You need to keep the legacy registerStore here. Otherwise the persist plugin won't be active. It works by overriding the registerStore method of the registry and reading the persist option. If you call register, the plugin won't catch it.

This will be solved once we finish migration of the block-editor store to the preferences package. It's being worked on in #39632.

Ah, bummer, I see.

I don't think we can remove this workaround yet then because if we do this:

export const store = createReduxStore( STORE_NAME, {
	...storeConfig,
	persist: [ 'preferences' ],
} );

unlock( store ).registerPrivateActions( privateActions );
unlock( store ).registerPrivateSelectors( privateSelectors );

registerStore( STORE_NAME, {
	...storeConfig,
	persist: [ 'preferences' ],
} );

Then the private selectors are not callable from public selectors as they are not bound to the store that's created by registerStore.

(When I try it I get a Uncaught TypeError: selector.registry is undefined error on load.)

I suppose we will wait until #39632 is merged!

I did start looking at #39632 one again. I've rebased it and hope to push some further options this week.

Then the private selectors are not callable from public selectors as they are not bound to the store that's created by registerStore.

Oh, there are two gotchas at work here:

1. Registering private selectors on the store object is a noop, because the store is not instantiated from that object! It's just a store descriptor object that's exported so that users can pass it to functions like select( store ) or dispatch( store ). The descriptor has an .instantiate method, but it's never called. The registerStore function creates a second store descriptor from STORE_NAME and storeConfig, and uses that internal one to actually instantiate the store. But that descriptor doesn't have any private selectors registered.
2. To get the private selectors pre-bound to the registry, they need to be registered after createReduxStore and before the .instantiate function is called, but registerStore calls them both within one statement:

   gutenberg/packages/data/src/registry.js

   Line 310 in 4d0f303

   createReduxStore( storeName, options ).instantiate( registry )

This memoization won't work because createSelector is called again and again on each call of getBlockEditingMode, creating a new instance with its own memoization cache each time.

createRegistrySelector is like:

createRegistrySelector = ( selectorFactory ) => ( ...args ) => selectorFactory( registry.select )( ...args );

I don't know how to solve this, maybe we'll need to patch createRegistrySelector to call the "factory" function only once.

I'm not sure if memoizing this selector is even a good idea. This particular implementation won't catch changes in select( blockStore ).hasContentRoleAttribute( name ). It's very unlikely that a block's registration properties would change, but still.

The selector doesn't do any very complex calculation, and the return value is a string, which doesn't need an unique identity. Let's just remove the createSelector memoization.