fix: reset list numbering when switching from unordered to ordered list

src/static/js/ace2_inner.ts

@@ -2307,14 +2307,23 @@ function Ace2Inner(editorInfo, cssManagers) {
       let position = 1;
       let curLevel = level;
       let listType;
+      let prevType = '';
       // loop over the lines
       while ((listType = getLineListType(line))) {
         // apply new num
         listType = /([a-z]+)([0-9]+)/.exec(listType);
         curLevel = Number(listType[2]);
+        const curType = listType[1];
         if (isNaN(curLevel) || listType[0] === 'indent') {
           return line;
         } else if (curLevel === level) {
+          // Reset position when switching between list types at the same level
+          // (e.g., bullet -> number). See https://github.com/ether/etherpad-lite/issues/5160
+          if (prevType && prevType !== curType) {
+            position = 1;
+          }
+          prevType = curType;
+
           buildKeepRange(rep, builder, loc, (loc = [line, 0]));
           buildKeepRange(rep, builder, loc, (loc = [line, 1]), [
             ['start', position],

src/tests/frontend-new/specs/ordered_list.spec.ts

@@ -54,6 +54,44 @@ test.describe('ordered_list.js', function () {
     });
   });
 
+  // Regression test for https://github.com/ether/etherpad-lite/issues/5160
+  test('issue #5160 ordered list increments correctly after unordered list', async function ({page}) {
+    const padBody = await getPadBody(page);
+    await clearPadContent(page);
+
+    // Create two unordered list items
+    const $insertUnorderedButton = page.locator('.buttonicon-insertunorderedlist');
+    await $insertUnorderedButton.click({force: true});
+    await writeToPad(page, 'bullet a');
+    await page.keyboard.press('Enter');
+    await writeToPad(page, 'bullet b');
+    await page.keyboard.press('Enter');
+
+    // Now switch to ordered list for the next items
+    const $insertOrderedButton = page.locator('.buttonicon-insertorderedlist');
+    await $insertOrderedButton.click({force: true});
+    await writeToPad(page, 'number 1');
+    await page.keyboard.press('Enter');
+    await writeToPad(page, 'number 2');
+    await page.keyboard.press('Enter');
+    await writeToPad(page, 'number 3');
+
+    // Wait for renumbering
+    await page.waitForTimeout(500);
+
+    // The first ordered list item (line 3) should have start=1
+    const thirdLine = padBody.locator('div').nth(2);
+    await expect(thirdLine.locator('ol')).toHaveAttribute('start', '1', {timeout: 5000});
+
+    // The second ordered list item (line 4) should have start=2
+    const fourthLine = padBody.locator('div').nth(3);
+    await expect(fourthLine.locator('ol')).toHaveAttribute('start', '2', {timeout: 5000});
+
+    // The third ordered list item (line 5) should have start=3
+    const fifthLine = padBody.locator('div').nth(4);
+    await expect(fifthLine.locator('ol')).toHaveAttribute('start', '3', {timeout: 5000});
+  });
+
   test.describe('Pressing Tab in an OL increases and decreases indentation', function () {
 
     test('indent and de-indent list item with keypress', async function ({page}) {