Make channel notes read-only when disconnected

Co-authored-by: Mikayla <mikayla@zed.dev>

crates/collab/src/rpc.rs

@@ -854,10 +854,13 @@ async fn connection_lost(
         .await
         .trace_err();
 
+    leave_channel_buffers_for_session(&session)
+        .await
+        .trace_err();
+
     futures::select_biased! {
         _ = executor.sleep(RECONNECT_TIMEOUT).fuse() => {
             leave_room_for_session(&session).await.trace_err();
-            leave_channel_buffers_for_session(&session).await.trace_err();
 
             if !session
                 .connection_pool()

crates/collab/src/tests/channel_buffer_tests.rs

@@ -1,5 +1,6 @@
 use crate::{rpc::RECONNECT_TIMEOUT, tests::TestServer};
 use call::ActiveCall;
+use channel::Channel;
 use client::UserId;
 use collab_ui::channel_view::ChannelView;
 use collections::HashMap;
@@ -334,6 +335,81 @@ async fn test_reopen_channel_buffer(deterministic: Arc<Deterministic>, cx_a: &mu
     });
 }
 
+#[gpui::test]
+async fn test_channel_buffer_disconnect(
+    deterministic: Arc<Deterministic>,
+    cx_a: &mut TestAppContext,
+    cx_b: &mut TestAppContext,
+) {
+    deterministic.forbid_parking();
+    let mut server = TestServer::start(&deterministic).await;
+    let client_a = server.create_client(cx_a, "user_a").await;
+    let client_b = server.create_client(cx_b, "user_b").await;
+
+    let channel_id = server
+        .make_channel("zed", (&client_a, cx_a), &mut [(&client_b, cx_b)])
+        .await;
+
+    let channel_buffer_a = client_a
+        .channel_store()
+        .update(cx_a, |channel, cx| {
+            channel.open_channel_buffer(channel_id, cx)
+        })
+        .await
+        .unwrap();
+
+    let channel_buffer_b = client_b
+        .channel_store()
+        .update(cx_b, |channel, cx| {
+            channel.open_channel_buffer(channel_id, cx)
+        })
+        .await
+        .unwrap();
+
+    server.forbid_connections();
+    server.disconnect_client(client_a.peer_id().unwrap());
+    deterministic.advance_clock(RECEIVE_TIMEOUT + RECONNECT_TIMEOUT);
+
+    channel_buffer_a.update(cx_a, |buffer, _| {
+        assert_eq!(
+            buffer.channel().as_ref(),
+            &Channel {
+                id: channel_id,
+                name: "zed".to_string()
+            }
+        );
+        assert!(!buffer.is_connected());
+    });
+
+    deterministic.run_until_parked();
+
+    server.allow_connections();
+    deterministic.advance_clock(RECEIVE_TIMEOUT + RECONNECT_TIMEOUT);
+
+    deterministic.run_until_parked();
+
+    client_a
+        .channel_store()
+        .update(cx_a, |channel_store, _| {
+            channel_store.remove_channel(channel_id)
+        })
+        .await
+        .unwrap();
+    deterministic.run_until_parked();
+
+    // Channel buffer observed the deletion
+    channel_buffer_b.update(cx_b, |buffer, _| {
+        assert_eq!(
+            buffer.channel().as_ref(),
+            &Channel {
+                id: channel_id,
+                name: "zed".to_string()
+            }
+        );
+        assert!(!buffer.is_connected());
+    });
+}
+
 #[track_caller]
 fn assert_collaborators(collaborators: &[proto::Collaborator], ids: &[Option<UserId>]) {
     assert_eq!(

crates/collab/src/tests/channel_tests.rs

@@ -799,7 +799,7 @@ async fn test_lost_channel_creation(
 
     deterministic.run_until_parked();
 
-    // Sanity check
+    // Sanity check, B has the invitation
     assert_channel_invitations(
         client_b.channel_store(),
         cx_b,
@@ -811,6 +811,7 @@ async fn test_lost_channel_creation(
         }],
     );
 
+    // A creates a subchannel while the invite is still pending.
     let subchannel_id = client_a
         .channel_store()
         .update(cx_a, |channel_store, cx| {
@@ -841,7 +842,7 @@ async fn test_lost_channel_creation(
         ],
     );
 
-    // Accept the invite
+    // Client B accepts the invite
     client_b
         .channel_store()
         .update(cx_b, |channel_store, _| {
@@ -852,7 +853,7 @@ async fn test_lost_channel_creation(
 
     deterministic.run_until_parked();
 
-    // B should now see the channel
+    // Client B should now see the channel
     assert_channels(
         client_b.channel_store(),
         cx_b,