Unclutter CALL STACK view by eliminating parent debug session

[weinand]

When debugging simple "one process" JS programs, there is always a top level debug session that clutters the CALL STACK view:

We should try to get rid of this either:

• by hiding it in the call stack view (e.g. by using tree's compressed feature), or
• introducing some new abstraction in the debug architecture (e.g. "debug context"), that a debug extension can use, but is not necessarily visible in the call stack view.

In the general case (with multiple debug sessions) it is still needed to have a parent, but we should better indicate the purpose of the parent. Today (as seen in the screenshot) we show the parent as a regular debug session and duplicate the stopped reason ("Paused on Breakpoint"). This is really confusing. As a first step we should remove the reason and show a different icon or no better no icon (and probably offer different context menu actions).

@connor4312 @isidorn what's your opinion?

[isidorn]

Love this suggestion, and I think we should really look into this to reduce the clutter and thus make debugging seem less complex.

Using the tree compressed feature might just work, however what would be the title in the example above. I think it should just be Launch Program?
Maybe I can try with the compressed tree approach and we will see what limitation we hit.

What do you think?

[connor4312]

Using the debug context is more work, but I think it's also the best way to solve this. For js-debug, we don't really care about the top level container being a "session", we just need 'something' to put our sessions in. If there was the concept of contexts, that would also be a more generalized solution to the stopAll in compound launch configs (#95964).

However a compressed tree would be much less complex on the vscode and api side. 👍 on trying that first and seeing where that gets us.

[isidorn]

Ok, so let's start with compact tree. Thus assigning to me, and once we have that we can figure out what to do next.

[isidorn]

I have pushed a first iteration of this, now we use a compressed tree in the call stack view. Please note the following:

• We only compress sessions like this (not other call stack elements)
• The label which we show is simply labels of compressed session conacateneted
• In the worst case this can be unexpected to some debuggers that use the .parentSession feature so we should double check with the python team since I think they use this feature
• When user right clicks, or does any action on this compressed element the action is executed on the last session

Potential follow up work:

• Fine tune the label, either by only using the parent label, or @connor4312 could make the child label more concise
• Contact other extension authors, for example python
• When there is only one compressed session maybe we should hide it as well?

Here's the current state of thigns. Try it out and let me know what you think