fix: show admin dates in algiers time

package.json

@@ -20,6 +20,7 @@
   "dependencies": {
     "@base-ui/react": "^1.8.0",
     "@better-auth/mongo-adapter": "^1.7.12",
+    "@date-fns/tz": "^1.5.0",
     "@hookform/resolvers": "^7.0.1",
     "@tanstack/react-table": "^9.3.1",
     "@vercel/analytics": "^2.0.1",

src/app/(admin)/admin/registrations/[id]/page.tsx

@@ -1,5 +1,5 @@
 import type { Metadata } from "next"
-import { differenceInYears, format } from "date-fns"
+import { differenceInYears } from "date-fns"
 import Link from "next/link"
 import { notFound } from "next/navigation"
 import { ArrowLeftIcon, ExternalLinkIcon } from "lucide-react"
@@ -14,6 +14,7 @@ import { McBadge } from "@/components/ui/mc-badge"
 import { adminRoutes } from "@/config/admin"
 import { ABOUT_QUESTIONS } from "@/const/registrations"
 import { requireStaff } from "@/lib/auth/session"
+import { formatCalendarDate, formatClubTime } from "@/lib/dates"
 import { listQuery, parseListParams } from "@/lib/registrations/list-params"
 import {
   RECOMMENDATIONS_ORIGIN,
@@ -112,7 +113,7 @@ export default async function RegistrationPage({
         <p className="paragraph-md text-muted-foreground">
           Submitted on{" "}
           <time dateTime={submittedAt.toISOString()}>
-            {format(submittedAt, "d MMMM yyyy 'at' HH:mm")}
+            {formatClubTime(submittedAt, "d MMMM yyyy 'at' HH:mm")}
           </time>
         </p>
       </header>
@@ -186,7 +187,8 @@ export default async function RegistrationPage({
               {registration.discord}
             </Field>
             <Field label="Date of birth">
-              {format(birthDate, "d MMMM yyyy")} ({differenceInYears(new Date(), birthDate)} years)
+              {formatCalendarDate(birthDate, "d MMMM yyyy")} (
+              {differenceInYears(new Date(), birthDate)} years)
             </Field>
             <Field label="Field of study">{registration.fieldOfStudy}</Field>
             <Field label="Year of study">{registration.yearOfStudy}</Field>

src/components/admin/registrations/recommendations-table.tsx

@@ -1,4 +1,4 @@
-import { format } from "date-fns"
+import { formatClubTime } from "@/lib/dates"
 import Link from "next/link"
 
 import { Reviewers } from "@/components/admin/registrations/reviewers"
@@ -92,7 +92,7 @@ export function RecommendationsTable({
             </McTableCell>
             <McTableCell className="whitespace-nowrap">
               <time dateTime={row.submittedAt}>
-                {format(new Date(row.submittedAt), "d MMM yyyy")}
+                {formatClubTime(new Date(row.submittedAt), "d MMM yyyy")}
               </time>
             </McTableCell>
           </McTableRow>

src/components/admin/registrations/registration-timeline.tsx

@@ -1,4 +1,4 @@
-import { format, formatDistanceToNow } from "date-fns"
+import { formatDistanceToNow } from "date-fns"
 import {
   CalendarClockIcon,
   CheckIcon,
@@ -10,6 +10,7 @@ import {
 } from "lucide-react"
 
 import { McBadge } from "@/components/ui/mc-badge"
+import { formatClubTime } from "@/lib/dates"
 import { recommendationTargetName } from "@/lib/registrations/recommendations"
 import type { ReviewState } from "@/lib/registrations/status"
 import { currentRecommendation, type TimelineEntry } from "@/lib/registrations/timeline"
@@ -99,7 +100,7 @@ export function RegistrationTimeline({ timeline }: { timeline: TimelineEntry[] }
               {badge && <McBadge variant={tone}>{badge}</McBadge>}
               <time
                 dateTime={entry.at.toISOString()}
-                title={format(entry.at, "d MMMM yyyy 'at' HH:mm")}
+                title={formatClubTime(entry.at, "d MMMM yyyy 'at' HH:mm")}
                 className="paragraph-sm text-muted-foreground sm:ml-auto"
               >
                 {formatDistanceToNow(entry.at, { addSuffix: true })}

src/components/admin/registrations/registrations-table.tsx

@@ -1,4 +1,4 @@
-import { format } from "date-fns"
+import { formatClubTime } from "@/lib/dates"
 import Link from "next/link"
 
 import { RecommendedBy } from "@/components/admin/registrations/recommended-by"
@@ -98,7 +98,7 @@ export function RegistrationsTable({
             </McTableCell>
             <McTableCell className="whitespace-nowrap">
               <time dateTime={row.submittedAt}>
-                {format(new Date(row.submittedAt), "d MMM yyyy")}
+                {formatClubTime(new Date(row.submittedAt), "d MMM yyyy")}
               </time>
             </McTableCell>
           </McTableRow>

src/components/admin/users-table.tsx

@@ -1,6 +1,6 @@
 "use client"
 
-import { format } from "date-fns"
+import { formatClubTime } from "@/lib/dates"
 import { UsersRoundIcon } from "lucide-react"
 
 import { CreateUserDialog } from "@/components/admin/create-user-dialog"
@@ -46,7 +46,7 @@ const columns = [
   column.accessor("createdAt", {
     header: "Created",
     sortFn: "datetime",
-    cell: ({ getValue }) => format(new Date(getValue()), "d MMM yyyy"),
+    cell: ({ getValue }) => formatClubTime(new Date(getValue()), "d MMM yyyy"),
   }),
   column.display({
     id: "actions",

src/lib/dates.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from "vitest"
+
+import { formatCalendarDate, formatClubTime } from "./dates"
+
+describe("formatClubTime", () => {
+  it("shows a UTC moment in Algiers time", () => {
+    expect(formatClubTime(new Date("2026-11-05T21:56:00Z"), "d MMM yyyy HH:mm")).toBe(
+      "5 Nov 2026 22:56",
+    )
+  })
+
+  it("moves a late evening UTC moment to the next day", () => {
+    expect(formatClubTime("2026-11-05T23:30:00.000Z", "d MMM yyyy")).toBe("6 Nov 2026")
+  })
+})
+
+describe("formatCalendarDate", () => {
+  it("keeps a birth date stored as midnight UTC on its day", () => {
+    expect(formatCalendarDate(new Date(Date.UTC(2004, 2, 1)), "d MMMM yyyy")).toBe("1 March 2004")
+  })
+})

src/lib/dates.ts

@@ -0,0 +1,18 @@
+import { tz } from "@date-fns/tz"
+import { format } from "date-fns"
+
+/** The club's timezone: moments (submissions, reviews) are shown in it, whatever the server's or browser's timezone. */
+export const CLUB_TIME_ZONE = "Africa/Algiers"
+
+const clubTime = tz(CLUB_TIME_ZONE)
+const utc = tz("UTC")
+
+/** Formats a moment stored in UTC (a submission, a review) in the club's local time. */
+export function formatClubTime(date: Date | string, pattern: string) {
+  return format(date, pattern, { in: clubTime })
+}
+
+/** Formats a calendar date stored as midnight UTC (a birth date), so it never shifts by a day. */
+export function formatCalendarDate(date: Date | string, pattern: string) {
+  return format(date, pattern, { in: utc })
+}