```python
# /// intent
# goal   = "Join the features from config.json with a default separator of ', ' and print the result"
# reads  = ["data/config.json"]
# writes = []
# output = "printed"
# ///

import json
from pathlib import Path

def join_features(features, sep=', '):
    return sep.join(features)

# Read the config file
config_path = Path('data/config.json')
config_text = config_path.read_text()
config = json.loads(config_text)

# Extract features and join them with default separator
features = config['features']
joined_features = join_features(features)

# Print the result
print(joined_features)
```