fix: make display timezone configurable via TIMEZONE env var

.env.example

@@ -7,4 +7,9 @@ DATABASE_URL=
 
 # Security
 PASSWORD=
-CRON_SECRET=<any-long-secret-string>
+CRON_SECRET=<any-long-secret-string>
+
+# Display timezone for date grouping in charts (IANA timezone name)
+# Examples: UTC, Europe/London, America/New_York, Asia/Tokyo
+# Defaults to Asia/Shanghai if not set. Set to your local timezone for correct day/hour grouping.
+TIMEZONE=

app/api/overview/route.ts

@@ -1,5 +1,5 @@
 import { NextResponse } from "next/server";
-import { assertEnv } from "@/lib/config";
+import { assertEnv, config } from "@/lib/config";
 import { getOverview } from "@/lib/queries/overview";
 
 export const runtime = "nodejs";
@@ -10,6 +10,7 @@ type CachedOverview = {
     overview: Awaited<ReturnType<typeof getOverview>>["overview"] | null;
     empty: boolean;
     days: number;
+    timezone: string;
     meta?: Awaited<ReturnType<typeof getOverview>>["meta"];
     filters?: Awaited<ReturnType<typeof getOverview>>["filters"];
   };
@@ -79,16 +80,17 @@ export async function GET(request: Request) {
       }
     }
 
-    const { overview, empty, days: appliedDays, meta, filters } = await getOverview(days, {
+    const { overview, empty, days: appliedDays, meta, filters, timezone } = await getOverview(days, {
       model: model || undefined,
       route: route || undefined,
       page,
       pageSize,
       start,
-      end
+      end,
+      timezone: config.timezone
     });
 
-    const payload = { overview, empty, days: appliedDays, meta, filters };
+    const payload = { overview, empty, days: appliedDays, meta, filters, timezone };
     setCached(cacheKey, payload);
     return NextResponse.json(payload, { status: 200 });
   } catch (error) {

app/explore/page.tsx

@@ -175,7 +175,6 @@ function computeTimeTicks([min, max]: [number, number], maxTickCount = 8): numbe
 }
 
 const timeFormatter = new Intl.DateTimeFormat("zh-CN", {
-  timeZone: "Asia/Shanghai",
   month: "2-digit",
   day: "2-digit",
   hour: "2-digit",

app/logs/page.tsx

@@ -26,8 +26,7 @@ function formatTimestamp(ts: number | undefined): string {
     hour: "2-digit",
     minute: "2-digit",
     second: "2-digit",
-    hour12: false,
-    timeZone: "Asia/Shanghai"
+    hour12: false
   });
 }
 

app/page.tsx

@@ -23,7 +23,7 @@ const PIE_COLORS = [
 ];
 
 type OverviewMeta = { page: number; pageSize: number; totalModels: number; totalPages: number };
-type OverviewAPIResponse = { overview: UsageOverview | null; empty: boolean; days: number; meta?: OverviewMeta; filters?: { models: string[]; routes: string[] } };
+type OverviewAPIResponse = { overview: UsageOverview | null; empty: boolean; days: number; timezone?: string; meta?: OverviewMeta; filters?: { models: string[]; routes: string[] } };
 
 type PriceForm = {
   model: string;
@@ -33,7 +33,6 @@ type PriceForm = {
 };
 
 const hourFormatter = new Intl.DateTimeFormat("en-CA", {
-  timeZone: "Asia/Shanghai",
   month: "2-digit",
   day: "2-digit",
   hour: "2-digit",
@@ -66,15 +65,21 @@ const numericTooltipFormatter: TooltipProps<number, string>["formatter"] = (valu
   return [formatNumberWithCommas(numericValue), name];
 };
 
-function formatHourKeyFromTs(ts: number) {
-  const parts = hourFormatter.formatToParts(new Date(ts));
+function formatHourKeyFromTs(ts: number, formatter: Intl.DateTimeFormat) {
+  const parts = formatter.formatToParts(new Date(ts));
   const month = parts.find((p) => p.type === "month")?.value ?? "00";
   const day = parts.find((p) => p.type === "day")?.value ?? "00";
   const hour = parts.find((p) => p.type === "hour")?.value ?? "00";
   return `${month}-${day} ${hour}`;
 }
 
-function buildHourlySeries(series: UsageSeriesPoint[], rangeHours?: number) {
+function buildHourlySeries(series: UsageSeriesPoint[], rangeHours?: number, timezone?: string) {
+  // Use the server's bucketing timezone for gap-fill labels so they match the
+  // labels returned for real data points. Falls back to the module-level formatter
+  // (browser timezone) when no timezone is provided.
+  const gapFormatter = timezone
+    ? new Intl.DateTimeFormat("en-CA", { timeZone: timezone, month: "2-digit", day: "2-digit", hour: "2-digit", hour12: false })
+    : hourFormatter;
   if (!series.length) return [] as UsageSeriesPoint[];
 
   const withTs = series
@@ -98,7 +103,7 @@ function buildHourlySeries(series: UsageSeriesPoint[], rangeHours?: number) {
       filled.push(rest);
     } else {
       filled.push({
-        label: formatHourKeyFromTs(ts),
+        label: formatHourKeyFromTs(ts, gapFormatter),
         timestamp: new Date(ts).toISOString(),
         requests: 0,
         tokens: 0,
@@ -167,6 +172,7 @@ export default function DashboardPage() {
     }
   }, []);
   const [overview, setOverview] = useState<UsageOverview | null>(null);
+  const [bucketTimezone, setBucketTimezone] = useState<string | undefined>(undefined);
   const [overviewError, setOverviewError] = useState<string | null>(null);
   const [overviewEmpty, setOverviewEmpty] = useState(false);
   const [loadingOverview, setLoadingOverview] = useState(true);
@@ -730,6 +736,7 @@ export default function DashboardPage() {
         const data: OverviewAPIResponse = await res.json();
         if (!active) return;
         setOverview(data.overview ?? null);
+        setBucketTimezone(data.timezone);
         setOverviewEmpty(Boolean(data.empty));
         setOverviewError(null);
         setPage(data.meta?.page ?? 1);
@@ -760,8 +767,8 @@ export default function DashboardPage() {
     if (!overviewData?.byHour) return [] as UsageSeriesPoint[];
     if (hourRange === "all") return overviewData.byHour;
     const hours = hourRange === "24h" ? 24 : 72;
-    return buildHourlySeries(overviewData.byHour, hours);
-  }, [hourRange, overviewData?.byHour]);
+    return buildHourlySeries(overviewData.byHour, hours, bucketTimezone);
+  }, [hourRange, overviewData?.byHour, bucketTimezone]);
 
   const hourlyLineStyle = useMemo(
     () => buildHourlyLineStyle(hourlySeries.length, 3),

app/records/page.tsx

@@ -60,8 +60,7 @@ function formatTimestamp(ts: string) {
     hour: "2-digit",
     minute: "2-digit",
     second: "2-digit",
-    hour12: false,
-    timeZone: "Asia/Shanghai"
+    hour12: false
   });
 }
 

lib/config.ts

@@ -10,14 +10,29 @@ const baseUrl = normalizeBaseUrl(process.env.CLIPROXY_API_BASE_URL);
 const password = process.env.PASSWORD || process.env.CLIPROXY_SECRET_KEY || "";
 const cronSecret = process.env.CRON_SECRET || "";
 
+function normalizeTimezone(raw: string | undefined): string {
+  const value = (raw || "").trim();
+  if (!value) return "Asia/Shanghai";
+  try {
+    Intl.DateTimeFormat(undefined, { timeZone: value });
+    return value;
+  } catch {
+    console.warn(`TIMEZONE env var "${value}" is not a valid IANA timezone. Falling back to Asia/Shanghai.`);
+    return "Asia/Shanghai";
+  }
+}
+
+const timezone = normalizeTimezone(process.env.TIMEZONE);
+
 export const config = {
   cliproxy: {
     baseUrl,
     apiKey: process.env.CLIPROXY_SECRET_KEY || ""
   },
   postgresUrl: process.env.DATABASE_URL || "",
   password,
-  cronSecret
+  cronSecret,
+  timezone
 };
 
 export function assertEnv() {

lib/queries/overview.ts

@@ -84,8 +84,8 @@ function normalizePageSize(value?: number | null) {
 
 export async function getOverview(
   daysInput?: number,
-  opts?: { model?: string | null; route?: string | null; page?: number | null; pageSize?: number | null; start?: string | Date | null; end?: string | Date | null }
-): Promise<{ overview: UsageOverview; empty: boolean; days: number; meta: OverviewMeta; filters: { models: string[]; routes: string[] } }> {
+  opts?: { model?: string | null; route?: string | null; page?: number | null; pageSize?: number | null; start?: string | Date | null; end?: string | Date | null; timezone?: string | null }
+): Promise<{ overview: UsageOverview; empty: boolean; days: number; meta: OverviewMeta; filters: { models: string[]; routes: string[] }; timezone: string }> {
   const startDate = parseDateInput(opts?.start);
   const endDate = parseDateInput(opts?.end);
   const hasCustomRange = startDate && endDate && endDate >= startDate;
@@ -106,8 +106,14 @@ export async function getOverview(
   if (opts?.route) filterWhereParts.push(eq(usageRecords.route, opts.route));
   const filterWhere = filterWhereParts.length ? and(...filterWhereParts) : undefined;
 
-  const dayExpr = sql`date_trunc('day', ${usageRecords.occurredAt} at time zone 'Asia/Shanghai')`;
-  const hourExpr = sql`date_trunc('hour', ${usageRecords.occurredAt} at time zone 'Asia/Shanghai')`;
+  const tz = opts?.timezone || "Asia/Shanghai";
+  // Use sql.raw() so the timezone is embedded as a SQL literal rather than a query
+  // parameter. PostgreSQL requires the GROUP BY expression to be textually identical
+  // to the SELECT expression; different parameter indices ($1 vs $3) would cause a
+  // "must appear in GROUP BY" error even when the values are equal.
+  const tzLiteral = sql.raw(`'${tz}'`);
+  const dayExpr = sql`date_trunc('day', ${usageRecords.occurredAt} at time zone ${tzLiteral})`;
+  const hourExpr = sql`date_trunc('hour', ${usageRecords.occurredAt} at time zone ${tzLiteral})`;
 
   const totalsPromise: Promise<TotalsRow[]> = db
     .select({
@@ -177,7 +183,7 @@ export async function getOverview(
   const byHourPromise: Promise<HourAggRow[]> = db
     .select({
       label: sql<string>`to_char(${hourExpr}, 'MM-DD HH24')`,
-      hourStart: sql<Date>`(${hourExpr}) at time zone 'Asia/Shanghai'`,
+      hourStart: sql<Date>`(${hourExpr}) at time zone ${tzLiteral}`,
       requests: sql<number>`count(*)`,
       tokens: sql<number>`sum(${usageRecords.totalTokens})`,
       inputTokens: sql<number>`sum(${usageRecords.inputTokens})`,
@@ -332,6 +338,7 @@ export async function getOverview(
     empty: totalRequests === 0,
     days,
     meta: { page, pageSize, totalModels, totalPages },
-    filters
+    filters,
+    timezone: tz
   };
 }