```python
# /// intent
# goal   = "Classify each valid row's size from data/rows.jsonl as small, medium, or large, and print the classification in file order."
# reads  = ["data/rows.jsonl"]
# writes = []
# output = "printed"
# ///

import json
from pathlib import Path

def classify_size(size):
    if size < 100:
        return "small"
    elif size < 200:
        return "medium"
    else:
        return "large"

# Read the JSONL file line by line
path = Path("data/rows.jsonl")
if path.exists():
    for line in path.read_text().splitlines():
        try:
            # Parse JSON from each line
            row = json.loads(line)
            # Check if 'size' is present and a number
            if "size" in row and isinstance(row["size"], (int, float)):
                # Classify and print the size
                classification = classify_size(row["size"])
                print(classification)
        except (json.JSONDecodeError, TypeError, ValueError):
            # Skip invalid lines
            continue
```
