Fix up spots where we still tried to treat `remote.channels.all` as a map.

In ae93188f0f4f36086622636ba9ae4810cbd1f8c9, `remote.channels.all` became a flat array of channels, instead of a map, in order to simplify some of the reasoning around how state changes propagate. However, I neglected to remove all Map-shaped calls referring to it.

This lead to some pretty interesting behaviour:

* The client could not track unread state, because reconciling local state against the remote state would find no remote state, then throw away local state entirely as a result.
* The client would not actually update when a new channel appeared.
* The client would not actually update when a channel disappeared.

3 files changed, 5 insertions, 4 deletions

diff --git a/ui/lib/session.svelte.js b/ui/lib/session.svelte.js
index 2dae3c4..0b754e5 100644
--- a/ui/lib/session.svelte.js
+++ b/ui/lib/session.svelte.js
@@ -114,7 +114,7 @@ class Session {
   onMessage(message) {
     const event = JSON.parse(message.data);
     this.remote.onEvent(event);
-    this.local.retainChannels(this.remote.channels.all.keys());
+    this.local.retainChannels(this.remote.channels.all);
     this.watchdog.reset(this.heartbeatMillis());
   }
 
diff --git a/ui/lib/state/local/channels.svelte.js b/ui/lib/state/local/channels.svelte.js
index d86d028..e3ee8df 100644
--- a/ui/lib/state/local/channels.svelte.js
+++ b/ui/lib/state/local/channels.svelte.js
@@ -82,7 +82,8 @@ export class Channels {
     }
   }
 
-  retainChannels(channelIds) {
+  retainChannels(channels) {
+    const channelIds = channels.map((channel) => channel.id);
     const retain = new Set(channelIds);
     for (const channelId of Array.from(this.all.keys())) {
       if (!retain.has(channelId)) {
diff --git a/ui/lib/state/remote/channels.svelte.js b/ui/lib/state/remote/channels.svelte.js
index 8b190dd..19946f2 100644
--- a/ui/lib/state/remote/channels.svelte.js
+++ b/ui/lib/state/remote/channels.svelte.js
@@ -29,10 +29,10 @@ export class Channels {
   }
 
   add({ at, id, name }) {
-    this.all.set(id, Channel.boot({ at, id, name }));
+    this.all.push(Channel.boot({ at, id, name }));
   }
 
   remove(id) {
-    this.all.delete(id);
+    this.all = this.all.filter((channel) => channel.id !== id);
   }
 }