diff --git a/app/Models/AiProvider.php b/app/Models/AiProvider.php
index c73e861..f7f42bf 100644
--- a/app/Models/AiProvider.php
+++ b/app/Models/AiProvider.php
@@ -9,7 +9,10 @@ class AiProvider extends Model
 {
     use HasFactory;
 
-    public const PROVIDERS = ['openai', 'stability_ai', 'elevenlabs', 'other'];
+    // 'youtube' isn't an AI provider, but reuses this same credentials
+    // shape: api_key holds an OAuth refresh_token, config holds
+    // client_id/client_secret. See YoutubePublishHandler.
+    public const PROVIDERS = ['openai', 'stability_ai', 'elevenlabs', 'youtube', 'other'];
 
     protected $fillable = [
         'name',
diff --git a/app/Providers/AppServiceProvider.php b/app/Providers/AppServiceProvider.php
index 722c92a..a44a36b 100644
--- a/app/Providers/AppServiceProvider.php
+++ b/app/Providers/AppServiceProvider.php
@@ -11,12 +11,15 @@ use App\Support\Publishing\PublisherManager;
 use App\Support\Publishing\RedditPublisher;
 use App\Support\Publishing\TwitterPublisher;
 use App\Support\Publishing\WordPressPublisher;
+use App\Support\VideoWorkflow\StepHandlers\MetadataGenerationHandler;
 use App\Support\VideoWorkflow\StepHandlers\ScriptGenerationHandler;
 use App\Support\VideoWorkflow\StepHandlers\StepHandlerManager;
 use App\Support\VideoWorkflow\StepHandlers\StoryboardHandler;
+use App\Support\VideoWorkflow\StepHandlers\ThumbnailGenerationHandler;
 use App\Support\VideoWorkflow\StepHandlers\TtsVoiceoverHandler;
 use App\Support\VideoWorkflow\StepHandlers\VideoEditingHandler;
 use App\Support\VideoWorkflow\StepHandlers\VideoGenerationHandler;
+use App\Support\VideoWorkflow\StepHandlers\YoutubePublishHandler;
 use Illuminate\Support\ServiceProvider;
 
 class AppServiceProvider extends ServiceProvider
@@ -45,6 +48,9 @@ class AppServiceProvider extends ServiceProvider
             $app->make(StoryboardHandler::class),
             $app->make(VideoGenerationHandler::class),
             $app->make(VideoEditingHandler::class),
+            $app->make(ThumbnailGenerationHandler::class),
+            $app->make(MetadataGenerationHandler::class),
+            $app->make(YoutubePublishHandler::class),
         ]));
     }
 
diff --git a/app/Support/VideoWorkflow/StepHandlers/MetadataGenerationHandler.php b/app/Support/VideoWorkflow/StepHandlers/MetadataGenerationHandler.php
new file mode 100644
index 0000000..e2b0583
--- /dev/null
+++ b/app/Support/VideoWorkflow/StepHandlers/MetadataGenerationHandler.php
@@ -0,0 +1,105 @@
+<?php
+
+namespace App\Support\VideoWorkflow\StepHandlers;
+
+use App\Models\AiProvider;
+use App\Models\WorkflowStep;
+use App\Support\AiProviders\AiGenerationException;
+use App\Support\AiProviders\AiProviderManager;
+use App\Support\AssetStorage\AssetStorage;
+use App\Support\VideoWorkflow\WorkflowEngine;
+
+/**
+ * Generates SEO-optimized title/description/tags/hashtags from the
+ * project's script via an OpenAI-backed AiProvider in JSON mode.
+ */
+class MetadataGenerationHandler implements StepHandler
+{
+    public function __construct(
+        private readonly AiProviderManager $aiProviders,
+        private readonly AssetStorage $assets,
+    ) {}
+
+    public function type(): string
+    {
+        return 'metadata_generation';
+    }
+
+    public function handle(WorkflowStep $step, WorkflowEngine $engine): void
+    {
+        $provider = AiProvider::query()->where('provider', 'openai')->where('is_active', true)->first();
+
+        if (! $provider) {
+            $engine->failStep($step, 'No active OpenAI provider configured.');
+
+            return;
+        }
+
+        $script = $this->resolveScript($step);
+
+        if (! $script) {
+            $engine->failStep($step, 'No script available to generate metadata from — complete a script_generation step first.');
+
+            return;
+        }
+
+        try {
+            $result = $this->aiProviders->generate($provider, $this->buildPrompt($script), ['json_mode' => true]);
+        } catch (AiGenerationException $e) {
+            $engine->failStep($step, $e->getMessage());
+
+            return;
+        }
+
+        $decoded = json_decode($result->content, true);
+
+        if (! is_array($decoded) || empty($decoded['title']) || empty($decoded['description'])) {
+            $engine->failStep($step, 'AI provider returned unusable metadata: missing title/description.');
+
+            return;
+        }
+
+        $decoded += ['tags' => [], 'hashtags' => []];
+
+        $asset = $this->assets->store(
+            $step->videoProject,
+            'other',
+            json_encode($decoded, JSON_PRETTY_PRINT),
+            'json',
+            step: $step,
+            mimeType: 'application/json',
+            metadata: ['kind' => 'metadata'],
+        );
+
+        $engine->completeStep($step, [
+            'asset_id' => $asset->id,
+            'title' => $decoded['title'],
+        ]);
+    }
+
+    private function resolveScript(WorkflowStep $step): ?string
+    {
+        $input = $step->input ?? [];
+
+        if (! empty($input['script'])) {
+            return $input['script'];
+        }
+
+        $scriptAsset = $step->videoProject->assets()
+            ->where('type', 'script')
+            ->orderByDesc('version')
+            ->first();
+
+        return $scriptAsset ? $this->assets->contents($scriptAsset) : null;
+    }
+
+    private function buildPrompt(string $script): string
+    {
+        return "Based on the following YouTube video script, generate SEO-optimized metadata.\n\n"
+            ."Script:\n{$script}\n\n"
+            .'Respond with JSON only, in exactly this shape: '
+            .'{"title": "...", "description": "...", "tags": ["...", "..."], "hashtags": ["#...", "#..."]}. '
+            .'Title must be under 100 characters. Description should be 2-4 paragraphs with a natural, '
+            .'keyword-rich summary. Provide 10-15 tags and 3-5 hashtags.';
+    }
+}
diff --git a/app/Support/VideoWorkflow/StepHandlers/ThumbnailGenerationHandler.php b/app/Support/VideoWorkflow/StepHandlers/ThumbnailGenerationHandler.php
new file mode 100644
index 0000000..2aed21b
--- /dev/null
+++ b/app/Support/VideoWorkflow/StepHandlers/ThumbnailGenerationHandler.php
@@ -0,0 +1,86 @@
+<?php
+
+namespace App\Support\VideoWorkflow\StepHandlers;
+
+use App\Models\AiProvider;
+use App\Models\VideoProject;
+use App\Models\WorkflowStep;
+use App\Support\AiProviders\AiGenerationException;
+use App\Support\AiProviders\AiProviderManager;
+use App\Support\AssetStorage\AssetStorage;
+use App\Support\VideoWorkflow\WorkflowEngine;
+
+/**
+ * Generates thumbnail candidates via a StabilityAI-backed AiProvider. One
+ * variant per style in step.input.styles (default: two contrasting styles),
+ * all stored as assets on the same step — the approval UI already shows
+ * every asset on an awaiting_approval step side by side, so this is the
+ * A/B comparison the task calls for, with no extra UI needed.
+ */
+class ThumbnailGenerationHandler implements StepHandler
+{
+    private const DEFAULT_STYLES = ['vibrant and colorful', 'minimalist and clean'];
+
+    public function __construct(
+        private readonly AiProviderManager $aiProviders,
+        private readonly AssetStorage $assets,
+    ) {}
+
+    public function type(): string
+    {
+        return 'thumbnail_generation';
+    }
+
+    public function handle(WorkflowStep $step, WorkflowEngine $engine): void
+    {
+        $provider = AiProvider::query()->where('provider', 'stability_ai')->where('is_active', true)->first();
+
+        if (! $provider) {
+            $engine->failStep($step, 'No active StabilityAI provider configured.');
+
+            return;
+        }
+
+        $input = $step->input ?? [];
+        $basePrompt = $input['prompt'] ?? $this->defaultPrompt($step->videoProject);
+        $styles = $input['styles'] ?? self::DEFAULT_STYLES;
+
+        $assetIds = [];
+
+        foreach (array_values($styles) as $i => $style) {
+            $prompt = "{$basePrompt}. Eye-catching YouTube thumbnail, bold, high contrast, {$style}.";
+
+            try {
+                $result = $this->aiProviders->generate($provider, $prompt);
+            } catch (AiGenerationException $e) {
+                $engine->failStep($step, 'variant '.($i + 1).": {$e->getMessage()}");
+
+                return;
+            }
+
+            $extension = str($result->contentType)->after('image/')->toString() ?: 'png';
+
+            $asset = $this->assets->store(
+                $step->videoProject,
+                'image',
+                $result->content,
+                $extension,
+                step: $step,
+                mimeType: $result->contentType,
+                metadata: ['kind' => 'thumbnail', 'variant' => $i + 1, 'style' => $style],
+            );
+
+            $assetIds[] = $asset->id;
+        }
+
+        $engine->completeStep($step, [
+            'asset_ids' => $assetIds,
+            'variant_count' => count($assetIds),
+        ]);
+    }
+
+    private function defaultPrompt(VideoProject $project): string
+    {
+        return trim(($project->title ?? '').'. '.($project->description ?? ''));
+    }
+}
diff --git a/app/Support/VideoWorkflow/StepHandlers/YoutubePublishHandler.php b/app/Support/VideoWorkflow/StepHandlers/YoutubePublishHandler.php
new file mode 100644
index 0000000..32ab5ac
--- /dev/null
+++ b/app/Support/VideoWorkflow/StepHandlers/YoutubePublishHandler.php
@@ -0,0 +1,186 @@
+<?php
+
+namespace App\Support\VideoWorkflow\StepHandlers;
+
+use App\Models\AiProvider;
+use App\Models\WorkflowStep;
+use App\Support\AssetStorage\AssetStorage;
+use App\Support\VideoWorkflow\WorkflowEngine;
+use Illuminate\Http\Client\ConnectionException;
+use Illuminate\Support\Facades\Http;
+use RuntimeException;
+
+/**
+ * Uploads the project's finished video to YouTube via the Data API v3's
+ * resumable upload protocol, using OAuth2 credentials stored as an
+ * AiProvider (provider='youtube'; api_key is a refresh_token, config holds
+ * client_id/client_secret — see AiProvider::PROVIDERS).
+ *
+ * Supports scheduling (step.input.publish_at sets status.publishAt, which
+ * requires privacyStatus=private per YouTube's API). Does NOT cover
+ * analytics retrieval — that's an ongoing query against a published
+ * video, not a one-shot publish action, so it doesn't fit this
+ * once-per-video step model. Would need a separate service/command.
+ */
+class YoutubePublishHandler implements StepHandler
+{
+    public function __construct(private readonly AssetStorage $assets) {}
+
+    public function type(): string
+    {
+        return 'youtube_publish';
+    }
+
+    public function handle(WorkflowStep $step, WorkflowEngine $engine): void
+    {
+        $credential = AiProvider::query()->where('provider', 'youtube')->where('is_active', true)->first();
+
+        if (! $credential) {
+            $engine->failStep($step, 'No active YouTube credential configured.');
+
+            return;
+        }
+
+        $videoAsset = $step->videoProject->assets()->where('type', 'video')->orderByDesc('version')->first();
+
+        if (! $videoAsset) {
+            $engine->failStep($step, 'No finished video available — complete a video_editing step first.');
+
+            return;
+        }
+
+        try {
+            $accessToken = $this->refreshAccessToken($credential);
+        } catch (RuntimeException|ConnectionException $e) {
+            $engine->failStep($step, "could not refresh YouTube access token: {$e->getMessage()}");
+
+            return;
+        }
+
+        $metadata = $this->resolveMetadata($step);
+        $input = $step->input ?? [];
+        $publishAt = $input['publish_at'] ?? null;
+
+        $snippet = [
+            'title' => $metadata['title'] ?? $step->videoProject->title,
+            'description' => $metadata['description'] ?? ($step->videoProject->description ?? ''),
+            'tags' => $metadata['tags'] ?? [],
+        ];
+        $status = array_filter([
+            'privacyStatus' => $publishAt ? 'private' : ($input['privacy_status'] ?? 'private'),
+            'publishAt' => $publishAt,
+        ]);
+
+        $videoBytes = $this->assets->contents($videoAsset);
+
+        try {
+            $initResponse = Http::withToken($accessToken)
+                ->withHeaders([
+                    'X-Upload-Content-Type' => 'video/mp4',
+                    'X-Upload-Content-Length' => (string) strlen($videoBytes),
+                ])
+                ->post('https://www.googleapis.com/upload/youtube/v3/videos?uploadType=resumable&part=snippet,status', [
+                    'snippet' => $snippet,
+                    'status' => $status,
+                ]);
+        } catch (ConnectionException $e) {
+            $engine->failStep($step, "could not connect to YouTube: {$e->getMessage()}");
+
+            return;
+        }
+
+        if ($initResponse->failed()) {
+            $engine->failStep($step, $initResponse->json('error.message') ?? 'unexpected response from YouTube while starting the upload');
+
+            return;
+        }
+
+        $uploadUrl = $initResponse->header('Location');
+
+        if (! $uploadUrl) {
+            $engine->failStep($step, 'unexpected response from YouTube: missing upload session location');
+
+            return;
+        }
+
+        try {
+            $uploadResponse = Http::withToken($accessToken)
+                ->withBody($videoBytes, 'video/mp4')
+                ->put($uploadUrl);
+        } catch (ConnectionException $e) {
+            $engine->failStep($step, "could not upload video to YouTube: {$e->getMessage()}");
+
+            return;
+        }
+
+        if ($uploadResponse->failed()) {
+            $engine->failStep($step, $uploadResponse->json('error.message') ?? 'unexpected response from YouTube while uploading the video');
+
+            return;
+        }
+
+        $videoId = $uploadResponse->json('id');
+
+        if (! $videoId) {
+            $engine->failStep($step, 'unexpected response from YouTube: missing video id');
+
+            return;
+        }
+
+        $engine->completeStep($step, [
+            'youtube_video_id' => $videoId,
+            'youtube_url' => "https://www.youtube.com/watch?v={$videoId}",
+        ]);
+    }
+
+    /**
+     * @throws RuntimeException|ConnectionException
+     */
+    private function refreshAccessToken(AiProvider $credential): string
+    {
+        $config = $credential->config ?? [];
+
+        $response = Http::asForm()->post('https://oauth2.googleapis.com/token', [
+            'client_id' => $config['client_id'] ?? null,
+            'client_secret' => $config['client_secret'] ?? null,
+            'refresh_token' => $credential->api_key,
+            'grant_type' => 'refresh_token',
+        ]);
+
+        if ($response->failed()) {
+            throw new RuntimeException($response->json('error_description') ?? 'token refresh failed');
+        }
+
+        $token = $response->json('access_token');
+
+        if (! $token) {
+            throw new RuntimeException('no access_token in refresh response');
+        }
+
+        return $token;
+    }
+
+    /**
+     * @return array<string, mixed>
+     */
+    private function resolveMetadata(WorkflowStep $step): array
+    {
+        $input = $step->input ?? [];
+
+        if (! empty($input['title']) || ! empty($input['description'])) {
+            return $input;
+        }
+
+        $metaAsset = $step->videoProject->assets()
+            ->where('type', 'other')
+            ->whereJsonContains('metadata->kind', 'metadata')
+            ->orderByDesc('version')
+            ->first();
+
+        if (! $metaAsset) {
+            return [];
+        }
+
+        return json_decode($this->assets->contents($metaAsset), true) ?? [];
+    }
+}
diff --git a/tests/Feature/Jobs/RunWorkflowStepJobTest.php b/tests/Feature/Jobs/RunWorkflowStepJobTest.php
index 9fdf6c2..1b40abb 100644
--- a/tests/Feature/Jobs/RunWorkflowStepJobTest.php
+++ b/tests/Feature/Jobs/RunWorkflowStepJobTest.php
@@ -28,7 +28,9 @@ test('it runs the matching handler and completes the step', function () {
 
 test('it fails the step when no handler is registered for its type', function () {
     $project = VideoProject::factory()->create();
-    $step = $this->engine->start($project, [['type' => 'thumbnail_generation']]);
+    // A made-up type — not a real WorkflowStep::TYPES value — so this test
+    // stays valid regardless of which real types have handlers over time.
+    $step = $this->engine->start($project, [['type' => 'some_future_step_type']]);
 
     (new RunWorkflowStepJob($step->id))->handle(app(StepHandlerManager::class), $this->engine);
 
diff --git a/tests/Feature/Livewire/VideoProjectsShowTest.php b/tests/Feature/Livewire/VideoProjectsShowTest.php
index e731094..4e8c7f2 100644
--- a/tests/Feature/Livewire/VideoProjectsShowTest.php
+++ b/tests/Feature/Livewire/VideoProjectsShowTest.php
@@ -31,9 +31,11 @@ test('starting the default pipeline creates steps and queues the first handled o
 
 test('starting from a template uses its steps and does not queue unhandled types', function () {
     Queue::fake();
+    // Made-up types — not real WorkflowStep::TYPES values — so this test
+    // stays valid regardless of which real types have handlers over time.
     $template = WorkflowTemplate::factory()->create(['steps' => [
-        ['type' => 'thumbnail_generation'],
-        ['type' => 'youtube_publish'],
+        ['type' => 'some_future_step_type'],
+        ['type' => 'another_future_step_type'],
     ]]);
     $project = VideoProject::factory()->create();
 
@@ -44,7 +46,6 @@ test('starting from a template uses its steps and does not queue unhandled types
     expect($project->fresh()->workflow_template_id)->toBe($template->id);
     expect($project->steps()->count())->toBe(2);
 
-    // thumbnail_generation has no handler yet, so nothing should be queued
     Queue::assertNotPushed(RunWorkflowStepJob::class);
 });
 
diff --git a/tests/Feature/VideoWorkflow/StepHandlers/MetadataGenerationHandlerTest.php b/tests/Feature/VideoWorkflow/StepHandlers/MetadataGenerationHandlerTest.php
new file mode 100644
index 0000000..8f791e5
--- /dev/null
+++ b/tests/Feature/VideoWorkflow/StepHandlers/MetadataGenerationHandlerTest.php
@@ -0,0 +1,90 @@
+<?php
+
+use App\Models\AiProvider;
+use App\Models\Asset;
+use App\Models\VideoProject;
+use App\Support\AiProviders\AiProviderManager;
+use App\Support\AssetStorage\AssetStorage;
+use App\Support\VideoWorkflow\StepHandlers\MetadataGenerationHandler;
+use App\Support\VideoWorkflow\WorkflowEngine;
+use Illuminate\Support\Facades\Http;
+use Illuminate\Support\Facades\Storage;
+
+beforeEach(function () {
+    Storage::fake();
+    $this->engine = new WorkflowEngine;
+    $this->assets = new AssetStorage;
+    $this->handler = new MetadataGenerationHandler(app(AiProviderManager::class), $this->assets);
+});
+
+test('it generates metadata from the script, stores it, and completes the step', function () {
+    $metadata = [
+        'title' => 'The Best Coffee Gadgets of 2026',
+        'description' => 'A deep dive into coffee gadgets.',
+        'tags' => ['coffee', 'gadgets'],
+        'hashtags' => ['#coffee', '#gadgets'],
+    ];
+    Http::fake(['api.openai.com/*' => Http::response(['choices' => [['message' => ['content' => json_encode($metadata)]]]])]);
+    AiProvider::factory()->create(['provider' => 'openai']);
+
+    $project = VideoProject::factory()->create();
+    $this->assets->store($project, 'script', 'A script about coffee gadgets.', 'txt');
+    $step = $this->engine->start($project, [['type' => 'metadata_generation']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    $fresh = $step->fresh();
+    expect($fresh->status)->toBe('completed');
+    expect($fresh->output['title'])->toBe('The Best Coffee Gadgets of 2026');
+
+    $asset = Asset::find($fresh->output['asset_id']);
+    expect($asset->type)->toBe('other');
+    expect($asset->metadata['kind'])->toBe('metadata');
+    $stored = json_decode(Storage::get($asset->disk_path), true);
+    expect($stored)->toBe($metadata);
+
+    Http::assertSent(function ($request) {
+        return str_contains($request['messages'][0]['content'], 'A script about coffee gadgets.')
+            && ($request['response_format']['type'] ?? null) === 'json_object';
+    });
+});
+
+test('it fails when there is no script to generate metadata from', function () {
+    AiProvider::factory()->create(['provider' => 'openai']);
+
+    $project = VideoProject::factory()->create();
+    $step = $this->engine->start($project, [['type' => 'metadata_generation']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toContain('No script available');
+});
+
+test('it fails when no active OpenAI provider is configured', function () {
+    $project = VideoProject::factory()->create();
+    $this->assets->store($project, 'script', 'a script', 'txt');
+    $step = $this->engine->start($project, [['type' => 'metadata_generation']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toContain('No active OpenAI provider');
+});
+
+test('it fails when the AI response is missing title or description', function () {
+    Http::fake(['api.openai.com/*' => Http::response(['choices' => [['message' => ['content' => '{"tags": []}']]]])]);
+    AiProvider::factory()->create(['provider' => 'openai']);
+
+    $project = VideoProject::factory()->create();
+    $this->assets->store($project, 'script', 'a script', 'txt');
+    $step = $this->engine->start($project, [['type' => 'metadata_generation']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toContain('unusable metadata');
+});
diff --git a/tests/Feature/VideoWorkflow/StepHandlers/ThumbnailGenerationHandlerTest.php b/tests/Feature/VideoWorkflow/StepHandlers/ThumbnailGenerationHandlerTest.php
new file mode 100644
index 0000000..6a4067b
--- /dev/null
+++ b/tests/Feature/VideoWorkflow/StepHandlers/ThumbnailGenerationHandlerTest.php
@@ -0,0 +1,79 @@
+<?php
+
+use App\Models\AiProvider;
+use App\Models\Asset;
+use App\Models\VideoProject;
+use App\Support\AiProviders\AiProviderManager;
+use App\Support\AssetStorage\AssetStorage;
+use App\Support\VideoWorkflow\StepHandlers\ThumbnailGenerationHandler;
+use App\Support\VideoWorkflow\WorkflowEngine;
+use Illuminate\Support\Facades\Http;
+use Illuminate\Support\Facades\Storage;
+
+beforeEach(function () {
+    Storage::fake();
+    $this->engine = new WorkflowEngine;
+    $this->handler = new ThumbnailGenerationHandler(app(AiProviderManager::class), new AssetStorage);
+});
+
+test('it generates two default-style variants and completes the step', function () {
+    Http::fake(['api.stability.ai/*' => Http::response(['image' => base64_encode('bytes')])]);
+    AiProvider::factory()->create(['provider' => 'stability_ai']);
+
+    $project = VideoProject::factory()->create(['title' => 'Top 10 Gadgets']);
+    $step = $this->engine->start($project, [['type' => 'thumbnail_generation']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    $fresh = $step->fresh();
+    expect($fresh->status)->toBe('completed');
+    expect($fresh->output['variant_count'])->toBe(2);
+    expect($fresh->output['asset_ids'])->toHaveCount(2);
+
+    $assets = Asset::whereIn('id', $fresh->output['asset_ids'])->get();
+    $assets->each(fn ($a) => expect($a->type)->toBe('image'));
+    expect($assets->pluck('metadata.style')->sort()->values()->all())
+        ->toBe(['minimalist and clean', 'vibrant and colorful']);
+
+    Http::assertSentCount(2);
+    Http::assertSent(fn ($request) => str_contains($request->body(), 'Top 10 Gadgets'));
+});
+
+test('explicit styles in input override the default variants', function () {
+    Http::fake(['api.stability.ai/*' => Http::response(['image' => base64_encode('bytes')])]);
+    AiProvider::factory()->create(['provider' => 'stability_ai']);
+
+    $project = VideoProject::factory()->create();
+    $step = $this->engine->start($project, [['type' => 'thumbnail_generation']]);
+    $step->update(['input' => ['styles' => ['noir', 'retro', 'futuristic']]]);
+
+    $this->handler->handle($step->fresh(), $this->engine);
+
+    expect($step->fresh()->output['variant_count'])->toBe(3);
+    Http::assertSentCount(3);
+});
+
+test('it fails the step when no active StabilityAI provider is configured', function () {
+    $project = VideoProject::factory()->create();
+    $step = $this->engine->start($project, [['type' => 'thumbnail_generation']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toContain('No active StabilityAI provider');
+});
+
+test('it fails the step and reports which variant failed', function () {
+    Http::fake(['api.stability.ai/*' => Http::response(['errors' => ['bad prompt']], 400)]);
+    AiProvider::factory()->create(['provider' => 'stability_ai']);
+
+    $project = VideoProject::factory()->create();
+    $step = $this->engine->start($project, [['type' => 'thumbnail_generation']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toContain('variant 1');
+});
diff --git a/tests/Feature/VideoWorkflow/StepHandlers/YoutubePublishHandlerTest.php b/tests/Feature/VideoWorkflow/StepHandlers/YoutubePublishHandlerTest.php
new file mode 100644
index 0000000..6148edd
--- /dev/null
+++ b/tests/Feature/VideoWorkflow/StepHandlers/YoutubePublishHandlerTest.php
@@ -0,0 +1,191 @@
+<?php
+
+use App\Models\AiProvider;
+use App\Models\VideoProject;
+use App\Support\AssetStorage\AssetStorage;
+use App\Support\VideoWorkflow\StepHandlers\YoutubePublishHandler;
+use App\Support\VideoWorkflow\WorkflowEngine;
+use Illuminate\Support\Facades\Http;
+use Illuminate\Support\Facades\Storage;
+
+beforeEach(function () {
+    Storage::fake();
+    $this->engine = new WorkflowEngine;
+    $this->assets = new AssetStorage;
+    $this->handler = new YoutubePublishHandler($this->assets);
+
+    $this->fakeYoutube = function (array $overrides = []) {
+        Http::fake(array_merge([
+            'oauth2.googleapis.com/*' => Http::response(['access_token' => 'access-token-123']),
+            'https://www.googleapis.com/upload/youtube/v3/videos*' => Http::response('', 200, [
+                'Location' => 'https://upload.example.com/session/abc123',
+            ]),
+            'upload.example.com/*' => Http::response(['id' => 'yt-video-id']),
+        ], $overrides));
+    };
+});
+
+test('it uploads the video with metadata and completes the step', function () {
+    ($this->fakeYoutube)();
+    AiProvider::factory()->create([
+        'provider' => 'youtube',
+        'api_key' => 'refresh-token-abc',
+        'config' => ['client_id' => 'cid', 'client_secret' => 'csecret'],
+    ]);
+
+    $project = VideoProject::factory()->create(['title' => 'Fallback Title']);
+    $this->assets->store($project, 'video', 'fake-mp4-bytes', 'mp4', mimeType: 'video/mp4');
+    $this->assets->store(
+        $project, 'other',
+        json_encode(['title' => 'Great Video', 'description' => 'A great description', 'tags' => ['a', 'b']]),
+        'json', mimeType: 'application/json', metadata: ['kind' => 'metadata'],
+    );
+
+    $step = $this->engine->start($project, [['type' => 'youtube_publish']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    $fresh = $step->fresh();
+    expect($fresh->status)->toBe('completed');
+    expect($fresh->output['youtube_video_id'])->toBe('yt-video-id');
+    expect($fresh->output['youtube_url'])->toBe('https://www.youtube.com/watch?v=yt-video-id');
+
+    Http::assertSent(function ($request) {
+        return $request->url() === 'https://oauth2.googleapis.com/token'
+            && $request['client_id'] === 'cid'
+            && $request['client_secret'] === 'csecret'
+            && $request['refresh_token'] === 'refresh-token-abc'
+            && $request['grant_type'] === 'refresh_token';
+    });
+
+    Http::assertSent(function ($request) {
+        return str_starts_with($request->url(), 'https://www.googleapis.com/upload/youtube/v3/videos')
+            && $request->hasHeader('Authorization', 'Bearer access-token-123')
+            && $request->hasHeader('X-Upload-Content-Type', 'video/mp4')
+            && $request['snippet']['title'] === 'Great Video'
+            && $request['snippet']['description'] === 'A great description'
+            && $request['status']['privacyStatus'] === 'private';
+    });
+
+    Http::assertSent(function ($request) {
+        return $request->url() === 'https://upload.example.com/session/abc123'
+            && $request->body() === 'fake-mp4-bytes';
+    });
+});
+
+test('it falls back to the project title/description when there is no metadata asset', function () {
+    ($this->fakeYoutube)();
+    AiProvider::factory()->create(['provider' => 'youtube', 'config' => ['client_id' => 'cid', 'client_secret' => 'cs']]);
+
+    $project = VideoProject::factory()->create(['title' => 'Fallback Title', 'description' => 'Fallback description']);
+    $this->assets->store($project, 'video', 'bytes', 'mp4', mimeType: 'video/mp4');
+    $step = $this->engine->start($project, [['type' => 'youtube_publish']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh()->status)->toBe('completed');
+
+    Http::assertSent(fn ($request) => ($request['snippet']['title'] ?? null) === 'Fallback Title'
+        && ($request['snippet']['description'] ?? null) === 'Fallback description');
+});
+
+test('publish_at input schedules the video and forces privacyStatus to private', function () {
+    ($this->fakeYoutube)();
+    AiProvider::factory()->create(['provider' => 'youtube', 'config' => ['client_id' => 'cid', 'client_secret' => 'cs']]);
+
+    $project = VideoProject::factory()->create();
+    $this->assets->store($project, 'video', 'bytes', 'mp4', mimeType: 'video/mp4');
+    $step = $this->engine->start($project, [['type' => 'youtube_publish']]);
+    $step->update(['input' => ['publish_at' => '2026-12-01T09:00:00Z', 'privacy_status' => 'public']]);
+
+    $this->handler->handle($step->fresh(), $this->engine);
+
+    expect($step->fresh()->status)->toBe('completed');
+
+    Http::assertSent(fn ($request) => ($request['status']['publishAt'] ?? null) === '2026-12-01T09:00:00Z'
+        && ($request['status']['privacyStatus'] ?? null) === 'private');
+});
+
+test('it fails when there is no finished video', function () {
+    AiProvider::factory()->create(['provider' => 'youtube']);
+    $project = VideoProject::factory()->create();
+    $step = $this->engine->start($project, [['type' => 'youtube_publish']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toContain('No finished video available');
+});
+
+test('it fails when no active YouTube credential is configured', function () {
+    $project = VideoProject::factory()->create();
+    $this->assets->store($project, 'video', 'bytes', 'mp4', mimeType: 'video/mp4');
+    $step = $this->engine->start($project, [['type' => 'youtube_publish']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toContain('No active YouTube credential');
+});
+
+test('it fails when the token refresh fails', function () {
+    ($this->fakeYoutube)(['oauth2.googleapis.com/*' => Http::response(['error_description' => 'invalid_grant'], 400)]);
+    AiProvider::factory()->create(['provider' => 'youtube']);
+
+    $project = VideoProject::factory()->create();
+    $this->assets->store($project, 'video', 'bytes', 'mp4', mimeType: 'video/mp4');
+    $step = $this->engine->start($project, [['type' => 'youtube_publish']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toContain('invalid_grant');
+});
+
+test('it fails when starting the upload session fails', function () {
+    ($this->fakeYoutube)(['https://www.googleapis.com/upload/youtube/v3/videos*' => Http::response(['error' => ['message' => 'quota exceeded']], 403)]);
+    AiProvider::factory()->create(['provider' => 'youtube']);
+
+    $project = VideoProject::factory()->create();
+    $this->assets->store($project, 'video', 'bytes', 'mp4', mimeType: 'video/mp4');
+    $step = $this->engine->start($project, [['type' => 'youtube_publish']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toBe('quota exceeded');
+});
+
+test('it fails when the upload session response has no Location header', function () {
+    ($this->fakeYoutube)(['https://www.googleapis.com/upload/youtube/v3/videos*' => Http::response('', 200)]);
+    AiProvider::factory()->create(['provider' => 'youtube']);
+
+    $project = VideoProject::factory()->create();
+    $this->assets->store($project, 'video', 'bytes', 'mp4', mimeType: 'video/mp4');
+    $step = $this->engine->start($project, [['type' => 'youtube_publish']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toContain('missing upload session location');
+});
+
+test('it fails when the final upload fails', function () {
+    ($this->fakeYoutube)(['upload.example.com/*' => Http::response(['error' => ['message' => 'upload interrupted']], 500)]);
+    AiProvider::factory()->create(['provider' => 'youtube']);
+
+    $project = VideoProject::factory()->create();
+    $this->assets->store($project, 'video', 'bytes', 'mp4', mimeType: 'video/mp4');
+    $step = $this->engine->start($project, [['type' => 'youtube_publish']]);
+
+    $this->handler->handle($step, $this->engine);
+
+    expect($step->fresh())
+        ->status->toBe('failed')
+        ->error->toBe('upload interrupted');
+});