diff --git a/client/src/api/client.ts b/client/src/api/client.ts
index 899453c8..01a15e1b 100644
--- a/client/src/api/client.ts
+++ b/client/src/api/client.ts
@@ -489,7 +489,7 @@ export const addonsApi = {
 
 export const airtrailApi = {
   getSettings: () => apiClient.get('/integrations/airtrail/settings').then(r => r.data),
-  saveSettings: (data: { url: string; apiKey?: string; allowInsecureTls?: boolean }) =>
+  saveSettings: (data: { url: string; apiKey?: string; allowInsecureTls?: boolean; writeEnabled?: boolean }) =>
     apiClient.put('/integrations/airtrail/settings', data).then(r => r.data),
   status: () => apiClient.get('/integrations/airtrail/status').then(r => r.data),
   test: (data: { url?: string; apiKey?: string; allowInsecureTls?: boolean }) =>
diff --git a/client/src/components/Settings/AirTrailConnectionSection.tsx b/client/src/components/Settings/AirTrailConnectionSection.tsx
index 874e8af5..d41d4694 100644
--- a/client/src/components/Settings/AirTrailConnectionSection.tsx
+++ b/client/src/components/Settings/AirTrailConnectionSection.tsx
@@ -19,6 +19,7 @@ export default function AirTrailConnectionSection(): React.ReactElement {
   const [url, setUrl] = useState('')
   const [apiKey, setApiKey] = useState('')
   const [allowInsecureTls, setAllowInsecureTls] = useState(false)
+  const [writeEnabled, setWriteEnabled] = useState(false)
   const [connected, setConnected] = useState(false)
   const [loading, setLoading] = useState(true)
   const [saving, setSaving] = useState(false)
@@ -30,6 +31,7 @@ export default function AirTrailConnectionSection(): React.ReactElement {
       .then(d => {
         setUrl(d.url || '')
         setAllowInsecureTls(!!d.allowInsecureTls)
+        setWriteEnabled(!!d.writeEnabled)
         setConnected(!!d.connected)
       })
       .catch(() => {})
@@ -46,7 +48,7 @@ export default function AirTrailConnectionSection(): React.ReactElement {
   const handleSave = async () => {
     setSaving(true)
     try {
-      const d = await airtrailApi.saveSettings({ url: url.trim(), allowInsecureTls, ...keyPayload() })
+      const d = await airtrailApi.saveSettings({ url: url.trim(), allowInsecureTls, writeEnabled, ...keyPayload() })
       const status = await airtrailApi.status().catch(() => ({ connected: false }))
       setConnected(!!status.connected)
       setApiKey('')
@@ -107,6 +109,14 @@ export default function AirTrailConnectionSection(): React.ReactElement {
           <span className="text-sm font-medium text-slate-700">{t('settings.airtrail.allowInsecureTls')}</span>
         </div>
 
+        <div>
+          <div className="flex items-center gap-3">
+            <ToggleSwitch on={writeEnabled} onToggle={() => setWriteEnabled(v => !v)} />
+            <span className="text-sm font-medium text-slate-700">{t('settings.airtrail.writeBack')}</span>
+          </div>
+          <p className="mt-1 text-xs text-slate-500">{t('settings.airtrail.writeBackHint')}</p>
+        </div>
+
         <div className="flex flex-wrap items-center gap-3">
           <button
             onClick={handleSave}
diff --git a/server/src/db/migrations.ts b/server/src/db/migrations.ts
index 45b48133..b8e3324e 100644
--- a/server/src/db/migrations.ts
+++ b/server/src/db/migrations.ts
@@ -3045,6 +3045,15 @@ function runMigrations(db: Database.Database): void {
         'CREATE UNIQUE INDEX IF NOT EXISTS idx_reservations_external ON reservations(external_source, external_id, trip_id)',
       );
     },
+    () => {
+      // Per-user opt-in for writing TREK edits back to AirTrail (#1240). Default
+      // off: AirTrail is the source of truth and TREK never writes unless asked.
+      try {
+        db.exec('ALTER TABLE users ADD COLUMN airtrail_write_enabled INTEGER DEFAULT 0');
+      } catch (err: any) {
+        if (!err.message?.includes('duplicate column name')) throw err;
+      }
+    },
   ];
 
   if (currentVersion < migrations.length) {
diff --git a/server/src/nest/integrations/airtrail.controller.ts b/server/src/nest/integrations/airtrail.controller.ts
index 39558623..1261abb6 100644
--- a/server/src/nest/integrations/airtrail.controller.ts
+++ b/server/src/nest/integrations/airtrail.controller.ts
@@ -43,6 +43,7 @@ export class AirtrailController {
       body.url,
       body.apiKey,
       !!body.allowInsecureTls,
+      !!body.writeEnabled,
       getClientIp(req),
     );
     if (!result.success) {
diff --git a/server/src/services/airtrail/airtrailMapper.ts b/server/src/services/airtrail/airtrailMapper.ts
index 392e31e1..e7ee158a 100644
--- a/server/src/services/airtrail/airtrailMapper.ts
+++ b/server/src/services/airtrail/airtrailMapper.ts
@@ -11,7 +11,7 @@ function airportCode(a: AirtrailAirport | null): string | null {
  * Airline/aircraft arrive as joined objects ({icao, iata, name, ...}); reduce
  * them to a single code (ICAO preferred, matching AirTrail's save shape).
  */
-function entityCode(e: AirtrailNamedCode | null | undefined): string | null {
+export function entityCode(e: AirtrailNamedCode | null | undefined): string | null {
   return e?.icao || e?.iata || null;
 }
 
diff --git a/server/src/services/airtrail/airtrailService.ts b/server/src/services/airtrail/airtrailService.ts
index f4ed6264..8938ee4f 100644
--- a/server/src/services/airtrail/airtrailService.ts
+++ b/server/src/services/airtrail/airtrailService.ts
@@ -12,14 +12,25 @@ interface UserConnRow {
   airtrail_url?: string | null;
   airtrail_api_key?: string | null;
   airtrail_allow_insecure_tls?: number | null;
+  airtrail_write_enabled?: number | null;
 }
 
 function readRow(userId: number): UserConnRow | undefined {
   return db
-    .prepare('SELECT airtrail_url, airtrail_api_key, airtrail_allow_insecure_tls FROM users WHERE id = ?')
+    .prepare(
+      'SELECT airtrail_url, airtrail_api_key, airtrail_allow_insecure_tls, airtrail_write_enabled FROM users WHERE id = ?',
+    )
     .get(userId) as UserConnRow | undefined;
 }
 
+/** Has this user opted in to TREK writing their flight edits back to AirTrail? (#1240) */
+export function isAirtrailWriteEnabled(userId: number): boolean {
+  const row = db.prepare('SELECT airtrail_write_enabled FROM users WHERE id = ?').get(userId) as
+    | { airtrail_write_enabled?: number | null }
+    | undefined;
+  return !!row?.airtrail_write_enabled;
+}
+
 /** Decrypted creds for outbound calls, or null when the user has no connection. */
 export function getAirtrailCredentials(userId: number): AirtrailCreds | null {
   const row = readRow(userId);
@@ -40,6 +51,7 @@ export function getConnectionSettings(userId: number) {
     url: row?.airtrail_url || '',
     apiKeyMasked: row?.airtrail_api_key ? KEY_MASK : '',
     allowInsecureTls: !!row?.airtrail_allow_insecure_tls,
+    writeEnabled: !!row?.airtrail_write_enabled,
     connected: !!(row?.airtrail_url && row?.airtrail_api_key),
   };
 }
@@ -49,6 +61,7 @@ export async function saveSettings(
   url: string | undefined,
   apiKey: string | undefined,
   allowInsecureTls: boolean,
+  writeEnabled: boolean,
   clientIp: string | null,
 ): Promise<{ success: boolean; warning?: string; error?: string }> {
   const trimmedUrl = (url || '').trim();
@@ -81,12 +94,12 @@ export async function saveSettings(
 
   if (newKey !== undefined) {
     db.prepare(
-      'UPDATE users SET airtrail_url = ?, airtrail_api_key = ?, airtrail_allow_insecure_tls = ? WHERE id = ?',
-    ).run(trimmedUrl || null, newKey, allowInsecureTls ? 1 : 0, userId);
+      'UPDATE users SET airtrail_url = ?, airtrail_api_key = ?, airtrail_allow_insecure_tls = ?, airtrail_write_enabled = ? WHERE id = ?',
+    ).run(trimmedUrl || null, newKey, allowInsecureTls ? 1 : 0, writeEnabled ? 1 : 0, userId);
   } else {
     db.prepare(
-      'UPDATE users SET airtrail_url = ?, airtrail_allow_insecure_tls = ? WHERE id = ?',
-    ).run(trimmedUrl || null, allowInsecureTls ? 1 : 0, userId);
+      'UPDATE users SET airtrail_url = ?, airtrail_allow_insecure_tls = ?, airtrail_write_enabled = ? WHERE id = ?',
+    ).run(trimmedUrl || null, allowInsecureTls ? 1 : 0, writeEnabled ? 1 : 0, userId);
     // Clearing the URL with no key left makes the connection meaningless — drop the key too.
     if (!trimmedUrl) {
       db.prepare('UPDATE users SET airtrail_api_key = NULL WHERE id = ?').run(userId);
diff --git a/server/src/services/airtrail/airtrailSync.ts b/server/src/services/airtrail/airtrailSync.ts
index c53f86fd..8e029f0a 100644
--- a/server/src/services/airtrail/airtrailSync.ts
+++ b/server/src/services/airtrail/airtrailSync.ts
@@ -13,8 +13,8 @@ import {
   listFlights,
   saveFlight,
 } from './airtrailClient';
-import { canonicalHash, mapFlightToReservation } from './airtrailMapper';
-import { getAirtrailCredentials } from './airtrailService';
+import { canonicalHash, entityCode, mapFlightToReservation } from './airtrailMapper';
+import { getAirtrailCredentials, isAirtrailWriteEnabled } from './airtrailService';
 
 /** Global on/off: the addon must be enabled and sync not explicitly turned off. */
 export function syncGloballyEnabled(): boolean {
@@ -144,7 +144,16 @@ function splitLocal(dt: string | null | undefined): { date: string | null; time:
   return { date: /^\d{4}-\d{2}-\d{2}$/.test(date) ? date : null, time: m ? m[1] : null };
 }
 
-function buildSavePayload(reservation: any, existing: AirtrailFlightRaw): AirtrailSavePayload | null {
+/**
+ * Build the POST /flight/save body. AirTrail's save fully overwrites the flight,
+ * so we start from the flight as AirTrail currently has it (`existing`, the raw
+ * GET object) and overwrite ONLY the fields TREK manages. Everything else —
+ * terminal, gate, scheduled/actual times, customFields, track, and any field
+ * AirTrail may add later — passes through untouched. We deliberately do NOT model
+ * those fields; spreading the raw object keeps us decoupled from AirTrail's schema
+ * (#1240).
+ */
+export function buildSavePayload(reservation: any, existing: AirtrailFlightRaw): AirtrailSavePayload | null {
   let meta: Record<string, any>;
   try {
     meta = reservation.metadata ? JSON.parse(reservation.metadata) : {};
@@ -183,7 +192,14 @@ function buildSavePayload(reservation: any, existing: AirtrailFlightRaw): Airtra
     if (ownSeat) ownSeat.seatNumber = seatNumber;
   }
 
+  // Spread the existing flight first to preserve every AirTrail-owned field, then
+  // overwrite only what TREK manages. `from`/`to`/`airline`/`aircraft` come back
+  // from GET as objects but the save shape wants codes — those are exactly the
+  // keys we override, so the spread never ships an object where a code is wanted.
   return {
+    // Cast so the spread carries through the AirTrail-owned keys we deliberately
+    // don't model (terminal, gate, scheduled/actual times, customFields, track, …).
+    ...(existing as unknown as Record<string, unknown>),
     id: Number(reservation.external_id),
     from: fromCode,
     to: toCode,
@@ -191,14 +207,18 @@ function buildSavePayload(reservation: any, existing: AirtrailFlightRaw): Airtra
     departureTime: dep.time,
     arrival: arr.date,
     arrivalTime: arr.time,
-    airline: meta.airline ?? null,
-    flightNumber: meta.flight_number ?? null,
-    aircraft: meta.aircraft ?? null,
-    aircraftReg: meta.aircraft_reg ?? null,
-    flightReason: meta.flight_reason ?? null,
-    note: reservation.notes ?? null,
+    // These are AirTrail-owned details TREK doesn't surface in its edit UI — a TREK
+    // edit can leave them out of `metadata`. Preserve AirTrail's current value when
+    // TREK has none rather than nulling it out (#1240). entityCode mirrors the
+    // import/hash code-selection so a writeback stays a no-op for the hash.
+    airline: meta.airline ?? entityCode(existing.airline) ?? null,
+    flightNumber: meta.flight_number ?? existing.flightNumber ?? null,
+    aircraft: meta.aircraft ?? entityCode(existing.aircraft) ?? null,
+    aircraftReg: meta.aircraft_reg ?? existing.aircraftReg ?? null,
+    flightReason: meta.flight_reason ?? existing.flightReason ?? null,
+    note: reservation.notes ?? existing.note ?? null,
     seats,
-  };
+  } as AirtrailSavePayload;
 }
 
 /**
@@ -219,9 +239,12 @@ export async function pushReservationToAirtrail(reservationId: number, tripId: n
     | undefined;
   if (!row || !row.sync_enabled) return;
 
-  const creds: AirtrailCreds | null = row.external_owner_user_id
-    ? getAirtrailCredentials(row.external_owner_user_id)
-    : null;
+  // AirTrail is read-only by default (#1240). Only push when the flight's owner has
+  // explicitly opted in. A no-op skip (not a detach): the link stays active so the
+  // inbound, AirTrail-wins pull keeps the reservation up to date.
+  if (!row.external_owner_user_id || !isAirtrailWriteEnabled(row.external_owner_user_id)) return;
+
+  const creds: AirtrailCreds | null = getAirtrailCredentials(row.external_owner_user_id);
   if (!creds) {
     detach(tripId, row.id); // owner disconnected — cannot push, so stop syncing
     return;
diff --git a/server/tests/unit/services/airtrailSync.test.ts b/server/tests/unit/services/airtrailSync.test.ts
new file mode 100644
index 00000000..7e04821d
--- /dev/null
+++ b/server/tests/unit/services/airtrailSync.test.ts
@@ -0,0 +1,160 @@
+import { describe, it, expect } from 'vitest';
+import { buildSavePayload } from '../../../src/services/airtrail/airtrailSync';
+import type { AirtrailAirport, AirtrailFlightRaw } from '../../../src/services/airtrail/airtrailClient';
+
+function airport(over: Partial<AirtrailAirport> = {}): AirtrailAirport {
+  return {
+    id: 1,
+    icao: 'KJFK',
+    iata: 'JFK',
+    name: 'John F. Kennedy Intl.',
+    lat: 40.6413,
+    lon: -73.7781,
+    tz: 'America/New_York',
+    country: 'US',
+    ...over,
+  };
+}
+
+/**
+ * An AirTrail flight as GET returns it, including the fields TREK doesn't model.
+ * Typed as the raw object (known shape + arbitrary passthrough keys) because the
+ * push spreads it wholesale rather than mapping each field — see buildSavePayload.
+ */
+function existingFlight(
+  over: Partial<AirtrailFlightRaw> & Record<string, unknown> = {},
+): AirtrailFlightRaw & Record<string, unknown> {
+  return {
+    id: 42,
+    from: airport(),
+    to: airport({ id: 2, icao: 'EGLL', iata: 'LHR', name: 'London Heathrow', tz: 'Europe/London' }),
+    date: '2021-09-01',
+    datePrecision: 'day',
+    departure: '2021-09-01T23:00:00.000+00:00',
+    arrival: '2021-09-02T07:00:00.000+00:00',
+    airline: { id: 1, icao: 'BAW', iata: 'BA', name: 'British Airways' },
+    flightNumber: 'BA178',
+    aircraft: { id: 1, icao: 'B772', name: 'Boeing 777' },
+    aircraftReg: 'G-VIIL',
+    flightReason: 'leisure',
+    note: 'window seat',
+    seats: [{ userId: 'u1', guestName: null, seat: 'window', seatNumber: '12A', seatClass: 'economy' }],
+    // AirTrail-owned detail TREK never surfaces — must survive a writeback (#1240).
+    departureScheduled: '2021-09-01',
+    departureScheduledTime: '18:45',
+    arrivalScheduled: '2021-09-02',
+    arrivalScheduledTime: '08:10',
+    takeoffActual: '2021-09-01',
+    takeoffActualTime: '19:12',
+    landingActual: '2021-09-02',
+    landingActualTime: '07:55',
+    departureTerminal: '7',
+    departureGate: 'B22',
+    arrivalTerminal: '5',
+    arrivalGate: 'A10',
+    customFields: { confirmation: 'ABC123' },
+    track: [{ lat: 40.6, lon: -73.7 }],
+    ...over,
+  };
+}
+
+/** A linked TREK reservation (the shape getReservationWithJoins returns). */
+function reservation(over: Record<string, unknown> = {}): Record<string, unknown> {
+  return {
+    external_id: '42',
+    reservation_time: '2021-09-01T19:00',
+    reservation_end_time: '2021-09-02T08:00',
+    notes: 'window seat',
+    metadata: JSON.stringify({ airline: 'BAW', flight_number: 'BA178', aircraft: 'B772', aircraft_reg: 'G-VIIL', flight_reason: 'leisure', seat: '12A' }),
+    endpoints: [
+      { role: 'from', code: 'JFK' },
+      { role: 'to', code: 'LHR' },
+    ],
+    ...over,
+  };
+}
+
+describe('airtrailSync.buildSavePayload', () => {
+  it('round-trips the AirTrail-owned fields TREK does not model (issue #1240)', () => {
+    const payload = buildSavePayload(reservation(), existingFlight());
+    expect(payload).not.toBeNull();
+    expect(payload).toMatchObject({
+      departureScheduled: '2021-09-01',
+      departureScheduledTime: '18:45',
+      arrivalScheduled: '2021-09-02',
+      arrivalScheduledTime: '08:10',
+      takeoffActual: '2021-09-01',
+      takeoffActualTime: '19:12',
+      landingActual: '2021-09-02',
+      landingActualTime: '07:55',
+      departureTerminal: '7',
+      departureGate: 'B22',
+      arrivalTerminal: '5',
+      arrivalGate: 'A10',
+      customFields: { confirmation: 'ABC123' },
+      track: [{ lat: 40.6, lon: -73.7 }],
+    });
+  });
+
+  it('preserves a non-day date precision instead of resetting it to day', () => {
+    const payload = buildSavePayload(reservation(), existingFlight({ datePrecision: 'month' }));
+    expect(payload?.datePrecision).toBe('month');
+  });
+
+  it('still applies the TREK-owned edits on top of the preserved fields', () => {
+    const payload = buildSavePayload(
+      reservation({
+        reservation_time: '2021-09-01T20:30',
+        notes: 'changed in TREK',
+        metadata: JSON.stringify({ airline: 'BAW', flight_number: 'BA999', seat: '3C' }),
+      }),
+      existingFlight(),
+    );
+    expect(payload).toMatchObject({
+      id: 42,
+      from: 'JFK',
+      to: 'LHR',
+      departure: '2021-09-01',
+      departureTime: '20:30',
+      flightNumber: 'BA999',
+      note: 'changed in TREK',
+    });
+    // The user's seat number is pushed onto their own AirTrail seat.
+    expect(payload?.seats[0].seatNumber).toBe('3C');
+    // …without disturbing the preserved AirTrail detail.
+    expect(payload?.departureTerminal).toBe('7');
+  });
+
+  it('preserves AirTrail aircraft/airline/reason when TREK metadata omits them (#1240)', () => {
+    // A TREK edit can drop these AirTrail-owned fields from metadata; the writeback
+    // must fall back to AirTrail's current values rather than nulling them.
+    const payload = buildSavePayload(reservation({ metadata: JSON.stringify({}) }), existingFlight());
+    expect(payload).toMatchObject({
+      airline: 'BAW', // entityCode(existing.airline) — icao preferred
+      aircraft: 'B772',
+      aircraftReg: 'G-VIIL',
+      flightReason: 'leisure',
+      flightNumber: 'BA178',
+      note: 'window seat',
+    });
+  });
+
+  it('keeps the existing seat manifest rather than replacing it', () => {
+    const payload = buildSavePayload(
+      reservation({ metadata: JSON.stringify({}) }),
+      existingFlight({
+        seats: [
+          { userId: 'u1', guestName: null, seat: 'window', seatNumber: '12A', seatClass: 'business' },
+          { userId: null, guestName: 'Guest', seat: 'aisle', seatNumber: '12B', seatClass: 'business' },
+        ],
+      }),
+    );
+    expect(payload?.seats).toHaveLength(2);
+    expect(payload?.seats[1]).toMatchObject({ guestName: 'Guest', seatNumber: '12B' });
+  });
+
+  it('returns null when an endpoint code is missing and no fallback exists', () => {
+    const payload = buildSavePayload(reservation({ endpoints: [] }), existingFlight({ from: airport({ iata: null, icao: null }) }));
+    expect(payload).toBeNull();
+  });
+});
diff --git a/shared/src/airtrail/airtrail.schema.ts b/shared/src/airtrail/airtrail.schema.ts
index 9d718974..5ad1ee8c 100644
--- a/shared/src/airtrail/airtrail.schema.ts
+++ b/shared/src/airtrail/airtrail.schema.ts
@@ -21,6 +21,11 @@ export const airtrailSettingsSchema = z.object({
   apiKey: z.string().max(512).optional(),
   /** Allow self-signed TLS certs (common on LAN instances). */
   allowInsecureTls: z.boolean().optional().default(false),
+  /**
+   * Opt in to writing TREK edits back to AirTrail (#1240). Off by default:
+   * AirTrail is the source of truth and TREK only reads from it.
+   */
+  writeEnabled: z.boolean().optional().default(false),
 });
 export type AirtrailSettings = z.infer<typeof airtrailSettingsSchema>;
 
@@ -28,6 +33,7 @@ export const airtrailConnectionSchema = z.object({
   url: z.string(),
   apiKeyMasked: z.string(),
   allowInsecureTls: z.boolean(),
+  writeEnabled: z.boolean(),
   connected: z.boolean(),
 });
 export type AirtrailConnection = z.infer<typeof airtrailConnectionSchema>;
diff --git a/shared/src/i18n/ar/settings.ts b/shared/src/i18n/ar/settings.ts
index a26ea57a..fd68c0ae 100644
--- a/shared/src/i18n/ar/settings.ts
+++ b/shared/src/i18n/ar/settings.ts
@@ -327,6 +327,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'يُنشأ في AirTrail ضمن الإعدادات ← الأمان. يُخزَّن مشفّرًا.',
   'settings.airtrail.allowInsecureTls': 'السماح بالشهادات الموقّعة ذاتيًا',
   'settings.airtrail.allowInsecureTlsHint': 'فعّل هذا فقط لنسخة موثوقة على شبكتك الخاصة.',
+  'settings.airtrail.writeBack': 'كتابة التغييرات إلى AirTrail',
+  'settings.airtrail.writeBackHint': 'مُعطّل افتراضيًا: AirTrail هو مصدر الحقيقة وTREK يقرأ منه فقط. فعّله لإرسال التعديلات التي تجريها في TREK إلى AirTrail.',
   'settings.airtrail.connected': 'متصل',
   'settings.airtrail.notConnected': 'غير متصل',
   'settings.airtrail.toast.saved': 'تم حفظ اتصال AirTrail',
diff --git a/shared/src/i18n/br/settings.ts b/shared/src/i18n/br/settings.ts
index 5aaf826c..74530550 100644
--- a/shared/src/i18n/br/settings.ts
+++ b/shared/src/i18n/br/settings.ts
@@ -333,6 +333,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Gerada no AirTrail em Configurações → Segurança. Armazenada de forma criptografada.',
   'settings.airtrail.allowInsecureTls': 'Permitir certificados autoassinados',
   'settings.airtrail.allowInsecureTlsHint': 'Ative apenas para uma instância confiável na sua própria rede.',
+  'settings.airtrail.writeBack': 'Gravar alterações de volta no AirTrail',
+  'settings.airtrail.writeBackHint': 'Desativado por padrão: o AirTrail é a fonte da verdade e o TREK apenas lê dele. Ative para enviar ao AirTrail as alterações feitas no TREK.',
   'settings.airtrail.connected': 'Conectado',
   'settings.airtrail.notConnected': 'Não conectado',
   'settings.airtrail.toast.saved': 'Conexão com o AirTrail salva',
diff --git a/shared/src/i18n/cs/settings.ts b/shared/src/i18n/cs/settings.ts
index 6cd6b27e..1e3c267b 100644
--- a/shared/src/i18n/cs/settings.ts
+++ b/shared/src/i18n/cs/settings.ts
@@ -334,6 +334,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Vygenerován v AirTrail v Nastavení → Zabezpečení. Uložen šifrovaně.',
   'settings.airtrail.allowInsecureTls': 'Povolit certifikáty podepsané sebou samým',
   'settings.airtrail.allowInsecureTlsHint': 'Povolte pouze pro důvěryhodnou instanci ve vlastní síti.',
+  'settings.airtrail.writeBack': 'Zapisovat změny zpět do AirTrail',
+  'settings.airtrail.writeBackHint': 'Ve výchozím stavu vypnuto: AirTrail je zdrojem pravdy a TREK z něj pouze čte. Zapněte, chcete-li odesílat úpravy provedené v TREK zpět do AirTrail.',
   'settings.airtrail.connected': 'Připojeno',
   'settings.airtrail.notConnected': 'Nepřipojeno',
   'settings.airtrail.toast.saved': 'Připojení k AirTrail uloženo',
diff --git a/shared/src/i18n/de/settings.ts b/shared/src/i18n/de/settings.ts
index e19170dc..fc6c4cc2 100644
--- a/shared/src/i18n/de/settings.ts
+++ b/shared/src/i18n/de/settings.ts
@@ -337,6 +337,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Wird in AirTrail unter Einstellungen → Sicherheit erstellt. Verschlüsselt gespeichert.',
   'settings.airtrail.allowInsecureTls': 'Selbstsignierte Zertifikate erlauben',
   'settings.airtrail.allowInsecureTlsHint': 'Nur für eine vertrauenswürdige Instanz im eigenen Netzwerk aktivieren.',
+  'settings.airtrail.writeBack': 'Änderungen zurück nach AirTrail schreiben',
+  'settings.airtrail.writeBackHint': 'Standardmäßig aus: AirTrail ist die maßgebliche Quelle und TREK liest nur. Aktivieren, um in TREK vorgenommene Änderungen zurück an AirTrail zu senden.',
   'settings.airtrail.connected': 'Verbunden',
   'settings.airtrail.notConnected': 'Nicht verbunden',
   'settings.airtrail.toast.saved': 'AirTrail-Verbindung gespeichert',
diff --git a/shared/src/i18n/en/settings.ts b/shared/src/i18n/en/settings.ts
index fc3380d4..dccadcc7 100644
--- a/shared/src/i18n/en/settings.ts
+++ b/shared/src/i18n/en/settings.ts
@@ -326,6 +326,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Generated in AirTrail under Settings → Security. Stored encrypted.',
   'settings.airtrail.allowInsecureTls': 'Allow self-signed certificates',
   'settings.airtrail.allowInsecureTlsHint': 'Enable only for a trusted instance on your own network.',
+  'settings.airtrail.writeBack': 'Write changes back to AirTrail',
+  'settings.airtrail.writeBackHint': 'Off by default: AirTrail is the source of truth and TREK only reads from it. Turn on to push edits made in TREK back to AirTrail.',
   'settings.airtrail.connected': 'Connected',
   'settings.airtrail.notConnected': 'Not connected',
   'settings.airtrail.toast.saved': 'AirTrail connection saved',
diff --git a/shared/src/i18n/es/settings.ts b/shared/src/i18n/es/settings.ts
index 0e804dad..8e4ed6b5 100644
--- a/shared/src/i18n/es/settings.ts
+++ b/shared/src/i18n/es/settings.ts
@@ -334,6 +334,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Generada en AirTrail en Ajustes → Seguridad. Se almacena cifrada.',
   'settings.airtrail.allowInsecureTls': 'Permitir certificados autofirmados',
   'settings.airtrail.allowInsecureTlsHint': 'Actívalo solo para una instancia de confianza en tu propia red.',
+  'settings.airtrail.writeBack': 'Escribir cambios de vuelta en AirTrail',
+  'settings.airtrail.writeBackHint': 'Desactivado por defecto: AirTrail es la fuente de referencia y TREK solo lee de él. Actívalo para enviar a AirTrail los cambios hechos en TREK.',
   'settings.airtrail.connected': 'Conectado',
   'settings.airtrail.notConnected': 'No conectado',
   'settings.airtrail.toast.saved': 'Conexión con AirTrail guardada',
diff --git a/shared/src/i18n/fr/settings.ts b/shared/src/i18n/fr/settings.ts
index d196f56c..3451ce20 100644
--- a/shared/src/i18n/fr/settings.ts
+++ b/shared/src/i18n/fr/settings.ts
@@ -339,6 +339,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Générée dans AirTrail sous Paramètres → Sécurité. Stockée chiffrée.',
   'settings.airtrail.allowInsecureTls': 'Autoriser les certificats auto-signés',
   'settings.airtrail.allowInsecureTlsHint': 'À activer uniquement pour une instance de confiance sur votre propre réseau.',
+  'settings.airtrail.writeBack': 'Réécrire les modifications dans AirTrail',
+  'settings.airtrail.writeBackHint': 'Désactivé par défaut : AirTrail fait référence et TREK se contente de le lire. Activez pour renvoyer vers AirTrail les modifications faites dans TREK.',
   'settings.airtrail.connected': 'Connecté',
   'settings.airtrail.notConnected': 'Non connecté',
   'settings.airtrail.toast.saved': 'Connexion AirTrail enregistrée',
diff --git a/shared/src/i18n/gr/settings.ts b/shared/src/i18n/gr/settings.ts
index e8674ee2..80052824 100644
--- a/shared/src/i18n/gr/settings.ts
+++ b/shared/src/i18n/gr/settings.ts
@@ -340,6 +340,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Δημιουργείται στο AirTrail από Ρυθμίσεις → Ασφάλεια. Αποθηκεύεται κρυπτογραφημένο.',
   'settings.airtrail.allowInsecureTls': 'Να επιτρέπονται αυτο-υπογεγραμμένα πιστοποιητικά',
   'settings.airtrail.allowInsecureTlsHint': 'Ενεργοποιήστε το μόνο για μια αξιόπιστη εγκατάσταση στο δικό σας δίκτυο.',
+  'settings.airtrail.writeBack': 'Εγγραφή αλλαγών πίσω στο AirTrail',
+  'settings.airtrail.writeBackHint': 'Απενεργοποιημένο από προεπιλογή: το AirTrail είναι η πηγή αλήθειας και το TREK μόνο διαβάζει από αυτό. Ενεργοποιήστε το για να στέλνετε πίσω στο AirTrail τις αλλαγές που κάνετε στο TREK.',
   'settings.airtrail.connected': 'Συνδέθηκε',
   'settings.airtrail.notConnected': 'Δεν συνδέθηκε',
   'settings.airtrail.toast.saved': 'Η σύνδεση με το AirTrail αποθηκεύτηκε',
diff --git a/shared/src/i18n/hu/settings.ts b/shared/src/i18n/hu/settings.ts
index 2ea67e6a..192515bc 100644
--- a/shared/src/i18n/hu/settings.ts
+++ b/shared/src/i18n/hu/settings.ts
@@ -336,6 +336,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Az AirTrailben a Beállítások → Biztonság menüpontban generálva. Titkosítva tárolva.',
   'settings.airtrail.allowInsecureTls': 'Önaláírt tanúsítványok engedélyezése',
   'settings.airtrail.allowInsecureTlsHint': 'Csak megbízható, saját hálózaton futó példány esetén engedélyezd.',
+  'settings.airtrail.writeBack': 'Módosítások visszaírása az AirTrailbe',
+  'settings.airtrail.writeBackHint': 'Alapértelmezés szerint kikapcsolva: az AirTrail a hiteles forrás, és a TREK csak olvas belőle. Kapcsold be, hogy a TREK-ben végzett módosításokat visszaküldje az AirTrailbe.',
   'settings.airtrail.connected': 'Csatlakoztatva',
   'settings.airtrail.notConnected': 'Nincs csatlakoztatva',
   'settings.airtrail.toast.saved': 'AirTrail-kapcsolat mentve',
diff --git a/shared/src/i18n/id/settings.ts b/shared/src/i18n/id/settings.ts
index dac5c269..171367fd 100644
--- a/shared/src/i18n/id/settings.ts
+++ b/shared/src/i18n/id/settings.ts
@@ -334,6 +334,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Dibuat di AirTrail pada Pengaturan → Keamanan. Disimpan terenkripsi.',
   'settings.airtrail.allowInsecureTls': 'Izinkan sertifikat yang ditandatangani sendiri',
   'settings.airtrail.allowInsecureTlsHint': 'Aktifkan hanya untuk instans tepercaya di jaringanmu sendiri.',
+  'settings.airtrail.writeBack': 'Tulis perubahan kembali ke AirTrail',
+  'settings.airtrail.writeBackHint': 'Nonaktif secara bawaan: AirTrail adalah sumber kebenaran dan TREK hanya membaca darinya. Aktifkan untuk mengirim perubahan yang dibuat di TREK kembali ke AirTrail.',
   'settings.airtrail.connected': 'Terhubung',
   'settings.airtrail.notConnected': 'Tidak terhubung',
   'settings.airtrail.toast.saved': 'Koneksi AirTrail disimpan',
diff --git a/shared/src/i18n/it/settings.ts b/shared/src/i18n/it/settings.ts
index acc504b8..eaa90aee 100644
--- a/shared/src/i18n/it/settings.ts
+++ b/shared/src/i18n/it/settings.ts
@@ -333,6 +333,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Generata in AirTrail in Impostazioni → Sicurezza. Memorizzata crittografata.',
   'settings.airtrail.allowInsecureTls': 'Consenti certificati autofirmati',
   'settings.airtrail.allowInsecureTlsHint': 'Abilita solo per un\'istanza attendibile sulla tua rete.',
+  'settings.airtrail.writeBack': 'Scrivi le modifiche su AirTrail',
+  'settings.airtrail.writeBackHint': 'Disattivato per impostazione predefinita: AirTrail è la fonte attendibile e TREK si limita a leggerlo. Attiva per inviare ad AirTrail le modifiche fatte in TREK.',
   'settings.airtrail.connected': 'Connesso',
   'settings.airtrail.notConnected': 'Non connesso',
   'settings.airtrail.toast.saved': 'Connessione AirTrail salvata',
diff --git a/shared/src/i18n/ja/settings.ts b/shared/src/i18n/ja/settings.ts
index 6646077d..e0c0f18a 100644
--- a/shared/src/i18n/ja/settings.ts
+++ b/shared/src/i18n/ja/settings.ts
@@ -313,6 +313,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'AirTrail の「設定 → セキュリティ」で生成します。暗号化して保存されます。',
   'settings.airtrail.allowInsecureTls': '自己署名証明書を許可する',
   'settings.airtrail.allowInsecureTlsHint': '自分のネットワーク内の信頼できるインスタンスの場合にのみ有効にしてください。',
+  'settings.airtrail.writeBack': '変更を AirTrail に書き戻す',
+  'settings.airtrail.writeBackHint': '既定ではオフ: AirTrail が信頼できる情報源で、TREK は読み取りのみを行います。TREK で行った編集を AirTrail に書き戻すにはオンにします。',
   'settings.airtrail.connected': '接続済み',
   'settings.airtrail.notConnected': '未接続',
   'settings.airtrail.toast.saved': 'AirTrail の接続を保存しました',
diff --git a/shared/src/i18n/ko/settings.ts b/shared/src/i18n/ko/settings.ts
index d34b03a1..69d5183b 100644
--- a/shared/src/i18n/ko/settings.ts
+++ b/shared/src/i18n/ko/settings.ts
@@ -330,6 +330,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'AirTrail의 설정 → 보안에서 생성됩니다. 암호화하여 저장됩니다.',
   'settings.airtrail.allowInsecureTls': '자체 서명 인증서 허용',
   'settings.airtrail.allowInsecureTlsHint': '자체 네트워크의 신뢰할 수 있는 인스턴스에서만 활성화하세요.',
+  'settings.airtrail.writeBack': '변경 사항을 AirTrail에 다시 기록',
+  'settings.airtrail.writeBackHint': '기본적으로 꺼져 있음: AirTrail이 신뢰할 수 있는 원본이며 TREK은 읽기만 합니다. TREK에서 변경한 내용을 AirTrail로 다시 보내려면 켜세요.',
   'settings.airtrail.connected': '연결됨',
   'settings.airtrail.notConnected': '연결되지 않음',
   'settings.airtrail.toast.saved': 'AirTrail 연결이 저장되었습니다',
diff --git a/shared/src/i18n/nl/settings.ts b/shared/src/i18n/nl/settings.ts
index 6639f4c1..203d695b 100644
--- a/shared/src/i18n/nl/settings.ts
+++ b/shared/src/i18n/nl/settings.ts
@@ -336,6 +336,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.allowInsecureTls': 'Zelfondertekende certificaten toestaan',
   'settings.airtrail.allowInsecureTlsHint':
     'Schakel dit alleen in voor een vertrouwde instantie op je eigen netwerk.',
+  'settings.airtrail.writeBack': 'Wijzigingen terugschrijven naar AirTrail',
+  'settings.airtrail.writeBackHint': 'Standaard uit: AirTrail is de bron van waarheid en TREK leest er alleen uit. Schakel in om in TREK gemaakte wijzigingen terug te sturen naar AirTrail.',
   'settings.airtrail.connected': 'Verbonden',
   'settings.airtrail.notConnected': 'Niet verbonden',
   'settings.airtrail.toast.saved': 'AirTrail-verbinding opgeslagen',
diff --git a/shared/src/i18n/pl/settings.ts b/shared/src/i18n/pl/settings.ts
index 43db4f7b..a954ac09 100644
--- a/shared/src/i18n/pl/settings.ts
+++ b/shared/src/i18n/pl/settings.ts
@@ -335,6 +335,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Wygenerowany w AirTrail w sekcji Ustawienia → Bezpieczeństwo. Przechowywany w postaci zaszyfrowanej.',
   'settings.airtrail.allowInsecureTls': 'Zezwalaj na certyfikaty samopodpisane',
   'settings.airtrail.allowInsecureTlsHint': 'Włącz tylko dla zaufanej instancji we własnej sieci.',
+  'settings.airtrail.writeBack': 'Zapisuj zmiany z powrotem w AirTrail',
+  'settings.airtrail.writeBackHint': 'Domyślnie wyłączone: AirTrail jest źródłem prawdy, a TREK tylko z niego odczytuje. Włącz, aby wysyłać zmiany wprowadzone w TREK z powrotem do AirTrail.',
   'settings.airtrail.connected': 'Połączono',
   'settings.airtrail.notConnected': 'Nie połączono',
   'settings.airtrail.toast.saved': 'Zapisano połączenie z AirTrail',
diff --git a/shared/src/i18n/ru/settings.ts b/shared/src/i18n/ru/settings.ts
index ac02578f..a753ec96 100644
--- a/shared/src/i18n/ru/settings.ts
+++ b/shared/src/i18n/ru/settings.ts
@@ -333,6 +333,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Создаётся в AirTrail в разделе «Настройки → Безопасность». Хранится в зашифрованном виде.',
   'settings.airtrail.allowInsecureTls': 'Разрешить самоподписанные сертификаты',
   'settings.airtrail.allowInsecureTlsHint': 'Включайте только для доверенного экземпляра в вашей собственной сети.',
+  'settings.airtrail.writeBack': 'Записывать изменения обратно в AirTrail',
+  'settings.airtrail.writeBackHint': 'По умолчанию выключено: AirTrail является источником истины, а TREK только читает из него. Включите, чтобы отправлять изменения, сделанные в TREK, обратно в AirTrail.',
   'settings.airtrail.connected': 'Подключено',
   'settings.airtrail.notConnected': 'Не подключено',
   'settings.airtrail.toast.saved': 'Подключение к AirTrail сохранено',
diff --git a/shared/src/i18n/tr/settings.ts b/shared/src/i18n/tr/settings.ts
index 99c61264..8c341fa1 100644
--- a/shared/src/i18n/tr/settings.ts
+++ b/shared/src/i18n/tr/settings.ts
@@ -334,6 +334,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'AirTrail\'de Ayarlar → Güvenlik altında oluşturulur. Şifreli olarak saklanır.',
   'settings.airtrail.allowInsecureTls': 'Kendinden imzalı sertifikalara izin ver',
   'settings.airtrail.allowInsecureTlsHint': 'Yalnızca kendi ağınızdaki güvenilir bir örnek için etkinleştirin.',
+  'settings.airtrail.writeBack': 'Değişiklikleri AirTrail’e geri yaz',
+  'settings.airtrail.writeBackHint': 'Varsayılan olarak kapalı: AirTrail asıl kaynaktır ve TREK yalnızca okur. TREK’te yapılan değişiklikleri AirTrail’e geri göndermek için açın.',
   'settings.airtrail.connected': 'Bağlandı',
   'settings.airtrail.notConnected': 'Bağlı değil',
   'settings.airtrail.toast.saved': 'AirTrail bağlantısı kaydedildi',
diff --git a/shared/src/i18n/uk/settings.ts b/shared/src/i18n/uk/settings.ts
index dd54c33d..9a45bf08 100644
--- a/shared/src/i18n/uk/settings.ts
+++ b/shared/src/i18n/uk/settings.ts
@@ -332,6 +332,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': 'Згенеровано в AirTrail у розділі Налаштування → Безпека. Зберігається в зашифрованому вигляді.',
   'settings.airtrail.allowInsecureTls': 'Дозволити самопідписані сертифікати',
   'settings.airtrail.allowInsecureTlsHint': 'Вмикайте лише для довіреного екземпляра у вашій власній мережі.',
+  'settings.airtrail.writeBack': 'Записувати зміни назад у AirTrail',
+  'settings.airtrail.writeBackHint': 'Типово вимкнено: AirTrail є джерелом істини, а TREK лише читає з нього. Увімкніть, щоб надсилати зміни, зроблені в TREK, назад до AirTrail.',
   'settings.airtrail.connected': 'Підключено',
   'settings.airtrail.notConnected': 'Не підключено',
   'settings.airtrail.toast.saved': 'Підключення AirTrail збережено',
diff --git a/shared/src/i18n/zh-TW/settings.ts b/shared/src/i18n/zh-TW/settings.ts
index aaf8cbc0..20d3fa72 100644
--- a/shared/src/i18n/zh-TW/settings.ts
+++ b/shared/src/i18n/zh-TW/settings.ts
@@ -319,6 +319,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': '在 AirTrail 的「設定 → 安全性」中產生。以加密方式儲存。',
   'settings.airtrail.allowInsecureTls': '允許自簽憑證',
   'settings.airtrail.allowInsecureTlsHint': '僅在你自己網路上受信任的執行個體啟用。',
+  'settings.airtrail.writeBack': '將變更寫回 AirTrail',
+  'settings.airtrail.writeBackHint': '預設關閉：AirTrail 是資料來源，TREK 僅從中讀取。開啟後會將在 TREK 中所做的修改寫回 AirTrail。',
   'settings.airtrail.connected': '已連接',
   'settings.airtrail.notConnected': '未連接',
   'settings.airtrail.toast.saved': '已儲存 AirTrail 連接',
diff --git a/shared/src/i18n/zh/settings.ts b/shared/src/i18n/zh/settings.ts
index 0729c916..c5a44bbb 100644
--- a/shared/src/i18n/zh/settings.ts
+++ b/shared/src/i18n/zh/settings.ts
@@ -318,6 +318,8 @@ const settings: TranslationStrings = {
   'settings.airtrail.apiKeyHint': '在 AirTrail 的“设置 → 安全”中生成。加密存储。',
   'settings.airtrail.allowInsecureTls': '允许自签名证书',
   'settings.airtrail.allowInsecureTlsHint': '仅对您自己网络中受信任的实例启用。',
+  'settings.airtrail.writeBack': '将更改写回 AirTrail',
+  'settings.airtrail.writeBackHint': '默认关闭：AirTrail 是数据来源，TREK 仅从中读取。开启后会将在 TREK 中所做的修改写回 AirTrail。',
   'settings.airtrail.connected': '已连接',
   'settings.airtrail.notConnected': '未连接',
   'settings.airtrail.toast.saved': 'AirTrail 连接已保存',