/data get entity @s prints the acting player's own UUID, not the world owner's

entity_nbt_in_level stamped UUID from level.player_uuid, the world owner's,
on a guest's turn too: on the server thread every player is a guest, so
/data get entity @s UUID gave every player offline_uuid("Player"). Use the
acting guest's UUID, as acting_uuid does. lan_e2e data_uuid checks the
guest and the host.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

crates/horizon-client/src/game/commands/data.rs

@@ -68,7 +68,12 @@ impl Game<'_> {
             .flatten()
     }
     fn entity_nbt_in_level(&mut self, t: Target) -> Option<Tag> {
-        let player_uuid = self.level.player_uuid;
+        // The acting player's own UUID: a guest's turn (the window's player on
+        // the server thread) keeps the world owner's in `level`.
+        let player_uuid = self
+            .lan_acting_uuid
+            .map(horizon_client::lan::playerdata::uuid_ints)
+            .or(self.level.player_uuid);
         Some(match t {
             Target::Guest(_) => {
                 return self

tools/lan_e2e.py

@@ -10989,6 +10989,22 @@ CHECKS += ['pet_death']
 CHECK_FNS['pet_death'] = check_pet_death
 
 
+def check_data_uuid(host, guest, out):
+    """EntityDataAccessor: `/data get entity @s UUID` prints the player who runs it, their own
+    offline UUID, for the guest and for the host (a server player too), not the world owner's."""
+    seen = {}
+    for game, name in ((guest, GUEST_NAME), (host, host.player)):
+        reply = server_reply(game, 'data get entity @s UUID', '[I;')
+        seen[name] = ','.join(re.findall(r'-?\d+', reply.partition('[I;')[2].partition(']')[0]))
+    for name, ints in seen.items():
+        assert ints == offline_uuid_ints(name), f"{name}'s UUID is not their own: {seen}"
+    return seen
+
+
+CHECKS += ['data_uuid']
+CHECK_FNS['data_uuid'] = check_data_uuid
+
+
 def check_arrow_pickup(host, guest, out):
     """ClientPacketListener.handleTakeItemEntity (#4486): an arrow a player picks up
     (AbstractArrow.playerTouch, once in the ground) flies into them on every client, the