Show legacy Jupyter execute_reply data in Console

[petetronic]

While the Jupyter specification mentions that the use of payloads is deprecated, a replacement has not been finalized. Some ipython output still makes use of the execute_reply message with a payload defined.

If the data in the payload is text/plain, we should at least consider showing this in the Positron Console REPL, even if it is not intended for Jupyter notebook cell output.

We may need a bit of plumbing in our runtime middleware to get these messages to the Console.

[petetronic]

One example that generates this type of output is the iPython %less magic. If you try to print the contents of a text file in your working directory, the content is returned on the shell channel in an execute_reply message, however we do not show this in the Console.

[petetronic]

Truncated example of a reply to %less yourfile.txt:

[Positron] RECV execute_reply from shell: 

{
    "header":
    {
        "msg_type": "execute_reply",
        ...
    },
    "parent_header":
    {
        "msg_type": "execute_request",
        ...
    },
    ...
    "content":
    {
        "status": "ok",
        ...
        "payload":
        [
            {
                "source": "page",
                "data":
                {
                    "text/plain": "Your text file content is returned here..."
                }
            }
        ]
    }
}

[petetronic]

We can discuss with the team if these output types are marked in some way different from those from execute_result.

[jmcphers]

Because this is file content, I've half a mind to have it hosted in an editor buffer instead of dumped into the Console. You said that some of these are decorated with ANSI escape sequences, though, right?

[petetronic]

Right, so another example I've seen is "help" like information about a magic. For example, %colors? tells you how to use the %colors magic. Its content describing the colors magic's options is sent in an execute_reply payload but it has ANSI control sequences to color items.

[petetronic]

(As an aside, some other magics, like the %ls alias, sends its output through the normal iopub execute_result, and that does show up in our Console today).

[seeM]

For reference, here are the magic commands I've found that use the page payload type:

• ? – entering a single question mark into the prompt is an alias for %pinfo
• ?? – alias for %pinfo2
• %magic
• %page
• %quickref
• %pycat
• %pdoc
• %psource
• %pfile
• %pinfo
• %psearch

I agree that we could probably intercept these and either display the result in a new buffer, or in the help pane.