return undefined
+}
+</script>
+
+<template>
+  <Table>
+    <TableHeader>
+      <TableRow v-for="headerGroup in table.getHeaderGroups()" :key="headerGroup.id">
+        <TableHead
+          v-for="header in headerGroup.headers"
+          :key="header.id"
+          :class="header.column.columnDef.meta?.align === 'right' ? 'text-right' : undefined"
+          :aria-sort="header.column.getCanSort() ? (ariaSort(header.column.getIsSorted()) ?? 'none') : undefined"
+        >
+          <button
+            v-if="header.column.getCanSort()"
+            type="button"
+            class="-mx-1.5 inline-flex items-center gap-1 rounded px-1.5 py-0.5 hover:text-foreground focus-visible:ring-3 focus-visible:ring-ring/50 focus-visible:outline-1 focus-visible:outline-ring"
+            @click="header.column.toggleSorting(header.column.getIsSorted() === 'asc')"
+          >
+            <FlexRender v-if="!header.isPlaceholder" :render="header.column.columnDef.header" :props="header.getContext()" />
+            <FontAwesomeIcon
+              :icon="header.column.getIsSorted() === 'asc' ? faSortUp : header.column.getIsSorted() === 'desc' ? faSortDown : faSort"
+              class="size-3 shrink-0"
+              :class="header.column.getIsSorted() ? 'text-foreground' : 'text-muted-foreground/60'"
+              aria-hidden="true"
+            />
+          </button>
+          <FlexRender v-else-if="!header.isPlaceholder" :render="header.column.columnDef.header" :props="header.getContext()" />
+        </TableHead>
+      </TableRow>
+    </TableHeader>
+    <TableBody>
+      <TableEmpty v-if="table.getRowModel().rows.length === 0" :colspan="columns.length" class="text-muted-foreground">
+        {{ emptyMessage ?? 'none' }}
+      </TableEmpty>
+      <TableRow v-for="row in table.getRowModel().rows" :key="row.id" :class="rowClass?.(row.original)">
+        <TableCell
+          v-for="cell in row.getVisibleCells()"
+          :key="cell.id"
+          :class="cell.column.columnDef.meta?.align === 'right' ? 'text-right tabular-nums' : undefined"
+        >
+          <FlexRender :render="cell.column.columnDef.cell" :props="cell.getContext()" />
+        </TableCell>
+      </TableRow>
+    </TableBody>
+  </Table>
+</template>
diff --git a/webui/src/components/OverviewView.vue b/webui/src/components/OverviewView.vue
index 073207b..751159e 100644
--- a/webui/src/components/OverviewView.vue
+++ b/webui/src/components/OverviewView.vue
@@ -1,15 +1,18 @@
 <script setup lang="ts">
+import type { ColumnDef } from '@tanstack/vue-table'
 import {
-  faChevronRight,
   faCircleCheck,
   faCircleXmark,
   faMagnifyingGlass,
   faTriangleExclamation,
   faXmark,
 } from '@fortawesome/free-solid-svg-icons'
-import { computed, reactive, ref, watch } from 'vue'
+import { computed, h, reactive, ref, watch } from 'vue'
 
+import DataTable from '@/components/DataTable.vue'
 import ModelChip from '@/components/ModelChip.vue'
+import { Accordion, AccordionContent, AccordionItem, AccordionTrigger } from '@/components/ui/accordion'
+import { Badge } from '@/components/ui/badge'
 import {
   Card,
   CardContent,
@@ -18,15 +21,6 @@ import {
   CardTitle,
 } from '@/components/ui/card'
 import { Input } from '@/components/ui/input'
-import {
-  Table,
-  TableBody,
-  TableCell,
-  TableEmpty,
-  TableHead,
-  TableHeader,
-  TableRow,
-} from '@/components/ui/table'
 import { formatAgo, formatTimestamp, routableModelId } from '@/lib/format'
 import { type ExpandState, clearExpandOverrides, computeExpandedProviders, toggleProviderExpand } from '@/lib/provider-expand'
 import { useDashboardStore } from '@/stores/dashboard'
@@ -35,42 +29,25 @@ import type { AdminAliasView, AdminProviderView } from '@/types/api'
 const dashboard = useDashboardStore()
 const overview = computed(() => dashboard.overview)
 
-// --- provider row expand/collapse ---
+// --- provider expand/collapse (shadcn-vue Accordion) ---
 //
-// Providers table rows expand to a model list (operator feature). This is
-// NOT shadcn-vue's Accordion or Collapsible component: both wrap
-// trigger+content in one <div>, which cannot legally sit between two
-// <tr> elements inside a <table>/<tbody>. This app renders entirely via
-// Vue's DOM APIs (createElement/appendChild), never by parsing an HTML
-// string, so the HTML5 parser's "foster parenting" algorithm — which
-// only runs while building a DOM tree FROM a token stream — never fires
-// here at all; a <div> placed as a <tbody> child by direct DOM
-// manipulation stays exactly where it was put. CSS2.1 §17.2.1 does
-// define this case: a non-row child of a row-group box is wrapped in
-// an anonymous table-row plus an anonymous table-cell, not left
-// undefined. What actually breaks is column alignment: that one
-// anonymous cell holds the div's entire contents, outside the table's
-// real column structure, so none of it lines up with the table's
-// actual columns. Either way, a <div> does not belong there.
-// (reka-ui's Collapsible primitives DO support an `as` prop that could in
-// principle render Root as a <tbody> and Trigger/Content as <tr> —
-// installed and inspected via the CLI to check, then not used:
-// CollapsibleContent's animation-measurement code calls
-// getBoundingClientRect() and sets inline transition/animation styles on
-// whatever element `as` names, an interaction with a <tr> this component
-// was never designed around and was not worth taking on for an instant
-// show/hide with no transition.) A second, plain <TableRow> toggled by
-// v-if is the correct table-native shape for an expandable row; it
-// reuses Accordion's own visual language (a rotating chevron, a
-// keyboard-accessible trigger) without misusing a component built for
-// block content.
+// Providers render as a real shadcn-vue Accordion (operator directive:
+// use the library component, restructure the layout to fit it — the
+// earlier hand-rolled table-row-toggle accordion is retired). The
+// trigger is one provider's summary line; the content holds its detail
+// (base URL, last refresh, last error) plus its model-id chips.
 //
-// Expand state itself (computeExpandedProviders/toggleProviderExpand/
-// clearExpandOverrides) is a plain, Vue-free module — lib/provider-expand.ts
-// — specifically so the exact toggle-during-search sequence a review
-// flagged is checkable by a throwaway assertion script outside Vue,
-// without standing up a component-test framework this project does not
-// otherwise have.
+// Expand STATE itself is unchanged: lib/provider-expand.ts's plain,
+// Vue-free two-set module (manuallyExpanded/manuallyCollapsed) — the
+// exact search-interaction bug fix a prior review flagged, checkable by
+// its own throwaway assertion script without mounting Vue. Only the
+// template-facing adapter changed: expandedProviderValues below is a
+// writable computed translating that Set-based state into the string[]
+// shape Accordion's `type="multiple"` v-model expects, and back —
+// clicking a trigger fires the setter with the new array; diffing it
+// against the previous effective set finds the one name that changed
+// and replays it through the SAME tested toggleProviderExpand used
+// before, so Accordion never owns this state itself, only displays it.
 const expandState: ExpandState = reactive({
   manuallyExpanded: new Set<string>(),
   manuallyCollapsed: new Set<string>(),
@@ -86,9 +63,8 @@ const hasQuery = computed(() => normalizedQuery.value.length > 0)
  * (routableModelId(p.name, m) — the same string ModelChip both displays
  * and copies), not the bare model id: copying a chip's text and pasting
  * it back into search must find it, and the routable form is strictly
- * more permissive (it contains the bare id as a substring, plus the
- * provider prefix), so this never hides a match the bare-id form would
- * have found.
+ * more permissive (it contains the bare id as a substring), so this
+ * never hides a match the bare-id form would have found.
  */
 function modelMatches(providerName: string, modelId: string): boolean {
   return routableModelId(providerName, modelId).toLowerCase().includes(normalizedQuery.value)
@@ -109,7 +85,7 @@ const filteredAliases = computed<AdminAliasView[]>(() => {
   return hasQuery.value ? all.filter(aliasMatches) : all
 })
 
-/** expandedProviders is what the template reads to decide which rows show their model list — see lib/provider-expand.ts's own doc comments for the manual/auto-expand/override semantics. */
+/** expandedProviders is the EFFECTIVE (possibly auto-expanded-by-search) set — see lib/provider-expand.ts's own doc comments for the manual/auto-expand/override semantics. */
 const expandedProviders = computed<Set<string>>(() =>
   computeExpandedProviders(
     expandState,
@@ -123,6 +99,26 @@ function toggleProvider(name: string): void {
   toggleProviderExpand(expandState, name, expandedProviders.value.has(name))
 }
 
+/**
+ * expandedProviderValues adapts expandedProviders (a Set) to Accordion's
+ * `type="multiple"` v-model contract (a string[]): reads out as
+ * Array.from(expandedProviders.value); writes replay each name whose
+ * membership changed through toggleProvider — Accordion never mutates
+ * expandState directly, it only tells this setter what changed.
+ */
+const expandedProviderValues = computed<string[]>({
+  get: () => Array.from(expandedProviders.value),
+  set: (newValues) => {
+    const next = new Set(newValues)
+    for (const name of expandedProviders.value) {
+      if (!next.has(name)) toggleProvider(name)
+    }
+    for (const name of next) {
+      if (!expandedProviders.value.has(name)) toggleProvider(name)
+    }
+  },
+})
+
 // A stale manuallyCollapsed suppression from one search must never
 // silently carry into a later, unrelated one — see ExpandState's own doc
 // comment. Watching modelQuery (not just the explicit clear button)
@@ -136,23 +132,32 @@ function visibleModels(p: AdminProviderView): string[] {
   return hasQuery.value ? p.models.filter((m) => modelMatches(p.name, m)) : p.models
 }
 
-/**
- * providerModelsId is the id shared by a provider's chevron button
- * (aria-controls, only set while expanded — see the template) and its
- * expanded content row (id). Provider names are not escaped before this
- * template-literal interpolation: buildAdapters (providers.go) rejects
- * any name that does not match configNamePattern
- * (`^[a-zA-Z0-9._-]+$`, providers.go) before this app ever sees it, so
- * no provider name this endpoint can return contains a character an
- * HTML id/attribute value needs escaped.
- */
-function providerModelsId(name: string): string {
-  return `provider-models-${name}`
-}
-
 function clearQuery(): void {
   modelQuery.value = ''
 }
+
+// --- model aliases (sortable DataTable, operator directive) ---
+//
+// The alias id gets the ModelChip copy treatment (an alias name IS the
+// routable string a caller sends as `model`); the target column stays
+// plain text.
+const aliasColumns: ColumnDef<AdminAliasView, unknown>[] = [
+  {
+    id: 'alias',
+    header: 'Alias',
+    accessorFn: (a) => a.alias,
+    cell: ({ row }) => h(ModelChip, { id: row.original.alias }),
+  },
+  {
+    id: 'target',
+    header: 'Target',
+    accessorFn: (a) => a.target,
+    cell: ({ row }) => h('span', { class: 'text-muted-foreground' }, row.original.target),
+  },
+]
+const aliasEmptyMessage = computed(() =>
+  !overview.value?.aliases.length ? 'none configured' : hasQuery.value ? `no aliases match "${modelQuery.value}"` : 'none',
+)
 </script>
 
 <template>
@@ -247,83 +252,51 @@ function clearQuery(): void {
         </div>
       </CardHeader>
       <CardContent>
-        <Table>
-          <TableHeader>
-            <TableRow>
-              <TableHead>Name</TableHead>
-              <TableHead>Type</TableHead>
-              <TableHead>Base URL</TableHead>
-              <TableHead class="text-right">Models</TableHead>
-              <TableHead>Last refresh</TableHead>
-              <TableHead>Last error</TableHead>
-            </TableRow>
-          </TableHeader>
-          <TableBody>
-            <TableEmpty v-if="!overview?.providers.length" :colspan="6" class="text-muted-foreground">
-              none
-            </TableEmpty>
-            <TableEmpty
-              v-else-if="hasQuery && filteredProviders.length === 0"
-              :colspan="6"
-              class="text-muted-foreground"
-            >
-              no providers match &quot;{{ modelQuery }}&quot;
-            </TableEmpty>
-            <template v-for="p in filteredProviders" :key="p.name">
-              <TableRow class="cursor-pointer select-none hover:bg-accent/50" @click="toggleProvider(p.name)">
-                <TableCell class="font-medium">
-                  <!--
-                    A real <button>, not role="button" on the <tr>: a <tr>
-                    carries table-row AT semantics (a screen reader
-                    announces it as part of the table's row/column
-                    structure), and overriding that to "button" strips
-                    those semantics from the whole row — exactly the kind
-                    of ARIA-over-native mistake the "semantics first"
-                    rule warns against. The button lives in the natural
-                    host, the chevron+name span, and needs no click
-                    handler of its own: its native click (mouse, or Enter/
-                    Space while focused — free, standard <button>
-                    behavior, no keydown handling to write) bubbles up to
-                    the row's own @click above, so exactly one place
-                    (the row) ever runs the actual toggle. aria-controls
-                    is set ONLY while expanded (not unconditionally): the
-                    content row is v-if, not v-show (Lazy rendering — see
-                    the models div below), so an id it would point to
-                    while collapsed does not exist in the DOM yet, and
-                    ARIA requires aria-controls name an id that exists.
-                  -->
-                  <button
-                    type="button"
-                    class="-my-1 flex items-center gap-2 rounded py-1 focus-visible:ring-3 focus-visible:ring-ring/50 focus-visible:outline-1 focus-visible:outline-ring"
-                    :aria-expanded="expandedProviders.has(p.name)"
-                    :aria-controls="expandedProviders.has(p.name) ? providerModelsId(p.name) : undefined"
-                  >
-                    <FontAwesomeIcon
-                      :icon="faChevronRight"
-                      class="size-3 shrink-0 text-muted-foreground transition-transform duration-150"
-                      :class="expandedProviders.has(p.name) ? 'rotate-90' : ''"
-                      aria-hidden="true"
-                    />
-                    {{ p.name }}
-                  </button>
-                </TableCell>
-                <TableCell class="text-muted-foreground">{{ p.type }}</TableCell>
-                <TableCell class="text-muted-foreground">{{ p.baseUrl }}</TableCell>
-                <TableCell class="text-right tabular-nums">{{ p.modelCount }}</TableCell>
-                <TableCell class="text-muted-foreground">{{ formatTimestamp(p.lastRefresh) }}</TableCell>
-                <TableCell class="text-destructive">{{ p.lastErr ?? '' }}</TableCell>
-              </TableRow>
-              <TableRow v-if="expandedProviders.has(p.name)" :id="providerModelsId(p.name)">
-                <TableCell colspan="6" class="whitespace-normal bg-muted/30">
-                  <div v-if="visibleModels(p).length" class="flex flex-wrap gap-1.5 py-1">
-                    <ModelChip v-for="m in visibleModels(p)" :key="m" :id="routableModelId(p.name, m)" />
-                  </div>
-                  <p v-else class="py-1 text-sm text-muted-foreground">no models known yet</p>
-                </TableCell>
-              </TableRow>
-            </template>
-          </TableBody>
-        </Table>
+        <p v-if="!overview?.providers.length" class="py-6 text-center text-sm text-muted-foreground">none</p>
+        <p
+          v-else-if="hasQuery && filteredProviders.length === 0"
+          class="py-6 text-center text-sm text-muted-foreground"
+        >
+          no providers match &quot;{{ modelQuery }}&quot;
+        </p>
+        <Accordion v-else v-model="expandedProviderValues" type="multiple" class="rounded-md border px-3">
+          <AccordionItem v-for="p in filteredProviders" :key="p.name" :value="p.name">
+            <AccordionTrigger>
+              <div class="flex flex-1 flex-wrap items-center gap-x-3 gap-y-1 pr-2 text-left">
+                <span class="font-medium">{{ p.name }}</span>
+                <Badge variant="secondary" class="font-normal">{{ p.type }}</Badge>
+                <span class="text-xs text-muted-foreground tabular-nums">{{ p.modelCount }} models</span>
+                <FontAwesomeIcon
+                  v-if="p.lastErr"
+                  :icon="faTriangleExclamation"
+                  class="size-3.5 shrink-0 text-destructive"
+                  aria-hidden="true"
+                />
+                <span class="text-xs text-muted-foreground">refreshed {{ formatAgo(p.lastRefresh) || 'never' }}</span>
+              </div>
+            </AccordionTrigger>
+            <AccordionContent>
+              <dl class="mb-3 grid grid-cols-2 gap-x-6 gap-y-1.5 text-sm sm:grid-cols-3">
+                <div>
+                  <dt class="text-xs text-muted-foreground">Base URL</dt>
+                  <dd class="break-all">{{ p.baseUrl }}</dd>
+                </div>
+                <div>
+                  <dt class="text-xs text-muted-foreground">Last refresh</dt>
+                  <dd>{{ formatTimestamp(p.lastRefresh) }}</dd>
+                </div>
+                <div v-if="p.lastErr">
+                  <dt class="text-xs text-muted-foreground">Last error</dt>
+                  <dd class="text-destructive">{{ p.lastErr }}</dd>
+                </div>
+              </dl>
+              <div v-if="visibleModels(p).length" class="flex flex-wrap gap-1.5">
+                <ModelChip v-for="m in visibleModels(p)" :key="m" :id="routableModelId(p.name, m)" />
+              </div>
+              <p v-else class="text-sm text-muted-foreground">no models known yet</p>
+            </AccordionContent>
+          </AccordionItem>
+        </Accordion>
       </CardContent>
     </Card>
 
@@ -333,30 +306,7 @@ function clearQuery(): void {
         <CardDescription>Operator-defined alias &rarr; target model mappings.</CardDescription>
       </CardHeader>
       <CardContent>
-        <Table>
-          <TableHeader>
-            <TableRow>
-              <TableHead>Alias</TableHead>
-              <TableHead>Target</TableHead>
-            </TableRow>
-          </TableHeader>
-          <TableBody>
-            <TableEmpty v-if="!overview?.aliases.length" :colspan="2" class="text-muted-foreground">
-              none configured
-            </TableEmpty>
-            <TableEmpty
-              v-else-if="hasQuery && filteredAliases.length === 0"
-              :colspan="2"
-              class="text-muted-foreground"
-            >
-              no aliases match &quot;{{ modelQuery }}&quot;
-            </TableEmpty>
-            <TableRow v-for="a in filteredAliases" :key="a.alias">
-              <TableCell class="font-medium">{{ a.alias }}</TableCell>
-              <TableCell class="text-muted-foreground">{{ a.target }}</TableCell>
-            </TableRow>
-          </TableBody>
-        </Table>
+        <DataTable :columns="aliasColumns" :data="filteredAliases" :empty-message="aliasEmptyMessage" />
       </CardContent>
     </Card>
 
diff --git a/webui/src/components/UsageTable.vue b/webui/src/components/UsageTable.vue
index 7220450..7004a49 100644
--- a/webui/src/components/UsageTable.vue
+++ b/webui/src/components/UsageTable.vue
@@ -1,85 +1,33 @@
 <script setup lang="ts">
-import { formatCost, formatLimits } from '@/lib/format'
-import {
-  Table,
-  TableBody,
-  TableCell,
-  TableEmpty,
-  TableHead,
-  TableHeader,
-  TableRow,
-} from '@/components/ui/table'
+import { computed } from 'vue'
+
+import DataTable from '@/components/DataTable.vue'
+import { usageColumns } from '@/lib/usage-columns'
 import type { AdminUsageEntryView } from '@/types/api'
 
 /**
- * UsageTable renders one scope kind's usage rows (users or groups) — the
- * shared table shape both need (vue.md: extract before you paste it
- * twice). The second column differs per kind: a user's row shows the group
- * it belongs to; a group's row shows its member count (looked up from the
- * Overview response, which is the only place member counts live).
+ * UsageTable renders one scope kind's usage rows (users, or a group's
+ * member users) as a sortable DataTable (shadcn-vue's DataTable pattern,
+ * via the shared usageColumns() defs — vue.md: extract before you paste
+ * it twice). The second column differs per kind: a user's row shows the
+ * group it belongs to; a group's row shows its member count (looked up
+ * from the Overview response, which is the only place member counts
+ * live).
  */
-defineProps<{
+const props = defineProps<{
   idLabel: string
   entries: AdminUsageEntryView[]
   secondaryColumnLabel: string
   secondaryValue: (entry: AdminUsageEntryView) => string
 }>()
+
+const columns = computed(() => usageColumns(props.idLabel, props.secondaryColumnLabel, props.secondaryValue))
 </script>
 
 <template>
-  <Table>
-    <TableHeader>
-      <TableRow>
-        <TableHead>{{ idLabel }}</TableHead>
-        <TableHead>{{ secondaryColumnLabel }}</TableHead>
-        <TableHead>Limits</TableHead>
-        <TableHead class="text-right">req/min</TableHead>
-        <TableHead class="text-right">req/day</TableHead>
-        <TableHead class="text-right">tokIn/day</TableHead>
-        <TableHead class="text-right">tokOut/day</TableHead>
-        <TableHead class="text-right">tokIn/month</TableHead>
-        <TableHead class="text-right">tokOut/month</TableHead>
-        <TableHead class="text-right">cost/day</TableHead>
-        <TableHead class="text-right">cost/month</TableHead>
-      </TableRow>
-    </TableHeader>
-    <TableBody>
-      <TableEmpty v-if="entries.length === 0" :colspan="11" class="text-muted-foreground">
-        none
-      </TableEmpty>
-      <TableRow
-        v-for="entry in entries"
-        :key="entry.id"
-        :class="entry.storeDown ? 'bg-destructive/10' : undefined"
-      >
-        <TableCell class="font-medium">{{ entry.id }}</TableCell>
-        <TableCell class="text-muted-foreground">{{ secondaryValue(entry) }}</TableCell>
-        <TableCell class="text-muted-foreground">{{ formatLimits(entry.limits) }}</TableCell>
-        <TableCell class="text-right tabular-nums">
-          {{ entry.storeDown ? '?' : entry.requestsPerMinute }}
-        </TableCell>
-        <TableCell class="text-right tabular-nums">
-          {{ entry.storeDown ? '?' : entry.requestsPerDay }}
-        </TableCell>
-        <TableCell class="text-right tabular-nums">
-          {{ entry.storeDown ? '?' : entry.tokensInPerDay }}
-        </TableCell>
-        <TableCell class="text-right tabular-nums">
-          {{ entry.storeDown ? '?' : entry.tokensOutPerDay }}
-        </TableCell>
-        <TableCell class="text-right tabular-nums">
-          {{ entry.storeDown ? '?' : entry.tokensInPerMonth }}
-        </TableCell>
-        <TableCell class="text-right tabular-nums">
-          {{ entry.storeDown ? '?' : entry.tokensOutPerMonth }}
-        </TableCell>
-        <TableCell class="text-right tabular-nums">
-          {{ entry.storeDown ? '?' : formatCost(entry.costPerDayMicroUsd) }}
-        </TableCell>
-        <TableCell class="text-right tabular-nums">
-          {{ entry.storeDown ? '?' : formatCost(entry.costPerMonthMicroUsd) }}
-        </TableCell>
-      </TableRow>
-    </TableBody>
-  </Table>
+  <DataTable
+    :columns="columns"
+    :data="entries"
+    :row-class="(entry) => (entry.storeDown ? 'bg-destructive/10' : undefined)"
+  />
 </template>
diff --git a/webui/src/components/UsageView.vue b/webui/src/components/UsageView.vue
index 6d11744..7477085 100644
--- a/webui/src/components/UsageView.vue
+++ b/webui/src/components/UsageView.vue
@@ -1,9 +1,15 @@
 <script setup lang="ts">
-import { computed } from 'vue'
+import type { SortingState } from '@tanstack/vue-table'
+import { faSort, faSortDown, faSortUp } from '@fortawesome/free-solid-svg-icons'
+import { FlexRender, getCoreRowModel, getSortedRowModel, useVueTable } from '@tanstack/vue-table'
+import { computed, ref } from 'vue'
 
+import { Accordion, AccordionContent, AccordionItem, AccordionTrigger } from '@/components/ui/accordion'
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card'
+import { valueUpdater } from '@/components/ui/table'
 import UsageTable from '@/components/UsageTable.vue'
-import { formatCost } from '@/lib/format'
+import { formatCost, formatLimits } from '@/lib/format'
+import { usageColumns } from '@/lib/usage-columns'
 import { useDashboardStore } from '@/stores/dashboard'
 import type { AdminUsageEntryView } from '@/types/api'
 
@@ -24,6 +30,66 @@ function memberCountOf(entry: AdminUsageEntryView): string {
   const count = memberCounts.value[entry.id]
   return count === undefined ? '' : String(count)
 }
+
+/**
+ * membersOf returns one group's own member users' usage rows — a user's
+ * row already carries its own group name (admin.go's
+ * adminUsageEntryView.GroupName, set in buildAdminUsage), so this is a
+ * plain client-side join against the SAME GET /admin/api/usage response
+ * already in the store, no extra fetch. Verified this field already
+ * exists and is already asserted by a backend test
+ * (admin_test.go's TestAdminUsage_MathAgainstSeededCounters checks
+ * alice.GroupName == "agroup") — no backend change was needed for this.
+ */
+function membersOf(group: AdminUsageEntryView): AdminUsageEntryView[] {
+  return (usage.value?.users ?? []).filter((u) => u.groupName === group.id)
+}
+
+// --- Groups accordion (operator directive) ---
+//
+// Groups render as a shadcn-vue Accordion, same component and rationale
+// as Providers (OverviewView.vue) — expanding a group shows its member
+// users' own usage rows below it. A group's row cannot ALSO be a literal
+// <table> row for the identical reason Providers' old expandable row was
+// retired: AccordionItem wraps its trigger+content in a <div>, illegal
+// directly inside a <tbody>/<tr>.
+//
+// "Sortable groups usage" (operator directive) is therefore implemented
+// headlessly: the SAME usageColumns() defs used by the real <table>-based
+// UsageTable (Users, and each group's own nested member list) drive a
+// second, unrendered useVueTable instance here purely for its
+// getSortedRowModel() — sortedGroupRows below. The small button toolbar
+// under the Groups heading toggles that sort exactly like DataTable.vue's
+// own sortable header buttons (same icons, same toggleSorting call,
+// same aria-sort), just laid out as a toolbar instead of <th>s, because
+// there is no <table> here to put a <th> in.
+const groupColumns = usageColumns('Name', 'Members', memberCountOf)
+const groupSorting = ref<SortingState>([])
+const groupsTable = useVueTable({
+  get data() {
+    return usage.value?.groups ?? []
+  },
+  get columns() {
+    return groupColumns
+  },
+  getCoreRowModel: getCoreRowModel(),
+  getSortedRowModel: getSortedRowModel(),
+  onSortingChange: (updater) => valueUpdater(updater, groupSorting),
+  state: {
+    get sorting() {
+      return groupSorting.value
+    },
+  },
+})
+const sortedGroupRows = computed(() => groupsTable.getRowModel().rows)
+
+/** ariaSort mirrors DataTable.vue's own helper — kept local since this toolbar isn't a <table> (aria-sort still applies to the toolbar buttons' own semantics, not a <th>, so it's set as a data attribute for styling/testing rather than the real ARIA property here). */
+function isSorted(id: string): false | 'asc' | 'desc' {
+  return groupsTable.getColumn(id)?.getIsSorted() ?? false
+}
+
+/** Which groups are open — plain array state (no search-driven auto-expand exists for this view, unlike Providers, so the two-set provider-expand.ts module is not needed here). */
+const expandedGroups = ref<string[]>([])
 </script>
 
 <template>
@@ -56,14 +122,87 @@ function memberCountOf(entry: AdminUsageEntryView): string {
     <Card>
       <CardHeader>
         <CardTitle>Groups</CardTitle>
+        <CardDescription>Expand a group to see its member users' own usage.</CardDescription>
       </CardHeader>
       <CardContent>
-        <UsageTable
-          id-label="Name"
-          secondary-column-label="Members"
-          :entries="usage?.groups ?? []"
-          :secondary-value="memberCountOf"
-        />
+        <div
+          v-if="sortedGroupRows.length"
+          class="mb-3 flex flex-wrap gap-x-4 gap-y-1 text-xs font-medium text-muted-foreground"
+        >
+          <button
+            v-for="header in groupsTable.getHeaderGroups()[0].headers"
+            :key="header.id"
+            type="button"
+            class="inline-flex items-center gap-1 rounded px-1 py-0.5 hover:text-foreground focus-visible:ring-3 focus-visible:ring-ring/50 focus-visible:outline-1 focus-visible:outline-ring"
+            :data-sort="isSorted(header.column.id) || 'none'"
+            @click="header.column.toggleSorting(isSorted(header.column.id) === 'asc')"
+          >
+            <FlexRender :render="header.column.columnDef.header" :props="header.getContext()" />
+            <FontAwesomeIcon
+              :icon="isSorted(header.column.id) === 'asc' ? faSortUp : isSorted(header.column.id) === 'desc' ? faSortDown : faSort"
+              class="size-3 shrink-0"
+              :class="isSorted(header.column.id) ? 'text-foreground' : 'text-muted-foreground/50'"
+              aria-hidden="true"
+            />
+          </button>
+        </div>
+
+        <Accordion v-if="sortedGroupRows.length" v-model="expandedGroups" type="multiple" class="rounded-md border px-3">
+          <AccordionItem v-for="row in sortedGroupRows" :key="row.original.id" :value="row.original.id">
+            <AccordionTrigger>
+              <div class="flex flex-1 flex-wrap items-center gap-x-4 gap-y-1 pr-2 text-left">
+                <span class="font-medium">{{ row.original.id }}</span>
+                <span class="text-xs text-muted-foreground tabular-nums">{{ memberCountOf(row.original) || '0' }} members</span>
+                <span class="text-xs text-muted-foreground tabular-nums">
+                  {{ row.original.storeDown ? '?' : row.original.requestsPerDay }} req/day
+                </span>
+                <span class="text-xs text-muted-foreground tabular-nums">
+                  {{ row.original.storeDown ? '?' : formatCost(row.original.costPerDayMicroUsd) }}/day
+                </span>
+              </div>
+            </AccordionTrigger>
+            <AccordionContent>
+              <dl class="mb-3 grid grid-cols-2 gap-x-6 gap-y-1.5 text-sm sm:grid-cols-4">
+                <div>
+                  <dt class="text-xs text-muted-foreground">Limits</dt>
+                  <dd>{{ formatLimits(row.original.limits) }}</dd>
+                </div>
+                <div>
+                  <dt class="text-xs text-muted-foreground">req/min</dt>
+                  <dd class="tabular-nums">{{ row.original.storeDown ? '?' : row.original.requestsPerMinute }}</dd>
+                </div>
+                <div>
+                  <dt class="text-xs text-muted-foreground">tokIn/day</dt>
+                  <dd class="tabular-nums">{{ row.original.storeDown ? '?' : row.original.tokensInPerDay }}</dd>
+                </div>
+                <div>
+                  <dt class="text-xs text-muted-foreground">tokOut/day</dt>
+                  <dd class="tabular-nums">{{ row.original.storeDown ? '?' : row.original.tokensOutPerDay }}</dd>
+                </div>
+                <div>
+                  <dt class="text-xs text-muted-foreground">tokIn/month</dt>
+                  <dd class="tabular-nums">{{ row.original.storeDown ? '?' : row.original.tokensInPerMonth }}</dd>
+                </div>
+                <div>
+                  <dt class="text-xs text-muted-foreground">tokOut/month</dt>
+                  <dd class="tabular-nums">{{ row.original.storeDown ? '?' : row.original.tokensOutPerMonth }}</dd>
+                </div>
+                <div>
+                  <dt class="text-xs text-muted-foreground">cost/month</dt>
+                  <dd class="tabular-nums">{{ row.original.storeDown ? '?' : formatCost(row.original.costPerMonthMicroUsd) }}</dd>
+                </div>
+              </dl>
+              <p class="mb-1.5 text-xs font-medium text-muted-foreground">Members</p>
+              <UsageTable
+                id-label="Name"
+                secondary-column-label="Group"
+                :entries="membersOf(row.original)"
+                :secondary-value="groupNameOf"
+              />
+            </AccordionContent>
+          </AccordionItem>
+        </Accordion>
+        <p v-else class="py-6 text-center text-sm text-muted-foreground">none</p>
       </CardContent>
     </Card>
 
diff --git a/webui/src/components/ui/accordion/Accordion.vue b/webui/src/components/ui/accordion/Accordion.vue
new file mode 100644
index 0000000..757d951
--- /dev/null
+++ b/webui/src/components/ui/accordion/Accordion.vue
@@ -0,0 +1,27 @@
+<script setup lang="ts">
+import type { AccordionRootEmits, AccordionRootProps } from 'reka-ui'
+import type { HTMLAttributes } from 'vue'
+import { reactiveOmit } from '@vueuse/core'
+import {
+  AccordionRoot,
+  useForwardPropsEmits,
+} from 'reka-ui'
+import { cn } from '@/lib/utils'
+
+const props = defineProps<AccordionRootProps & { class?: HTMLAttributes['class'] }>()
+const emits = defineEmits<AccordionRootEmits>()
+
+const delegatedProps = reactiveOmit(props, 'class')
+const forwarded = useForwardPropsEmits(delegatedProps, emits)
+</script>
+
+<template>
+  <AccordionRoot
+    v-slot="slotProps"
+    data-slot="accordion"
+    v-bind="forwarded"
+    :class="cn('flex w-full flex-col', props.class)"
+  >
+    <slot v-bind="slotProps" />
+  </AccordionRoot>
+</template>
diff --git a/webui/src/components/ui/accordion/AccordionContent.vue b/webui/src/components/ui/accordion/AccordionContent.vue
new file mode 100644
index 0000000..394dd71
--- /dev/null
+++ b/webui/src/components/ui/accordion/AccordionContent.vue
@@ -0,0 +1,28 @@
+<script setup lang="ts">
+import type { AccordionContentProps } from 'reka-ui'
+import type { HTMLAttributes } from 'vue'
+import { reactiveOmit } from '@vueuse/core'
+import { AccordionContent } from 'reka-ui'
+import { cn } from '@/lib/utils'
+
+const props = defineProps<AccordionContentProps & { class?: HTMLAttributes['class'] }>()
+
+const delegatedProps = reactiveOmit(props, 'class')
+</script>
+
+<template>
+  <AccordionContent
+    data-slot="accordion-content"
+    v-bind="delegatedProps"
+    class="data-open:animate-accordion-down data-closed:animate-accordion-up text-sm overflow-hidden"
+  >
+    <div
+      :class="cn(
+        'pt-0 pb-2.5 [&_a]:underline [&_a]:underline-offset-3 [&_a]:hover:text-foreground [&_p:not(:last-child)]:mb-4',
+        props.class,
+      )"
+    >
+      <slot />
+    </div>
+  </AccordionContent>
+</template>
diff --git a/webui/src/components/ui/accordion/AccordionItem.vue b/webui/src/components/ui/accordion/AccordionItem.vue
new file mode 100644
index 0000000..31a89dd
--- /dev/null
+++ b/webui/src/components/ui/accordion/AccordionItem.vue
@@ -0,0 +1,24 @@
+<script setup lang="ts">
+import type { AccordionItemProps } from 'reka-ui'
+import type { HTMLAttributes } from 'vue'
+import { reactiveOmit } from '@vueuse/core'
+import { AccordionItem, useForwardProps } from 'reka-ui'
+import { cn } from '@/lib/utils'
+
+const props = defineProps<AccordionItemProps & { class?: HTMLAttributes['class'] }>()
+
+const delegatedProps = reactiveOmit(props, 'class')
+
+const forwardedProps = useForwardProps(delegatedProps)
+</script>
+
+<template>
+  <AccordionItem
+    v-slot="slotProps"
+    data-slot="accordion-item"
+    v-bind="forwardedProps"
+    :class="cn('not-last:border-b', props.class)"
+  >
+    <slot v-bind="slotProps" />
+  </AccordionItem>
+</template>
diff --git a/webui/src/components/ui/accordion/AccordionTrigger.vue b/webui/src/components/ui/accordion/AccordionTrigger.vue
new file mode 100644
index 0000000..6c52446
--- /dev/null
+++ b/webui/src/components/ui/accordion/AccordionTrigger.vue
@@ -0,0 +1,47 @@
+<script setup lang="ts">
+import type { AccordionTriggerProps } from 'reka-ui'
+
+import type { HTMLAttributes } from 'vue'
+import { faChevronDown, faChevronUp } from '@fortawesome/free-solid-svg-icons'
+import { reactiveOmit } from '@vueuse/core'
+import {
+  AccordionHeader,
+  AccordionTrigger,
+} from 'reka-ui'
+import { cn } from '@/lib/utils'
+
+const props = defineProps<AccordionTriggerProps & { class?: HTMLAttributes['class'] }>()
+
+const delegatedProps = reactiveOmit(props, 'class')
+</script>
+
+<template>
+  <AccordionHeader class="flex">
+    <AccordionTrigger
+      data-slot="accordion-trigger"
+      v-bind="delegatedProps"
+      :class="
+        cn(
+          'focus-visible:ring-ring/50 focus-visible:border-ring focus-visible:after:border-ring **:data-[slot=accordion-trigger-icon]:text-muted-foreground rounded-lg py-2.5 text-left text-sm font-medium hover:underline focus-visible:ring-3 **:data-[slot=accordion-trigger-icon]:ml-auto **:data-[slot=accordion-trigger-icon]:size-4 group/accordion-trigger relative flex flex-1 items-start justify-between border border-transparent transition-all outline-none disabled:pointer-events-none disabled:opacity-50',
+          props.class,
+        )
+      "
+    >
+      <slot />
+      <slot name="icon">
+        <FontAwesomeIcon
+          :icon="faChevronDown"
+          data-slot="accordion-trigger-icon"
+          aria-hidden="true"
+          class="pointer-events-none shrink-0 group-aria-expanded/accordion-trigger:hidden"
+        />
+        <FontAwesomeIcon
+          :icon="faChevronUp"
+          data-slot="accordion-trigger-icon"
+          aria-hidden="true"
+          class="pointer-events-none hidden shrink-0 group-aria-expanded/accordion-trigger:inline"
+        />
+      </slot>
+    </AccordionTrigger>
+  </AccordionHeader>
+</template>
diff --git a/webui/src/components/ui/accordion/index.ts b/webui/src/components/ui/accordion/index.ts
new file mode 100644
index 0000000..9340ac0
--- /dev/null
+++ b/webui/src/components/ui/accordion/index.ts
@@ -0,0 +1,4 @@
+export { default as Accordion } from './Accordion.vue'
+export { default as AccordionContent } from './AccordionContent.vue'
+export { default as AccordionItem } from './AccordionItem.vue'
+export { default as AccordionTrigger } from './AccordionTrigger.vue'
diff --git a/webui/src/components/ui/table/index.ts b/webui/src/components/ui/table/index.ts
index 2b4ce39..1fda83a 100644
--- a/webui/src/components/ui/table/index.ts
+++ b/webui/src/components/ui/table/index.ts
@@ -7,3 +7,4 @@ export { default as TableFooter } from './TableFooter.vue'
 export { default as TableHead } from './TableHead.vue'
 export { default as TableHeader } from './TableHeader.vue'
 export { default as TableRow } from './TableRow.vue'
+export { valueUpdater } from './utils'
diff --git a/webui/src/components/ui/table/utils.ts b/webui/src/components/ui/table/utils.ts
new file mode 100644
index 0000000..ed3e301
--- /dev/null
+++ b/webui/src/components/ui/table/utils.ts
@@ -0,0 +1,20 @@
+import type { RowData, Updater } from '@tanstack/vue-table'
+import type { Ref } from 'vue'
+
+/**
+ * valueUpdater applies one TanStack Table `Updater<T>` — either a new
+ * value, or a function from the old value to the new one — to a plain Vue
+ * ref. This is the standard shadcn-vue glue between TanStack Table's
+ * callback-based state updates (`onSortingChange`, etc.) and Vue's
+ * ref-based reactivity (shadcn-vue docs: /docs/components/data-table).
+ */
+export function valueUpdater<T>(updaterOrValue: Updater<T>, ref: Ref<T>): void {
+  ref.value = typeof updaterOrValue === 'function' ? (updaterOrValue as (old: T) => T)(ref.value) : updaterOrValue
+}
+
+declare module '@tanstack/vue-table' {
+  interface ColumnMeta<TData extends RowData, TValue> {
+    /** Right-align this column's header button and cell content, with tabular-nums — set on numeric columns (DataTable.vue reads this). */
+    align?: 'right'
+  }
+}
diff --git a/webui/src/lib/usage-columns.ts b/webui/src/lib/usage-columns.ts
new file mode 100644
index 0000000..197e79e
--- /dev/null
+++ b/webui/src/lib/usage-columns.ts
@@ -0,0 +1,75 @@
+import type { ColumnDef } from '@tanstack/vue-table'
+import { h } from 'vue'
+
+import { formatCost, formatLimits } from '@/lib/format'
+import type { AdminUsageEntryView } from '@/types/api'
+
+/**
+ * numericColumn builds one right-aligned, sortable numeric column that
+ * reads '?' instead of a stale number while the entry's own scope has a
+ * down store — DataTable.vue's cell renderer, not the accessor, does this
+ * check, so sorting itself still uses the entry's real underlying value
+ * (a storeDown row sorts by its last-known number, same as the rest of
+ * the table; only the DISPLAYED text is masked). Mirrors the pre-DataTable
+ * UsageTable.vue template's own `entry.storeDown ? '?' : ...` convention.
+ */
+function numericColumn(
+  id: string,
+  header: string,
+  read: (entry: AdminUsageEntryView) => number,
+  format: (n: number) => string = String,
+): ColumnDef<AdminUsageEntryView, unknown> {
+  return {
+    id,
+    header,
+    accessorFn: read,
+    meta: { align: 'right' },
+    cell: ({ row }) => (row.original.storeDown ? '?' : format(read(row.original))),
+  }
+}
+
+/**
+ * usageColumns builds the shared TanStack `ColumnDef` set for one
+ * AdminUsageEntryView table. Used by UsageTable.vue (the flat Users list,
+ * and — reused unmodified — a group's nested member-user list inside the
+ * Usage view's Groups accordion) and, headlessly (no `<Table>` render, see
+ * that view's own doc comment for why), by UsageView.vue's Groups sort
+ * bar, so both surfaces sort by the exact same column semantics.
+ * idLabel/secondaryColumnLabel name the first two columns; secondaryValue
+ * reads the second column's per-row value (a user's group name, or a
+ * group's member count).
+ */
+export function usageColumns(
+  idLabel: string,
+  secondaryColumnLabel: string,
+  secondaryValue: (entry: AdminUsageEntryView) => string,
+): ColumnDef<AdminUsageEntryView, unknown>[] {
+  return [
+    {
+      id: 'id',
+      header: idLabel,
+      accessorFn: (entry) => entry.id,
+      cell: ({ row }) => h('span', { class: 'font-medium' }, row.original.id),
+    },
+    {
+      id: 'secondary',
+      header: secondaryColumnLabel,
+      accessorFn: secondaryValue,
+      cell: ({ row }) => h('span', { class: 'text-muted-foreground' }, secondaryValue(row.original)),
+    },
+    {
+      id: 'limits',
+      header: 'Limits',
+      accessorFn: (entry) => formatLimits(entry.limits),
+      cell: ({ row }) => h('span', { class: 'text-muted-foreground' }, formatLimits(row.original.limits)),
+    },
+    numericColumn('reqMin', 'req/min', (e) => e.requestsPerMinute),
+    numericColumn('reqDay', 'req/day', (e) => e.requestsPerDay),
+    numericColumn('tokInDay', 'tokIn/day', (e) => e.tokensInPerDay),
+    numericColumn('tokOutDay', 'tokOut/day', (e) => e.tokensOutPerDay),
+    numericColumn('tokInMonth', 'tokIn/month', (e) => e.tokensInPerMonth),
+    numericColumn('tokOutMonth', 'tokOut/month', (e) => e.tokensOutPerMonth),
+    numericColumn('costDay', 'cost/day', (e) => e.costPerDayMicroUsd, formatCost),
+    numericColumn('costMonth', 'cost/month', (e) => e.costPerMonthMicroUsd, formatCost),
+  ]
+}