Fix destructive sales and backup restore regressions

inventory/templates/inventory/sale_form.html

@@ -1346,9 +1346,9 @@ <h5 class="payment-title mb-3">{% if request.LANGUAGE_CODE == 'en' %}Payment Met
                         <i class="bi bi-wallet2"></i>
                         {% if request.LANGUAGE_CODE == 'en' %}Balance{% else %}余额{% endif %}
                     </button>
-                    <button type="button" class="payment-btn" data-payment="credit">
+                    <button type="button" class="payment-btn" data-payment="other">
                         <i class="bi bi-journal-text"></i>
-                        {% if request.LANGUAGE_CODE == 'en' %}Credit{% else %}挂账{% endif %}
+                        {% if request.LANGUAGE_CODE == 'en' %}Other{% else %}其他{% endif %}
                     </button>
                 </div>
             </div>

inventory/templates/inventory/sale_item_form.html

@@ -476,16 +476,19 @@ <h4 class="card-title mb-0">添加销售商品</h4>
                                 </tr>
                             </thead>
                             <tbody id="sale-items">
-                                {% for item in sale.saleitems.all %}
+                                {% for item in items %}
                                 <tr>
                                     <td>{{ item.product.name }}</td>
                                     <td>{{ item.quantity }}</td>
                                     <td>{{ item.actual_price }}</td>
                                     <td>{{ item.subtotal }}</td>
                                     <td>
-                                        <a href="{% url 'sale_item_delete' sale.id item.id %}" class="btn btn-sm btn-outline-danger" title="删除">
-                                            <i class="bi bi-trash"></i>
-                                        </a>
+                                        <form method="post" action="{% url 'sale_item_delete' sale.id item.id %}" class="d-inline">
+                                            {% csrf_token %}
+                                            <button type="submit" class="btn btn-sm btn-outline-danger" title="删除">
+                                                <i class="bi bi-trash"></i>
+                                            </button>
+                                        </form>
                                     </td>
                                 </tr>
                                 {% endfor %}

inventory/templates/inventory/system/backup_list.html

@@ -148,7 +148,11 @@ <h5 class="modal-title" id="deleteBackupModalLabel">删除备份</h5>
             </div>
             <div class="modal-footer">
                 <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">取消</button>
-                <a href="#" id="confirm-delete-backup" class="btn btn-danger">确认删除</a>
+                <form method="post" id="delete-backup-form" class="d-inline">
+                    {% csrf_token %}
+                    <input type="hidden" name="confirm" value="on">
+                    <button type="submit" class="btn btn-danger">确认删除</button>
+                </form>
             </div>
         </div>
     </div>
@@ -160,13 +164,13 @@ <h5 class="modal-title" id="deleteBackupModalLabel">删除备份</h5>
         const deleteBackupModal = new bootstrap.Modal(document.getElementById('deleteBackupModal'));
         const deleteButtons = document.querySelectorAll('.delete-backup');
         const backupNameToDelete = document.getElementById('backup-name-to-delete');
-        const confirmDeleteButton = document.getElementById('confirm-delete-backup');
+        const deleteBackupForm = document.getElementById('delete-backup-form');
 
         deleteButtons.forEach(button => {
             button.addEventListener('click', function() {
                 const backupName = this.getAttribute('data-backup-name');
                 backupNameToDelete.textContent = backupName;
-                confirmDeleteButton.href = `/system/backup/delete/${backupName}/`;
+                deleteBackupForm.action = `/system/backup/delete/${backupName}/`;
                 deleteBackupModal.show();
             });
         });

inventory/templates/inventory/system/delete_backup.html

@@ -0,0 +1,27 @@
+{% extends 'inventory/base.html' %}
+
+{% block title %}删除备份 - {{ block.super }}{% endblock %}
+
+{% block content %}
+<div class="row justify-content-center">
+    <div class="col-md-6">
+        <div class="card">
+            <div class="card-header bg-danger text-white">
+                <h5 class="card-title mb-0">删除备份</h5>
+            </div>
+            <div class="card-body">
+                <p>确定要删除备份 <strong>{{ backup_name }}</strong> 吗？</p>
+                <p class="text-danger">此操作不可恢复。</p>
+                <form method="post">
+                    {% csrf_token %}
+                    <input type="hidden" name="confirm" value="on">
+                    <div class="d-flex justify-content-between">
+                        <a href="{% url 'backup_list' %}" class="btn btn-outline-secondary">取消</a>
+                        <button type="submit" class="btn btn-danger">确认删除</button>
+                    </div>
+                </form>
+            </div>
+        </div>
+    </div>
+</div>
+{% endblock %}

inventory/tests/test_sale_status.py

@@ -141,6 +141,19 @@ def test_cannot_delete_item_from_cancelled_sale(self):
         self.inventory.refresh_from_db()
         self.assertEqual(self.inventory.quantity, restored_quantity)
 
+    def test_get_does_not_delete_item_or_restore_inventory(self):
+        sale = self._make_sale(status='DRAFT')
+        item = sale.items.get()
+        self.inventory.refresh_from_db()
+        before = self.inventory.quantity
+
+        response = self.client.get(reverse('sale_item_delete', args=[sale.id, item.id]))
+
+        self.assertEqual(response.status_code, 405)
+        self.assertTrue(SaleItem.objects.filter(pk=item.pk).exists())
+        self.inventory.refresh_from_db()
+        self.assertEqual(self.inventory.quantity, before)
+
     def test_delete_item_persists_recalculated_total(self):
         sale = self._make_sale(status='DRAFT')
         extra = SaleItem.objects.create(
@@ -160,6 +173,20 @@ def test_delete_item_persists_recalculated_total(self):
         sale.refresh_from_db()
         self.assertEqual(sale.total_amount, Decimal('20.00'))  # 删除后总额已落库
 
+    def test_sale_detail_does_not_rewrite_persisted_amounts(self):
+        sale = self._make_sale(status='COMPLETED')
+        sale.total_amount = Decimal('15.00')
+        sale.discount_amount = Decimal('0.00')
+        sale.final_amount = Decimal('15.00')
+        sale.save()
+
+        response = self.client.get(reverse('sale_detail', args=[sale.id]))
+
+        self.assertEqual(response.status_code, 200)
+        sale.refresh_from_db()
+        self.assertEqual(sale.total_amount, Decimal('15.00'))
+        self.assertEqual(sale.final_amount, Decimal('15.00'))
+
     def test_sale_complete_page_renders_for_draft_sale(self):
         sale = self._make_sale(status='DRAFT')
 
@@ -203,3 +230,19 @@ def test_sale_complete_insufficient_balance_does_not_credit_member(self):
         self.assertEqual(member.purchase_count, 0)
         self.assertEqual(member.total_spend, Decimal('0.00'))
         self.assertFalse(MemberTransaction.objects.filter(member=member).exists())
+
+    def test_sale_complete_rejects_unsupported_credit_payment(self):
+        sale = self._make_sale(status='DRAFT')
+
+        response = self.client.post(
+            reverse('sale_complete', args=[sale.id]),
+            {
+                'payment_method': 'credit',
+                'remark': 'unsupported',
+            },
+        )
+
+        self.assertRedirects(response, reverse('sale_complete', args=[sale.id]))
+        sale.refresh_from_db()
+        self.assertEqual(sale.status, 'DRAFT')
+        self.assertEqual(sale.payment_method, 'cash')

inventory/tests/test_sales_balance_payment.py

@@ -97,3 +97,11 @@ def test_sale_create_balance_payment_rolls_back_when_balance_is_insufficient(sel
         self.assertEqual(self.member.balance, Decimal('5.00'))
         self.inventory.refresh_from_db()
         self.assertEqual(self.inventory.quantity, 10)
+
+    def test_sale_create_rejects_unsupported_credit_payment(self):
+        response = self.client.post(reverse('sale_create'), self.sale_post_data('credit'))
+
+        self.assertRedirects(response, reverse('sale_create'))
+        self.assertFalse(Sale.objects.exists())
+        self.inventory.refresh_from_db()
+        self.assertEqual(self.inventory.quantity, 10)

inventory/tests/test_views.py

@@ -1,6 +1,8 @@
 import json
 import os
+import shutil
 import tempfile
+from unittest import mock
 
 from django.core import management
 from django.test import TestCase, Client
@@ -321,3 +323,93 @@ def test_restore_backup_flushes_records_missing_from_snapshot(self):
         self.assertEqual(response.status_code, 302)
         self.assertEqual(response['Location'], reverse('system_settings'))
         self.assertFalse(Product.objects.filter(pk=product.pk).exists())
+
+    def test_restore_backup_page_renders_with_backup_context(self):
+        backup_name = 'page_context'
+        backup_dir = os.path.join(self.backup_root, backup_name)
+        os.makedirs(backup_dir, exist_ok=True)
+        with open(os.path.join(backup_dir, 'backup_info.json'), 'w', encoding='utf-8') as backup_info:
+            json.dump(
+                {
+                    'name': backup_name,
+                    'created_at': '2026-05-30T11:00:00',
+                    'created_by': self.user.username,
+                    'includes_media': False,
+                },
+                backup_info,
+            )
+
+        with self.settings(BACKUP_ROOT=self.backup_root, TEMP_DIR=self.temp_dir):
+            response = self.client.get(reverse('restore_backup', args=[backup_name]))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, backup_name)
+
+    def test_restore_backup_rolls_back_database_and_media_when_media_restore_fails(self):
+        backup_name = 'media_failure'
+        backup_dir = os.path.join(self.backup_root, backup_name)
+        media_backup_dir = os.path.join(backup_dir, 'media')
+        media_root = os.path.join(self.temp_parent.name, 'media')
+        os.makedirs(media_backup_dir, exist_ok=True)
+        os.makedirs(media_root, exist_ok=True)
+
+        with open(os.path.join(media_backup_dir, 'backup.txt'), 'w', encoding='utf-8') as backup_file:
+            backup_file.write('backup media')
+        with open(os.path.join(media_root, 'current.txt'), 'w', encoding='utf-8') as current_file:
+            current_file.write('current media')
+
+        db_file = os.path.join(backup_dir, 'db.json')
+        with self.settings(BACKUP_ROOT=self.backup_root, TEMP_DIR=self.temp_dir, MEDIA_ROOT=media_root):
+            management.call_command(
+                'dumpdata',
+                '--exclude',
+                'auth.permission',
+                '--exclude',
+                'contenttypes',
+                '--exclude',
+                'sessions.session',
+                '--indent',
+                '4',
+                '--output',
+                db_file,
+                verbosity=0,
+            )
+
+        with open(os.path.join(backup_dir, 'backup_info.json'), 'w', encoding='utf-8') as backup_info:
+            json.dump(
+                {
+                    'name': backup_name,
+                    'created_at': '2026-05-30T11:00:00',
+                    'created_by': self.user.username,
+                    'includes_media': True,
+                },
+                backup_info,
+            )
+
+        category = Category.objects.create(name='恢复失败后仍应存在的分类')
+        product = Product.objects.create(
+            barcode='media-restore-failure-product',
+            name='恢复失败后仍应存在的商品',
+            category=category,
+            price=Decimal('10.00'),
+            cost=Decimal('5.00'),
+        )
+
+        original_copytree = shutil.copytree
+
+        def fail_when_replacing_media(src, dst, *args, **kwargs):
+            if dst == media_root:
+                raise OSError('simulated media restore failure')
+            return original_copytree(src, dst, *args, **kwargs)
+
+        with self.settings(BACKUP_ROOT=self.backup_root, TEMP_DIR=self.temp_dir, MEDIA_ROOT=media_root):
+            with mock.patch('inventory.views.system.backup.shutil.copytree', side_effect=fail_when_replacing_media):
+                response = self.client.post(
+                    reverse('restore_backup', args=[backup_name]),
+                    {'confirm_restore': 'on', 'restore_media': 'on'},
+                )
+
+        self.assertEqual(response.status_code, 200)
+        self.assertTrue(Product.objects.filter(pk=product.pk).exists())
+        self.assertTrue(os.path.exists(os.path.join(media_root, 'current.txt')))
+        self.assertFalse(os.path.exists(os.path.join(media_root, 'backup.txt')))