Merge local channel data and remote to maintain state

When we hit the boot endpoint, we get the server's view of things. If we
just setChannels with that, we overwrite all our locally-stored info in
on things like lastReadAt. So we need to merge data.

Eventually, this might militate for a `meta` key containing an object of
locally stored data, rather than having to handle each key specially.

1 files changed, 3 insertions, 9 deletions

diff --git a/ui/routes/(app)/ch/[channel]/+page.svelte b/ui/routes/(app)/ch/[channel]/+page.svelte
index dbdb507..d64a8c9 100644
--- a/ui/routes/(app)/ch/[channel]/+page.svelte
+++ b/ui/routes/(app)/ch/[channel]/+page.svelte
@@ -33,16 +33,10 @@
   }
 
   function setLastRead() {
-    const channelObject = $channelsList.getChannel(channel);
     const lastInView = getLastVisibleMessage();
-    if (!channelObject || !lastInView) {
-      return;
-    }
-    const at = DateTime.fromISO(lastInView.dataset.at);
-    // Do it this way, rather than with Math.max tricks, to avoid assignment
-    // when we don't need it, to minimize reactive changes:
-    if (at > channelObject.lastReadAt) {
-      channelObject.lastReadAt = at;
+    if (lastInView) {
+      const at = DateTime.fromISO(lastInView.dataset.at);
+      $channelsList.updateLastReadAt(channel, at);
     }
   }