fix(server): detach additional-destination apps instead of deleting them on server delete

Deleting a server with "Delete all resources" (UI) or ?force=true (API)
deleted every application that used the server, also applications that
use it only as an additional destination, for example after Promote.

Server delete now deletes only resources whose main destination is on
the server. Applications that use it only as an additional destination
lose their additional_destinations row for the server, and their
containers on it are stopped (best effort). The check for resources and
the transfer archive path use the same Server::primaryResources().
The delete confirmation lists the resources to delete and the
applications that keep running on another server.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/Models/Server.php

@@ -2,6 +2,7 @@
 
 namespace App\Models;
 
+use App\Actions\Application\StopApplicationOneServer;
 use App\Actions\Proxy\StartProxy;
 use App\Actions\Server\InstallDocker;
 use App\Actions\Server\InstallPrerequisites;
@@ -32,6 +33,7 @@ use App\Traits\HasSafeStringAttribute;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Casts\Attribute;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\MorphMany;
 use Illuminate\Database\Eloquent\SoftDeletes;
 use Illuminate\Http\Exceptions\ThrottleRequestsException;
@@ -1751,6 +1753,47 @@ $siteAddress {
         return $applications->concat($databases)->concat($services->get());
     }
 
+    /**
+     * The resources that deleting this server with "Delete all resources" deletes. An application that has this server
+     * only as an additional destination runs on another server, so it is detached instead.
+     *
+     * @return Collection<int, Model>
+     */
+    public function primaryResources(): Collection
+    {
+        return $this->primaryApplications()
+            ->concat($this->databases())
+            ->concat($this->services()->get());
+    }
+
+    /**
+     * Remove this server from the applications that use it only as an additional destination.
+     * The applications keep running on their other servers.
+     *
+     * @param  bool  $stopContainers  stop and remove the containers of the applications on this server (best effort)
+     */
+    public function detachAdditionalApplications(bool $stopContainers = true): void
+    {
+        $applications = $this->additionalApplications();
+        if ($stopContainers) {
+            foreach ($applications as $application) {
+                try {
+                    StopApplicationOneServer::run($application, $this);
+                } catch (\Throwable $e) {
+                    logger()->warning('Could not stop the containers of an application on a deleted server.', [
+                        'application_id' => $application->id,
+                        'server_id' => $this->id,
+                        'error' => $e->getMessage(),
+                    ]);
+                }
+            }
+        }
+        DB::table('additional_destinations')
+            ->where('server_id', $this->id)
+            ->whereIn('application_id', $applications->pluck('id'))
+            ->delete();
+    }
+
     public function stopUnmanaged($id)
     {
         return instant_remote_process([dockerStopCommand(0, escapeshellarg($id), $this)], $this);
@@ -1841,18 +1884,6 @@ $siteAddress {
         }
     }
 
-    public function hasDefinedResources()
-    {
-        $applications = $this->applications()->count() > 0;
-        $databases = $this->databases()->count() > 0;
-        $services = $this->services()->count() > 0;
-        if ($applications || $databases || $services) {
-            return true;
-        }
-
-        return false;
-    }
-
     public function databases()
     {
         // Get destination IDs for this server in two efficient queries
@@ -1892,22 +1923,13 @@ $siteAddress {
             ->reject(fn ($item) => $item instanceof StandalonePostgresql && $item->isInstanceDatabase());
     }
 
+    /**
+     * The applications whose primary destination is on this server, plus the applications that use this server as an
+     * additional destination.
+     */
     public function applications()
     {
-        // Get destination IDs for this server in two efficient queries
-        $standaloneDockerIds = StandaloneDocker::where('server_id', $this->id)->pluck('id');
-        $swarmDockerIds = SwarmDocker::where('server_id', $this->id)->pluck('id');
-
-        // Query all applications in a single query using polymorphic conditions
-        $applications = Application::where(function ($query) use ($standaloneDockerIds, $swarmDockerIds) {
-            $query->where(function ($q) use ($standaloneDockerIds) {
-                $q->where('destination_type', StandaloneDocker::class)
-                    ->whereIn('destination_id', $standaloneDockerIds);
-            })->orWhere(function ($q) use ($swarmDockerIds) {
-                $q->where('destination_type', SwarmDocker::class)
-                    ->whereIn('destination_id', $swarmDockerIds);
-            });
-        })->get();
+        $applications = $this->primaryApplications();
 
         // Get additional server applications
         $additionalApplicationIds = DB::table('additional_destinations')
@@ -1922,6 +1944,45 @@ $siteAddress {
         return $applications;
     }
 
+    /**
+     * The applications whose primary destination is on this server.
+     *
+     * @return Collection<int, Application>
+     */
+    public function primaryApplications(): Collection
+    {
+        // Get destination IDs for this server in two efficient queries
+        $standaloneDockerIds = StandaloneDocker::where('server_id', $this->id)->pluck('id');
+        $swarmDockerIds = SwarmDocker::where('server_id', $this->id)->pluck('id');
+
+        // Query all applications in a single query using polymorphic conditions
+        return Application::where(function ($query) use ($standaloneDockerIds, $swarmDockerIds) {
+            $query->where(function ($q) use ($standaloneDockerIds) {
+                $q->where('destination_type', StandaloneDocker::class)
+                    ->whereIn('destination_id', $standaloneDockerIds);
+            })->orWhere(function ($q) use ($swarmDockerIds) {
+                $q->where('destination_type', SwarmDocker::class)
+                    ->whereIn('destination_id', $swarmDockerIds);
+            });
+        })->get();
+    }
+
+    /**
+     * The applications that use this server only as an additional destination. Their primary destination is on
+     * another server.
+     *
+     * @return Collection<int, Application>
+     */
+    public function additionalApplications(): Collection
+    {
+        $applicationIds = DB::table('additional_destinations')
+            ->where('server_id', $this->id)
+            ->whereNotIn('application_id', $this->primaryApplications()->pluck('id'))
+            ->pluck('application_id');
+
+        return Application::query()->with('destination.server')->whereIn('id', $applicationIds)->get();
+    }
+
     public function dockerComposeBasedApplications()
     {
         return $this->applications()->filter(function ($application) {