From 59feec1fe24a13995da3478ed74b742e7e348364 Mon Sep 17 00:00:00 2001
From: Henry Heino <46334387+personalizedrefrigerator@users.noreply.github.com>
Date: Sat, 26 Oct 2024 13:03:13 -0700
Subject: [PATCH] Desktop,Mobile: Fix list renumbering in the Markdown editor
 resets the first list item number to 1 (#11220)

---
 .../utils/renumberSelectedLists.test.ts       | 26 +++++++++++++++++++
 .../markdown/utils/renumberSelectedLists.ts   | 10 ++++++-
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/packages/editor/CodeMirror/markdown/utils/renumberSelectedLists.test.ts b/packages/editor/CodeMirror/markdown/utils/renumberSelectedLists.test.ts
index f7c4a1836..17d777a0b 100644
--- a/packages/editor/CodeMirror/markdown/utils/renumberSelectedLists.test.ts
+++ b/packages/editor/CodeMirror/markdown/utils/renumberSelectedLists.test.ts
@@ -38,4 +38,30 @@ describe('renumberSelectedLists', () => {
 			'# End',
 		].join('\n'));
 	});
+
+	it('should preserve the first list number if not 1', async () => {
+		const listText = [
+			'2. This',
+			'4. is',
+			'5. a',
+			'6. test',
+		].join('\n');
+
+		const editor = await createTestEditor(
+			`${listText}\n\n# End`,
+			EditorSelection.range(0, listText.length),
+			['OrderedList', 'ATXHeading1'],
+		);
+
+		editor.dispatch(renumberSelectedLists(editor.state));
+
+		expect(editor.state.doc.toString()).toBe([
+			'2. This',
+			'3. is',
+			'4. a',
+			'5. test',
+			'',
+			'# End',
+		].join('\n'));
+	});
 });
diff --git a/packages/editor/CodeMirror/markdown/utils/renumberSelectedLists.ts b/packages/editor/CodeMirror/markdown/utils/renumberSelectedLists.ts
index 1e6aabfd0..e67db80b3 100644
--- a/packages/editor/CodeMirror/markdown/utils/renumberSelectedLists.ts
+++ b/packages/editor/CodeMirror/markdown/utils/renumberSelectedLists.ts
@@ -13,6 +13,14 @@ const renumberSelectedLists = (state: EditorState): TransactionSpec => {
 	// Re-numbers ordered lists and sublists with numbers on each line in [linesToHandle]
 	const handleLines = (linesToHandle: Line[]) => {
 		const changes: ChangeSpec[] = [];
+		if (linesToHandle.length === 0) {
+			return changes;
+		}
+
+		let firstListNumber = Number(listItemRegex.exec(linesToHandle[0].text)?.[2]);
+		if (!isFinite(firstListNumber) || firstListNumber < 1) {
+			firstListNumber = 1;
+		}
 
 		type ListItemRecord = {
 			nextListNumber: number;
@@ -20,7 +28,7 @@ const renumberSelectedLists = (state: EditorState): TransactionSpec => {
 		};
 		const listNumberStack: ListItemRecord[] = [];
 		let currentGroupIndentation = '';
-		let nextListNumber = 1;
+		let nextListNumber = firstListNumber;
 		let prevLineNumber;
 
 		for (const line of linesToHandle) {