add popover

packages/z-flutter/lib/main.dart

@@ -254,6 +254,74 @@ class _MainAppState extends State<MainApp> {
     return _groupColors[groupIndex % _groupColors.length];
   }
 
+  static const _months = [
+    'Jan',
+    'Feb',
+    'Mar',
+    'Apr',
+    'May',
+    'Jun',
+    'Jul',
+    'Aug',
+    'Sep',
+    'Oct',
+    'Nov',
+    'Dec',
+  ];
+
+  String _formatDate(DateTime d) {
+    return '${_months[d.month - 1]} ${d.day}, ${d.year}';
+  }
+
+  String _formatDateRange(DateTime start, DateTime? end) {
+    final s = _formatDate(start);
+    if (end == null) return s;
+    final e = _formatDate(end);
+    return s == e ? s : '$s – $e';
+  }
+
+  Widget? _buildPopoverContent(String entryId) {
+    final item = _state?.items[entryId];
+    if (item == null) return null;
+
+    final start = DateTime.parse(item.start);
+    final end = item.end != null ? DateTime.parse(item.end!) : null;
+
+    return Column(
+      mainAxisSize: MainAxisSize.min,
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        Text(
+          item.title,
+          style: const TextStyle(fontWeight: FontWeight.bold, fontSize: 13),
+          maxLines: 1,
+          overflow: TextOverflow.ellipsis,
+        ),
+        if (item.description != null && item.description!.isNotEmpty) ...[
+          const SizedBox(height: 4),
+          Text(
+            item.description!,
+            style: const TextStyle(fontSize: 12),
+            maxLines: 2,
+            overflow: TextOverflow.ellipsis,
+          ),
+        ],
+        const SizedBox(height: 4),
+        Text(
+          _formatDateRange(start, end),
+          style: TextStyle(fontSize: 11, color: Colors.grey[400]),
+        ),
+      ],
+    );
+  }
+
+  Widget _buildCompactDate(DateTime start, DateTime end) {
+    return Text(
+      _formatDateRange(start, end),
+      style: const TextStyle(fontSize: 12, fontWeight: FontWeight.w500),
+    );
+  }
+
   @override
   Widget build(BuildContext context) {
     final viewport = _viewport;
@@ -269,25 +337,29 @@ class _MainAppState extends State<MainApp> {
             ? const Center(child: Text('Waiting for state...'))
             : ZTimelineScope(
                 viewport: viewport,
-                child: Column(
-                  children: [
-                    const ZTimelineBreadcrumb(),
-                    const ZTimelineTieredHeader(),
-                    Expanded(
-                      child: ZTimelineInteractor(
-                        child: ZTimelineView(
-                          groups: _groups,
-                          entries: _entries,
-                          viewport: viewport,
-                          labelBuilder: _labelForEntry,
-                          colorBuilder: _colorForEntry,
-                          enableDrag: true,
-                          onEntryMoved: _onEntryMoved,
-                          onEntryResized: _onEntryResized,
+                child: EntryPopoverOverlay(
+                  popoverContentBuilder: _buildPopoverContent,
+                  compactDateBuilder: _buildCompactDate,
+                  child: Column(
+                    children: [
+                      const ZTimelineBreadcrumb(),
+                      const ZTimelineTieredHeader(),
+                      Expanded(
+                        child: ZTimelineInteractor(
+                          child: ZTimelineView(
+                            groups: _groups,
+                            entries: _entries,
+                            viewport: viewport,
+                            labelBuilder: _labelForEntry,
+                            colorBuilder: _colorForEntry,
+                            enableDrag: true,
+                            onEntryMoved: _onEntryMoved,
+                            onEntryResized: _onEntryResized,
+                          ),
                         ),
                       ),
-                    ),
-                  ],
+                    ],
+                  ),
                 ),
               ),
       ),