v0.3.1

newest-frame.js now only drops frames in the page by default, and once a page reports that it fell behind, the server paces its stream by the page's acknowledgements until it keeps up again. The template and the site pace this way by default, and pacing is no longer experimental.

• live: newest-frame.js is the build of github.com/mbolli/datastar-attribute-newest-frame; live/VERSION names the commit. The template and the site leave __reopen off: at CPU 6x it held the Game of Life to 4 frames a second, 0.37 s behind where no fix was 0.10 s, and the page stayed on the slow stream for good. data-newest-frame__reopen keeps v0.3.0's behaviour. The slow-link check as the page starts is unchanged.
• live: a stream with Spec.Ack starts unpaced; Hub.Pace paces it once its page is behind, and then it sends a write only once the page has acknowledged the last (Hub.Ack). Spec.Release (DefaultRelease, 5 s) ends the pacing once the page keeps up, measured against the round trip the page reports (Hub.RoundTrip) with Spec.ReleaseSlack (DefaultReleaseSlack, 100 ms). Spec.Window paces a stream from the start.
• live, prom: Hub.Behind(id) counts a page's report that it fell behind its stream. prom exports it as <namespace>_live_newest_frame_behind_total and <namespace>_live_newest_frame_behind_streams_total, and the pacing as <namespace>_live_paces_total, _releases_total and _acks_total; the "lith apps" dashboard draws them.
• Template: <body> posts each newest-frame-behind to POST /pace, which counts it and paces the stream, and each paced write has the page post POST /ack after the paint. Both routes reach only the streams of the request's session; /pace is limited per session and /ack per stream. A slow page gets about a third of the bytes; on a slow phone on a 300 ms link it lags 0.60 s at 1.45 frames a second, against 0.47 s at 2.74 with the plugin alone. A page that keeps up pays nothing. Without Ack in the stream's Spec, /pace only counts.
• Template: the binary serves its metrics for Prometheus on a loopback listener of its own (-metrics, by default -addr's port + 100). The unit now allows loopback and no other host. lith-new requires lith/prom and lith/dbmetrics/prom, and every release tags prom/vX.Y.Z.
• Docs: what a frame costs the page (mostly its elements, not its bytes), counting the pages that fall behind, and pacing a stream by the page, with what it costs. The slow-page numbers come from the corrected TestLifeDrift: 27.15 s behind at the median in 150 s, not 42.6 s after 2 minutes.

To update an app made from an earlier template:

• Copy internal/web/pace.go, add its routes POST /pace and POST /ack with their limiters (paces, acks) to the server, and add both routes to edge.CSRF's Datastar routes.
• In the stream handler, give the Spec the ID streamID(sid, tab) and Ack: ackEvent(tab). An app that calls Watch or Unwatch passes the same ID.
• Copy the template's <body> attributes, data-newest-frame data-on:newest-frame-behind={ behind }, and behind in internal/views/expr.go.
• For the metrics, copy cmd/app/metrics.go, the unit's network lines and deploy/observability/app.metrics.yml, and install the "lith apps" dashboard again. An app that calls out adds its addresses to the unit's IPAddressAllow.