refactor: improve proximity cache logging per review feedback

Address PR review feedback: - Add explicit loop with debug logging for disconnected proximity neighbors (aligns with get_broadcast_targets_update pattern) - Log the count of proximity neighbors found for debugging - Add code comment documenting the async race condition with CacheAnnounce messages and why the fallback handles it 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: sanity

crates/core/src/operations/update.rs

@@ -929,12 +929,38 @@ pub(crate) async fn request_update(
  // This is critical for peer-to-peer updates when peers are directly connected
  // but not explicitly subscribed (e.g., River chat rooms where both peers cache
  // the contract but haven't established a subscription tree).
- let target_from_proximity = op_manager
+ //
+ // Note: The proximity cache is populated asynchronously via CacheAnnounce messages,
+ // so there may be a brief race window after a peer caches a contract before its
+ // neighbors receive the announcement. This is acceptable - the ring-based fallback
+ // handles this case, and the proximity cache improves the common case where
+ // announcements have propagated.
+ let proximity_neighbors: Vec<_> = op_manager
  .proximity_cache
  .neighbors_with_contract(&key)
  .into_iter()
  .filter(|addr| addr != &sender_addr)
- .find_map(|addr| op_manager.ring.connection_manager.get_peer_by_addr(addr));
+ .collect();
+
+ let mut target_from_proximity = None;
+ for addr in &proximity_neighbors {
+ match op_manager.ring.connection_manager.get_peer_by_addr(*addr) {
+ Some(peer) => {
+ target_from_proximity = Some(peer);
+ break;
+ }
+ None => {
+ // Neighbor is in proximity cache but no longer connected.
+ // This is normal during connection churn - the proximity cache
+ // will be cleaned up when the disconnect is processed.
+ tracing::debug!(
+ %key,
+ peer = %addr,
+ "UPDATE: Proximity cache neighbor not connected, trying next"
+ );
+ }
+ }
+ }
 
  let target = if let Some(remote_subscriber) = target_from_subscribers {
  remote_subscriber
@@ -944,6 +970,7 @@ pub(crate) async fn request_update(
  tracing::debug!(
  %key,
  target = ?proximity_neighbor.socket_addr(),
+ proximity_neighbors_found = proximity_neighbors.len(),
  "UPDATE: Using proximity cache neighbor as target"
  );
  proximity_neighbor