feat: add unified asset retry endpoint

backend/tests/test_stories.py

@@ -264,7 +264,10 @@ class TestAudio:
         mock_tts_provider.assert_awaited_once()
 
     def test_get_audio_failure_updates_status(self, auth_client: TestClient, test_story):
-        with patch("app.services.provider_router.text_to_speech", new_callable=AsyncMock) as mock_tts:
+        with patch(
+            "app.services.provider_router.text_to_speech",
+            new_callable=AsyncMock,
+        ) as mock_tts:
             mock_tts.side_effect = Exception("TTS provider timeout")
             response = auth_client.get(f"/api/audio/{test_story.id}")
             assert response.status_code == 500
@@ -383,12 +386,83 @@ class TestImageGenerateSuccess:
         assert data["last_error"] is None
 
 
+class TestAssetRetry:
+    """Tests for unified asset retry endpoint."""
+
+    def test_retry_cover_image_success(
+        self,
+        auth_client: TestClient,
+        degraded_story_with_text,
+        mock_image_provider,
+    ):
+        response = auth_client.post(
+            f"/api/stories/{degraded_story_with_text.id}/assets/retry",
+            json={"assets": ["image"]},
+        )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert data["image_url"] == "https://example.com/image.png"
+        assert data["generation_status"] == "completed"
+        assert data["image_status"] == "ready"
+        assert data["audio_status"] == "not_requested"
+        assert data["last_error"] is None
+        mock_image_provider.assert_awaited_once()
+
+    def test_retry_storybook_missing_page_image_success(
+        self,
+        auth_client: TestClient,
+        storybook_story,
+    ):
+        async def image_side_effect(prompt: str, **kwargs):
+            return "https://example.com/retried-page.png"
+
+        with patch(
+            "app.services.story_service.generate_image",
+            new_callable=AsyncMock,
+        ) as mock_image:
+            mock_image.side_effect = image_side_effect
+
+            response = auth_client.post(
+                f"/api/stories/{storybook_story.id}/assets/retry",
+                json={"assets": ["image"]},
+            )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert data["generation_status"] == "completed"
+        assert data["image_status"] == "ready"
+        assert data["audio_status"] == "not_requested"
+        assert data["last_error"] is None
+        assert data["pages"][1]["image_url"] == "https://example.com/retried-page.png"
+        mock_image.assert_awaited_once()
+
+    def test_retry_audio_on_storybook_is_rejected(
+        self,
+        auth_client: TestClient,
+        storybook_story,
+    ):
+        response = auth_client.post(
+            f"/api/stories/{storybook_story.id}/assets/retry",
+            json={"assets": ["audio"]},
+        )
+
+        assert response.status_code == 400
+        assert response.json()["detail"] == "Story has no text"
+
+
 class TestStorybookGenerate:
     """Tests for storybook generation status handling."""
 
     def test_generate_storybook_success(self, auth_client: TestClient):
-        with patch("app.services.story_service.generate_storybook", new_callable=AsyncMock) as mock_storybook:
-            with patch("app.services.story_service.generate_image", new_callable=AsyncMock) as mock_image:
+        with patch(
+            "app.services.story_service.generate_storybook",
+            new_callable=AsyncMock,
+        ) as mock_storybook:
+            with patch(
+                "app.services.story_service.generate_image",
+                new_callable=AsyncMock,
+            ) as mock_image:
                 mock_storybook.return_value = build_storybook_output()
                 mock_image.side_effect = [
                     "https://example.com/storybook-cover.png",
@@ -422,8 +496,14 @@ class TestStorybookGenerate:
             slug = prompt.split()[0].lower()
             return f"https://example.com/{slug}.png"
 
-        with patch("app.services.story_service.generate_storybook", new_callable=AsyncMock) as mock_storybook:
-            with patch("app.services.story_service.generate_image", new_callable=AsyncMock) as mock_image:
+        with patch(
+            "app.services.story_service.generate_storybook",
+            new_callable=AsyncMock,
+        ) as mock_storybook:
+            with patch(
+                "app.services.story_service.generate_image",
+                new_callable=AsyncMock,
+            ) as mock_image:
                 mock_storybook.return_value = build_storybook_output()
                 mock_image.side_effect = image_side_effect