src/pobsync_backend/forms.py

@@ -249,12 +249,18 @@ class RetentionApplyForm(forms.Form):
     kind = forms.ChoiceField(choices=(("scheduled", "Scheduled"), ("manual", "Manual"), ("all", "All")))
     protect_bases = forms.BooleanField(required=False)
     max_delete = forms.IntegerField(min_value=0, initial=10)
+    confirm_delete_count = forms.IntegerField(min_value=0)
     confirm_host = forms.CharField()
 
-    def __init__(self, *args, host_name: str, **kwargs) -> None:
+    def __init__(self, *args, host_name: str, expected_delete_count: int | None = None, **kwargs) -> None:
         self.host_name = host_name
+        self.expected_delete_count = expected_delete_count
         super().__init__(*args, **kwargs)
         self.fields["confirm_host"].help_text = f"Type {host_name} to confirm deletion."
+        if expected_delete_count is not None:
+            self.fields["confirm_delete_count"].help_text = (
+                f"Type {expected_delete_count} to confirm the current number of planned deletions."
+            )
 
     def clean_confirm_host(self) -> str:
         value = self.cleaned_data["confirm_host"].strip()
@@ -262,6 +268,12 @@ class RetentionApplyForm(forms.Form):
             raise forms.ValidationError(f"Type {self.host_name} to confirm.")
         return value
 
+    def clean_confirm_delete_count(self) -> int:
+        value = self.cleaned_data["confirm_delete_count"]
+        if self.expected_delete_count is not None and value != self.expected_delete_count:
+            raise forms.ValidationError(f"Type {self.expected_delete_count} to confirm the delete count.")
+        return value
+
 
 class ScheduleConfigForm(forms.ModelForm):
     cron_expr = forms.CharField(

src/pobsync_backend/templates/pobsync_backend/retention_plan.html

@@ -123,6 +123,13 @@
           <div class="helptext">{{ apply_form.confirm_host.help_text }}</div>
         </div>
 
+        <div class="field">
+          {{ apply_form.confirm_delete_count.errors }}
+          <label for="{{ apply_form.confirm_delete_count.id_for_label }}">Confirm delete count</label>
+          {{ apply_form.confirm_delete_count }}
+          <div class="helptext">{{ apply_form.confirm_delete_count.help_text }}</div>
+        </div>
+
         <div class="actions">
           <button type="submit">Apply retention</button>
         </div>

src/pobsync_backend/tests/test_views.py

@@ -1412,6 +1412,8 @@ class ViewTests(TestCase):
         self.assertContains(response, "newest")
         self.assertContains(response, "Would Delete")
         self.assertContains(response, "outside retention policy")
+        self.assertContains(response, "Confirm delete count")
+        self.assertContains(response, "Type 1 to confirm the current number of planned deletions.")
 
     def test_retention_plan_warns_when_scheduled_prune_limit_is_exceeded(self) -> None:
         self.client.force_login(self.staff_user)
@@ -1546,6 +1548,7 @@ class ViewTests(TestCase):
                         "kind": "scheduled",
                         "max_delete": "1",
                         "confirm_host": host.host,
+                        "confirm_delete_count": "1",
                     },
                     follow=True,
                 )
@@ -1569,6 +1572,7 @@ class ViewTests(TestCase):
                 "kind": "scheduled",
                 "max_delete": "1",
                 "confirm_host": "wrong",
+                "confirm_delete_count": "1",
             },
             follow=True,
         )
@@ -1577,6 +1581,34 @@ class ViewTests(TestCase):
         self.assertContains(response, "Retention apply confirmation is invalid.")
         self.assertEqual(SnapshotRecord.objects.count(), 1)
 
+    def test_retention_apply_rejects_mismatched_delete_count_confirmation(self) -> None:
+        self.client.force_login(self.staff_user)
+        host = HostConfig.objects.create(
+            host="web-01",
+            address="web-01.example.test",
+            retention_daily=0,
+            retention_weekly=0,
+            retention_monthly=0,
+            retention_yearly=0,
+        )
+        self._snapshot(host, "20260518-021500Z__OLDSNAP")
+        self._snapshot(host, "20260519-021500Z__NEWSNAP")
+
+        response = self.client.post(
+            reverse("apply_host_retention", args=[host.host]),
+            {
+                "kind": "scheduled",
+                "max_delete": "1",
+                "confirm_host": host.host,
+                "confirm_delete_count": "0",
+            },
+            follow=True,
+        )
+
+        self.assertRedirects(response, reverse("host_retention_plan", args=[host.host]))
+        self.assertContains(response, "Retention apply confirmation is invalid.")
+        self.assertEqual(SnapshotRecord.objects.count(), 2)
+
     def test_retention_apply_requires_post(self) -> None:
         self.client.force_login(self.staff_user)
         host = HostConfig.objects.create(host="web-01", address="web-01.example.test")

src/pobsync_backend/views.py

@@ -542,10 +542,12 @@ def host_retention_plan(request, host: str):
         "scheduled_prune_exceeded": scheduled_prune_limit is not None and delete_count > scheduled_prune_limit,
         "apply_form": RetentionApplyForm(
             host_name=host_config.host,
+            expected_delete_count=delete_count,
             initial={
                 "kind": kind,
                 "protect_bases": protect_bases,
                 "max_delete": delete_count,
+                "confirm_delete_count": delete_count,
             },
         ),
     }
@@ -556,7 +558,26 @@ def host_retention_plan(request, host: str):
 @require_POST
 def apply_host_retention(request, host: str):
     host_config = get_object_or_404(HostConfig, host=host)
-    form = RetentionApplyForm(request.POST, host_name=host_config.host)
+    raw_kind = request.POST.get("kind", "scheduled")
+    raw_protect_bases = request.POST.get("protect_bases") in {"1", "true", "on", "yes"}
+    expected_delete_count = None
+    if raw_kind in {"scheduled", "manual", "all"}:
+        try:
+            plan = run_sql_retention_plan(
+                host=host_config.host,
+                kind=raw_kind,
+                protect_bases=raw_protect_bases,
+            )
+        except PobsyncError as exc:
+            messages.error(request, str(exc))
+            return redirect("host_retention_plan", host=host_config.host)
+        expected_delete_count = len(plan.get("delete") or [])
+
+    form = RetentionApplyForm(
+        request.POST,
+        host_name=host_config.host,
+        expected_delete_count=expected_delete_count,
+    )
     if not form.is_valid():
         messages.error(request, "Retention apply confirmation is invalid.")
         return redirect("host_retention_plan", host=host_config.host)