Bulk update: diff generated fields only

planBulkUpdate compared fresh field values with the stored text, so a
peer's "...00Z" created_at (or a web build's millisecond date) read as a
change and got a fresh clock, erasing the created_by node signal; a
record without a priority field got one written. Compare the note's own
generated fields before and after instead.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WzxdWXdsB7CQPNXVN829G1

lib/data/note_bulk.dart

@@ -31,6 +31,10 @@ Log planBulkUpdate(
     final note = noteFromRecord(current);
     final next = note.copyWith(priority: priority, status: status);
     if (next.priority == note.priority && next.status == note.status) continue;
+    // Generated against generated, never against the stored text: a peer's
+    // `...00Z` (or a web build's millisecond date) would otherwise read as
+    // a change and get a fresh clock, erasing the `created_at` node signal.
+    final before = noteFields(note, hlc);
     plan[id] = Record(
       id: id,
       fields: {
@@ -38,7 +42,7 @@ Log planBulkUpdate(
           next.copyWith(updatedAt: now),
           hlc,
         ).entries)
-          if (current.fields[key]?.$1 != value.$1) key: value,
+          if (before[key]?.$1 != value.$1) key: value,
       },
     );
   }

pubspec.yaml

@@ -16,7 +16,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 # In Windows, build-name is used as the major, minor, and patch parts
 # of the product and file versions while build-number is used as the build suffix.
-version: 1.0.68+1
+version: 1.0.69+1
 
 environment:
   sdk: ^3.12.2

test/note_repository_bulk_test.dart

@@ -75,6 +75,33 @@ void main() {
     expect((await repo.listNotes()).single.status, Status.done);
   });
 
+  test(
+    'a stored value Dart would format differently keeps its clock',
+    () async {
+      final (repo, _) = await _open();
+      final peer = Hlc(wallTimeMs: 1000, counter: 0, nodeId: 'mcp');
+      // A peer's (or a web build's) timestamp text, and no priority field.
+      await repo.importLog({
+        'a': Record(
+          id: 'a',
+          fields: {
+            'text': ('A', peer),
+            'status': (0, peer),
+            'created_at': ('2026-01-01T00:00:00Z', peer),
+            'updated_at': ('2026-01-01T00:00:00Z', peer),
+          },
+        ),
+      });
+
+      await repo.bulkUpdate({'a'}, status: Status.done);
+
+      final fields = repo.exportLog()['a']!.fields;
+      expect(fields['created_at'], ('2026-01-01T00:00:00Z', peer));
+      expect(fields.containsKey('priority'), isFalse);
+      expect(fields['status']!.$2.nodeId, 'dev');
+    },
+  );
+
   test('no write when nothing changes or ids are unknown/deleted', () async {
     final (repo, p) = await _open();
     await repo.upsert(noteFixture('a', 'A'));