diff --git a/crates/loro-core/src/container/text/tracker.rs b/crates/loro-core/src/container/text/tracker.rs
index 07d3c858..993f4d49 100644
--- a/crates/loro-core/src/container/text/tracker.rs
+++ b/crates/loro-core/src/container/text/tracker.rs
@@ -77,6 +77,11 @@ impl Tracker {
         }
     }
 
+    /// check whether id_to_cursor correctly reflect the status of the content
+    fn check_consistency(&self) {
+        todo!()
+    }
+
     fn turn_on(&mut self, _id: IdSpan) {}
     fn turn_off(&mut self, _id: IdSpan) {}
     fn checkout(&mut self, _vv: VersionVector) {}
diff --git a/crates/loro-core/src/container/text/tracker/y_span.rs b/crates/loro-core/src/container/text/tracker/y_span.rs
index b1140612..337efaa8 100644
--- a/crates/loro-core/src/container/text/tracker/y_span.rs
+++ b/crates/loro-core/src/container/text/tracker/y_span.rs
@@ -62,6 +62,7 @@ pub enum StatusChange {
 pub(super) type YSpanTreeTrait = CumulateTreeTrait<YSpan, 10>;
 
 impl YSpan {
+    /// this is the last id of the span, which is **included** by self
     #[inline]
     pub fn last_id(&self) -> ID {
         self.id.inc(self.len as i32 - 1)
@@ -77,7 +78,7 @@ impl YSpan {
     pub fn contain_id(&self, id: ID) -> bool {
         self.id.client_id == id.client_id
             && self.id.counter <= id.counter
-            && self.last_id().counter > id.counter
+            && self.last_id().counter >= id.counter
     }
 }
 
diff --git a/crates/rle/src/rle_tree/cursor.rs b/crates/rle/src/rle_tree/cursor.rs
index 573924d5..157741c3 100644
--- a/crates/rle/src/rle_tree/cursor.rs
+++ b/crates/rle/src/rle_tree/cursor.rs
@@ -5,7 +5,7 @@ use crate::{Rle, RleTreeTrait};
 use super::{node::LeafNode, tree_trait::Position};
 
 /// when len > 0, it acts as a selection. When iterating the tree, the len should be the size of the element.
-#[derive(PartialEq, Eq)]
+#[derive(PartialEq, Eq, Debug)]
 pub struct UnsafeCursor<'tree, 'bump, T: Rle, A: RleTreeTrait<T>> {
     pub leaf: NonNull<LeafNode<'bump, T, A>>,
     pub index: usize,
@@ -32,11 +32,13 @@ impl<'tree, 'bump, T: Rle, A: RleTreeTrait<T>> Clone for UnsafeCursor<'tree, 'bu
 impl<'tree, 'bump: 'tree, T: Rle, A: RleTreeTrait<T>> Copy for UnsafeCursor<'tree, 'bump, T, A> {}
 
 #[repr(transparent)]
+#[derive(Debug)]
 pub struct SafeCursor<'tree, 'bump, T: Rle, A: RleTreeTrait<T>>(
     pub(crate) UnsafeCursor<'tree, 'bump, T, A>,
 );
 
 #[repr(transparent)]
+#[derive(Debug)]
 pub struct SafeCursorMut<'tree, 'bump, T: Rle, A: RleTreeTrait<T>>(
     pub(crate) UnsafeCursor<'tree, 'bump, T, A>,
 );
diff --git a/crates/rle/src/rle_tree/iter.rs b/crates/rle/src/rle_tree/iter.rs
index a759658b..9aebf326 100644
--- a/crates/rle/src/rle_tree/iter.rs
+++ b/crates/rle/src/rle_tree/iter.rs
@@ -137,6 +137,7 @@ impl<'tree, 'bump: 'tree, T: Rle, A: RleTreeTrait<T>> Iterator for Iter<'tree, '
                                         end.offset - cursor.offset,
                                     )
                                 });
+                                cursor.offset = end.offset;
                                 self.cursor = None;
                                 return ans;
                             }