The upgrade to 11D5145e exposed lapses in my Storyboard:
	“'invalid nib registered for identifier (Document Cell) - nib must contain exactly one top level object which must be a UITableViewCell instance’.
It seems every upgrade eliminates more cruft.
I deleted the custom class DocumentCell in favor of good old UITableViewCell, and fixed that snafu.
But, somehow in the master view, the cells of discovered documents never set userInteractionEnabled = YES.
We’re not getting NSPersistentStoreDidImportUbiquitousContentChangesNotification.
But that’s a separate issue. I’ll commit the UI changes now.
Trouble with two things:
[1] I no longer know when to update a discovered document’s cell (PSCDidImport, PSCStoresDidChange…).
[2] I did something nasty to the table view’s cells; their colors go stale.
A few days ago, I upgraded my devices to iOS 7.1 (11D5145e), and to Xcode Version 5.1 (5B103i) aka Xcode51-Beta5.
Two things broke:
[1] the “Storyboard/UITableView/UITableViewCell” connection; and
[2] how to determine when a discovered document’s object graph becomes available.

[1] Xcode51-Beta5 discovered the Storyboard snafu; it’s just pickier.
I just ditched the DocumentCell class and reverted to plain UITableViewCell.

[2] Suddenly, the previous version posted to GitHub just wouldn’t permit the user to inspect a discovered document; its row/cell remained grey (userInteractionEnabled=NO).
I had relied on NSPersistentStoreDidImportUbiquitousContentChangesNotification to signal when a document’s object graph became available.
After several hours of peeking and poking, I discovered a useful signal is now:

	NSConcreteNotification 0x165ea720 {name =
	com.apple.coredata.ubiquity.importer.didfinishimport;
	object = <NSPersistentStoreCoordinator: 0x16695b40>;
	userInfo = {
             deleted = "{(\n)}";
             inserted = "{(\n    0x16586180 <x-coredata://E24729CE-4C32-4961-A228-005264DCA31B/ModelVersion/p2>,\n    0x165de350 <x-coredata://E24729CE-4C32-4961-A228-005264DCA31B/TextEntry/p2>\n)}";
             updated = "{(\n)}";
             }}

I’ve adopted a work-around.
See:
	-[DocumentsListController+Making receivedNotification:document:]
and
	-[NSDictionary+NPAssisting isDocumentViewable].
Mostly, I just updated, added and renamed some documentation files. In the code, I deleted some blocks of code that had been commented out or fell into disuse.
Adding, renaming documentation files

Adding, renaming documentation files