It just got stranger.
Same project. I've been tinkering with it for about an hour a night.
I don't think I've changed anything significant structurally, although
I have restarted the JVM.
I created a new file, world_test.cljc, in the same shared/ folder as
connection_test.cljc.
cider set up the ns directive the same way, so it's
(ns .shared.world-test ...)
This time, trying to compile it failed with the error "Namespace
.shared.world-test has a segment starting with an invaild JavaScript
identifier"
Aside from misspelling "invalid", that's about what I expect.
And now the original '.shared.connection-test ns fails with the same error.