The add-on lives in Google's Script Editor but, in keeping with best practices, this repo is the source of truth, and the script editor will be overwritten with local changes.

This process needs to be performed once:

1. npm install to install all dependencies
2. Follow the first step here: Node Google Apps Quickstart - "Independent Developer Console Project" is recommended.
3. Download the JSON oAuth details
4. ./node_modules/bin/gapps auth <PATH-TO-JSON-OAUTH-FILE> and follow instructions
5. Edit the generated gapps.config.json file and change the value for path to be src
6. Create a new apps script here: https://script.google.com
7. Get the script ID from the URL (everything between the /d/ and /edit - script.google.com/a/google.com/d/SCRIPT_ID_HERE/edit)
8. ./node_modules/bin/gapps init <SCRIPT_ID>
9. Create a new WordPress.com App:
10. Set the redirect URL to be https://script.google.com/macros/d/SCRIPT_ID/usercallback
11. Make a note of the app client ID and client secret
12. In the app script, go to File and Project Properties
13. Select the Script properties tab
14. Add OauthClientId and set the value to your app
15. Add OauthClientSecret and set the value to your app

Everything is now setup.

npm run deploy

This will use node-google-apps-script to upload the src directory to the add-on's script editor.

In the script editor choose "Publish" → "Test as add-on…" and then select a document to test with.

That will open a new window with your document. You will then see your project in the Add-ons menu.