fix(usage): render resource timestamps in their rollup tz, not browser-local

src/pages/usage/components/gpu-instances-tab.tsx

@@ -32,7 +32,8 @@ import {
 import {
   bucketKey,
   generateBucketRange,
-  Granularity
+  Granularity,
+  parseRollup
 } from '../utils/time-buckets';
 import { buildTrendSeries } from '../utils/trend-series';
 import MetricChartCard from './metric-chart-card';
@@ -328,12 +329,14 @@ const GpuInstancesTab: React.FC = () => {
         />
       )
     };
-    // Last Active is a UTC instant (max bucket hour) → show formatted local time.
+    // Last Active = the last active day. The backend sends a rollup-tz instant
+    // with its offset; parseRollup keeps that wall clock (no browser-tz convert),
+    // consistent with the trend chart buckets. Shown date-only.
     const lastActiveCol = {
       title: intl.formatMessage({ id: 'usage.table.lastActive' }),
       dataIndex: 'last_active',
       key: 'last_active',
-      render: (v?: string) => (v ? dayjs(v).format('YYYY-MM-DD HH:mm:ss') : '-')
+      render: (v?: string) => (v ? parseRollup(v).format('YYYY-MM-DD') : '-')
     };
     if (activeTableTab === 'gpu_type') {
       return [

src/pages/usage/components/resource-events.tsx

@@ -24,6 +24,7 @@ import {
   ResourceEventItem,
   ResourceEventsResponse
 } from '../apis/resource';
+import { parseRollup } from '../utils/time-buckets';
 import ResourceFilterBar from './resource-filter-bar';
 
 // Only these four are ever emitted (see resource_event_logger): create/delete
@@ -177,8 +178,10 @@ const ResourceEvents: React.FC = () => {
         title: intl.formatMessage({ id: 'usage.events.col.time' }),
         dataIndex: 'occurred_at',
         key: 'occurred_at',
+        // Backend sends the rollup-tz instant with its offset; parseRollup keeps
+        // it (no conversion to the browser tz).
         render: (v: string) =>
-          v ? dayjs(v).format('YYYY-MM-DD HH:mm:ss') : '-',
+          v ? parseRollup(v).format('YYYY-MM-DD HH:mm:ss') : '-',
         width: 200
       },
       {

src/pages/usage/components/storage-tab.tsx

@@ -28,7 +28,8 @@ import useResourceMeta from '../hooks/use-resource-meta';
 import {
   bucketKey,
   generateBucketRange,
-  Granularity
+  Granularity,
+  parseRollup
 } from '../utils/time-buckets';
 import { buildTrendSeries } from '../utils/trend-series';
 import MetricChartCard from './metric-chart-card';
@@ -293,12 +294,14 @@ const StorageTab: React.FC = () => {
         render: (v: number) => (v ?? 0).toFixed(2)
       }
     ];
-    // Last Active is a UTC instant (max bucket hour) → show formatted local time.
+    // Last Active = the last active day. The backend sends a rollup-tz instant
+    // with its offset; parseRollup keeps that wall clock (no browser-tz convert),
+    // consistent with the trend chart buckets. Shown date-only.
     const lastActiveCol = {
       title: intl.formatMessage({ id: 'usage.table.lastActive' }),
       dataIndex: 'last_active',
       key: 'last_active',
-      render: (v?: string) => (v ? dayjs(v).format('YYYY-MM-DD HH:mm:ss') : '-')
+      render: (v?: string) => (v ? parseRollup(v).format('YYYY-MM-DD') : '-')
     };
     if (activeTableTab === 'volume') {
       return [

src/pages/usage/utils/time-buckets.ts

@@ -13,8 +13,24 @@ export type Granularity = 'hour' | 'day' | 'week' | 'month';
 // Cap the hourly axis so a wide date range doesn't render hundreds of bars.
 const HOUR_MAX_DAYS = 7;
 
+/**
+ * Parse a usage timestamp keeping the offset the backend embedded (the rollup
+ * tz, e.g. ``+08:00``) — i.e. render that wall clock verbatim, NOT converted to
+ * the browser's timezone. The typed equivalent of ``dayjs.parseZone``:
+ * ``.utcOffset(offset)`` re-displays the same instant at the embedded offset
+ * (``Z`` → UTC). A dayjs object (an axis cursor) or an offset-less date string
+ * passes through.
+ */
+export const parseRollup = (value: any): dayjs.Dayjs => {
+  if (dayjs.isDayjs(value)) return value;
+  const m = typeof value === 'string' && value.match(/([+-]\d{2}:?\d{2}|Z)$/i);
+  return m
+    ? dayjs(value).utcOffset(m[1].toUpperCase() === 'Z' ? 0 : m[1])
+    : dayjs(value);
+};
+
 export const bucketKey = (value: any, granularity: Granularity): string => {
-  const d = dayjs(value);
+  const d = parseRollup(value);
   if (granularity === 'hour') return d.format('YYYY-MM-DD HH:00');
   if (granularity === 'month') return d.format('YYYY-MM');
   return d.format('YYYY-MM-DD'); // day / week (week-start date as returned)