fix: Unread notificaitons on startup

toju-app/src/app/domains/notifications/README.md

@@ -143,6 +143,8 @@ Unread state is modeled as a combination of persisted read markers plus in-memor
 
 Important design constraint: unread counters are intentionally not persisted. The persisted state stores only the user-controlled settings and the read markers needed to derive unread counts again.
 
+Read markers are written with the same server-adjusted clock that chat messages use, so a visible channel does not become unread again after reload when the signaling server clock is ahead of the local desktop clock.
+
 ### Why baselines exist
 
 The domain must avoid marking an entire historical backlog as unread the first time a room appears.
@@ -176,6 +178,7 @@ Unread is cleared by channel, not globally.
 
 - `markCurrentChannelReadIfActive()` only runs when the window is focused and the document is visible.
 - If a live message arrives in the currently visible text channel, the domain immediately marks that channel read instead of incrementing unread.
+- When a startup message load or sync batch recomputes unread counts for the viewed server, the currently visible text channel is re-cleared and its read marker advances to the newest visible message in that batch.
 - Window focus and document visibility changes both clear taskbar attention and mark the active channel read.
 - `pruneUnreadState()` removes deleted or non-text channels from the unread maps and re-derives room totals from channel totals.