diff --git a/src/browser/Page.zig b/src/browser/Page.zig
index 95433ce1..d053f0ab 100644
--- a/src/browser/Page.zig
+++ b/src/browser/Page.zig
@@ -2907,23 +2907,7 @@ pub fn updateRangesForCharacterDataReplace(self: *Page, target: *Node, offset: u
     var it: ?*std.DoublyLinkedList.Node = self._live_ranges.first;
     while (it) |link| : (it = link.next) {
         const ar: *AbstractRange = @fieldParentPtr("_range_link", link);
-
-        if (ar._start_container == target) {
-            if (ar._start_offset > offset and ar._start_offset <= offset + count) {
-                ar._start_offset = offset;
-            } else if (ar._start_offset > offset + count) {
-                // Use i64 intermediate to avoid u32 underflow when count > data_len
-                ar._start_offset = @intCast(@as(i64, ar._start_offset) + @as(i64, data_len) - @as(i64, count));
-            }
-        }
-
-        if (ar._end_container == target) {
-            if (ar._end_offset > offset and ar._end_offset <= offset + count) {
-                ar._end_offset = offset;
-            } else if (ar._end_offset > offset + count) {
-                ar._end_offset = @intCast(@as(i64, ar._end_offset) + @as(i64, data_len) - @as(i64, count));
-            }
-        }
+        ar.updateForCharacterDataReplace(target, offset, count, data_len);
     }
 }
 
@@ -2936,25 +2920,7 @@ pub fn updateRangesForSplitText(self: *Page, target: *Node, new_node: *Node, off
     var it: ?*std.DoublyLinkedList.Node = self._live_ranges.first;
     while (it) |link| : (it = link.next) {
         const ar: *AbstractRange = @fieldParentPtr("_range_link", link);
-
-        // Step 7b: ranges on the original node with start > offset move to new node
-        if (ar._start_container == target and ar._start_offset > offset) {
-            ar._start_container = new_node;
-            ar._start_offset = ar._start_offset - offset;
-        }
-        // Step 7c: ranges on the original node with end > offset move to new node
-        if (ar._end_container == target and ar._end_offset > offset) {
-            ar._end_container = new_node;
-            ar._end_offset = ar._end_offset - offset;
-        }
-        // Step 7d: ranges on parent with start == node_index + 1 increment
-        if (ar._start_container == parent and ar._start_offset == node_index + 1) {
-            ar._start_offset += 1;
-        }
-        // Step 7e: ranges on parent with end == node_index + 1 increment
-        if (ar._end_container == parent and ar._end_offset == node_index + 1) {
-            ar._end_offset += 1;
-        }
+        ar.updateForSplitText(target, new_node, offset, parent, node_index);
     }
 }
 
@@ -2965,13 +2931,7 @@ pub fn updateRangesForNodeInsertion(self: *Page, parent: *Node, child_index: u32
     var it: ?*std.DoublyLinkedList.Node = self._live_ranges.first;
     while (it) |link| : (it = link.next) {
         const ar: *AbstractRange = @fieldParentPtr("_range_link", link);
-
-        if (ar._start_container == parent and ar._start_offset > child_index) {
-            ar._start_offset += 1;
-        }
-        if (ar._end_container == parent and ar._end_offset > child_index) {
-            ar._end_offset += 1;
-        }
+        ar.updateForNodeInsertion(parent, child_index);
     }
 }
 
@@ -2981,37 +2941,10 @@ pub fn updateRangesForNodeRemoval(self: *Page, parent: *Node, child: *Node, chil
     var it: ?*std.DoublyLinkedList.Node = self._live_ranges.first;
     while (it) |link| : (it = link.next) {
         const ar: *AbstractRange = @fieldParentPtr("_range_link", link);
-
-        // Steps 4-5: ranges whose start/end is an inclusive descendant of child
-        // get moved to (parent, child_index).
-        if (isInclusiveDescendantOf(ar._start_container, child)) {
-            ar._start_container = parent;
-            ar._start_offset = child_index;
-        }
-        if (isInclusiveDescendantOf(ar._end_container, child)) {
-            ar._end_container = parent;
-            ar._end_offset = child_index;
-        }
-
-        // Steps 6-7: ranges on parent at offsets > child_index get decremented.
-        if (ar._start_container == parent and ar._start_offset > child_index) {
-            ar._start_offset -= 1;
-        }
-        if (ar._end_container == parent and ar._end_offset > child_index) {
-            ar._end_offset -= 1;
-        }
+        ar.updateForNodeRemoval(parent, child, child_index);
     }
 }
 
-fn isInclusiveDescendantOf(node: *Node, potential_ancestor: *Node) bool {
-    var current: ?*Node = node;
-    while (current) |n| {
-        if (n == potential_ancestor) return true;
-        current = n.parentNode();
-    }
-    return false;
-}
-
 // TODO: optimize and cleanup, this is called a lot (e.g., innerHTML = '')
 pub fn parseHtmlAsChildren(self: *Page, node: *Node, html: []const u8) !void {
     const previous_parse_mode = self._parse_mode;
diff --git a/src/browser/webapi/AbstractRange.zig b/src/browser/webapi/AbstractRange.zig
index 231c635d..e766ac29 100644
--- a/src/browser/webapi/AbstractRange.zig
+++ b/src/browser/webapi/AbstractRange.zig
@@ -218,6 +218,91 @@ fn isInclusiveAncestorOf(potential_ancestor: *Node, node: *Node) bool {
     return isAncestorOf(potential_ancestor, node);
 }
 
+/// Update this range's boundaries after a replaceData mutation on target.
+/// All parameters are in UTF-16 code unit offsets.
+pub fn updateForCharacterDataReplace(self: *AbstractRange, target: *Node, offset: u32, count: u32, data_len: u32) void {
+    if (self._start_container == target) {
+        if (self._start_offset > offset and self._start_offset <= offset + count) {
+            self._start_offset = offset;
+        } else if (self._start_offset > offset + count) {
+            // Use i64 intermediate to avoid u32 underflow when count > data_len
+            self._start_offset = @intCast(@as(i64, self._start_offset) + @as(i64, data_len) - @as(i64, count));
+        }
+    }
+
+    if (self._end_container == target) {
+        if (self._end_offset > offset and self._end_offset <= offset + count) {
+            self._end_offset = offset;
+        } else if (self._end_offset > offset + count) {
+            self._end_offset = @intCast(@as(i64, self._end_offset) + @as(i64, data_len) - @as(i64, count));
+        }
+    }
+}
+
+/// Update this range's boundaries after a splitText operation.
+/// Steps 7b-7e of the DOM spec splitText algorithm.
+pub fn updateForSplitText(self: *AbstractRange, target: *Node, new_node: *Node, offset: u32, parent: *Node, node_index: u32) void {
+    // Step 7b: ranges on the original node with start > offset move to new node
+    if (self._start_container == target and self._start_offset > offset) {
+        self._start_container = new_node;
+        self._start_offset = self._start_offset - offset;
+    }
+    // Step 7c: ranges on the original node with end > offset move to new node
+    if (self._end_container == target and self._end_offset > offset) {
+        self._end_container = new_node;
+        self._end_offset = self._end_offset - offset;
+    }
+    // Step 7d: ranges on parent with start == node_index + 1 increment
+    if (self._start_container == parent and self._start_offset == node_index + 1) {
+        self._start_offset += 1;
+    }
+    // Step 7e: ranges on parent with end == node_index + 1 increment
+    if (self._end_container == parent and self._end_offset == node_index + 1) {
+        self._end_offset += 1;
+    }
+}
+
+/// Update this range's boundaries after a node insertion.
+pub fn updateForNodeInsertion(self: *AbstractRange, parent: *Node, child_index: u32) void {
+    if (self._start_container == parent and self._start_offset > child_index) {
+        self._start_offset += 1;
+    }
+    if (self._end_container == parent and self._end_offset > child_index) {
+        self._end_offset += 1;
+    }
+}
+
+/// Update this range's boundaries after a node removal.
+pub fn updateForNodeRemoval(self: *AbstractRange, parent: *Node, child: *Node, child_index: u32) void {
+    // Steps 4-5: ranges whose start/end is an inclusive descendant of child
+    // get moved to (parent, child_index).
+    if (isInclusiveDescendantOf(self._start_container, child)) {
+        self._start_container = parent;
+        self._start_offset = child_index;
+    }
+    if (isInclusiveDescendantOf(self._end_container, child)) {
+        self._end_container = parent;
+        self._end_offset = child_index;
+    }
+
+    // Steps 6-7: ranges on parent at offsets > child_index get decremented.
+    if (self._start_container == parent and self._start_offset > child_index) {
+        self._start_offset -= 1;
+    }
+    if (self._end_container == parent and self._end_offset > child_index) {
+        self._end_offset -= 1;
+    }
+}
+
+fn isInclusiveDescendantOf(node: *Node, potential_ancestor: *Node) bool {
+    var current: ?*Node = node;
+    while (current) |n| {
+        if (n == potential_ancestor) return true;
+        current = n.parentNode();
+    }
+    return false;
+}
+
 pub const JsApi = struct {
     pub const bridge = js.Bridge(AbstractRange);
 
diff --git a/src/browser/webapi/Range.zig b/src/browser/webapi/Range.zig
index a5789a64..66ce1c93 100644
--- a/src/browser/webapi/Range.zig
+++ b/src/browser/webapi/Range.zig
@@ -358,7 +358,7 @@ pub fn insertNode(self: *Range, node: *Node, page: *Page) !void {
 
     // Per spec step 11: if range was collapsed, extend end to include inserted node.
     // Non-collapsed ranges are already handled by the live range update in the insert path.
-    if (was_collapsed and self._proto._start_container == self._proto._end_container) {
+    if (was_collapsed) {
         self._proto._end_offset = self._proto._start_offset + 1;
     }
 }