Check that a change made nothing worse

Keep a good run as the baseline, then compare after your change.

vegaload run -target http://127.0.0.1:8080/widgets -protocol http1 \
  -vus 10 -duration 30s -out baseline.json

# ... change your code, restart the service ...

vegaload run -target http://127.0.0.1:8080/widgets -protocol http1 \
  -vus 10 -duration 30s -baseline baseline.json -max-regression 10

The run exits with code 3 if p95 or the error rate is more than 10 percent worse. To compare two files you already have: vegaload compare baseline.json candidate.json.