```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):
    return {1: "small", 2: "medium"}.get(size // 100, "large")

# Read and process each line in rows.jsonl
path = Path("data/rows.jsonl")
if not path.exists():
    print("File data/rows.jsonl not found.")
else:
    text = path.read_text()
    for line in text.splitlines():
        line = line.strip()
        if not line:
            continue
        try:
            data = json.loads(line)
            if 'size' in data:
                size = data['size']
                classification = classify_size(size)
                print(classification)
        except json.JSONDecodeError:
            continue
```