feat(posts): block combining an image and a video in one post

A Bluesky post embed is images XOR video, so a post that carries both can't
be published there. Enforce it per selected platform:

- Add ContentType::supportsMixedMedia() (false only for BlueskyPost) and reject
  image+video in ContentTypeCompatibleWithMedia when the type forbids it.
- Mirror it client-side (useMediaRules forbidsMixedMedia + usePostCompliance)
  so the editor blocks scheduling with an inline reason before submit, like
  every other per-platform compatibility check.
- Add the no_mixed_media message in all three locales (en/es/pt-BR).
- Cover the rule and enum, including the GIF-counts-as-image case.

app/Enums/PostPlatform/ContentType.php

@@ -216,6 +216,20 @@ public function supportsImage(): bool
         };
     }
 
+    /**
+     * Whether a single post may carry images and a video together. Most
+     * targets accept only one or the other; this is conservative and lists
+     * only the types we've confirmed reject mixed media (e.g. a Bluesky post
+     * embed is `images` XOR `video`, never both).
+     */
+    public function supportsMixedMedia(): bool
+    {
+        return match ($this) {
+            self::BlueskyPost => false,
+            default => true,
+        };
+    }
+
     /**
      * Whether this content type carries a text caption visible to viewers.
      * Stories are image-overlay only — viewers don't see a separate caption.

app/Rules/ContentTypeCompatibleWithMedia.php

@@ -61,6 +61,10 @@ public function validate(string $attribute, mixed $value, Closure $fail): void
         if ($hasVideo && ! $contentType->supportsVideo()) {
             $fail("{$contentType->label()} does not support videos.");
         }
+
+        if ($hasImage && $hasVideo && ! $contentType->supportsMixedMedia()) {
+            $fail("{$contentType->label()} can't combine an image and a video in the same post.");
+        }
     }
 
     /**

lang/en/posts.php

@@ -342,6 +342,7 @@
             'too_few_files' => 'Add at least :min files for this format.',
             'no_videos' => 'Only images are allowed for this format.',
             'no_images' => 'Only videos are allowed for this format.',
+            'no_mixed_media' => "Images and videos can't be combined in the same post.",
             'no_gifs' => 'GIFs are not supported here.',
             'video_too_large' => 'Video exceeds the size limit for this platform.',
             'video_too_long' => 'Video must be under :seconds seconds for this format.',

lang/es/posts.php

@@ -342,6 +342,7 @@
             'too_few_files' => 'Agrega al menos :min archivos para este formato.',
             'no_videos' => 'Solo se permiten imágenes en este formato.',
             'no_images' => 'Solo se permiten videos en este formato.',
+            'no_mixed_media' => 'No se pueden combinar imágenes y videos en la misma publicación.',
             'no_gifs' => 'Los GIFs no son compatibles aquí.',
             'video_too_large' => 'El video supera el límite de tamaño de esta plataforma.',
             'video_too_long' => 'El video debe durar menos de :seconds segundos en este formato.',

lang/pt-BR/posts.php

@@ -342,6 +342,7 @@
             'too_few_files' => 'Adicione pelo menos :min arquivos para este formato.',
             'no_videos' => 'Apenas imagens são permitidas neste formato.',
             'no_images' => 'Apenas vídeos são permitidos neste formato.',
+            'no_mixed_media' => 'Não é possível combinar imagem e vídeo na mesma publicação.',
             'no_gifs' => 'GIFs não são suportados aqui.',
             'video_too_large' => 'Vídeo excede o limite de tamanho desta plataforma.',
             'video_too_long' => 'Vídeo deve ter menos de :seconds segundos neste formato.',

resources/js/composables/useMediaRules.ts

@@ -7,6 +7,7 @@ export interface MediaRules {
     acceptVideos: boolean;
     requiresMedia: boolean;
     acceptsGif: boolean;
+    forbidsMixedMedia?: boolean;
     maxImageBytes?: number;
     maxVideoBytes?: number;
     maxVideoDurationSec?: number;
@@ -131,10 +132,11 @@ const CONTENT_TYPE_RULES: Record<string, MediaRules> = {
         maxImageBytes: 8 * MB, maxVideoBytes: 1 * GB, maxVideoDurationSec: 5 * 60,
     },
 
-    // Bluesky — accepts GIF; tight image size (auto-resized by backend)
+    // Bluesky — accepts GIF; tight image size (auto-resized by backend).
+    // The embed is images XOR video, so the two can't be combined in one post.
     bluesky_post: {
         maxFiles: 4, acceptImages: true, acceptVideos: true, requiresMedia: false,
-        acceptsGif: true,
+        acceptsGif: true, forbidsMixedMedia: true,
         maxVideoBytes: 100 * MB, maxVideoDurationSec: 60,
     },
 

resources/js/composables/usePostCompliance.ts

@@ -99,6 +99,7 @@ export const getMediaIncompatibilityReason = (
     if (rules.requiresMedia && total === 0) return trans('posts.edit.compliance.requires_media');
     if (!rules.acceptVideos && videos.length > 0) return trans('posts.edit.compliance.no_videos');
     if (!rules.acceptImages && images.length > 0) return trans('posts.edit.compliance.no_images');
+    if (rules.forbidsMixedMedia && videos.length > 0 && images.length > 0) return trans('posts.edit.compliance.no_mixed_media');
     if (!rules.acceptsGif && gifs.length > 0) return trans('posts.edit.compliance.no_gifs');
     if (total > rules.maxFiles) return trans('posts.edit.compliance.too_many_files', { max: String(rules.maxFiles) });
     if (rules.minFiles && total < rules.minFiles) return trans('posts.edit.compliance.too_few_files', { min: String(rules.minFiles) });

tests/Unit/Enums/ContentTypeTest.php

@@ -86,6 +86,14 @@
     expect(ContentType::YouTubeShort->supportsImage())->toBeFalse();
 });
 
+test('content type supports mixed media correctly', function () {
+    // A Bluesky embed is images XOR video, so it can't carry both.
+    expect(ContentType::BlueskyPost->supportsMixedMedia())->toBeFalse();
+    // Multi-attachment messengers can mix an image and a video.
+    expect(ContentType::DiscordMessage->supportsMixedMedia())->toBeTrue();
+    expect(ContentType::TelegramPost->supportsMixedMedia())->toBeTrue();
+});
+
 test('content type requires media correctly', function () {
     expect(ContentType::InstagramReel->requiresMedia())->toBeTrue();
     expect(ContentType::TikTokVideo->requiresMedia())->toBeTrue();

tests/Unit/Rules/ContentTypeCompatibleWithMediaTest.php

@@ -94,6 +94,48 @@ function runMediaRule(string $contentType, array $media): array
     expect($errors)->toHaveCount(1);
 });
 
+test('bluesky rejects an image and a video in the same post', function () {
+    $media = [
+        ['type' => MediaType::Image->value, 'mime_type' => 'image/jpeg'],
+        ['type' => MediaType::Video->value, 'mime_type' => 'video/mp4'],
+    ];
+
+    $errors = runMediaRule(ContentType::BlueskyPost->value, $media);
+
+    expect($errors)->toHaveCount(1);
+    expect($errors[0])->toContain("can't combine an image and a video");
+});
+
+test('bluesky still accepts an image-only or video-only post', function () {
+    $image = [['type' => MediaType::Image->value, 'mime_type' => 'image/jpeg']];
+    $video = [['type' => MediaType::Video->value, 'mime_type' => 'video/mp4']];
+
+    expect(runMediaRule(ContentType::BlueskyPost->value, $image))->toBe([]);
+    expect(runMediaRule(ContentType::BlueskyPost->value, $video))->toBe([]);
+});
+
+test('bluesky rejects an animated gif combined with a video', function () {
+    // A GIF counts as an image, so gif + video is still mixed media.
+    $media = [
+        ['type' => MediaType::Image->value, 'mime_type' => 'image/gif'],
+        ['type' => MediaType::Video->value, 'mime_type' => 'video/mp4'],
+    ];
+
+    $errors = runMediaRule(ContentType::BlueskyPost->value, $media);
+
+    expect($errors)->toHaveCount(1);
+    expect($errors[0])->toContain("can't combine an image and a video");
+});
+
+test('a mixed-media content type accepts an image and a video together', function () {
+    $media = [
+        ['type' => MediaType::Image->value, 'mime_type' => 'image/jpeg'],
+        ['type' => MediaType::Video->value, 'mime_type' => 'video/mp4'],
+    ];
+
+    expect(runMediaRule(ContentType::DiscordMessage->value, $media))->toBe([]);
+});
+
 test('does nothing for invalid content type values', function () {
     expect(runMediaRule('not_a_real_content_type', []))->toBe([]);
 });