Squashed commit of the following:

commit 38d03588b1
Merge: 8e987d0 6f4aa3b
Author: ncoronel <ncoronel@quo.ar>
Date:   Wed Aug 26 10:25:23 2026 -0300

    Merge branch 'fix/cart-expiration-notification' of https://gitea.quo.ar/tbianchini/shopit-front into fix/cart-expiration-notification

commit 8e987d0ce6
Author: ncoronel <ncoronel@quo.ar>
Date:   Wed Aug 26 10:02:26 2026 -0300

    fix(purchase-status): clear cart on approved purchase

commit e171b9a233
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 17:06:07 2026 -0300

    refactor(checkout): use purchase id route segment

commit 643d43adea
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 17:05:59 2026 -0300

    fix(checkout): handle expired purchase exits

commit d89d01b511
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 16:47:17 2026 -0300

    fix(checkout): refresh expired carts

commit eeb245209b
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 16:46:12 2026 -0300

    fix(checkout): show backend start errors

commit 9d3754c2d8
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 16:33:44 2026 -0300

    fix(cart): refresh state after expiration

commit 6f4aa3b1bd
Author: ncoronel <ncoronel@quo.ar>
Date:   Wed Aug 26 10:02:26 2026 -0300

    fix(purchase-status): clear cart on approved purchase

commit 2b342ec235
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 17:06:07 2026 -0300

    refactor(checkout): use purchase id route segment

commit d06b146104
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 17:05:59 2026 -0300

    fix(checkout): handle expired purchase exits

commit f4e0a9e028
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 16:47:17 2026 -0300

    fix(checkout): refresh expired carts

commit 8c2b738806
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 16:46:12 2026 -0300

    fix(checkout): show backend start errors

commit 1362d0c163
Author: ncoronel <ncoronel@quo.ar>
Date:   Tue Aug 25 16:33:44 2026 -0300

    fix(cart): refresh state after expiration

src/app/core/services/auth/auth.guards.spec.ts

@@ -24,12 +24,12 @@ describe('auth guards', () => {
     });
 
     const result = TestBed.runInInjectionContext(() =>
-      authGuard(null as never, { url: '/checkout?mode=direct' } as never),
+      authGuard(null as never, { url: '/checkout/25' } as never),
     );
 
     expect(result instanceof UrlTree).toBe(true);
     expect(TestBed.inject(Router).serializeUrl(result as UrlTree)).toBe(
-      '/login?returnUrl=%2Fcheckout%3Fmode%3Ddirect',
+      '/login?returnUrl=%2Fcheckout%2F25',
     );
   });
 
@@ -39,7 +39,7 @@ describe('auth guards', () => {
     });
 
     const result = TestBed.runInInjectionContext(() =>
-      authGuard(null as never, { url: '/checkout' } as never),
+      authGuard(null as never, { url: '/checkout/25' } as never),
     );
 
     expect(result).toBe(true);

src/app/core/services/checkout.service.ts

@@ -45,6 +45,21 @@ export function isInsufficientStockResponse(value: unknown): value is Insufficie
   );
 }
 
+export interface ExpiredStockReservationResponse {
+  code: 'stock_reservation.expired';
+  message: string;
+}
+
+export function isExpiredStockReservationResponse(
+  value: unknown,
+): value is ExpiredStockReservationResponse {
+  return (
+    typeof value === 'object' &&
+    value !== null &&
+    (value as Partial<ExpiredStockReservationResponse>).code === 'stock_reservation.expired'
+  );
+}
+
 export type StartCheckoutPayload =
   | {
       cart_id: number;