feat(ui): handle PresenceList in lobby — show online users

The lobby now populates from PresenceList signal events:
- Relay broadcasts user list on register/deregister
- JS receives "presence_list" signal-event
- Updates lobbyUsers map (excluding self)
- Renders user rows with identicon, name, fingerprint

Users appear in the lobby as soon as they register their
signal channel — no need to join voice first.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/wzp-client/src/featherchat.rs

@@ -138,6 +138,7 @@ pub fn signal_to_call_type(signal: &SignalMessage) -> CallSignalType {
         | SignalMessage::UpgradeResponse { .. }
         | SignalMessage::UpgradeConfirm { .. }
         | SignalMessage::QualityCapability { .. } => CallSignalType::Offer, // quality negotiation
+        SignalMessage::PresenceList { .. } => CallSignalType::Offer, // lobby presence
         SignalMessage::QualityDirective { .. } => CallSignalType::Offer, // relay-initiated
     }
 }

crates/wzp-proto/src/lib.rs

@@ -27,7 +27,7 @@ pub use codec_id::{CodecId, QualityProfile};
 pub use error::*;
 pub use packet::{
     CallAcceptMode, HangupReason, MediaHeader, MediaPacket, MiniFrameContext, MiniHeader,
-    QualityReport, RoomParticipant, SignalMessage, TrunkEntry, TrunkFrame, FRAME_TYPE_FULL,
+    PresenceUser, QualityReport, RoomParticipant, SignalMessage, TrunkEntry, TrunkFrame, FRAME_TYPE_FULL,
     FRAME_TYPE_MINI,
 };
 pub use bandwidth::{BandwidthEstimator, CongestionState};

crates/wzp-proto/src/packet.rs

@@ -156,6 +156,14 @@ impl MediaHeader {
     }
 }
 
+/// A user visible in the signal presence list.
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct PresenceUser {
+    pub fingerprint: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub alias: Option<String>,
+}
+
 /// Quality report appended to a media packet when Q flag is set (4 bytes).
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct QualityReport {
@@ -1020,6 +1028,16 @@ pub enum SignalMessage {
         reason: Option<String>,
     },
 
+    // ── Signal presence ───────────────────────────────────────────
+
+    /// Relay broadcasts the list of currently registered signal
+    /// users to all connected clients. Sent on every register/
+    /// deregister so clients can maintain a live lobby user list.
+    PresenceList {
+        /// List of online users. Each entry is { fingerprint, alias }.
+        users: Vec<PresenceUser>,
+    },
+
     // ── Quality upgrade negotiation (#28, #29) ──────────────────
 
     /// Peer proposes upgrading to a higher quality profile.

crates/wzp-relay/src/main.rs

@@ -1016,6 +1016,13 @@ async fn main() -> anyhow::Result<()> {
 
                 info!(%addr, fingerprint = %client_fp, alias = ?client_alias, "signal client registered");
 
+                // Broadcast updated presence to all signal clients
+                {
+                    let hub = signal_hub.lock().await;
+                    let presence = hub.presence_list();
+                    hub.broadcast(&presence).await;
+                }
+
                 // Signal recv loop
                 loop {
                     match transport.recv_signal().await {
@@ -1560,6 +1567,9 @@ async fn main() -> anyhow::Result<()> {
                 {
                     let mut hub = signal_hub.lock().await;
                     hub.unregister(&client_fp);
+                    // Broadcast updated presence to remaining clients
+                    let presence_msg = hub.presence_list();
+                    hub.broadcast(&presence_msg).await;
                 }
                 {
                     let mut reg = presence.lock().await;

crates/wzp-relay/src/signal_hub.rs

@@ -86,6 +86,26 @@ impl SignalHub {
     pub fn alias(&self, fp: &str) -> Option<&str> {
         self.clients.get(fp).and_then(|c| c.alias.as_deref())
     }
+
+    /// Build a PresenceList message with all online users.
+    pub fn presence_list(&self) -> SignalMessage {
+        let users: Vec<wzp_proto::PresenceUser> = self
+            .clients
+            .values()
+            .map(|c| wzp_proto::PresenceUser {
+                fingerprint: c.fingerprint.clone(),
+                alias: c.alias.clone(),
+            })
+            .collect();
+        SignalMessage::PresenceList { users }
+    }
+
+    /// Broadcast a message to ALL connected signal clients.
+    pub async fn broadcast(&self, msg: &SignalMessage) {
+        for client in self.clients.values() {
+            let _ = client.transport.send_signal(msg).await;
+        }
+    }
 }
 
 #[cfg(test)]

desktop/src-tauri/src/lib.rs

@@ -1451,6 +1451,20 @@ fn do_register_signal(
                         });
                     }
                 }
+                Ok(Some(SignalMessage::PresenceList { users })) => {
+                    tracing::info!(count = users.len(), "signal: PresenceList received");
+                    // Emit to JS frontend for lobby user list
+                    let user_list: Vec<serde_json::Value> = users.iter().map(|u| {
+                        serde_json::json!({
+                            "fingerprint": u.fingerprint,
+                            "alias": u.alias,
+                        })
+                    }).collect();
+                    let _ = app_clone.emit("signal-event", serde_json::json!({
+                        "type": "presence_list",
+                        "users": user_list,
+                    }));
+                }
                 Ok(Some(SignalMessage::UpgradeProposal { call_id, proposal_id, proposed_profile, local_loss_pct, local_rtt_ms })) => {
                     tracing::info!(%call_id, %proposal_id, ?proposed_profile, "signal: UpgradeProposal from peer");
                     emit_call_debug(&app_clone, "recv:UpgradeProposal", serde_json::json!({

desktop/src/main.ts

@@ -435,6 +435,20 @@ async function pollStatus() {
 listen("signal-event", (event: any) => {
   const data = event.payload;
   switch (data.type) {
+    case "presence_list":
+      // Relay sent updated user list
+      lobbyUsers.clear();
+      for (const u of data.users || []) {
+        if (u.fingerprint === myFingerprint) continue; // don't show self
+        lobbyUsers.set(u.fingerprint, {
+          fingerprint: u.fingerprint,
+          alias: u.alias || null,
+          inVoice: false,
+          speaking: false,
+        });
+      }
+      renderLobbyUsers();
+      break;
     case "ringing":
       // We placed a call, it's ringing
       break;