feat(alerts): a covering rule's hosts fold away behind its "N hosts" (#5483)

#5483 "Alerts list: a covering rule's hosts start collapsed behind a toggle;
no dashed rows", from the operator's review of the Alerts list. Each rule is
its own tbody; its hosts sit in another, hidden until "N hosts" is pressed.
A rule with a host that isn't quiet opens on its own and names the host where
"last fired" was, so a problem never hides behind the fold. Host rows lose the
dashed rules for a sunken band under the indent.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

steward/templates/alerts/list.html

@@ -3,7 +3,8 @@
    when it last fired, what it fires on, and its History and Disable. The
    whole row opens the rule (.row-link, its name is the link); deleting one is
    on its own page, behind the confirm dialog. A rule covering hosts (#5464)
-   lists its per-host rules under it; each opens its history. #}
+   lists its per-host rules under it, closed behind its "N hosts" toggle
+   unless one of them isn't quiet (#5483); each opens its history. #}
 {% extends "base.html" %}
 {% block title %}Alerts — Steward{% endblock %}
 {% from "_macros.html" import page_header, status_badge, empty_state %}
@@ -35,22 +36,27 @@
                 <th></th>
             </tr>
         </thead>
+        {% for rule in rules %}
+        {% set kids = (children or {}).get(rule.id, []) %}
+        {% set fired = (last_fired or {}).get(rule.id) %}
+        {% set restless = (uneasy or {}).get(rule.id, []) %}
         <tbody>
-            {% for rule in rules %}
-            {% set kids = (children or {}).get(rule.id, []) %}
-            {% set fired = (last_fired or {}).get(rule.id) %}
             <tr class="row-link{% if not rule.enabled %} row-off{% endif %}">
                 <td class="cell-name">
                   <a class="row-target" href="{{ ('/alerts/rules/' ~ rule.id ~ '/edit') if can_edit else ('/alerts/history?rule=' ~ rule.id) }}" title="{{ rule.name }}">{{ rule.name }}</a>
                   <div class="cell-sub">{{ source_label(rule.source_module) }}
-                    {%- if rule.covers != "resource" %} · {{ kids|length }} host{{ "s" if kids|length != 1 }}{% endif %}</div>
+                    {%- if rule.covers != "resource" %} · <button type="button" class="row-toggle row-inner"
+                      aria-expanded="{{ 'true' if restless else 'false' }}" aria-controls="hosts-{{ rule.id }}"
+                      onclick="toggleHosts(this)">{{ kids|length }} host{{ "s" if kids|length != 1 }}</button>{% endif %}</div>
                 </td>
                 <td>
                   {%- set now_label = (rule_state or {}).get(rule.id) %}
                   {%- if not rule.enabled %}<span class="tone-dim">off</span>
                   {%- elif now_label and now_label not in ('inactive', 'resolved') %}{{ status_badge(now_label) }}
                   {%- else %}<span class="tone-ok" title="Within its threshold">quiet</span>{% endif -%}
-                  <div class="cell-sub">{% if fired %}last fired {{ fired|ago }}{% else %}never fired{% endif %}</div>
+                  <div class="cell-sub">
+                    {%- if restless %}on {{ restless|join(", ") }}
+                    {%- elif fired %}last fired {{ fired|ago }}{% else %}never fired{% endif %}</div>
                 </td>
                 <td>
                   {% if rule.covers == "group" %}every host in {{ rule.cover_group }}{% elif rule.covers == "all_hosts" %}every host{% else %}{{ rule.resource_name }}{% endif %} · {{ rule_condition(rule) }}
@@ -71,6 +77,9 @@
                     {% endif %}
                 </td>
             </tr>
+        </tbody>
+        {% if kids %}
+        <tbody id="hosts-{{ rule.id }}" class="row-children"{% if not restless %} hidden{% endif %}>
             {% for kid in kids %}
             {% set kid_label = (rule_state or {}).get(kid.id) %}
             {% set kid_fired = (last_fired or {}).get(kid.id) %}
@@ -88,10 +97,19 @@
                 <td class="td-actions"><a href="/alerts/history?rule={{ kid.id }}" class="btn btn-sm btn-ghost">History</a></td>
             </tr>
             {% endfor %}
-            {% endfor %}
         </tbody>
+        {% endif %}
+        {% endfor %}
     </table>
 </div>
+<script>
+// A covering rule's hosts (#5483): closed unless one of them isn't quiet.
+function toggleHosts(btn) {
+  var open = btn.getAttribute('aria-expanded') !== 'true';
+  btn.setAttribute('aria-expanded', open ? 'true' : 'false');
+  document.getElementById(btn.getAttribute('aria-controls')).hidden = !open;
+}
+</script>
 {% else %}
 <div class="card">{{ empty_state("No alert rules yet.", "New rule" if can_edit else none, "/alerts/rules/new" if can_edit else none) }}</div>
 {% endif %}