Executing fresh inside fresh

[KSXGitHub]

My use case with VS Code

When I use VS Code as my editor, I often use its Integrated Terminal to interact with git. And VS Code itself (code --wait) is my git commit editor.

Whenever I run git commit -v (without message) in my Integrated Terminal, a new VS Code tab would open for me to edit my message. I finish my commit message by Ctrl + SCtrl + W and git would register that message.

VS Code has few properties that make this works well:

1. VS Code enforce single instance. So a code --wait <filename> would open a new tab inside an existing VS Code window. VS Code only create a new window if the path is a directory instead of a file.
2. The --wait flag tells the code process to wait for the open tab from another code instance to close before closing.
3. An editor tab opened by code --wait would immediately grab focus from the Integrated Terminal.
4. Closing the editor tab opened by code --wait would immediately return the user focus to the Integrated Terminal, enabling the user to continue with other commands (git push for example).

Fresh doesn't support such use case

1. Opening fresh inside an Integrated Terminal of fresh would create a nested fresh instance.
2. The nested fresh instance shall not receive the usual keyboard shortcuts nor mouse signals because the parent fresh has intercepted all of them.
3. Closing the nested fresh is impossible. Ctrl + Q would close the parent fresh itself. Attempting the menu bar doesn't work either.

Suggestions

1. Add a mechanism for the fresh command to create new tab inside existing fresh instance instead of a new one. The fresh command should wait for the tab.
2. Add a mechanism to detect prevent nested fresh. Perhaps via an environment variable? When there is a parent fresh, running the fresh command should create a new editor tab.
3. Regarding single instance detection. It's not necessary. We only concern with preventing fresh inside fresh. A terminal application is expected to always create a new instance, so even when one fresh instance already exist in one terminal emulator session, another fresh instance should still be created in another unrelated terminal emulator session.
4. Grabbing focus: I'm not sure if VS Code commit message tab only grabs focus when it was spawned by a command or it grabs focus regardless.
5. Closing a tab should return the user to the previously viewed tab. I think this mechanism should be implemented by fresh already. (This seems obvious, but the browser tabs don't work this way, closing a browser tab would switch the user to the tab stand next to it instead)

[KSXGitHub]

@sinelaw I opened a discussion instead of an issue because I thought maybe you have better ideas.

[sinelaw]

It's implemented since a few versions ago - there's session mode and you can spawn a child to cause the session to open a new file.

fresh -a . # start a new session with cur dir as name

fresh --cmd session open-file SESSION_NAME path/to/file

[sinelaw]

Makes sense, it's a bit like emacsclient too.
Probably by creating a named pipe or lockfile (need to see what will work cross-platform, probably no named pipe :)