0.2.6-dev: traffic counters — HTTP body bytes by category (assets / audio / code / data) and WebSocket wire / payload bytes since the start at GET /healthz?traffic=1, and the page's own downloads (Resource Timing transferSize) as a traffic line in the 问题反馈 diagnostics (host bandwidth layer 0.4); golden: unchanged

docs/design/overview.md

@@ -48,7 +48,8 @@ server/
     media.js               /media/… extension-less audio → public/assets/audio
     files.js               one file → response: MIME, gzip (.skel/.atlas/.json/.js/.css …), ETag / 304, cache policy, ranges
     buildTag.js            build tag of the served browser runtime (/healthz build, public/js/ui/buildGuard.js)
-    routes.js              request listener: 414 / 400 / 405 guards, GET /healthz, then static files
+    routes.js              request listener: 414 / 400 / 405 guards, GET /healthz (?traffic=1: the counters), then static files
+    traffic.js             traffic counters: HTTP body bytes by category (assets / audio / code / data), WebSocket wire / payload
     common.js              security headers, URL split, error page, JSON replies, bare 400 for unparseable requests
     boot.js                boot banner (Local / LAN / tunnel URLs), port-in-use hint, graceful SIGINT / SIGTERM
   net.js                   session registry, send helpers, per-connection rate limit, message validation (uses shared/protocol.js)