```python
def crumb_split(trail: str) -> list:
    """Split a breadcrumb trail on forward slashes and discard every empty segment."""
    return [part for part in trail.split('/') if part]

def crumb_join(parts: list) -> str:
    """Join segments back with a single slash between them and no slash at either end."""
    return '/' + '/'.join(filter(None, parts)) + '/'
```