Check off task-list items

Short answer: In Read mode, click a task-list checkbox to tick or untick it. Unmarked writes the change straight to the file. In Write mode, put the cursor on the line and press ⌘L to flip the box.

A task list in Markdown is a list where each item starts with a checkbox. You write it with a dash, a space, and a bracket pair:

- [ ] Draft the intro
- [x] Outline the sections
- [ ] Send for review

- [ ] is unchecked. - [x] is checked. Unmarked reads these as GFM task lists, so a checklist you wrote on GitHub behaves the same here.

Tick a box in Read mode

Read mode shows the rendered document, and the checkboxes in it are live.

1. Open the file and switch to Read mode (⌘E toggles Read and Write).
2. Click a checkbox. An empty box ticks; a ticked box clears.

The click writes the [ ] to [x] edit back into the source and saves it in place, in your original file. No separate save step, no hidden copy. Reopen the file a week later and the boxes sit exactly where you left them.

Read mode is the one to use when you're running a list rather than editing prose. You tick items as you go and never touch the source.

Toggle a box in Write mode

Write mode shows the source, so you flip checkboxes from the keyboard.

1. Put the cursor anywhere on the task line.
2. Press ⌘L.

⌘L is the Toggle checkbox shortcut. It flips the box on the current line between checked and unchecked. It works on existing task lines only.

If you'd rather build the list from scratch, the "+ Insert" menu in Write mode has a Task option that drops in a fresh checkbox line.

Note: A checkbox only toggles when the line is an actual task-list item, written - [ ] or - [x]. A bare [ ] sitting in a paragraph is just text, and a list item without the brackets is a normal bullet. If a click or ⌘L does nothing, check that the line starts with the dash, a space, and the bracket pair.