fix(peer): coalesce full UI view publications

Keep one queued and one replaceable pending snapshot for remote-library and Call-to-Play views while preserving lifecycle-event FIFO delivery. Generation barriers and fenced drains prevent stale nonempty views from crossing disable or acknowledgement boundaries.

Test Plan:
- just test
- just clippy
- focused burst, lifecycle ordering, fence, repeated-barrier, and stale-view tests
- independent ordering review
- git diff --check

crates/lanspread-tauri-deno-ts/src-tauri/src/lib.rs

@@ -35,6 +35,8 @@ use lanspread_peer::{
     NoopStreamInstallProvider,
     PeerCommand,
     PeerEvent,
+    PeerEventReceiver,
+    PeerEventSender,
     PeerGameDB,
     PeerIdentity,
     PeerIdentityDurability,
@@ -47,6 +49,7 @@ use lanspread_peer::{
     UnpackFuture,
     Unpacker,
     migrate_legacy_state,
+    peer_event_channel,
     scoped_blocking,
     start_peer_with_options,
 };
@@ -687,7 +690,7 @@ struct InstallSettings {
     language: String,
 }
 
-struct PeerEventTx(UnboundedSender<PeerEvent>);
+struct PeerEventTx(PeerEventSender);
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, serde::Serialize)]
 enum UiOperationKind {
@@ -4086,7 +4089,7 @@ fn emit_game_id_event(app_handle: &AppHandle, event: &str, id: &str, label: &str
 
 fn spawn_peer_event_loop(
     app_handle: AppHandle,
-    mut rx_peer_event: UnboundedReceiver<PeerEvent>,
+    mut rx_peer_event: PeerEventReceiver,
     mut rx_ui_state: UnboundedReceiver<UiStateCommand>,
 ) {
     let tasks = app_handle
@@ -4228,6 +4231,7 @@ fn set_identity_diagnostic_in_loop(
     Ok(next)
 }
 
+#[cfg(test)]
 fn take_exactly_queued<T>(
     receiver: &mut UnboundedReceiver<T>,
     count: usize,
@@ -4243,15 +4247,17 @@ fn take_exactly_queued<T>(
 
 async fn drain_queued_peer_events(
     app_handle: &AppHandle,
-    receiver: &mut UnboundedReceiver<PeerEvent>,
+    receiver: &mut PeerEventReceiver,
 ) -> Result<(), String> {
     // The core replies only after all events for the requested transition have
-    // been enqueued. Once this UI command wins the fair select, snapshot the
-    // peer queue and process that exact FIFO prefix. Later autonomous traffic
-    // remains for the normal event-loop turn and cannot contaminate this
-    // transition's acknowledgement boundary.
-    let count = receiver.len();
-    let queued = take_exactly_queued(receiver, count)?;
+    // been enqueued. Once this UI command wins the fair select, hold the shared
+    // producer fence while draining every event already admitted, including a
+    // coalesced pending view. Later autonomous traffic remains for the normal
+    // event-loop turn and cannot contaminate this transition's acknowledgement
+    // boundary.
+    let queued = receiver
+        .drain_ready()
+        .map_err(|error| format!("peer-event queue changed while applying its fence: {error}"))?;
     for event in queued {
         handle_peer_event(app_handle, event).await;
     }
@@ -4260,7 +4266,7 @@ async fn drain_queued_peer_events(
 
 async fn fence_queued_peer_events(
     app_handle: &AppHandle,
-    receiver: &mut UnboundedReceiver<PeerEvent>,
+    receiver: &mut PeerEventReceiver,
 ) -> Result<LocalNetworkSharingSnapshot, String> {
     drain_queued_peer_events(app_handle, receiver).await?;
     current_local_network_sharing(app_handle.state::<LanSpreadState>().inner())
@@ -4268,7 +4274,7 @@ async fn fence_queued_peer_events(
 
 async fn reset_game_transfer_status_in_loop(
     app_handle: &AppHandle,
-    receiver: &mut UnboundedReceiver<PeerEvent>,
+    receiver: &mut PeerEventReceiver,
 ) -> Result<GameTransferStatusSnapshot, String> {
     // A successful game-root command has already caused core to enqueue its
     // preceding events. Drain that bounded prefix before terminalizing the old
@@ -4290,7 +4296,7 @@ async fn reset_game_transfer_status_in_loop(
 async fn handle_ui_state_command(
     app_handle: &AppHandle,
     command: UiStateCommand,
-    peer_events: &mut UnboundedReceiver<PeerEvent>,
+    peer_events: &mut PeerEventReceiver,
 ) {
     match command {
         UiStateCommand::MutateSharing { mutation, reply } => {
@@ -4629,7 +4635,7 @@ struct ProtocolMismatchSnapshot {
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
     // channel to receive events from the peer
-    let (tx_peer_event, rx_peer_event) = tokio::sync::mpsc::unbounded_channel::<PeerEvent>();
+    let (tx_peer_event, rx_peer_event) = peer_event_channel();
     let (tx_ui_state, rx_ui_state) = tokio::sync::mpsc::unbounded_channel::<UiStateCommand>();
 
     tauri::Builder::default()