StartPageOptionsModal should not render if content was added to a page

[richtabor]

Currently the StartPageOptionsModal renders when you add a new post/page, but also when you remove all the content on a page. This makes for a disorienting experience, as a modal pops up out unexpectedly.

I think the modal should only render when creating a new page.

If any content has been added to the page, then removed, the StartPageOptionsModal should not render again.

If we want to still provide a mechanism for users to view the modal, we can add a snackbar notification "Choose a starter pattern." that renders in this scenario (after content has been added and the content is removed) which provides an action "View patterns" for viewing the starter patterns.

Current experience

I delete the last top-level block on my page and the modal pops up unexpectedly.

CleanShot.2023-09-06.at.14.01.26.mp4

[richtabor]

You can test the above using https://github.com/WordPress/twentytwentyfour. The theme will have a starter patterns added; so this will become more prevalent than it is today (where hardly any themes are leveraging this flow).

Related: WordPress/twentytwentyfour#209

[Mamaduka]

Can you reproduce the bug without the Gutenberg plugin?

This is probably a regression after #53673. The modal state is now local to a StartPageOptionsModal component. It's rendered based on the shouldEnableModal condition; mounting/unmounting resets the local state.

I can also see a modal flash when updating an existing page without the content. Here's the Replay link: https://app.replay.io/recording/the-start-page-options-modal-flashes-when-updating-page--c1d0ebdb-4d57-41ef-8a88-41e433e9b52f

cc @jsnajdr

[jsnajdr]

I can reproduce this even with #53673 reverted, the bug must have been there for a very long time.

The bug manifests in two ways:

1. What @richtabor reports: if you have an existing saved page, and remove all blocks and also the title, the page becomes "unsaveable and with no content" -- a condition that triggers displaying the modal.
2. What @Mamaduka found: if you have a page that has a title but no content, it's "saveable" -- this is a condition different from the first case. But when it's being saved, it becomes "unsaveable" (per the isEditedPostSaveable selector) while the save is in progress. Condition for the modal is satisfied -- flash!

We'll need to improve the condition to really match only pages that are brand new and empty.

[jsnajdr]

Fixing in #54227 🙂 I'm looking forward to trying out the starter patterns in Twenty Twenty-Four 👍