The base issue #37892 is about moving the IDLE Shell prompt away from the first line of user code input, so that code starts at the margin where continuation lines start and we can use space indents.  I said the prompt could either go left, into a sidebar, or up, on a line by itself.

I opened this sub-isssue for the first option and Tal surprised me a few days later with a patch.  I expected a few months of development, but we were stuck last fall with mysterious Pipelines failures on Ubuntu and Windows.  I discoverer yesterday that the failures were due to Pipelines stealing sys.stdout output that was supposed to go to the Shell being tested.  The tests now pass and I believe PR 22682 is about ready for the beta next Monday.

Today I implemented the second option; it only took 3 simple changes on 3 lines.  PR 25678 for #37892.  I have tested with single and multiline statements, without and with debugger on, and all seems ok so far.  I am not surprised because indents now use the well-tested editor branch in the newline_and_indent_event method. So I think this is also ready for the beta.

For me, either fix is a pleasure to use and a relief, like having tiny thorn removed after 15 years. Anyone with a local repository can make a couple of branch to test now.  Or wait until next week.

My intention is to merge one or both options into 3.10.0b1 and allow user testing and feedback, further patching, and another beta release before backporting to 3.9 (perhaps late next June).  It is too late for 3.8.

Tal, I completely agree with not switching between straight margin and space indents versus the mis-design of an uneven margin and tab intents.  But I want the option of using either improved mode for myself as well as others.  I think Shell will have be cleared and restarted when switching.

Raymond, about interactive sessions for the docs: some have secondary prompts, some do not.  The sorting how-to uses the former.  (Would you like some .rst markup included?)  I don't know if the latter always have the same format.

I have long thought that there should be several output formats for a shell session, including one ready to run.  But no patches yet that I know of, or even any exactly specified requests.  Anyway, anything possible before should remain possible.  What is needed is a shell parser (for each mode) that would yield a sequence of code, traceback, and output objects.  Then various document builders could be written.