Capture deeplink arguments after launch?

While the app is currently running, is it possible to capture deeplink arguments?

Here's a minimal app with deeplink support to reproduce what I mean.

app.py

# write captured arguments to a file
import sys
with open('/Users/test.txt', 'w') as f:
    f.write(sys.argv)
while True:  # run forever to simulate a GUI of some kind
    pass

setup.py

# regular setup for a deeplink + passing args at launch
from setuptools import setup

OPTIONS = {
    'argv_emulation': True,
    'plist': {
        'CFBundleURLTypes': [
            {
                'CFBundleURLName': 'MyApplication',
                'CFBundleURLSchemes': ['myapp'],
            },
        ],
    },
    'strip': True,
}

setup(
    app=['app.py'],
    options={'py2app': OPTIONS},
    setup_requires=['py2app']
)

With this setup, I run the usual packaging.

python setup.py py2app -A
mv dist/app.app /Applications
open dist/app.app
# then close the app

Now I can try the deeplink for "page1".

open myapp://page1

The app opens, and it remains open. At this point, /Users/test.txt contains the deeplink "page1".

['app.py', 'myapp://page1']

Still with the application open, I try a new deeplink for "page2". This focuses the existing application.

open myapp://page2

However, this time, the script isn't rerun as it's already running. If I check /Users/test.txt, it will still be "page1":

['app.py', 'myapp://page1']

Is there a way to setup the deeplink so that the script is rerun (even if the app is already open), making the file above say "page2"?

For what it's worth, this works perfectly fine if you directly run the app, using dist/app.app/Contents/MacOS/app page1 and dist/app.app/Contents/MacOS/app page2, so it must be a deeplink-specific issue.
My hacky idea is to have a run-only app accept the deeplinks, open, communicate the deeplink to another process/app, then immediately exit. Seems like overkill (maybe?)

ronaldoussoren / py2app

Capture deeplink arguments after launch? #499