Thanks for the PR @goatnath, it looks really cool! Good feedback, @hthienloc!

I'm glad khal support is optional, it's likely getting deprecated or changed in our upcoming dank calendar release.
Otherwise, there are a few issues to address here:

1. The PR currently prevents DMS from starting because CalendarOverviewCard.qml is missing a closing } near line 958.

2. When khal finishes loading, it replaces eventsByDate and can wipe out tasks loaded earlier. Keeping local tasks and khal events separately, then merging them, would avoid this race.

3. The separate Python CRUD processes can run concurrently and overwrite each other’s changes. A single in-memory model backed by an atomic FileView write would also remove the Python dependency.

4. Several delegate bindings access modelData without checking whether it is null, which can produce QML TypeError warnings during model updates.

5. Completion is already stored as a boolean, so task titles should remain clean. A completed property and DankIcon would avoid adding and later parsing Unicode checkbox characters.

6. During dragging, animation is disabled for every item. Disabling it only on the dragged item would let neighboring tasks move smoothly.

7. The reorder fallback checks IDs against id_to_item, which contains every task, so omitted tasks can be silently dropped. It should check against the submitted ordered IDs instead.

There is also trailing whitespace in both changed files, although make lint-qml otherwise passes. Once these issues and the syntax error are fixed, we’ll be glad to take another look.