gantterAi™ has three ways to group work under a parent: summary tasks in the Gantt view, rollups on boards, and summary tags while you're still planning. They look similar but calculate progress differently.
Create a summary (parent) task in the Gantt view
Select the task that should go under the parent. The parent is the task directly above it.
Click Indent tasks (the right arrow) in the toolbar, or press Ctrl+→. To move a task back out, use Unindent tasks (the left arrow) or Ctrl+←.
The task above turns bold. It's now a summary task.
On the Gantt chart, the summary task's bar is black. Hover over it to see that it's a summary task.
Create a rollup on a board
Click the tag you want to put under a rollup.
In the rollup dropdown, pick an existing rollup or add a new one.
Click Save Task. Open the tag again to see the rollup.
How progress is calculated
Summary task: dates and % complete come from its subtasks. When all subtasks are done, the summary is 100% complete, even if its end date hasn't arrived.
Rollup: you set its dates, and % complete is based on how much of its duration has passed as well as its subtasks. A two-month rollup with all its work finished in the first month still shows about 50% until the second month passes.
Once a rollup's end date is in the past, it and a summary task show the same result, because no more work can be added.
Save and commit vs. Add summary tag
Save and commit: the tag is confirmed work. It's locked in, and the people assigned get notifications and reminders.
Add summary tag: the tag is tentative. It goes to the area below the board marked In planning until you decide to commit it.