diff --git a/packages/codemirror/src/extensions/custom_tab.ts b/packages/codemirror/src/extensions/custom_tab.ts
index 3987827dd..e0f39690a 100644
--- a/packages/codemirror/src/extensions/custom_tab.ts
+++ b/packages/codemirror/src/extensions/custom_tab.ts
@@ -1,5 +1,5 @@
 import { indentLess, indentMore } from "@codemirror/commands";
-import { EditorSelection, EditorState, SelectionRange, type ChangeSpec } from "@codemirror/state";
+import { EditorSelection, EditorState, SelectionRange, type Transaction, type ChangeSpec } from "@codemirror/state";
 import type { KeyBinding } from "@codemirror/view";
 
 /**
@@ -19,8 +19,6 @@ const smartIndentWithTab: KeyBinding[] = [
             }
 
             const { selection } = state;
-            const changes: ChangeSpec[] = [];
-            const newSelections: SelectionRange[] = [];
 
             // Step 1: Handle non-empty selections → replace with tab
             if (selection.ranges.some(range => !range.empty)) {
@@ -40,55 +38,69 @@ const smartIndentWithTab: KeyBinding[] = [
                     // Multiple lines are selected, indent each line.
                     return indentMore({ state, dispatch });
                 } else {
-                    // Single line selection, replace with tab.
-                    for (let range of selection.ranges) {
-                        changes.push({ from: range.from, to: range.to, insert: "\t" });
-                        newSelections.push(EditorSelection.cursor(range.from + 1));
-                    }
-
-                    dispatch(
-                        state.update({
-                            changes,
-                            selection: EditorSelection.create(newSelections),
-                            scrollIntoView: true,
-                            userEvent: "input"
-                        })
-                    );
+                    return handleSingleLineSelection(state, dispatch);
                 }
-
-                return true;
             }
 
             // Step 2: Handle empty selections
-            for (let range of selection.ranges) {
-                const line = state.doc.lineAt(range.head);
-                const beforeCursor = state.doc.sliceString(line.from, range.head);
-
-                if (/^\s*$/.test(beforeCursor)) {
-                    // Only whitespace before cursor → indent line
-                    return indentMore({ state, dispatch });
-                } else {
-                    // Insert tab character at cursor
-                    changes.push({ from: range.head, to: range.head, insert: "\t" });
-                    newSelections.push(EditorSelection.cursor(range.head + 1));
-                }
-            }
-
-            if (changes.length) {
-                dispatch(
-                    state.update({
-                        changes,
-                        selection: EditorSelection.create(newSelections),
-                        scrollIntoView: true,
-                        userEvent: "input"
-                    })
-                );
-                return true;
-            }
-
-            return false;
+            return handleEmptySelections(state, dispatch);
         },
         shift: indentLess
     },
 ]
 export default smartIndentWithTab;
+
+function handleSingleLineSelection(state: EditorState, dispatch: (transaction: Transaction) => void) {
+    const changes: ChangeSpec[] = [];
+    const newSelections: SelectionRange[] = [];
+
+    // Single line selection, replace with tab.
+    for (let range of state.selection.ranges) {
+        changes.push({ from: range.from, to: range.to, insert: "\t" });
+        newSelections.push(EditorSelection.cursor(range.from + 1));
+    }
+
+    dispatch(
+        state.update({
+            changes,
+            selection: EditorSelection.create(newSelections),
+            scrollIntoView: true,
+            userEvent: "input"
+        })
+    );
+
+    return true;
+}
+
+function handleEmptySelections(state: EditorState, dispatch: (transaction: Transaction) => void) {
+    const changes: ChangeSpec[] = [];
+    const newSelections: SelectionRange[] = [];
+
+    for (let range of state.selection.ranges) {
+        const line = state.doc.lineAt(range.head);
+        const beforeCursor = state.doc.sliceString(line.from, range.head);
+
+        if (/^\s*$/.test(beforeCursor)) {
+            // Only whitespace before cursor → indent line
+            return indentMore({ state, dispatch });
+        } else {
+            // Insert tab character at cursor
+            changes.push({ from: range.head, to: range.head, insert: "\t" });
+            newSelections.push(EditorSelection.cursor(range.head + 1));
+        }
+    }
+
+    if (changes.length) {
+        dispatch(
+            state.update({
+                changes,
+                selection: EditorSelection.create(newSelections),
+                scrollIntoView: true,
+                userEvent: "input"
+            })
+        );
+        return true;
+    }
+
+    return false;
+}