nice overview working

lib/models/transaction_meta.dart

@@ -11,6 +11,7 @@ class TxLabel {
     required this.color,
     this.icon = Icons.label_outline,
     this.custom = false,
+    this.parentId,
   });
 
   final String id;
@@ -19,25 +20,127 @@ class TxLabel {
   final IconData icon;
   final bool custom;
 
+  /// Optional parent label id for nesting (sub-labels).
+  final String? parentId;
+
+  bool get isRoot => parentId == null || parentId!.isEmpty;
+
+  TxLabel copyWith({
+    String? name,
+    Color? color,
+    IconData? icon,
+    String? parentId,
+    bool clearParent = false,
+  }) {
+    return TxLabel(
+      id: id,
+      name: name ?? this.name,
+      color: color ?? this.color,
+      icon: icon ?? this.icon,
+      custom: custom,
+      parentId: clearParent ? null : (parentId ?? this.parentId),
+    );
+  }
+
   Map<String, dynamic> toJson() => {
         'id': id,
         'name': name,
         // ignore: deprecated_member_use — wide compatibility across Flutter versions
         'color': color.value,
         'custom': custom,
+        if (parentId != null && parentId!.isNotEmpty) 'parentId': parentId,
       };
 
   factory TxLabel.fromJson(Map<String, dynamic> json) {
+    final parent = json['parentId'] as String?;
     return TxLabel(
       id: json['id'] as String? ?? 'custom',
       name: json['name'] as String? ?? 'Label',
       color: Color(json['color'] as int? ?? 0xFF64748B),
       custom: json['custom'] as bool? ?? true,
+      parentId: (parent != null && parent.isNotEmpty) ? parent : null,
     );
   }
 }
 
-/// Built-in presets (no "uncategorized" / "other").
+/// One row in a depth-first label tree walk.
+class LabelTreeEntry {
+  const LabelTreeEntry({required this.label, required this.depth});
+
+  final TxLabel label;
+  final int depth;
+}
+
+/// Max nesting depth (root = 0).
+const int kMaxLabelDepth = 3;
+
+/// Depth-first tree order using each label's [TxLabel.parentId].
+List<LabelTreeEntry> flattenLabelTree(
+  Iterable<TxLabel> labels, {
+  String? Function(String id)? parentOf,
+}) {
+  final byId = <String, TxLabel>{
+    for (final label in labels) label.id: label,
+  };
+  String? resolveParent(String id) {
+    if (parentOf != null) return parentOf(id);
+    return byId[id]?.parentId;
+  }
+
+  final children = <String?, List<TxLabel>>{};
+  for (final label in byId.values) {
+    final parent = resolveParent(label.id);
+    final key = (parent != null && byId.containsKey(parent)) ? parent : null;
+    (children[key] ??= []).add(label);
+  }
+  for (final list in children.values) {
+    list.sort((a, b) => a.name.toLowerCase().compareTo(b.name.toLowerCase()));
+  }
+
+  final out = <LabelTreeEntry>[];
+  void walk(String? parentId, int depth) {
+    final kids = children[parentId];
+    if (kids == null) return;
+    for (final label in kids) {
+      out.add(LabelTreeEntry(label: label, depth: depth));
+      if (depth < kMaxLabelDepth) {
+        walk(label.id, depth + 1);
+      }
+    }
+  }
+
+  walk(null, 0);
+  return out;
+}
+
+/// Visible indent depth among [visibleIds] only (skip missing ancestors).
+int labelVisibleDepth(
+  String labelId,
+  Set<String> visibleIds,
+  String? Function(String id) parentOf,
+) {
+  var depth = 0;
+  var parent = parentOf(labelId);
+  final seen = <String>{labelId};
+  while (parent != null && parent.isNotEmpty && seen.add(parent)) {
+    if (visibleIds.contains(parent)) depth++;
+    parent = parentOf(parent);
+  }
+  return depth;
+}
+
+/// Filter-only id for txs with no labels (not an assignable category).
+const String kUncategorizedFilterId = '__uncategorized__';
+
+/// Chip presentation for [kUncategorizedFilterId] refine filters.
+const TxLabel kUncategorizedFilterLabel = TxLabel(
+  id: kUncategorizedFilterId,
+  name: 'Uncategorized',
+  color: Color(0xFF64748B),
+  icon: Icons.label_off_outlined,
+);
+
+/// Built-in presets (no "uncategorized" / "other" as assignable labels).
 const List<TxLabel> kBuiltinLabels = [
   TxLabel(
     id: 'groceries',
@@ -205,7 +308,10 @@ class TxExactTemplate {
   }
 }
 
-/// Strip bank noise so "AH Campus … Transactie:123" matches other AH Campus txs.
+/// Strip bank noise so supermarket / POS lines group by merchant stem.
+///
+/// Example: `BCK*AH CAMPUS DIEMEN ZUID NLD Pasvolgnr:…` → `ah campus`
+/// Example: `Albert Heijn 1562 Utrecht` → `albert heijn`
 String merchantKeyFromDescription(String description) {
   var s = description
       .trim()
@@ -240,8 +346,58 @@ String merchantKeyFromDescription(String description) {
   }
 
   s = s
-      .replaceAll(RegExp(r'\s+nld\s*$'), '')
       .replaceAll(RegExp(r'^bck\*'), '')
+      .replaceAll(RegExp(r'\s+'), ' ')
       .trim();
-  return s;
+
+  // Drop trailing country / city noise and store / terminal numbers.
+  s = s.replaceAll(
+    RegExp(
+      r'\s+(nld|nl|nederland|netherlands|bel|belgium|deu|germany|de)\s*$',
+    ),
+    '',
+  );
+  // Remove digit runs (store ids, amounts embedded in text, etc.).
+  s = s.replaceAll(RegExp(r'\b\d+\b'), ' ');
+  s = s.replaceAll(RegExp(r'\s+'), ' ').trim();
+
+  // Keep a short stem so "ah campus diemen zuid" ≈ "ah campus".
+  final words = [
+    for (final w in s.split(' '))
+      if (w.length > 1) w,
+  ];
+  if (words.isEmpty) return s;
+  if (words.length <= 2) return words.join(' ');
+  // Prefer first two tokens for long POS strings; three when the 2nd is tiny
+  // ("de", "van") so "albert heijn" / "jumbo city" stay intact.
+  if (words[1].length <= 2 && words.length >= 3) {
+    return words.take(3).join(' ');
+  }
+  return words.take(2).join(' ');
 }
+
+/// Default “apply to similar” pattern — usually the merchant stem.
+String defaultSimilarPattern(String description) =>
+    merchantKeyFromDescription(description);
+
+/// Match [description] against a simple contains needle or `/regex/`.
+bool descriptionMatchesPattern(String description, String pattern) {
+  final raw = pattern.trim();
+  if (raw.isEmpty) return false;
+  final hay = description.toLowerCase();
+
+  if (raw.length >= 3 && raw.startsWith('/') && raw.endsWith('/')) {
+    final body = raw.substring(1, raw.length - 1);
+    if (body.isEmpty) return false;
+    try {
+      return RegExp(body, caseSensitive: false).hasMatch(description);
+    } catch (_) {
+      return hay.contains(raw.toLowerCase());
+    }
+  }
+
+  final needle = raw.toLowerCase();
+  if (needle.length < 2) return false;
+  return hay.contains(needle);
+}
+