A stored log, timeline_entries, with one row per thing that happened. Each source writes its row in the same transaction as its own record, so the history outlives the 30/90/365-day retention of the tables it points to: - alert events (core/alerts._add_event): fired, resolved, acknowledged, went silent, readings back; - finished Ansible runs (executor, and the startup sweep of interrupted runs): changed something, changed nothing, failed, dry run; - audit rows (core/audit.log_audit): Steward's settings, users and access, sign-ins, backups. Actions another writer records are left to it. Entries carry a kind (fixed) and an area (Service, Host OS, Hardware, Storage, Network, Security, Monitoring). Settings → Timeline edits the areas and each type's area and visibility; both are applied when the timeline is read, so a change re-sorts past entries and a hidden type comes back when shown. Kept forever unless a retention is set. The first start fills the timeline from the last 90 days of records once, skipping any already covered. A host rename carries its entries. UI: Timeline in the sidebar (filter by host, area, kind; scrolls on), a History card on each host page. MCP: get_timeline. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>