diff --git a/public/css/style.css b/public/css/style.css
index 17f9d13..4b23c5e 100644
--- a/public/css/style.css
+++ b/public/css/style.css
@@ -132,6 +132,70 @@ body::after {
 .card-drop-before::before { left: -6px; }
 .card-drop-after::after { right: -6px; }
 
+/* Group fan preview */
+.group-fan {
+    position: fixed;
+    z-index: 50;
+    padding: 8px;
+    background: var(--t-bg);
+    border: 1px solid var(--t-border);
+    border-radius: 6px;
+    box-shadow: 0 8px 30px -6px rgba(0,0,0,0.4);
+    pointer-events: auto;
+    animation: fanIn 0.25s ease;
+    max-width: min(720px, 95vw);
+}
+@keyframes fanIn {
+    from { opacity: 0; transform: translateY(6px) scale(0.95); }
+    to { opacity: 1; transform: translateY(0) scale(1); }
+}
+.group-fan-grid {
+    display: grid;
+    grid-template-columns: repeat(var(--fan-cols, 6), 104px);
+    gap: 5px;
+    position: relative;
+    overflow: hidden;
+}
+.group-fan-grid::after {
+    content: '';
+    position: absolute;
+    top: 0; bottom: 0; right: 0;
+    width: 0;
+    background: linear-gradient(to right, transparent, var(--t-bg));
+    pointer-events: none;
+    transition: width 0.2s;
+}
+.group-fan-grid.has-more::after { width: 40px; }
+.group-fan-card {
+    width: 104px;
+    background: var(--t-surface);
+    border: 1px solid var(--t-border);
+    border-radius: 4px;
+    cursor: pointer;
+    overflow: hidden;
+    transition: border-color 0.12s, transform 0.12s;
+}
+.group-fan-card:hover {
+    border-color: var(--t-muted);
+    box-shadow: 0 2px 8px rgba(0,0,0,0.25);
+}
+.group-fan-bar { height: 2px; }
+.group-fan-title {
+    padding: 5px 6px;
+    font-size: 9px;
+    line-height: 1.3;
+    color: var(--t-bright);
+    display: -webkit-box;
+    -webkit-line-clamp: 2;
+    -webkit-box-orient: vertical;
+    overflow: hidden;
+}
+.group-fan-thumb {
+    height: 44px;
+    background-size: cover;
+    background-position: center;
+}
+
 /* Board card animation */
 #board > div {
     transition: transform 0.2s ease, opacity 0.2s ease;
diff --git a/public/index.php b/public/index.php
index 6486d5e..7d14145 100644
--- a/public/index.php
+++ b/public/index.php
@@ -421,6 +421,9 @@ if (str_starts_with($route, '/api/')) {
                 <span class="text-[10px] text-t-dim font-pixel ml-1">v0.1</span>
             </div>
             <div class="flex items-center gap-3">
+                <button id="gallery-btn" class="flex items-center gap-2 px-2.5 py-1.5 text-xs border border-t-border text-t-muted hover:border-t-accent hover:text-t-accent transition-colors">
+                    <i class="ph ph-image-square text-sm"></i><span class="font-pixel text-[10px]">images</span>
+                </button>
                 <button id="search-btn" class="flex items-center gap-2 px-2.5 py-1.5 text-xs border border-t-border text-t-muted hover:border-t-accent hover:text-t-accent transition-colors">
                     <i class="ph ph-magnifying-glass text-sm"></i><span class="font-pixel text-[10px]">search</span>
                     <kbd class="text-[9px] text-t-dim border border-t-border rounded px-1 py-0.5 ml-1 font-pixel">ctrl+k</kbd>
@@ -451,9 +454,6 @@ if (str_starts_with($route, '/api/')) {
             <button id="import-btn" class="flex items-center gap-1.5 px-2.5 py-1 text-xs border border-t-border text-t-muted hover:border-t-accent hover:text-t-accent transition-colors">
                 <i class="ph ph-upload-simple text-sm"></i><span class="font-pixel text-[10px]">import</span>
             </button>
-            <button id="gallery-btn" class="flex items-center gap-1.5 px-2.5 py-1 text-xs border border-t-border text-t-muted hover:border-t-accent hover:text-t-accent transition-colors">
-                <i class="ph ph-images text-sm"></i><span class="font-pixel text-[10px]">images</span>
-            </button>
             <button id="export-btn" class="flex items-center gap-1.5 px-2.5 py-1 text-xs border border-t-border text-t-muted hover:border-t-accent hover:text-t-accent transition-colors">
                 <i class="ph ph-download-simple text-sm"></i><span class="font-pixel text-[10px]">export</span>
             </button>
diff --git a/public/js/modules/board.js b/public/js/modules/board.js
index d3677cd..72d663b 100644
--- a/public/js/modules/board.js
+++ b/public/js/modules/board.js
@@ -57,6 +57,7 @@ export function renderBoard() {
     cards = sortedCards(cards);
     window._refreshTasks?.();
 
+    hideFan();
     renderGroupBar(cards);
 
     if (!cards.length) {
@@ -127,6 +128,60 @@ function renderGroupBar(cards) {
     }
 }
 
+// ── Group fan preview ──
+
+let fanEl = null;
+let fanTimer = null;
+let fanGroupId = null;
+
+function showFan(groupEl, parentId) {
+    hideFan();
+    const parent = state.cards.find(c => c.id == parentId);
+    if (!parent) return;
+    const children = getChildren(parentId);
+    const all = children;
+    const maxShow = 12;
+    const visible = all.slice(0, maxShow);
+    const hasMore = all.length > maxShow;
+
+    fanGroupId = parentId;
+    fanEl = document.createElement('div');
+    fanEl.className = 'group-fan';
+    const cols = Math.min(6, visible.length);
+    fanEl.innerHTML = `<div class="group-fan-grid ${hasMore ? 'has-more' : ''}" style="--fan-cols:${cols}">${visible.map(c => {
+        const img = firstImage(c.body);
+        return `<div class="group-fan-card" data-fan-id="${c.id}">
+            <div class="group-fan-bar" style="background:${c.color}"></div>
+            ${img ? `<div class="group-fan-thumb" style="background-image:url('${img}')"></div>` : ''}
+            <div class="group-fan-title font-pixel">${esc(c.title)}</div>
+        </div>`;
+    }).join('')}</div>`;
+
+    document.body.appendChild(fanEl);
+
+    // Position below the group card
+    const rect = groupEl.getBoundingClientRect();
+    const fanW = fanEl.offsetWidth;
+    let left = rect.left + rect.width / 2 - fanW / 2;
+    left = Math.max(8, Math.min(left, innerWidth - fanW - 8));
+    let top = rect.bottom + 6;
+    if (top + fanEl.offsetHeight > innerHeight - 40) top = rect.top - fanEl.offsetHeight - 6;
+    fanEl.style.left = left + 'px';
+    fanEl.style.top = top + 'px';
+
+    fanEl.querySelectorAll('[data-fan-id]').forEach(card => {
+        card.addEventListener('click', () => { hideFan(); window._openDetail(card.dataset.fanId); });
+    });
+
+    fanEl.addEventListener('mouseleave', hideFan);
+}
+
+function hideFan() {
+    if (fanTimer) { clearTimeout(fanTimer); fanTimer = null; }
+    if (fanEl) { fanEl.remove(); fanEl = null; }
+    fanGroupId = null;
+}
+
 // ── Card event binding ──
 
 function bindCardEvents() {
@@ -136,8 +191,26 @@ function bindCardEvents() {
 
     board.querySelectorAll('[data-id]').forEach(el => {
         const id = el.dataset.id;
+        const children = getChildren(id);
+        const isGroup = children.length > 0 && !state.activeGroup;
         let clickTimer = null;
 
+        // Group fan on long hover
+        if (isGroup) {
+            el.addEventListener('mouseenter', () => {
+                fanTimer = setTimeout(() => showFan(el, id), 800);
+            });
+            el.addEventListener('mouseleave', e => {
+                // Don't hide if moving to the fan itself
+                if (fanEl && fanEl.contains(e.relatedTarget)) return;
+                if (fanTimer) { clearTimeout(fanTimer); fanTimer = null; }
+                // Delay hiding to allow moving to fan
+                if (fanEl && fanGroupId == id) {
+                    setTimeout(() => { if (fanGroupId == id && fanEl && !fanEl.matches(':hover')) hideFan(); }, 200);
+                }
+            });
+        }
+
         el.addEventListener('click', () => {
             if (clickTimer) return;
             clickTimer = setTimeout(() => { clickTimer = null; window._openDetail(id); }, 200);