Use your Today's Plan account as a bridge to automatically sync your original Zwift indoor activities to Tredict.

With Tredict you have direct "Today's Plan" integration.
By connecting your Zwift account to Today's Plan, you can have your Zwift workouts automatically synced to Tredict.

This looks like this: Zwift -> Today's Plan -> Tredict

How do my Zwift activities get to Tredict?

1. If you don't have a Today's Plan account, create one first.
   Create Today's Plan account
2. Connect to Today's Plan from within Zwift.
   Connecting Zwift and other platforms
3. If you haven't already done so, connect to Today's Plan from within Tredict.
   Connect Tredict with Today's Plan

Tredict then looks every 5 minutes to see if there is a new Zwift file. The synchronisation is therefore minimally delayed. In the meantime, you can take a quick shower.

Pro-tip: Connect Dropbox as well

If you connect your Tredict account to Dropbox, you can automatically upload your original Zwift files to Dropbox.
So it is possible to sync your Zwift rides to Intervals.icu or to other platforms that support a Dropbox sync.

Direct Zwift support?

Of course, direct Zwift integration with Tredict would be ideal.
You can express your wish for a direct Tredict integration in the Zwift forum and vote for it!
Zwift Forum