ui: fleet update page + endpoints

- POST /api/fleet/update, POST /api/fleet-updates/{id}/cancel,
  GET /api/fleet-updates/{id} (admin-only).
- GET /settings/fleet-update + /partial for htmx polling.
- Renders idle / running / terminal states with per-host progress.
- Tests cover happy path, derive-host-ids, conflict, cancel, get,
  and RBAC.

web/templates/pages/fleet_update.html

@@ -0,0 +1,32 @@
+{{define "title"}}Fleet update · restic-manager{{end}}
+
+{{define "content"}}
+{{$page := .Page}}
+<div class="max-w-[1280px] mx-auto px-8 pb-14">
+
+  {{/* breadcrumbs */}}
+  <div class="crumbs pt-6">
+    <a href="/">Dashboard</a><span class="sep">/</span>
+    <a href="/settings">Settings</a><span class="sep">/</span>
+    <span class="text-ink-mid">fleet update</span>
+  </div>
+
+  {{/* page header */}}
+  <div class="flex items-baseline justify-between mt-3.5">
+    <div>
+      <h1 class="text-[22px] font-medium tracking-[-0.005em]">
+        Fleet update
+        <span class="text-ink-fade font-normal text-[14px] ml-2 mono">target {{$page.TargetVersion}}</span>
+      </h1>
+      <p class="text-ink-mute text-[12px] mt-1 max-w-[760px] leading-[1.55]">
+        Rolling, sequential agent self-update. One host at a time, halts on first failure,
+        cancellable mid-roll. Only online hosts whose <span class="mono">agent_version</span>
+        differs from the server are eligible.
+      </p>
+    </div>
+  </div>
+
+  {{template "fleet_update_inner" .}}
+
+</div>
+{{end}}

web/templates/partials/fleet_update_inner.html

@@ -0,0 +1,171 @@
+{{/*
+  fleet_update_inner — inner panel for /settings/fleet-update.
+  Rendered both as part of the full page and as the htmx polling
+  fragment via /settings/fleet-update/partial.
+
+  Expects .Page to be a fleetUpdatePage struct (see fleet_update.go).
+*/}}
+{{define "fleet_update_inner"}}
+{{$page := .Page}}
+<div id="fleet-update-panel" class="mt-5"
+     hx-get="{{$page.PollURL}}"
+     hx-trigger="every 3s [document.visibilityState==='visible']"
+     hx-select="#fleet-update-panel"
+     hx-swap="outerHTML">
+
+{{if and $page.Active (eq $page.Active.Status "running")}}
+
+  {{/* ---------- running state ---------- */}}
+  <div class="panel rounded-[7px] px-5 py-4">
+    <div class="flex items-baseline justify-between">
+      <div>
+        <span class="mono text-[12px] text-ink-fade">fleet update</span>
+        <span class="mono text-[12px] text-accent ml-2">running</span>
+        <span class="mono text-[11px] text-ink-fade ml-2">{{$page.Active.ID}}</span>
+      </div>
+      <form hx-post="/api/fleet-updates/{{$page.Active.ID}}/cancel" hx-swap="none">
+        <button class="btn btn-danger" type="submit"
+                onclick="return confirm('Cancel this fleet update? Hosts already updated stay updated; pending hosts will be skipped.');">
+          Cancel
+        </button>
+      </form>
+    </div>
+    <div class="text-[11.5px] text-ink-mute mt-1">
+      target <span class="mono text-ink-mid">{{$page.Active.TargetVersion}}</span>
+      · started <span class="mono text-ink-mid">{{relTime $page.Active.StartedAt}}</span>
+      {{if $page.Active.CurrentHostID}}
+        · waiting on <span class="mono text-ink-mid">{{index $page.HostNames $page.Active.CurrentHostID}}</span>
+      {{end}}
+    </div>
+  </div>
+
+  {{template "fleet_update_rows" $page}}
+
+{{else if $page.Active}}
+
+  {{/* ---------- terminal state (completed / halted / cancelled) ---------- */}}
+  <div class="panel rounded-[7px] px-5 py-4">
+    <div class="flex items-baseline justify-between">
+      <div>
+        <span class="mono text-[12px] text-ink-fade">last fleet update</span>
+        {{if eq $page.Active.Status "completed"}}
+          <span class="mono text-[12px] text-ok ml-2">completed</span>
+        {{else if eq $page.Active.Status "halted"}}
+          <span class="mono text-[12px] text-bad ml-2">halted</span>
+        {{else if eq $page.Active.Status "cancelled"}}
+          <span class="mono text-[12px] text-warn ml-2">cancelled</span>
+        {{else}}
+          <span class="mono text-[12px] text-ink-mid ml-2">{{$page.Active.Status}}</span>
+        {{end}}
+        <span class="mono text-[11px] text-ink-fade ml-2">{{$page.Active.ID}}</span>
+      </div>
+    </div>
+    <div class="text-[11.5px] text-ink-mute mt-1">
+      target <span class="mono text-ink-mid">{{$page.Active.TargetVersion}}</span>
+      · started <span class="mono text-ink-mid">{{relTime $page.Active.StartedAt}}</span>
+      {{if $page.Active.CompletedAt}} · finished <span class="mono text-ink-mid">{{relTime $page.Active.CompletedAt}}</span>{{end}}
+    </div>
+    {{if $page.Active.HaltedReason}}
+      <div class="text-[12px] text-bad mt-2">{{$page.Active.HaltedReason}}</div>
+    {{end}}
+  </div>
+
+  {{template "fleet_update_rows" $page}}
+
+  {{if gt (len $page.OutOfDateHosts) 0}}
+    <div class="mt-5">
+      {{template "fleet_update_idle_panel" $page}}
+    </div>
+  {{end}}
+
+{{else}}
+
+  {{template "fleet_update_idle_panel" $page}}
+
+{{end}}
+</div>
+{{end}}
+
+{{define "fleet_update_rows"}}
+{{$page := .}}
+<div class="panel mt-3 rounded-[7px] overflow-hidden">
+  <div class="hairline grid items-baseline px-4 py-2.5 text-[11px] text-ink-fade uppercase tracking-[0.08em]"
+       style="grid-template-columns: 0.4fr 1.5fr 0.8fr 1.2fr 1.5fr; column-gap: 18px;">
+    <div>#</div>
+    <div>Host</div>
+    <div>Status</div>
+    <div>Job</div>
+    <div>Detail</div>
+  </div>
+  {{range $page.ActiveRows}}
+    <div class="grid items-center px-4 py-2.5 text-[12.5px] hairline"
+         style="grid-template-columns: 0.4fr 1.5fr 0.8fr 1.2fr 1.5fr; column-gap: 18px;">
+      <div class="mono text-ink-fade">{{.Position}}</div>
+      <div class="mono text-ink">{{if .HostName}}{{.HostName}}{{else}}{{.HostID}}{{end}}</div>
+      <div>
+        {{if eq .Status "pending"}}<span class="text-ink-fade">pending</span>
+        {{else if eq .Status "running"}}<span class="text-accent">running…</span>
+        {{else if eq .Status "succeeded"}}<span class="text-ok">succeeded</span>
+        {{else if eq .Status "failed"}}<span class="text-bad font-medium">failed</span>
+        {{else if eq .Status "skipped"}}<span class="text-ink-mute">skipped</span>
+        {{else}}<span class="text-ink-mute">{{.Status}}</span>{{end}}
+      </div>
+      <div>
+        {{if .JobID}}<a class="link mono text-[11.5px]" href="/jobs/{{.JobID}}">{{.JobID}}</a>{{else}}<span class="text-ink-fade">—</span>{{end}}
+      </div>
+      <div class="mono text-[11.5px] text-ink-mute truncate" title="{{.FailedReason}}">{{.FailedReason}}</div>
+    </div>
+  {{end}}
+</div>
+{{end}}
+
+{{define "fleet_update_idle_panel"}}
+{{$page := .}}
+<div class="panel rounded-[7px] px-5 py-4">
+  {{if eq (len $page.OutOfDateHosts) 0}}
+    <div class="flex items-center gap-3">
+      <span class="dot dot-online"></span>
+      <div>
+        <div class="text-ink text-[14px] font-medium">All hosts are up to date.</div>
+        <div class="text-ink-mute text-[12px] mt-0.5">
+          Every online agent matches server version <span class="mono">{{$page.TargetVersion}}</span>.
+        </div>
+      </div>
+    </div>
+  {{else}}
+    <div class="flex items-baseline justify-between">
+      <h2 class="text-[14px] font-medium">{{len $page.OutOfDateHosts}} host{{if ne (len $page.OutOfDateHosts) 1}}s{{end}} out of date</h2>
+      <span class="mono text-[11px] text-ink-fade">target {{$page.TargetVersion}}</span>
+    </div>
+    <ul class="mt-3 space-y-1 text-[12px]">
+      {{range $page.OutOfDateHosts}}
+        <li class="flex items-center gap-3">
+          <span class="dot dot-online"></span>
+          <span class="mono text-ink">{{.Name}}</span>
+          <span class="mono text-ink-mute">{{if .AgentVersion}}{{.AgentVersion}}{{else}}—{{end}} → {{$page.TargetVersion}}</span>
+        </li>
+      {{end}}
+    </ul>
+
+    <form id="fleet-update-start-form" class="mt-4 flex items-center gap-3"
+          hx-post="/api/fleet/update"
+          hx-headers='{"Content-Type":"application/json"}'
+          hx-vals='{}'
+          hx-swap="none"
+          hx-on::after-request="if(event.detail.successful) location.reload()">
+      <label class="text-[11.5px] text-ink-mute">
+        Type the count
+        <span class="mono text-ink-mid">({{len $page.OutOfDateHosts}})</span>
+        to enable Start:
+      </label>
+      <input type="text" id="fleet-update-confirm" class="field mono text-[12.5px]"
+             style="width: 80px; padding: 5px 8px;"
+             oninput="document.getElementById('fleet-update-start-btn').disabled = (this.value !== '{{len $page.OutOfDateHosts}}');"
+             autocomplete="off" />
+      <button type="submit" id="fleet-update-start-btn" class="btn btn-amber" disabled>
+        Start fleet update
+      </button>
+    </form>
+  {{end}}
+</div>
+{{end}}