states

The happy path is one state out of six. Interfaces are judged on the other five, because that is where people are stuck, waiting or worried.

Enumerate before building

For every region that depends on data, write the list:

State	When	What is shown
Loading, first time	no data yet	skeleton in the final layout
Loading, again	data exists, refreshing	keep the data, subtle indicator
Empty	request succeeded, nothing to show	one line, one action
Partial	some of the data, or a page of it	what we have, plus a clear edge
Error	request failed	what happened, what to do, retry
Stale / offline	data may be old	the data, marked
Success	an action completed	in place, quietly

If a region only handles two of these, it is not finished.