fix(reservations): keep the linked expense price when a booking is edited

A booking's linked expense price lives in reservations.metadata.price
(written by BudgetService.syncReservationPrice). The booking form rebuilds
metadata from its fields on every save and only carries transit /
airtrail_ids over, so PUT /api/trips/:tripId/reservations/:id overwrote the
stored metadata and the price vanished from the card until the expense was
re-saved.

ReservationsService.update() now carries price / priceCurrency from the
stored metadata into an incoming metadata object that does not set them,
as long as a budget item is still linked to the booking. A payload that
sets price itself, a booking without a linked expense, and an explicit
metadata: null behave exactly as before.

Closes #2233

server/src/nest/reservations/reservations.service.ts

@@ -720,6 +720,15 @@ export class ReservationsService {
       }
     }
 
+    // metadata.price / priceCurrency are owned by the linked expense
+    // (BudgetService.syncReservationPrice writes them), not by the booking form:
+    // the client rebuilds metadata from the form on every save and only carries
+    // transit / airtrail_ids over, so a plain edit used to wipe the price off the
+    // card until the expense was re-saved. Keep them while a linked item exists;
+    // a payload that sets them itself, or a booking without a linked expense,
+    // is left untouched.
+    const nextMetadata = this.keepLinkedExpensePrice(id, tripId, metadata, current.metadata);
+
     const resolvedType = (type ?? current.type) || 'other';
     const nextReservationTime = resolvedType === 'hotel'
       ? null
@@ -790,7 +799,7 @@ export class ReservationsService {
       status || null,
       type || null,
       resolvedAccId,
-      metadata !== undefined ? (metadata ? JSON.stringify(metadata) : null) : current.metadata,
+      nextMetadata !== undefined ? (nextMetadata ? JSON.stringify(nextMetadata) : null) : current.metadata,
       needs_review === undefined ? null : (needs_review ? 1 : 0),
       id
     );
@@ -800,7 +809,7 @@ export class ReservationsService {
     }
 
     // Sync check-in/out to accommodation if linked
-    const resolvedMeta = metadata !== undefined ? metadata : (current.metadata ? JSON.parse(current.metadata as string) : null);
+    const resolvedMeta = nextMetadata !== undefined ? nextMetadata : (current.metadata ? JSON.parse(current.metadata as string) : null);
     if (resolvedAccId && resolvedMeta) {
       const meta = (typeof resolvedMeta === 'string' ? JSON.parse(resolvedMeta) : resolvedMeta) as AccommodationTimesMeta;
       if (meta.check_in_time || meta.check_in_end_time || meta.check_out_time) {
@@ -824,6 +833,32 @@ export class ReservationsService {
     return { reservation, accommodationChanged };
   }
 
+  /**
+   * Carry `price` / `priceCurrency` from the stored metadata into an incoming
+   * metadata object that doesn't set them, as long as a budget item is still
+   * linked to the booking. Returns the incoming value untouched otherwise —
+   * `undefined` (field absent) and `null` (explicit clear) pass straight through.
+   */
+  private keepLinkedExpensePrice(id: string | number, tripId: string | number, incoming: unknown, stored: string | null | undefined): unknown {
+    if (!incoming || typeof incoming !== 'object' || Array.isArray(incoming) || !stored) return incoming;
+    const next = incoming as Record<string, unknown>;
+    if (next.price !== undefined) return incoming;
+    let prev: Record<string, unknown>;
+    try {
+      const parsed: unknown = JSON.parse(stored);
+      if (!parsed || typeof parsed !== 'object') return incoming;
+      prev = parsed as Record<string, unknown>;
+    } catch {
+      return incoming;
+    }
+    if (prev.price === undefined) return incoming;
+    const linked = this.db.get('SELECT id FROM budget_items WHERE trip_id = ? AND reservation_id = ?', tripId, id);
+    if (!linked) return incoming;
+    const kept: Record<string, unknown> = { ...next, price: prev.price };
+    if (prev.priceCurrency !== undefined && next.priceCurrency === undefined) kept.priceCurrency = prev.priceCurrency;
+    return kept;
+  }
+
   /** The accommodation + budget-item + reservation deletes are one logical
    *  cascade — all-or-nothing. */
   remove(id: string | number, tripId: string | number): { deleted: { id: number; title: string; type: string; accommodation_id: number | null } | undefined; accommodationDeleted: boolean; deletedBudgetItemId: number | null } {

server/tests/unit/nest/reservations.service.test.ts

@@ -200,6 +200,47 @@ describe('ReservationsService (DI-native, real SQL)', () => {
       expect(reservation.accommodation_id).toBeNull();
     });
 
+    it('RESV-SVC-033: a metadata payload without `price` keeps the linked expense price (and currency) from the stored metadata', () => {
+      const { trip } = ownerTrip();
+      const res = createReservation(testDb, trip.id, { title: 'Flight', type: 'flight' });
+      const item = createBudgetItem(testDb, trip.id, { name: 'Flight', total_price: 2040 });
+      testDb.prepare('UPDATE budget_items SET reservation_id = ? WHERE id = ?').run(res.id, item.id);
+      testDb.prepare('UPDATE reservations SET metadata = ? WHERE id = ?')
+        .run(JSON.stringify({ airline: 'CZ', seat: '72K', price: '2040', priceCurrency: 'CNY' }), res.id);
+      const current = svc.getReservation(String(res.id), String(trip.id))!;
+      // What the booking form sends back: rebuilt from its fields, price not among them.
+      const { reservation } = svc.update(String(res.id), String(trip.id), { metadata: { airline: 'CZ', seat: '12A' } }, current);
+      expect(JSON.parse(reservation.metadata as string)).toEqual({ airline: 'CZ', seat: '12A', price: '2040', priceCurrency: 'CNY' });
+    });
+
+    it('RESV-SVC-034: a payload that sets `price` itself, or a booking with no linked expense, is stored as sent', () => {
+      const { trip } = ownerTrip();
+      const linkedRes = createReservation(testDb, trip.id, { title: 'Linked', type: 'flight' });
+      const item = createBudgetItem(testDb, trip.id, { name: 'Linked', total_price: 100 });
+      testDb.prepare('UPDATE budget_items SET reservation_id = ? WHERE id = ?').run(linkedRes.id, item.id);
+      testDb.prepare('UPDATE reservations SET metadata = ? WHERE id = ?').run(JSON.stringify({ price: '100' }), linkedRes.id);
+      let current = svc.getReservation(String(linkedRes.id), String(trip.id))!;
+      let { reservation } = svc.update(String(linkedRes.id), String(trip.id), { metadata: { price: '150' } }, current);
+      expect(JSON.parse(reservation.metadata as string)).toEqual({ price: '150' });
+
+      const orphanRes = createReservation(testDb, trip.id, { title: 'Orphan', type: 'flight' });
+      testDb.prepare('UPDATE reservations SET metadata = ? WHERE id = ?').run(JSON.stringify({ price: '999' }), orphanRes.id);
+      current = svc.getReservation(String(orphanRes.id), String(trip.id))!;
+      ({ reservation } = svc.update(String(orphanRes.id), String(trip.id), { metadata: { seat: '1A' } }, current));
+      expect(JSON.parse(reservation.metadata as string)).toEqual({ seat: '1A' });
+    });
+
+    it('RESV-SVC-035: metadata null still clears the stored metadata, linked expense or not', () => {
+      const { trip } = ownerTrip();
+      const res = createReservation(testDb, trip.id, { title: 'Flight', type: 'flight' });
+      const item = createBudgetItem(testDb, trip.id, { name: 'Flight', total_price: 50 });
+      testDb.prepare('UPDATE budget_items SET reservation_id = ? WHERE id = ?').run(res.id, item.id);
+      testDb.prepare('UPDATE reservations SET metadata = ? WHERE id = ?').run(JSON.stringify({ price: '50' }), res.id);
+      const current = svc.getReservation(String(res.id), String(trip.id))!;
+      const { reservation } = svc.update(String(res.id), String(trip.id), { metadata: null }, current);
+      expect(reservation.metadata).toBeNull();
+    });
+
     it('RESV-SVC-010: endpoints [] wipes stored endpoints; an absent field leaves them alone', () => {
       const { trip } = ownerTrip();
       const res = createReservation(testDb, trip.id, { title: 'Bus' });