The dashboard's host widgets took 18-60 s. Every "latest reading" query (hosts overview, host-agent fleet, host page, vitals, SNMP, MCP get_host) searched plugin_metrics for the newest row per metric. Postgres has no skip scan, so each one read every raw sample in the 7-day window. - plugin_metric_latest: one row per (source, resource, metric). record_metrics upserts it in the same transaction, moving forward only and in sorted key order. Migration 0030 seeds it by stepping the existing index. - Retention drops a latest row once its sample leaves the raw window, so a resource that stopped reporting disappears when its history does, as before. Renames carry it along. - A quiet host keeps its last values, marked stale. A time-bounded query would have shown it as missing. - Vitals sparklines span the 6 h they claim, averaged in SQL to ~120 points, instead of fetching 6 h raw and drawing the last 120 samples. - Dashboard and share-view cells: "Loading…" until the first answer; a 20 s deadline per fetch; "Couldn't load (why)" with Retry now and an automatic retry for cells that don't poll; "as of HH:MM" in the header, and "couldn't refresh · as of" when a refresh fails over shown data. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>