nostrverse: reject out-of-order presence events

Track event_created_at on RoomUser and skip presence updates
whose created_at is older, preventing stale replaceable events
from overwriting newer positions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jb55

crates/notedeck_nostrverse/src/presence.rs

@@ -189,20 +189,27 @@ pub fn poll_presence(
         }
 
         let velocity = nostr_events::parse_presence_velocity(note);
+        let created_at = note.created_at();
 
         // Update or insert user
         if let Some(user) = users.iter_mut().find(|u| u.pubkey == pubkey) {
+            // Skip stale events — replaceable events can arrive out of order
+            if created_at <= user.event_created_at {
+                continue;
+            }
             // Update authoritative state; preserve display_position for smooth lerp
             user.position = position;
             user.velocity = velocity;
             user.update_time = now;
             user.last_seen = now;
+            user.event_created_at = created_at;
         } else {
             let mut user = RoomUser::new(pubkey, "anon".to_string(), position);
             user.velocity = velocity;
             user.display_position = position; // snap on first appearance
             user.update_time = now;
             user.last_seen = now;
+            user.event_created_at = created_at;
             users.push(user);
         }
         changed = true;

crates/notedeck_nostrverse/src/room_state.rs

@@ -231,6 +231,9 @@ pub struct RoomUser {
     pub is_self: bool,
     /// Monotonic timestamp (seconds) of last presence update
     pub last_seen: f64,
+    /// Nostr event created_at of the latest accepted presence event.
+    /// Used to ignore out-of-order replaceable events.
+    pub event_created_at: u64,
     /// Runtime: renderbud scene object handle for avatar
     pub scene_object_id: Option<ObjectId>,
     /// Runtime: loaded model handle for avatar
@@ -248,6 +251,7 @@ impl RoomUser {
             update_time: 0.0,
             is_self: false,
             last_seen: 0.0,
+            event_created_at: 0,
             scene_object_id: None,
             model_handle: None,
         }