Make trajectories_path support file path (#4840)

config.template.toml

@@ -32,7 +32,8 @@ workspace_base = "./workspace"
 # Enable saving and restoring the session when run from CLI
 #enable_cli_session = false
 
-# Path to store trajectories
+# Path to store trajectories, can be a folder or a file
+# If it's a folder, the session id will be used as the file name
 #trajectories_path="./trajectories"
 
 # File store path

openhands/core/main.py

@@ -212,7 +212,11 @@ async def on_event(event: Event):
 
     # save trajectories if applicable
     if config.trajectories_path is not None:
-        file_path = os.path.join(config.trajectories_path, sid + '.json')
+        # if trajectories_path is a folder, use session id as file name
+        if os.path.isdir(config.trajectories_path):
+            file_path = os.path.join(config.trajectories_path, sid + '.json')
+        else:
+            file_path = config.trajectories_path
         os.makedirs(os.path.dirname(file_path), exist_ok=True)
         histories = [event_to_trajectory(event) for event in state.history]
         with open(file_path, 'w') as f: