diff --git a/app/Http/Controllers/App/PostAiCreateController.php b/app/Http/Controllers/App/PostAiCreateController.php
index 84dcbd20..cac14ec8 100644
--- a/app/Http/Controllers/App/PostAiCreateController.php
+++ b/app/Http/Controllers/App/PostAiCreateController.php
@@ -9,7 +9,6 @@
 use App\Enums\PostPlatform\ContentType;
 use App\Http\Requests\App\Ai\StartPostCreationRequest;
 use App\Jobs\Ai\StreamPostCreation;
-use App\Models\Media;
 use App\Models\SocialAccount;
 use App\Models\Workspace;
 use Illuminate\Http\JsonResponse;
@@ -198,7 +197,9 @@ private function buildMediaArray(Workspace $workspace, array $state): array
      */
     private function createMediaItem(Workspace $workspace, string $path, array $meta = []): array
     {
-        $media = new Media([
+        // Use the relationship (not `mediable_type = Workspace::class`) so
+        // the morph map alias `'workspace'` is persisted instead of the FQCN.
+        $media = $workspace->media()->create([
             'collection' => 'ai-generated',
             'type' => MediaType::Image,
             'path' => $path,
@@ -208,10 +209,6 @@ private function createMediaItem(Workspace $workspace, string $path, array $meta
             'order' => 0,
         ]);
 
-        $media->mediable_type = Workspace::class;
-        $media->mediable_id = $workspace->id;
-        $media->save();
-
         return [
             'id' => $media->id,
             'path' => $media->path,
diff --git a/app/Http/Controllers/App/PostTemplateController.php b/app/Http/Controllers/App/PostTemplateController.php
index 86a80fca..a6de5061 100644
--- a/app/Http/Controllers/App/PostTemplateController.php
+++ b/app/Http/Controllers/App/PostTemplateController.php
@@ -7,7 +7,6 @@
 use App\Actions\Post\CreatePost;
 use App\Enums\Media\Type as MediaType;
 use App\Http\Resources\App\PostTemplateResource;
-use App\Models\Media;
 use App\Models\SocialAccount;
 use App\Models\Workspace;
 use App\Services\Image\TemplateImageGenerator;
@@ -122,7 +121,9 @@ private function interpolate(string $text, Workspace $workspace): string
      */
     private function createMediaItem(Workspace $workspace, string $path): array
     {
-        $media = new Media([
+        // Use the relationship (not `mediable_type = Workspace::class`) so
+        // the morph map alias `'workspace'` is persisted instead of the FQCN.
+        $media = $workspace->media()->create([
             'collection' => 'ai-generated',
             'type' => MediaType::Image,
             'path' => $path,
@@ -132,10 +133,6 @@ private function createMediaItem(Workspace $workspace, string $path): array
             'order' => 0,
         ]);
 
-        $media->mediable_type = Workspace::class;
-        $media->mediable_id = $workspace->id;
-        $media->save();
-
         return [
             'id' => $media->id,
             'path' => $media->path,
diff --git a/tests/Unit/MediaPolymorphTest.php b/tests/Unit/MediaPolymorphTest.php
new file mode 100644
index 00000000..f34ee3f3
--- /dev/null
+++ b/tests/Unit/MediaPolymorphTest.php
@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Models\Workspace;
+
+/**
+ * Regression test for a bug where Media rows ended up with
+ * `mediable_type = "App\Models\Workspace"` (FQCN) instead of the
+ * morphMap alias `"workspace"`. The bug source was code that did
+ *   `$media->mediable_type = Workspace::class;`
+ * which bypasses the morph map. Using the relationship
+ * (`$workspace->media()->create([...])` or
+ * `$media->mediable()->associate($workspace)`) is the correct path.
+ */
+test('Workspace::media()->create persists the morphMap alias, not the FQCN', function () {
+    $workspace = Workspace::factory()->create();
+
+    $media = $workspace->media()->create([
+        'collection' => 'ai-generated',
+        'type' => 'image',
+        'path' => 'test/dummy.webp',
+        'original_filename' => 'dummy.webp',
+        'mime_type' => 'image/webp',
+        'size' => 100,
+        'order' => 0,
+    ]);
+
+    expect($media->mediable_type)->toBe('workspace');
+    expect($media->mediable_type)->not->toBe(Workspace::class);
+    expect($media->mediable->is($workspace))->toBeTrue();
+});