ui: dashboard crit-alerts banner

internal/server/http/ui_handlers.go

@@ -122,10 +122,11 @@ func (s *Server) version() string {
 
 // dashboardPage is the data the dashboard template renders against.
 type dashboardPage struct {
-	Hosts        []dashboardHostRow
-	HostCount    int
-	Summary      store.FleetSummary
-	PendingHosts []store.PendingHost // announce-and-approve queue (P2-18d)
+	Hosts         []dashboardHostRow
+	HostCount     int
+	Summary       store.FleetSummary
+	PendingHosts  []store.PendingHost // announce-and-approve queue (P2-18d)
+	CritOpenCount int
 }
 
 // dashboardHostRow carries a host plus the per-row Run-now decision
@@ -239,12 +240,18 @@ func (s *Server) handleUIDashboard(w stdhttp.ResponseWriter, r *stdhttp.Request)
 		slog.Warn("ui dashboard: list pending hosts", "err", perr)
 	}
 
+	critOpenCount := 0
+	if crit, err := s.deps.Store.ListAlerts(r.Context(), store.AlertFilter{Status: "open", Severity: "critical"}); err == nil {
+		critOpenCount = len(crit)
+	}
+
 	view := s.baseView(r, u)
 	view.Page = dashboardPage{
-		Hosts:        rows,
-		HostCount:    len(hosts),
-		Summary:      summary,
-		PendingHosts: pending,
+		Hosts:         rows,
+		HostCount:     len(hosts),
+		Summary:       summary,
+		PendingHosts:  pending,
+		CritOpenCount: critOpenCount,
 	}
 	if err := s.deps.UI.Render(w, "dashboard", view); err != nil {
 		slog.Error("ui: render dashboard", "err", err)

internal/server/ui/ui.go

@@ -94,6 +94,7 @@ func New() (*Renderer, error) {
 		"templates/partials/host_chrome.html",
 		"templates/partials/tree_node.html",
 		"templates/partials/alert_row.html",
+		"templates/partials/crit_banner.html",
 	}
 
 	pageEntries, err := fs.Glob(web.FS, "templates/pages/*.html")

web/templates/pages/dashboard.html

@@ -4,6 +4,7 @@
 <div class="max-w-[1280px] mx-auto px-8">
 
   {{$page := .Page}}
+  {{template "crit_banner" .Page}}
   {{if eq $page.HostCount 0}}
 
     {{/* ---------- empty state ---------- */}}

web/templates/partials/crit_banner.html

@@ -0,0 +1,13 @@
+{{define "crit_banner"}}
+{{if gt .CritOpenCount 0}}
+<div class="crit-banner flex items-center justify-between mb-4 px-4 py-2.5 rounded-md text-[13px]"
+     style="border: 1px solid color-mix(in oklch, var(--bad), transparent 60%);
+            background: color-mix(in oklch, var(--bad), transparent 88%);">
+  <div class="flex items-center gap-3">
+    <span class="dot dot-critical"></span>
+    <span><span class="text-bad font-medium">{{.CritOpenCount}} critical alert{{if ne .CritOpenCount 1}}s{{end}}</span> open across the fleet</span>
+  </div>
+  <a href="/alerts?severity=critical&status=open" class="btn btn-danger">Review →</a>
+</div>
+{{end}}
+{{end}}