macOS: revisit usage of -n for open from CLI

[bpasero]

This is a follow up to #102975. Wondering whether we could drop our usage of -n when running with open command and rather rely on the open-file event in Electron to get the data passed in:

https://github.com/electron/electron/blob/13-x-y/docs/api/app.md#event-open-file-macos

My understanding is that this event would fire when a second instance is launched via open and without -n.

It probably needs an upstream fix to get access to more data. Similar to the work we are doing for request single instance lock.

[bpasero]

I ran a quick test by removing the -n from cli.ts and printing the events from open-file here:

vscode/src/vs/code/electron-main/app.ts

Line 226 in 9525d0e

app.on('open-file', (event, path) => {

And did not get any call, so maybe this is not working as I had thought.

[deepak1556]

@bpasero why cannot we handle this case via the singleinstance api ?

app.on('second-instance', (event, commandLine, workingDirectory) => {
    // Someone tried to run a second instance, parse commandline for `-n`
   // and force new window if needed
})

If possible I would like to not rely on platform specific event and keep it consistent for all platform via a single entry point, thoughts ?

[bpasero]

@deepak1556 yes sounds good, I wasn't sure whether when you use open with an existing app identifier that is running triggers the single instance flow too.

[deepak1556]

Yup it will, as open just ends up launching the app process, and there are certain files that are setup in the user data directory to identify an active instance associated with it https://github.com/electron/electron/blob/3b1c9dfc5400ceffb75a934cb6b8686fc5ba3fcd/chromium_src/chrome/browser/process_singleton_posix.cc#L5-L38 should clarify things :)

[deepak1556]

Merging to #97626, since we want to eventually end up with it.