Clicking "Message" added the user to the sidebar list but the right-hand
message pane stayed on the previously-active conversation. setDirectMessageRecipient
called setFocusedDmConversation (which only tracks read-state) and never set
activeDmConversationId — the value buildDmConversationData reads to choose which
thread the right pane renders — so it kept resolving the stale id.
Set activeDmConversationId directly (mirroring handleDmConversationSelect), and
switch the mobile pane to the thread for explicit selections (not the auto
thread-default).
Regression: tests/ui/dm-set-recipient-active.test.mjs.
Co-Authored-By: Claude Opus 4.8 <[email protected]>