perf-ab

Run before/after page-load performance comparisons with the perf-ab CLI (adobecom/perf-tools). Always runs real Lighthouse 13.6.0 with the mobile profile and real DevTools throttling (Moto G Power, Slow 4G, 4x CPU), by default on a GitHub Actions runner with verified US egress, or on this machine with --local when the user says to run it locally; cold (new Chrome + empty profile per run, no warm-ups), alternating runs; downloads the official Lighthouse reports, traces and before/after medians. Compares a production page (e.g. www.adobe.com) as-is against an injected head.html snippet (e.g. preload links), fetchpriority changes, guarded source patches, Milo / MAS PR files or branch values. Also analyzes DevTools trace JSON files attached by the user. Use when asked to "compare before and after", "A/B test", "perf test a milo/mas PR or branch", "measure the impact on LCP/TBT/PageSpeed score", "test preloads", "run traces", or when the user attaches Trace-*.json files to compare.