fix

src/entities/tasks/demo.rs

@@ -283,13 +283,21 @@ pub fn demo_system(
                 let idle_dorfs: SmallVec<[Entity; 8]> =
                     idle_dorfs.into_iter().map(|(e, _)| e).collect();
 
+                // Track destinations reserved this tick to avoid assigning the same tile
+                // to multiple dorfs before any have physically dropped their cargo.
+                let mut reserved: SmallVec<[IVec3; 8]> = SmallVec::new();
+
                 for dorf_entity in idle_dorfs {
-                    // Compute haul destination fresh for each assignment —
-                    // as logs accumulate near origin, each new assignment correctly
-                    // finds the next free tile.
+                    // Compute haul destination fresh for each assignment,
+                    // excluding tiles already reserved this tick.
                     let dest = tilemap
-                        .find_nearest_free_cargo_tile(IVec3::ZERO, HAUL_DEST_SEARCH_RADIUS)
+                        .find_nearest_free_cargo_tile(
+                            IVec3::ZERO,
+                            HAUL_DEST_SEARCH_RADIUS,
+                            &reserved,
+                        )
                         .unwrap_or(IVec3::ZERO);
+                    reserved.push(dest);
 
                     let Some((log_entity, log_pos)) = unassigned.pop_front() else {
                         break;

src/entities/tasks/executor.rs

@@ -276,7 +276,7 @@ pub fn task_executor_system(
                                 if chosen_drop.is_none() {
                                     *chosen_drop = Some(
                                         tilemap_mut
-                                            .find_nearest_free_cargo_tile(*dest, 8)
+                                            .find_nearest_free_cargo_tile(*dest, 8, &[])
                                             .unwrap_or(*dest),
                                     );
                                 }
@@ -331,7 +331,7 @@ pub fn task_executor_system(
                                 if chosen_drop.is_none() {
                                     *chosen_drop = Some(
                                         tilemap_mut
-                                            .find_nearest_free_cargo_tile(*pos, 8)
+                                            .find_nearest_free_cargo_tile(*pos, 8, &[])
                                             .unwrap_or(*pos),
                                     );
                                 }