Fix browser download directory to automatically use /shared-downloads in Docker

- Add model validator to BrowserProfile that sets downloads_path to /shared-downloads in Docker environments
- Add Chrome --download-default-directory flag when downloads_path is configured
- Ensures downloads go directly to shared directory without manual save_as() calls
- Fixes issue where save_as() resulted in empty files due to temp location copying

Co-Authored-By: jerry@browserless.io <jerry@browserless.io>

Author: devin-ai-integration[bot]

browser_use/browser/profile.py

@@ -642,6 +642,13 @@ def warn_storage_state_user_data_dir_conflict(self) -> Self:
 			)
 		return self
 
+	@model_validator(mode='after')
+	def set_docker_downloads_path(self) -> Self:
+		"""Set downloads_path to /shared-downloads in Docker environments if not already set."""
+		if IN_DOCKER and not self.downloads_path:
+			self.downloads_path = '/shared-downloads'
+		return self
+
 	def get_args(self) -> list[str]:
 		if isinstance(self.ignore_default_args, list):
 			default_args = set(CHROME_DEFAULT_ARGS) - set(self.ignore_default_args)
@@ -669,6 +676,7 @@ def get_args(self) -> list[str]:
 				if self.window_position
 				else []
 			),
+			*([f'--download-default-directory={self.downloads_path}'] if self.downloads_path else []),
 		]
 
 		final_args_list = BrowserLaunchArgs.args_as_list(BrowserLaunchArgs.args_as_dict(pre_conversion_args))