servePluginUi's Bun.serve leaves idleTimeout at Bun's 10s default, so the old
15s keepalive could never arrive — an idle status feed was closed before its
first ping, which is exactly what a live host showed. Default is now 5s.
Also adds the regression suite that should have caught it: the original test
only covered a finite, self-driving stream. The new one exercises the
production shape (PubSub-backed, published after the response opens) plus the
keepalive — with a reader that does not re-enter read(), which is what made the
first version of this test lie.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
