improve pending visibility, allow multiple users to have pending changes against locos.

lib/components/pages/loco_timeline/timeline_grid.dart

@@ -716,9 +716,14 @@ bool _isOverlappingStart(LocoAttrVersion entry, Set<int> approvedStartKeys) {
 
 List<_ValueSegment> _segmentsForEntries(
   List<LocoAttrVersion> items,
-  DateTime now,
-) {
+  DateTime now, {
+  bool? clampToNextStart,
+}) {
   if (items.isEmpty) return const [];
+  final hasPending = items.any((e) => e.isPending);
+  final hasApproved = items.any((e) => !e.isPending);
+  final shouldClamp =
+      clampToNextStart ?? (hasPending && hasApproved);
   final sorted = [...items];
   sorted.sort(
     (a, b) => (_effectiveStart(a) ?? now)
@@ -731,7 +736,13 @@ List<_ValueSegment> _segmentsForEntries(
     final nextStart = i < sorted.length - 1
         ? _effectiveStart(sorted[i + 1])
         : null;
-    final rawEnd = entry.validTo ?? nextStart ?? now;
+    DateTime? rawEnd = entry.validTo;
+    if (nextStart != null) {
+      if (rawEnd == null || (shouldClamp && nextStart.isBefore(rawEnd))) {
+        rawEnd = nextStart;
+      }
+    }
+    rawEnd ??= now;
     final end = _safeEnd(start, rawEnd);
     segments.add(
       _ValueSegment(
@@ -745,6 +756,53 @@ List<_ValueSegment> _segmentsForEntries(
   return segments;
 }
 
+List<LocoAttrVersion> _applyPendingOverrides(
+  List<LocoAttrVersion> approved,
+  List<LocoAttrVersion> pending,
+) {
+  if (pending.isEmpty) return approved;
+  final pendingByStart = <int, LocoAttrVersion>{};
+  final extraPending = <LocoAttrVersion>[];
+  for (final entry in pending) {
+    final start = _effectiveStart(entry);
+    if (start == null) continue;
+    final key = _startKey(start);
+    pendingByStart[key] = entry;
+  }
+
+  final applied = <LocoAttrVersion>[];
+  final seenKeys = <int>{};
+  for (final entry in approved) {
+    final start = _effectiveStart(entry);
+    if (start == null) continue;
+    final key = _startKey(start);
+    if (pendingByStart.containsKey(key)) {
+      if (!seenKeys.contains(key)) {
+        applied.add(pendingByStart[key]!);
+        seenKeys.add(key);
+      }
+    } else {
+      applied.add(entry);
+      seenKeys.add(key);
+    }
+  }
+
+  for (final entry in pendingByStart.values) {
+    final start = _effectiveStart(entry);
+    if (start == null) continue;
+    final key = _startKey(start);
+    if (!seenKeys.contains(key)) {
+      extraPending.add(entry);
+      seenKeys.add(key);
+    }
+  }
+
+  if (extraPending.isNotEmpty) {
+    applied.addAll(extraPending);
+  }
+  return applied;
+}
+
 List<DateTime> _buildBoundaries(
   List<_ValueSegment> segments,
   DateTime now,
@@ -904,14 +962,17 @@ class _TimelineModel {
       }
 
       final hasOverlap = overlapByUser.isNotEmpty;
-      final canToggle = pending.length > 1 && !hasOverlap;
+      final canToggle = pending.isNotEmpty && !hasOverlap;
       final isExpanded = expandedAttrCodes.contains(attr);
+      final shouldShowPendingRows = isExpanded || hasOverlap;
 
       final nonOverlapPending =
           pending.where((e) => !_isOverlappingStart(e, approvedStartKeys)).toList();
-      final baseEntries = isExpanded ? approved : [...approved, ...nonOverlapPending];
-      final baseSegments =
-          isExpanded ? approvedSegments : _segmentsForEntries(baseEntries, now);
+      final baseEntries =
+          shouldShowPendingRows ? approved : [...approved, ...nonOverlapPending];
+      final baseSegments = shouldShowPendingRows
+          ? approvedSegments
+          : _segmentsForEntries(baseEntries, now);
 
       rowSpecs.add(
         _TimelineRowSpec.primary(
@@ -923,7 +984,6 @@ class _TimelineModel {
       );
       allSegments.addAll(baseSegments);
 
-      final shouldShowPendingRows = isExpanded || hasOverlap;
       if (shouldShowPendingRows) {
         final users = isExpanded
             ? pendingByUser.keys.toList()
@@ -934,11 +994,9 @@ class _TimelineModel {
               ? (pendingByUser[user] ?? const [])
               : (overlapByUser[user] ?? const []);
           if (pendingEntries.isEmpty) continue;
-          final userPendingSegments = _segmentsForEntries(pendingEntries, now);
-          final combinedSegments = [
-            ...approvedSegments,
-            ...userPendingSegments,
-          ];
+          final appliedEntries =
+              _applyPendingOverrides(approved, pendingEntries);
+          final combinedSegments = _segmentsForEntries(appliedEntries, now);
           rowSpecs.add(
             _TimelineRowSpec.pending(
               attrCode: attr,