feat: choose how dates are displayed (Standard / French / US)

Settings → General, beside the language. An operator reading 2026-07-30 as the
7th of the 30th month is reading their own log wrongly, and that is a display
problem.

Storage stays ISO/ADIF, deliberately and permanently: it is what ADIF
specifies, it sorts correctly as text, and a stored format that followed a UI
preference would make the log unreadable the day the preference changed. Exports
and uploads are untouched.

Two details that decide whether it actually works:

  - The columns are rebuilt when the format changes. The formatters are captured
    inside AG-Grid's column definitions, so nothing else would notice and the
    table would keep the old format until something forced a rebuild.
  - main.tsx re-reads the choice after the portable prefs are pulled from the
    database. The module reads localStorage at import time, which is BEFORE that
    sync — so a copied data/ folder would have shown ISO until the next launch.

UTC is not part of the choice and never will be: a logbook is kept in UTC, and
showing local time would make the display disagree with the QSO's own record
twice a year.

changelog.json

@@ -16,7 +16,8 @@
       "A recording in progress can be stopped and TRANSMITTED to the station being worked, keyed and sent like a voice-keyer message — for when they ask to hear their own signal. The audio is kept and still saved with the QSO, and recording can be resumed.",
       "The award reference table can be sorted by reference (the default) or by description — click either heading, click again to reverse. Both the grid and list views follow.",
       "Deleting a QSO can now withdraw it from QRZ.com and Club Log as well — Settings → External services, off by default. Club Log matches on callsign, time and band so it works for any QSO; QRZ.com can only remove records OpsLog uploaded itself, since its API deletes by record number only.",
-      "QSL and upload status columns are coloured: Y green, N red, R blue. Colour only, no badges. Applies everywhere the QSO table is used — recent QSOs, worked before, NET Control and the QSL manager."
+      "QSL and upload status columns are coloured: Y green, N red, R blue. Colour only, no badges. Applies everywhere the QSO table is used — recent QSOs, worked before, NET Control and the QSL manager.",
+      "Settings → General chooses how dates are displayed: Standard (2026-07-30), French (30-07-2026) or US (07-30-2026). Display only — the log is always stored in the ADIF standard format, and exports are unaffected."
     ],
     "fr": [
       "Le backend Kenwood est désormais éprouvé face à une radio qui répond : OpsLog dialogue avec l'émulateur TS-2000 qu'il embarque déjà pour les amplis ACOM, ce qui vérifie fréquence, mode, VFO, split et PTT de bout en bout. Un essai sur un vrai Kenwood reste nécessaire, mais le dialogue n'est plus non testé.",
@@ -32,7 +33,8 @@
       "Un enregistrement en cours peut être arrêté puis ÉMIS vers la station travaillée, radio passée en émission comme un message du manipulateur vocal — pour quand elle demande à entendre son propre signal. L'audio est conservé et toujours enregistré avec le QSO, et l'enregistrement peut reprendre.",
       "Le tableau des références d'un diplôme peut être trié par référence (par défaut) ou par description — cliquez sur l'en-tête, un second clic inverse l'ordre. Les vues grille et liste suivent toutes deux.",
       "Supprimer un QSO peut désormais le retirer aussi de QRZ.com et Club Log — Réglages → Services externes, désactivé par défaut. Club Log retrouve le contact par indicatif, heure et bande, donc cela vaut pour n'importe quel QSO ; QRZ.com ne peut retirer que les enregistrements envoyés par OpsLog, son API ne supprimant que par numéro d'enregistrement.",
-      "Les colonnes de statut QSL et d'envoi sont colorées : Y en vert, N en rouge, R en bleu. Couleur seule, sans pastille. Partout où le tableau des QSO est utilisé — QSO récents, déjà contacté, NET Control et le gestionnaire de QSL."
+      "Les colonnes de statut QSL et d'envoi sont colorées : Y en vert, N en rouge, R en bleu. Couleur seule, sans pastille. Partout où le tableau des QSO est utilisé — QSO récents, déjà contacté, NET Control et le gestionnaire de QSL.",
+      "Réglages → Général permet de choisir l'affichage des dates : Standard (2026-07-30), Français (30-07-2026) ou US (07-30-2026). Affichage seulement — le journal reste toujours enregistré au format standard ADIF, et les exports ne changent pas."
     ]
   },
   {

frontend/src/App.tsx

@@ -100,6 +100,7 @@ import { SendSpotModal, type RecentSpotQSO } from '@/components/SendSpotModal';
 import { WinkeyerPanel, type WKStatus, type WKMacro } from '@/components/WinkeyerPanel';
 import { RotorCompass } from '@/components/RotorCompass';
 import { writeUiPref } from '@/lib/uiPref';
+import { formatDateTimeUTC } from '@/lib/dateFormat';
 import { setGridPrefsProfile, flushGridPrefs } from '@/lib/gridPrefs';
 import { DvkPanel, type DVKMsg, type DVKStat } from '@/components/DvkPanel';
 
@@ -169,11 +170,7 @@ function parseAwardRefs(s: any): Record<string, string> {
 }
 
 function fmtDateUTC(s: any): string {
-  if (!s) return '';
-  const d = new Date(s);
-  if (isNaN(d.getTime())) return s;
-  const p = (n: number) => String(n).padStart(2, '0');
-  return `${d.getUTCFullYear()}-${p(d.getUTCMonth() + 1)}-${p(d.getUTCDate())} ${p(d.getUTCHours())}:${p(d.getUTCMinutes())}`;
+  return formatDateTimeUTC(s);
 }
 function fmtFreq(hz?: number): string {
   if (!hz) return '';

frontend/src/components/RecentQSOsGrid.tsx

@@ -5,6 +5,7 @@ import {
 } from 'ag-grid-community';
 import { hamlogGridTheme } from '@/lib/gridTheme';
 import { qslStatusCellClass } from '@/lib/qslStatus';
+import { formatDateTimeUTC, formatDateOnly, getDateFormat, subscribeDateFormat } from '@/lib/dateFormat';
 import { AgGridReact } from 'ag-grid-react';
 import { Columns3, FilterX, ListChecks } from 'lucide-react';
 import type { QSOForm } from '@/types';
@@ -86,23 +87,13 @@ function fmtMhzDots(hz?: number): string {
   return `${i}.${f.slice(0, 3)}.${f.slice(3, 6)}`;
 }
 
+// Both formatters follow the display preference (Settings → General). What is
+// STORED never changes — see lib/dateFormat.
 function fmtDateUTC(s: any): string {
-  if (!s) return '';
-  const d = new Date(s);
-  if (isNaN(d.getTime())) return s;
-  const p = (n: number) => String(n).padStart(2, '0');
-  return `${d.getUTCFullYear()}-${p(d.getUTCMonth() + 1)}-${p(d.getUTCDate())} ${p(d.getUTCHours())}:${p(d.getUTCMinutes())}`;
+  return formatDateTimeUTC(s);
 }
 function fmtDateOnly(s: any): string {
-  if (!s) return '';
-  const t = String(s).trim();
-  // QSL/LoTW/eQSL/ClubLog dates are ADIF YYYYMMDD; upload dates may be ISO.
-  const m = t.match(/^(\d{4})(\d{2})(\d{2})/);
-  if (m) return `${m[1]}-${m[2]}-${m[3]}`;
-  const d = new Date(t);
-  if (isNaN(d.getTime())) return t;
-  const p = (n: number) => String(n).padStart(2, '0');
-  return `${d.getUTCFullYear()}-${p(d.getUTCMonth() + 1)}-${p(d.getUTCDate())}`;
+  return formatDateOnly(s);
 }
 
 // Full catalog of selectable columns, grouped for the picker. `defaultVisible`
@@ -304,7 +295,11 @@ export function RecentQSOsGrid({ rows, myGrid, selectAllSignal, selectRowSignal,
   const [dispCount, setDispCount] = useState(0); // rows currently displayed (post column filters) — drives Select all ↔ Unselect all
 
   // Localized column catalog — rebuilt when the language changes.
-  const COL_CATALOG = useMemo(() => makeColCatalog(t, myGrid), [t, myGrid]);
+  // Rebuild the columns when the format changes: the formatters are captured
+  // inside the column definitions, so nothing else would notice.
+  const [dateFmt, setDateFmt] = useState(getDateFormat);
+  useEffect(() => subscribeDateFormat(() => setDateFmt(getDateFormat())), []);
+  const COL_CATALOG = useMemo(() => makeColCatalog(t, myGrid), [t, myGrid, dateFmt]);
 
   // Right-click: if the clicked row isn't already part of the selection,
   // select just it; then open the bulk-action menu on the whole selection.

frontend/src/components/SettingsModal.tsx

@@ -69,6 +69,7 @@ import {
 } from '@/components/ui/select';
 import { cn } from '@/lib/utils';
 import { writeUiPref } from '@/lib/uiPref';
+import { getDateFormat, setDateFormat, type DateFormat } from '@/lib/dateFormat';
 import { useI18n, FlagGB, FlagFR, type Lang } from '@/lib/i18n';
 import { useTheme, CONCRETE_THEMES, type ThemeChoice } from '@/lib/theme';
 import { OperatingPanel } from '@/components/OperatingPanel';
@@ -1143,6 +1144,7 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
   // a trace already running came back unticked; the operator ticks the box to
   // turn it on, which turns it off, and the log they send has no trace in it.
   // Reported by a Xiegu user. Hydrated from the backend below.
+  const [dateFmtSel, setDateFmtSel] = useState<DateFormat>(getDateFormat);
   const [wkTrace, setWkTrace] = useState(false);
   const [civTrace, setCivTrace] = useState(false);
   useEffect(() => {
@@ -5222,6 +5224,27 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
             </div>
           </div>
 
+          {/* Display only. The log is stored in ISO/ADIF whatever is chosen here
+              — that is what ADIF specifies and what sorts correctly, and a
+              stored format that followed a preference would make the log
+              unreadable the day the preference changed. */}
+          <div className="flex items-center gap-3">
+            <Label className="text-sm w-40">{t('gen.dateFormat')}</Label>
+            <div className="inline-flex rounded-md border border-border overflow-hidden">
+              {([['iso', t('gen.dateStandard'), '2026-07-30 14:25'],
+                 ['fr', t('gen.dateFR'), '30-07-2026 14:25'],
+                 ['us', t('gen.dateUS'), '07-30-2026 14:25']] as [DateFormat, string, string][]).map(([code, label, sample]) => (
+                <button key={code} type="button" title={sample}
+                  onClick={() => { setDateFormat(code); setDateFmtSel(code); }}
+                  className={cn('flex flex-col items-start px-3 py-1 text-sm font-medium border-l border-border first:border-l-0',
+                    dateFmtSel === code ? 'bg-primary text-primary-foreground' : 'bg-card text-muted-foreground hover:bg-muted')}>
+                  {label}
+                  <span className="text-[10px] font-mono opacity-70">{sample}</span>
+                </button>
+              ))}
+            </div>
+          </div>
+
           <ThemeSelector />
 
           <label className="flex items-center gap-2 text-sm cursor-pointer">

frontend/src/components/WorkedBeforeGrid.tsx

@@ -14,6 +14,7 @@ import { Checkbox } from '@/components/ui/checkbox';
 import { Badge } from '@/components/ui/badge';
 import type { WorkedBeforeView, QSOForm } from '@/types';
 import { makeColCatalog, GROUP_ORDER, groupLabel } from './RecentQSOsGrid';
+import { getDateFormat, subscribeDateFormat } from '@/lib/dateFormat';
 import { QSOContextMenu, type QSOMenuState } from './QSOContextMenu';
 import { loadLocal, loadRemote, saveState, seedLocal, whenGridPrefsReady } from '@/lib/gridPrefs';
 import { useI18n } from '@/lib/i18n';
@@ -63,7 +64,9 @@ export function WorkedBeforeGrid({ wb, myGrid, busy, currentCall, onRowDoubleCli
   const [menu, setMenu] = useState<QSOMenuState>(null);
 
   // Localized column catalog (shared with the Recent QSOs grid).
-  const COL_CATALOG = useMemo(() => makeColCatalog(t, myGrid), [t, myGrid]);
+  const [dateFmt, setDateFmt] = useState(getDateFormat);
+  useEffect(() => subscribeDateFormat(() => setDateFmt(getDateFormat())), []);
+  const COL_CATALOG = useMemo(() => makeColCatalog(t, myGrid), [t, myGrid, dateFmt]);
 
   function handleRowDoubleClicked(e: RowDoubleClickedEvent<WorkedEntry>) {
     if (e.data && onRowDoubleClicked) onRowDoubleClicked(e.data);

frontend/src/lib/dateFormat.ts

@@ -0,0 +1,91 @@
+// How dates are DISPLAYED. Nothing here touches what is stored.
+//
+// The log keeps ADIF/ISO throughout — the database, ADIF export, LoTW, every
+// upload. This is the reading layer only, because an operator reading
+// "2026-07-30" as the 7th of the 30th month is reading their own log wrongly,
+// and that is a display problem, not a data one.
+//
+// Storage stays ISO deliberately and permanently: it sorts correctly as text,
+// it is what ADIF specifies, and a log whose stored format followed a UI
+// preference would become unreadable the day the preference changed.
+import { writeUiPref } from '@/lib/uiPref';
+
+export type DateFormat = 'iso' | 'fr' | 'us';
+
+const KEY = 'opslog.dateFormat';
+
+function read(): DateFormat {
+	const v = localStorage.getItem(KEY);
+	return v === 'fr' || v === 'us' ? v : 'iso';
+}
+
+let current: DateFormat = read();
+
+// A minimal store so every grid and panel re-renders the moment the format
+// changes, rather than showing the old one until the next restart.
+const listeners = new Set<() => void>();
+
+export function getDateFormat(): DateFormat {
+	return current;
+}
+
+export function setDateFormat(f: DateFormat): void {
+	current = f;
+	writeUiPref(KEY, f);
+	listeners.forEach((l) => l());
+}
+
+export function subscribeDateFormat(fn: () => void): () => void {
+	listeners.add(fn);
+	return () => listeners.delete(fn);
+}
+
+// reloadDateFormat re-reads the stored value — for after the portable prefs
+// have been synced from the database at startup, which happens AFTER this
+// module's first read.
+export function reloadDateFormat(): void {
+	const v = read();
+	if (v !== current) {
+		current = v;
+		listeners.forEach((l) => l());
+	}
+}
+
+const pad = (n: number) => String(n).padStart(2, '0');
+
+// order arranges the three parts. Separators stay '-' in every format: a slash
+// in the French one would be conventional but it also invites the reader to
+// take it for a US date, which is exactly the confusion being fixed.
+function order(y: number, m: number, d: number): string {
+	switch (current) {
+		case 'fr':
+			return `${pad(d)}-${pad(m)}-${y}`;
+		case 'us':
+			return `${pad(m)}-${pad(d)}-${y}`;
+	}
+	return `${y}-${pad(m)}-${pad(d)}`;
+}
+
+// formatDateTimeUTC renders a timestamp with the time, in UTC.
+//
+// UTC is not negotiable and is not part of the preference: a logbook is kept in
+// UTC, and a date shown in local time would disagree with the QSO's own record
+// twice a year.
+export function formatDateTimeUTC(s: unknown): string {
+	if (!s) return '';
+	const d = new Date(String(s));
+	if (isNaN(d.getTime())) return String(s);
+	return `${order(d.getUTCFullYear(), d.getUTCMonth() + 1, d.getUTCDate())} ${pad(d.getUTCHours())}:${pad(d.getUTCMinutes())}`;
+}
+
+// formatDateOnly renders a date with no time. It accepts both the ADIF form
+// (YYYYMMDD, used by every QSL and upload date) and anything Date can parse.
+export function formatDateOnly(s: unknown): string {
+	if (!s) return '';
+	const t = String(s).trim();
+	const m = t.match(/^(\d{4})(\d{2})(\d{2})/);
+	if (m) return order(Number(m[1]), Number(m[2]), Number(m[3]));
+	const d = new Date(t);
+	if (isNaN(d.getTime())) return t;
+	return order(d.getUTCFullYear(), d.getUTCMonth() + 1, d.getUTCDate());
+}

frontend/src/lib/i18n.tsx

@@ -63,7 +63,7 @@ const en: Dict = {
   // Language chooser
   'lang.choose': 'Choose your language', 'lang.chooseHint': 'You can change this later in Settings → General.',
   'lang.english': 'English', 'lang.french': 'Français', 'whatsnew.title': "What's new", 'whatsnew.close': 'Got it', 'whatsnew.none': 'No changelog available for this version yet.',
-  'settings.language': 'Language', 'settings.languageHint': 'Interface language.',
+  'settings.language': 'Language', 'gen.dateFormat': 'Date display', 'gen.dateStandard': 'Standard', 'gen.dateFR': 'French', 'gen.dateUS': 'US', 'settings.languageHint': 'Interface language.',
   'stats.tab': 'Statistics', 'stats.title': 'Logbook statistics', 'stats.loading': 'Crunching the log…',
   'stats.noData': 'No data', 'stats.charts': 'Charts', 'stats.table': 'Table', 'stats.refresh': 'Refresh',
   'stats.qsos': 'QSOs', 'stats.uniqueCalls': 'Unique callsigns', 'stats.entities': 'Entities',
@@ -475,7 +475,7 @@ const fr: Dict = {
   'lang.choose': 'Choisissez votre langue', 'lang.chooseHint': 'Modifiable plus tard dans Réglages → Général.',
   'lang.english': 'English', 'lang.french': 'Français', 'whatsnew.title': 'Nouveautés', 'whatsnew.close': 'Compris', 'whatsnew.none': 'Aucune nouveauté pour cette version pour le moment.',
   'upd.checking': 'Recherche de mises à jour…', 'upd.upToDate': 'Vous êtes à jour',
-  'settings.language': 'Langue', 'settings.languageHint': "Langue de l'interface.",
+  'settings.language': 'Langue', 'gen.dateFormat': 'Affichage des dates', 'gen.dateStandard': 'Standard', 'gen.dateFR': 'Fran\u00e7ais', 'gen.dateUS': 'US', 'settings.languageHint': "Langue de l'interface.",
   'stats.tab': 'Statistiques', 'stats.title': 'Statistiques du journal', 'stats.loading': 'Analyse du journal…',
   'stats.noData': 'Aucune donnée', 'stats.charts': 'Graphiques', 'stats.table': 'Tableau', 'stats.refresh': 'Rafraîchir',
   'stats.qsos': 'QSO', 'stats.uniqueCalls': 'Indicatifs uniques', 'stats.entities': 'Entités',

frontend/src/lib/uiPref.ts

@@ -28,6 +28,7 @@ const PORTABLE_KEYS = [
   'opslog.groupDigitalSlots', // matrix + cluster: all digital modes count as ONE (DXCC-style) instead of per-mode slots
   'opslog.clusterShowFilters', // cluster filter sidebar shown (tab + Main pane)
   'opslog.mapBasemap',    // world map basemap (light / street / satellite)
+  'opslog.dateFormat',    // how dates are DISPLAYED (iso / fr / us); storage stays ISO
   'opslog.mapGreyline',   // world map: grey line (day/night terminator) shown
   'opslog.awardRefSort', 'opslog.awardRefSortDir', // award reference table: sort column and direction
   // Cluster filter selections — restored on reopen.

frontend/src/main.tsx

@@ -6,6 +6,7 @@ import { syncPortablePrefs } from './lib/uiPref'
 import { I18nProvider } from './lib/i18n'
 import { ThemeProvider, initTheme } from './lib/theme'
 import { ErrorBoundary, installGlobalErrorLogging } from './components/ErrorBoundary'
+import { reloadDateFormat } from './lib/dateFormat'
 
 const container = document.getElementById('root')
 
@@ -18,6 +19,10 @@ syncPortablePrefs().finally(() => {
     // Stamp the persisted theme onto <html> before render so the correct
     // palette is applied immediately (portable pref hydrated just above).
     initTheme()
+    // The date format module read localStorage at import time, which is BEFORE
+    // the portable prefs were pulled from the database. Re-read it now, or a
+    // copied data/ folder would show ISO until the next launch.
+    reloadDateFormat()
     // Catch what a boundary cannot: errors thrown from timers, event handlers and
     // rejected promises. Installed before the first render so a fault during
     // startup is reported too.