src/web/src/features/medios/pages/MedioDetailPage.tsx

@@ -5,15 +5,7 @@ import { CanPerform } from '@/components/auth/CanPerform'
 import { useMedio } from '../hooks/useMedio'
 import { DeactivateMedioModal } from '../components/DeactivateMedioModal'
 import { tipoMedioLabel } from '../tipoMedio'
-
-function formatDate(iso: string | null): string {
-  if (!iso) return '—'
-  return new Date(iso).toLocaleDateString('es-AR', {
-    year: 'numeric',
-    month: 'short',
-    day: 'numeric',
-  })
-}
+import { formatInstantOrDash } from '@/lib/dateFormat'
 
 export function MedioDetailPage() {
   const { id } = useParams<{ id: string }>()
@@ -69,11 +61,11 @@ export function MedioDetailPage() {
         </div>
         <div className="flex justify-between text-sm">
           <span className="text-muted-foreground">Creado</span>
-          <span>{formatDate(medio.fechaCreacion)}</span>
+          <span>{formatInstantOrDash(medio.fechaCreacion)}</span>
         </div>
         <div className="flex justify-between text-sm">
           <span className="text-muted-foreground">Modificado</span>
-          <span>{formatDate(medio.fechaModificacion)}</span>
+          <span>{formatInstantOrDash(medio.fechaModificacion)}</span>
         </div>
       </div>
 

src/web/src/features/puntos-de-venta/pages/PuntoDeVentaDetailPage.tsx

@@ -7,15 +7,7 @@ import { useMedio } from '../../medios/hooks/useMedio'
 import { DeactivatePuntoDeVentaModal } from '../components/DeactivatePuntoDeVentaModal'
 import { MedioInactivoBanner } from '../components/MedioInactivoBanner'
 import { PdvInactivoBanner } from '../components/PdvInactivoBanner'
-
-function formatDate(iso: string | null): string {
-  if (!iso) return '—'
-  return new Date(iso).toLocaleDateString('es-AR', {
-    year: 'numeric',
-    month: 'short',
-    day: 'numeric',
-  })
-}
+import { formatInstantOrDash } from '@/lib/dateFormat'
 
 export function PuntoDeVentaDetailPage() {
   const { id } = useParams<{ id: string }>()
@@ -70,11 +62,11 @@ export function PuntoDeVentaDetailPage() {
         </div>
         <div className="flex justify-between text-sm">
           <span className="text-muted-foreground">Creado</span>
-          <span>{formatDate(pdv.fechaCreacion)}</span>
+          <span>{formatInstantOrDash(pdv.fechaCreacion)}</span>
         </div>
         <div className="flex justify-between text-sm">
           <span className="text-muted-foreground">Modificado</span>
-          <span>{formatDate(pdv.fechaModificacion)}</span>
+          <span>{formatInstantOrDash(pdv.fechaModificacion)}</span>
         </div>
       </div>
 

src/web/src/features/secciones/pages/SeccionDetailPage.tsx

@@ -7,15 +7,7 @@ import { DeactivateSeccionModal } from '../components/DeactivateSeccionModal'
 import { MedioInactivoBanner } from '../components/MedioInactivoBanner'
 import { tipoSeccionLabel } from '../tipoSeccion'
 import { useMedio } from '../../medios/hooks/useMedio'
-
-function formatDate(iso: string | null): string {
-  if (!iso) return '—'
-  return new Date(iso).toLocaleDateString('es-AR', {
-    year: 'numeric',
-    month: 'short',
-    day: 'numeric',
-  })
-}
+import { formatInstantOrDash } from '@/lib/dateFormat'
 
 export function SeccionDetailPage() {
   const { id } = useParams<{ id: string }>()
@@ -75,11 +67,11 @@ export function SeccionDetailPage() {
         </div>
         <div className="flex justify-between text-sm">
           <span className="text-muted-foreground">Creado</span>
-          <span>{formatDate(seccion.fechaCreacion)}</span>
+          <span>{formatInstantOrDash(seccion.fechaCreacion)}</span>
         </div>
         <div className="flex justify-between text-sm">
           <span className="text-muted-foreground">Modificado</span>
-          <span>{formatDate(seccion.fechaModificacion)}</span>
+          <span>{formatInstantOrDash(seccion.fechaModificacion)}</span>
         </div>
       </div>
 

src/web/src/features/users/components/UsersTable.tsx

@@ -3,21 +3,13 @@ import type { ColumnDef } from '@tanstack/react-table'
 import { Badge } from '@/components/ui/badge'
 import { DataTable } from '@/components/ui/data-table'
 import type { UserListItem } from '../types'
+import { formatInstantOrDash } from '@/lib/dateFormat'
 
 interface UsersTableProps {
   rows: UserListItem[]
   onRowClick: (user: UserListItem) => void
 }
 
-function formatDate(iso: string | null): string {
-  if (!iso) return '—'
-  return new Date(iso).toLocaleDateString('es-AR', {
-    year: 'numeric',
-    month: 'short',
-    day: 'numeric',
-  })
-}
-
 export function UsersTable({ rows, onRowClick }: UsersTableProps) {
   const columns = useMemo<ColumnDef<UserListItem>[]>(
     () => [
@@ -81,7 +73,7 @@ export function UsersTable({ rows, onRowClick }: UsersTableProps) {
         header: 'Último login',
         cell: ({ row }) => (
           <span className="text-muted-foreground">
-            {formatDate(row.original.ultimoLogin)}
+            {formatInstantOrDash(row.original.ultimoLogin)}
           </span>
         ),
         meta: { priority: 'low' },

src/web/src/lib/dateFormat.ts

@@ -87,6 +87,15 @@ export function parseCivilDate(yyyyMmDd: string): { year: number; month: number;
     return { year: y, month: m, day: d };
 }
 
+/**
+ * Formatea un instante UTC (Cat1) nullable a string legible en zona horaria Argentina.
+ * Retorna '—' cuando el valor es null o undefined.
+ */
+export function formatInstantOrDash(iso: string | null | undefined): string {
+    if (!iso) return '—';
+    return formatInstant(iso);
+}
+
 /**
  * Retorna el día anterior a una fecha civil Argentina en formato "yyyy-MM-dd".
  * Usa Date.UTC para aritmética pura — sin conversión de timezone en ningún momento.

src/web/src/pages/admin/audit/AuditPage.tsx

@@ -18,20 +18,7 @@ import {
   toApiFilter,
   type AuditFiltersValue,
 } from './AuditFilters'
-
-/** Formatea un ISO datetime a hora local AR (dd/mm/yyyy HH:mm:ss). */
-function formatOccurredAt(iso: string): string {
-  const d = new Date(iso)
-  if (Number.isNaN(d.getTime())) return iso
-  return d.toLocaleString('es-AR', {
-    year: 'numeric',
-    month: '2-digit',
-    day: '2-digit',
-    hour: '2-digit',
-    minute: '2-digit',
-    second: '2-digit',
-  })
-}
+import { formatInstant } from '@/lib/dateFormat'
 
 /** Copia texto al clipboard con fallback + toast. */
 async function copyToClipboard(text: string, label: string): Promise<void> {
@@ -123,7 +110,7 @@ export function AuditPage() {
         header: 'Fecha',
         cell: ({ row }) => (
           <span className="font-mono text-xs text-foreground">
-            {formatOccurredAt(row.original.occurredAt)}
+            {formatInstant(row.original.occurredAt)}
           </span>
         ),
         meta: { priority: 'high' },

src/web/src/tests/lib/dateFormat.test.ts

@@ -2,6 +2,7 @@ import { describe, it, expect, afterEach, vi } from 'vitest';
 import {
     AR_TZ,
     formatInstant,
+    formatInstantOrDash,
     formatCivilDate,
     formatCivilDateRange,
     todayArgentina,
@@ -33,6 +34,21 @@ describe('dateFormat.ts', () => {
         });
     });
 
+    describe('formatInstantOrDash (Cat1 nullable)', () => {
+        it('returns "—" for null', () => {
+            expect(formatInstantOrDash(null)).toBe('—');
+        });
+
+        it('returns "—" for undefined', () => {
+            expect(formatInstantOrDash(undefined)).toBe('—');
+        });
+
+        it('delegates to formatInstant for valid ISO', () => {
+            const iso = '2026-05-01T01:30:00.000Z';
+            expect(formatInstantOrDash(iso)).toBe(formatInstant(iso));
+        });
+    });
+
     describe('formatCivilDate (Cat2 — yyyy-MM-dd → dd/MM/yyyy)', () => {
         it('splits manually without new Date()', () => {
             expect(formatCivilDate('2026-05-01')).toBe('01/05/2026');