address CodeRabbit review: fix 4 critical + 12 major issues

Critical:
- Remove dead backend.utils.validation PyInstaller hidden import
- Fix story_items table rebuild to preserve track/trim/version columns
- Guard cache migration against same source/destination path
- Fix regeneration audio overwrite (use random uuid suffix per take)

Major:
- Engine selector: validate language on Qwen switch, clear stale modelSize
- Sync language validation regex between profile create and generate (22 langs)
- Guard CUDA download against duplicate concurrent requests
- Only set model_size for engines that support multiple sizes
- Fix 404 swallowed by generic except in history export
- Validate audio_path before FileResponse in export-audio
- Transcription: stream uploads in 1MB chunks, use robust cache check,
  call complete_download() on Whisper download success
- Set clean version as default when effects chain validation fails
- Return explicit error when Windows port occupied by non-voicebox process

app/src/components/Generation/EngineModelSelector.tsx

@@ -42,8 +42,15 @@ function handleEngineChange(form: UseFormReturn<GenerationFormValues>, value: st
     const [, modelSize] = value.split(':');
     form.setValue('engine', 'qwen');
     form.setValue('modelSize', modelSize as '1.7B' | '0.6B');
+    // Validate language is supported by Qwen
+    const currentLang = form.getValues('language');
+    const available = getLanguageOptionsForEngine('qwen');
+    if (!available.some((l) => l.value === currentLang)) {
+      form.setValue('language', available[0]?.value ?? 'en');
+    }
   } else {
     form.setValue('engine', value as GenerationFormValues['engine']);
+    form.setValue('modelSize', undefined as unknown as '1.7B' | '0.6B');
     if (ENGLISH_ONLY_ENGINES.has(value)) {
       form.setValue('language', 'en');
     } else {

backend/build_binary.py

@@ -66,7 +66,7 @@ def build_server(cuda=False):
         '--hidden-import', 'backend.utils.cache',
         '--hidden-import', 'backend.utils.progress',
         '--hidden-import', 'backend.utils.hf_progress',
-        '--hidden-import', 'backend.utils.validation',
+
         '--hidden-import', 'backend.services.cuda',
         '--hidden-import', 'backend.services.effects',
         '--hidden-import', 'backend.utils.effects',

backend/database/migrations.py

@@ -92,14 +92,20 @@ def _migrate_story_items(engine, inspector, tables: set[str]) -> None:
                     story_id VARCHAR NOT NULL,
                     generation_id VARCHAR NOT NULL,
                     start_time_ms INTEGER NOT NULL DEFAULT 0,
+                    track INTEGER NOT NULL DEFAULT 0,
+                    trim_start_ms INTEGER NOT NULL DEFAULT 0,
+                    trim_end_ms INTEGER NOT NULL DEFAULT 0,
+                    version_id VARCHAR,
                     created_at DATETIME,
                     FOREIGN KEY (story_id) REFERENCES stories(id),
                     FOREIGN KEY (generation_id) REFERENCES generations(id)
                 )
             """))
             conn.execute(text("""
-                INSERT INTO story_items_new (id, story_id, generation_id, start_time_ms, created_at)
+                INSERT INTO story_items_new (id, story_id, generation_id, start_time_ms, track, trim_start_ms, trim_end_ms, version_id, created_at)
-                SELECT id, story_id, generation_id, start_time_ms, created_at FROM story_items
+                SELECT id, story_id, generation_id, start_time_ms,
+                    COALESCE(track, 0), COALESCE(trim_start_ms, 0), COALESCE(trim_end_ms, 0), version_id, created_at
+                FROM story_items
             """))
             conn.execute(text("DROP TABLE story_items"))
             conn.execute(text("ALTER TABLE story_items_new RENAME TO story_items"))

backend/models.py

@@ -64,7 +64,7 @@ class GenerationRequest(BaseModel):
 
     profile_id: str
     text: str = Field(..., min_length=1, max_length=50000)
-    language: str = Field(default="en", pattern="^(zh|en|ja|ko|de|fr|ru|pt|es|it|he)$")
+    language: str = Field(default="en", pattern="^(zh|en|ja|ko|de|fr|ru|pt|es|it|he|ar|da|el|fi|hi|ms|nl|no|pl|sv|sw|tr)$")
     seed: Optional[int] = Field(None, ge=0)
     model_size: Optional[str] = Field(default="1.7B", pattern="^(1\\.7B|0\\.6B)$")
     instruct: Optional[str] = Field(None, max_length=500)

backend/routes/cuda.py

@@ -29,6 +29,11 @@ async def download_cuda_backend():
     if cuda.get_cuda_binary_path() is not None:
         raise HTTPException(status_code=409, detail="CUDA backend already downloaded")
 
+    progress_manager = get_progress_manager()
+    existing = progress_manager.get_progress(cuda.PROGRESS_KEY)
+    if existing and existing.get("status") == "downloading":
+        raise HTTPException(status_code=409, detail="CUDA backend download already in progress")
+
     async def _download():
         try:
             await cuda.download_cuda_binary()

backend/routes/generations.py

@@ -33,7 +33,7 @@ async def generate_speech(
     from ..backends import engine_has_model_sizes
 
     engine = data.engine or "qwen"
-    model_size = data.model_size or "1.7B"
+    model_size = (data.model_size or "1.7B") if engine_has_model_sizes(engine) else None
 
     generation = await history.create_generation(
         profile_id=data.profile_id,

backend/routes/history.py

@@ -126,28 +126,28 @@ async def export_generation(
     db: Session = Depends(get_db),
 ):
     """Export a generation as a ZIP archive."""
+    generation = db.query(DBGeneration).filter_by(id=generation_id).first()
+    if not generation:
+        raise HTTPException(status_code=404, detail="Generation not found")
+
     try:
-        generation = db.query(DBGeneration).filter_by(id=generation_id).first()
-        if not generation:
-            raise HTTPException(status_code=404, detail="Generation not found")
-
         zip_bytes = export_import.export_generation_to_zip(generation_id, db)
-
-        safe_text = "".join(c for c in generation.text[:30] if c.isalnum() or c in (" ", "-", "_")).strip()
-        if not safe_text:
-            safe_text = "generation"
-        filename = f"generation-{safe_text}.voicebox.zip"
-
-        return StreamingResponse(
-            io.BytesIO(zip_bytes),
-            media_type="application/zip",
-            headers={"Content-Disposition": safe_content_disposition("attachment", filename)},
-        )
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
         raise HTTPException(status_code=500, detail=str(e))
 
+    safe_text = "".join(c for c in generation.text[:30] if c.isalnum() or c in (" ", "-", "_")).strip()
+    if not safe_text:
+        safe_text = "generation"
+    filename = f"generation-{safe_text}.voicebox.zip"
+
+    return StreamingResponse(
+        io.BytesIO(zip_bytes),
+        media_type="application/zip",
+        headers={"Content-Disposition": safe_content_disposition("attachment", filename)},
+    )
+
 
 @router.get("/history/{generation_id}/export-audio")
 async def export_generation_audio(
@@ -159,8 +159,11 @@ async def export_generation_audio(
     if not generation:
         raise HTTPException(status_code=404, detail="Generation not found")
 
+    if not generation.audio_path:
+        raise HTTPException(status_code=404, detail="Generation has no audio file")
+
     audio_path = Path(generation.audio_path)
-    if not audio_path.exists():
+    if not audio_path.is_file():
         raise HTTPException(status_code=404, detail="Audio file not found")
 
     safe_text = "".join(c for c in generation.text[:30] if c.isalnum() or c in (" ", "-", "_")).strip()

backend/routes/models.py

@@ -129,6 +129,9 @@ async def migrate_models(request: models.ModelMigrateRequest):
     if not source.exists():
         raise HTTPException(status_code=404, detail="Current model cache directory not found")
 
+    if source.resolve() == destination.resolve():
+        raise HTTPException(status_code=400, detail="Source and destination are the same directory")
+
     model_dirs = [d for d in source.iterdir() if d.name.startswith("models--") and d.is_dir()]
     if not model_dirs:
         return {"moved": 0, "errors": [], "source": str(source), "destination": str(destination)}

backend/routes/transcription.py

@@ -13,6 +13,8 @@ from ..utils.tasks import get_task_manager
 
 router = APIRouter()
 
+UPLOAD_CHUNK_SIZE = 1024 * 1024  # 1MB
+
 
 @router.post("/transcribe", response_model=models.TranscriptionResponse)
 async def transcribe_audio(
@@ -21,8 +23,8 @@ async def transcribe_audio(
 ):
     """Transcribe audio file to text."""
     with tempfile.NamedTemporaryFile(suffix=".wav", delete=False) as tmp:
-        content = await file.read()
+        while chunk := await file.read(UPLOAD_CHUNK_SIZE):
-        tmp.write(content)
+            tmp.write(chunk)
         tmp_path = tmp.name
 
     try:
@@ -32,27 +34,20 @@ async def transcribe_audio(
         duration = len(audio) / sr
 
         whisper_model = transcribe.get_whisper_model()
-
         model_size = whisper_model.model_size
-        whisper_hf_repos = {
-            "large": "openai/whisper-large-v3",
-            "turbo": "openai/whisper-large-v3-turbo",
-        }
-        model_name = whisper_hf_repos.get(model_size, f"openai/whisper-{model_size}")
 
-        from huggingface_hub import constants as hf_constants
+        if not whisper_model.is_loaded() and not whisper_model._is_model_cached(model_size):
-
-        repo_cache = Path(hf_constants.HF_HUB_CACHE) / ("models--" + model_name.replace("/", "--"))
-        if not repo_cache.exists():
             progress_model_name = f"whisper-{model_size}"
+            task_manager = get_task_manager()
 
             async def download_whisper_background():
                 try:
                     await whisper_model.load_model_async(model_size)
+                    task_manager.complete_download(progress_model_name)
                 except Exception as e:
-                    get_task_manager().error_download(progress_model_name, str(e))
+                    task_manager.error_download(progress_model_name, str(e))
 
-            get_task_manager().start_download(progress_model_name)
+            task_manager.start_download(progress_model_name)
             create_background_task(download_whisper_background())
 
             raise HTTPException(

backend/services/generation.py

@@ -176,7 +176,11 @@ def _save_generate(
 
         error_msg = validate_effects_chain(effects_chain)
         if error_msg:
-            print(f"Warning: invalid effects chain, skipping: {error_msg}")
+            import logging
+            logging.getLogger(__name__).warning("invalid effects chain, skipping: %s", error_msg)
+            versions_mod.set_default_version(
+                versions_mod.list_versions(generation_id, db)[0].id, db
+            )
         else:
             processed_audio = apply_effects(audio, sample_rate, effects_chain)
             processed_path = config.get_generations_dir() / f"{generation_id}_processed.wav"
@@ -225,7 +229,9 @@ def _save_regenerate(
     """
     from . import versions as versions_mod
 
-    suffix = version_id[:8] if version_id else generation_id[:8]
+    import uuid as _uuid
+
+    suffix = _uuid.uuid4().hex[:8]
     audio_path = config.get_generations_dir() / f"{generation_id}_{suffix}.wav"
     save_audio(audio, str(audio_path), sample_rate)
 

tauri/src-tauri/src/main.rs

@@ -113,11 +113,17 @@ async fn start_server(
             &format!("127.0.0.1:{}", SERVER_PORT).parse().unwrap(),
             std::time::Duration::from_secs(1),
         ).is_ok() {
-            // Port is in use — check if it's a voicebox process via tasklist
+            // Port is in use — check if it's a voicebox process
             if let Some(pid) = find_voicebox_pid_on_port(SERVER_PORT) {
                 println!("Found existing voicebox-server on port {} (PID: {}), reusing it", SERVER_PORT, pid);
                 *state.server_pid.lock().unwrap() = Some(pid);
                 return Ok(format!("http://127.0.0.1:{}", SERVER_PORT));
+            } else {
+                return Err(format!(
+                    "Port {} is already in use by another application. \
+                     Close the other application or change the Voicebox port.",
+                    SERVER_PORT
+                ));
             }
         }
     }