I think you might be able to do that even today if your project structure is correct and if you would create issues for each task you need to do.

So if you have

main-project
|--- child-a
|--- child-b

you could create the main issue in main-project and sub tasks in child-a and child-b. Now these sub-tasks need to reference the main issue via issue links (e.g. the default parent/child issue link or you create your own "tasks" issue link).

Once you have connected your main issue with your sub tasks you can define a state transition that automatically does something once all sub tasks reach a state, e.g. change the main issue to closed if all sub tasks are closed.

Finally you can make pull requests for each sub task and once all are merged the main issue should be automatically closed.

Of course, I figured this out myself, but it creates unnecessary issues for every subproject, which is a clutter I would like to avoid.

Of course, I figured this out myself, but it creates unnecessary issues for every subproject, which is a clutter I would like to avoid.

Yeah it is personal preference. Some call it clutter, some like that they can track the progress that way and to make sure nothing has forgotten. I just wanted to make sure you know about this way.

Github mitigates the extra work a bit by allowing to write a todo list in the main issue and automatically create issues from each todo item. In OneDev you have to do it manually. Would be cool if OneDev would understand todo lists in issues and you could link a PR to a todo item of an issue. So you could do something like "Close this issue if all todos are done".

@robin May I ask why is this closed?

There is already workarounds and this will not likely to be implemented.