diff --git a/routers/focus.py b/routers/focus.py
index 9420f64..d21ad0a 100644
--- a/routers/focus.py
+++ b/routers/focus.py
@@ -71,7 +71,7 @@ async def focus_view(
         dl = item.get("domain_name") or "General"
         dc = item.get("domain_color") or ""
         if dk not in domain_map:
-            domain_map[dk] = {"label": dl, "color": dc, "rows": []}
+            domain_map[dk] = {"key": dk, "label": dl, "color": dc, "rows": []}
         domain_map[dk]["rows"].append(item)
 
     hierarchy = list(domain_map.values())
diff --git a/static/style.css b/static/style.css
index 01fc77c..b30a62e 100644
--- a/static/style.css
+++ b/static/style.css
@@ -1107,6 +1107,9 @@ a:hover { color: var(--accent-hover); }
     transition: width 0.3s;
 }
 
+/* ---- Focus Domain Toggle ---- */
+.focus-domain-header:hover td { background: var(--surface3); }
+
 /* ---- Focus Drag-and-Drop ---- */
 .focus-drag-row { cursor: grab; }
 .focus-drag-row.dragging { opacity: 0.4; background: var(--accent-soft); }
diff --git a/templates/focus.html b/templates/focus.html
index 8728beb..c3f1122 100644
--- a/templates/focus.html
+++ b/templates/focus.html
@@ -22,14 +22,18 @@
 </colgroup>
 {% for domain in hierarchy %}
     <tbody>
-    <tr><td colspan="9" style="padding:2px 8px;border-bottom:1px solid var(--border);background:var(--surface2);">
-        <span style="display:inline-flex;align-items:center;gap:6px;">
-            <span style="width:8px;height:8px;border-radius:50%;background:{{ domain.color or 'var(--accent)' }};flex-shrink:0;"></span>
-            <span style="font-weight:700;font-size:0.8rem;letter-spacing:0.03em;text-transform:uppercase;color:var(--text)">{{ domain.label }}</span>
-        </span>
-    </td></tr>
+    <tr class="focus-domain-header" data-domain-key="{{ domain.key }}" style="cursor:pointer;">
+        <td colspan="9" style="padding:2px 8px;border-bottom:1px solid var(--border);background:var(--surface2);">
+            <span style="display:inline-flex;align-items:center;gap:6px;">
+                <svg class="focus-domain-chevron" width="12" height="12" viewBox="0 0 12 12" fill="none" stroke="currentColor" stroke-width="2" style="transition:transform 0.15s;flex-shrink:0;color:var(--muted);"><polyline points="4 2 8 6 4 10"/></svg>
+                <span style="width:8px;height:8px;border-radius:50%;background:{{ domain.color or 'var(--accent)' }};flex-shrink:0;"></span>
+                <span style="font-weight:700;font-size:0.8rem;letter-spacing:0.03em;text-transform:uppercase;color:var(--text)">{{ domain.label }}</span>
+                <span style="font-size:0.72rem;color:var(--muted);font-weight:400;">{{ domain.rows|length }}</span>
+            </span>
+        </td>
+    </tr>
     </tbody>
-    <tbody class="focus-drag-group">
+    <tbody class="focus-drag-group" data-domain-key="{{ domain.key }}">
     {% for item in domain.rows %}
     <tr class="focus-drag-row" draggable="true" data-id="{{ item.id }}" style="border-bottom:1px solid var(--border);{{ 'opacity:0.6;' if item.completed }}">
         <td style="padding:1px 1px;vertical-align:middle;">{% with reorder_url="/focus/reorder", item_id=item.id, extra_fields={"focus_date": focus_date|string} %}{% include 'partials/reorder_arrows.html' %}{% endwith %}</td>
@@ -191,6 +195,26 @@
         });
     }
 
+    // Domain group collapse/expand
+    document.querySelectorAll('.focus-domain-header').forEach(function(header) {
+        var key = 'focus-domain-' + header.dataset.domainKey;
+        var tbody = document.querySelector('tbody.focus-drag-group[data-domain-key="' + header.dataset.domainKey + '"]');
+        var chevron = header.querySelector('.focus-domain-chevron');
+        // Restore saved state
+        if (localStorage.getItem(key) === 'true') {
+            tbody.style.display = 'none';
+            chevron.style.transform = 'rotate(0deg)';
+        } else {
+            chevron.style.transform = 'rotate(90deg)';
+        }
+        header.addEventListener('click', function() {
+            var hidden = tbody.style.display === 'none';
+            tbody.style.display = hidden ? '' : 'none';
+            chevron.style.transform = hidden ? 'rotate(90deg)' : 'rotate(0deg)';
+            localStorage.setItem(key, !hidden);
+        });
+    });
+
     // Drag-and-drop reorder within domain groups
     var dragRow = null;
     var dragGroup = null;