From 7060d3521a06c516bffa1a9b37d44fe8e3a0631b Mon Sep 17 00:00:00 2001
From: Michel de Graaf <michel@re-invention.nl>
Date: Thu, 10 Sep 2026 13:59:04 +0200
Subject: [PATCH] fix(rooms): start a room's roster from the member list, not
 the join echo

soulfind tells a room about a new member, the new member included, before
it sends them the room's member list. The roster was started from that
echo, so for a moment after joining a room read as holding nobody but us,
and `room users` returns on the first roster it sees: it could print only
the asking user. That is the flake in room_users_lists_who_is_in_the_room.

A join or leave now only updates a roster the server has sent in full,
which is also what room_members already promised for a room we have not
joined. The e2e test waits for the resident's own member list instead of a
fixed second, so it no longer races the resident's join either.
---
 soulseek-rs-lib/src/client/context.rs     |  8 +++++---
 soulseek-rs-lib/src/client/tests/rooms.rs | 19 +++++++++++++++++++
 soulseek-rs/tests/cli_e2e.rs              |  7 ++++++-
 3 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/soulseek-rs-lib/src/client/context.rs b/soulseek-rs-lib/src/client/context.rs
index b51a58a..8606abf 100644
--- a/soulseek-rs-lib/src/client/context.rs
+++ b/soulseek-rs-lib/src/client/context.rs
@@ -100,10 +100,12 @@ impl ClientContext {
                 // the whole board again on the next join.
                 self.room_tickers.remove(room);
             }
+            // Only a roster the server has sent in full is kept current: the
+            // joiner hears of their own arrival before the member list.
             RoomEvent::UserJoined { room, username } => {
-                let members =
-                    self.room_members.entry(room.clone()).or_default();
-                if let Err(at) = members.binary_search(username) {
+                if let Some(members) = self.room_members.get_mut(room)
+                    && let Err(at) = members.binary_search(username)
+                {
                     members.insert(at, username.clone());
                 }
             }
diff --git a/soulseek-rs-lib/src/client/tests/rooms.rs b/soulseek-rs-lib/src/client/tests/rooms.rs
index 0af6784..d504839 100644
--- a/soulseek-rs-lib/src/client/tests/rooms.rs
+++ b/soulseek-rs-lib/src/client/tests/rooms.rs
@@ -39,6 +39,25 @@ fn the_room_roster_follows_the_joins_and_leaves_the_server_reports() {
     assert!(context.room_members("lobby").is_empty());
 }
 
+#[test]
+fn a_join_announced_before_the_member_list_does_not_start_a_roster() {
+    // soulfind tells a room about a joiner, the joiner included, before it
+    // sends them the member list. A roster started from that echo reads as a
+    // room holding nobody else.
+    let mut context = ClientContext::new();
+    context.apply_room_event(RoomEvent::UserJoined {
+        room: "lobby".to_string(),
+        username: "me".to_string(),
+    });
+    assert!(context.room_members("lobby").is_empty());
+
+    context.apply_room_event(RoomEvent::Joined {
+        room: "lobby".to_string(),
+        users: vec!["me".to_string(), "alice".to_string()],
+    });
+    assert_eq!(context.room_members("lobby"), ["alice", "me"]);
+}
+
 #[test]
 fn a_user_joining_twice_is_listed_once() {
     let mut context = ClientContext::new();
diff --git a/soulseek-rs/tests/cli_e2e.rs b/soulseek-rs/tests/cli_e2e.rs
index 040e663..a65e3e4 100644
--- a/soulseek-rs/tests/cli_e2e.rs
+++ b/soulseek-rs/tests/cli_e2e.rs
@@ -2418,7 +2418,12 @@ fn room_users_lists_who_is_in_the_room() {
     let server = server_or_skip!();
     let resident = server.client("cli_e2e_resident", Vec::new());
     resident.join_room("cli_e2e_roster").expect("join");
-    settle();
+    // The member list reaches the resident once the server has them in.
+    let deadline = Instant::now() + Duration::from_secs(10);
+    while resident.room_members("cli_e2e_roster").is_empty() {
+        assert!(Instant::now() < deadline, "the resident never got in");
+        std::thread::sleep(Duration::from_millis(50));
+    }
 
     let output = cli(
         &server,