fix: auto-download default model and avoid passing None to RealESRGANer

app/services/realesrgan_bridge.py

@@ -7,6 +7,8 @@ import cv2
 import numpy as np
 
 from app.config import settings
+from app.services import model_manager
+import urllib.request
 
 logger = logging.getLogger(__name__)
 
@@ -45,6 +47,24 @@ class RealESRGANBridge:
             model_path = os.path.join(settings.models_dir, f'{model_name}.pth')
             if not os.path.exists(model_path):
                 logger.warning(f'Model not found at {model_path}, will attempt to auto-download')
+                if settings.auto_model_download:
+                    # Try to locate known model URL and download it
+                    try:
+                        meta = model_manager.KNOWN_MODELS.get(model_name)
+                        if meta and meta.get('url'):
+                            os.makedirs(settings.models_dir, exist_ok=True)
+                            url = meta['url']
+                            logger.info(f'Downloading model {model_name} from {url}')
+                            urllib.request.urlretrieve(url, model_path)
+                            logger.info(f'Model downloaded to {model_path}')
+                        else:
+                            logger.error(f'No download URL known for model: {model_name}')
+                    except Exception as e:
+                        logger.error(f'Automatic model download failed: {e}', exc_info=True)
+
+            if not os.path.exists(model_path):
+                logger.error(f'Model file still not found: {model_path} - aborting initialization')
+                return False
             
             # Load model
             model = RRDBNet(
@@ -58,7 +78,7 @@ class RealESRGANBridge:
             
             self.upsampler = RealESRGANer(
                 scale=scale,
-                model_path=model_path if os.path.exists(model_path) else None,
+                model_path=model_path,
                 model=model,
                 tile=settings.tile_size,
                 tile_pad=settings.tile_pad,