simple-notes-sync

inventory69 da371436cd fix(editor): IMPL_15 - Add Item respects separator position in checklist

Changes:
- NoteEditorViewModel.kt: Add calculateInsertIndexForNewItem() helper method
- NoteEditorViewModel.kt: Rewrite addChecklistItemAtEnd() to insert before
  first checked item (MANUAL/UNCHECKED_FIRST) instead of appending at list end
- NoteEditorViewModel.kt: Add cross-boundary guard to addChecklistItemAfter()
  preventing new unchecked items from being inserted inside checked section
- ChecklistSortingTest.kt: Add ChecklistSortOption import
- ChecklistSortingTest.kt: Add 10 IMPL_15 unit tests covering all sort modes,
  edge cases (empty list, all checked, no checked), and position stability

Root cause: addChecklistItemAtEnd() appended new unchecked items at the end
of the flat list, after checked items. The UI splits items by count
(subList(0, uncheckedCount)), not by isChecked state — causing checked items
to appear above the separator and new items below it.

Fix: Insert new items at the semantically correct position per sort mode.
MANUAL/UNCHECKED_FIRST: before first checked item (above separator).
All other modes: at list end (no separator visible, no visual issue).

All 19 unit tests pass (9 existing + 10 new). No UI changes required.

2026-02-11 21:34:18 +01:00