From 22a62714232bc20c5522453ff59b56fd8a1980ff Mon Sep 17 00:00:00 2001
From: 01zulfi <85733202+01zulfi@users.noreply.github.com>
Date: Wed, 14 Jan 2026 10:56:31 +0500
Subject: [PATCH] editor: fix duplicate block-id on splitting node (#9198)

Signed-off-by: 01zulfi <85733202+01zulfi@users.noreply.github.com>
---
 .../block-id/__tests__/block-id.test.ts       | 46 +++++++++++++++++++
 .../src/extensions/block-id/block-id.ts       | 33 +++++++++----
 .../editor/src/extensions/heading/heading.ts  |  5 +-
 .../heading => utils}/batch-attribute-step.ts |  0
 4 files changed, 73 insertions(+), 11 deletions(-)
 create mode 100644 packages/editor/src/extensions/block-id/__tests__/block-id.test.ts
 rename packages/editor/src/{extensions/heading => utils}/batch-attribute-step.ts (100%)

diff --git a/packages/editor/src/extensions/block-id/__tests__/block-id.test.ts b/packages/editor/src/extensions/block-id/__tests__/block-id.test.ts
new file mode 100644
index 000000000..6d2a0898a
--- /dev/null
+++ b/packages/editor/src/extensions/block-id/__tests__/block-id.test.ts
@@ -0,0 +1,46 @@
+/*
+This file is part of the Notesnook project (https://notesnook.com/)
+
+Copyright (C) 2023 Streetwriters (Private) Limited
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+import { test, expect } from "vitest";
+import { createEditor, h } from "../../../../test-utils";
+import { Heading } from "../../heading";
+import { BlockId } from "../block-id";
+
+test("splitting a node with blockId should generate new blockId for the new node", async () => {
+  const el = h("div", [
+    h("h1", ["A heading one"], { "data-block-id": "blockid" })
+  ]);
+  const { editor } = createEditor({
+    extensions: {
+      heading: Heading.configure({ levels: [1, 2, 3, 4, 5, 6] }),
+      blockId: BlockId
+    },
+    initialContent: el.outerHTML
+  });
+
+  editor.commands.setTextSelection(9);
+  const event = new KeyboardEvent("keydown", { key: "Enter" });
+  editor.view.dom.dispatchEvent(event);
+  await new Promise((resolve) => setTimeout(resolve, 100));
+
+  const headings = editor.getJSON().content;
+  expect(headings?.[0].attrs?.blockId).toBe("blockid");
+  expect(headings?.[1].attrs?.blockId).not.toBeUndefined();
+  expect(headings?.[1].attrs?.blockId).not.toBe("blockid");
+});
diff --git a/packages/editor/src/extensions/block-id/block-id.ts b/packages/editor/src/extensions/block-id/block-id.ts
index ca16d7696..e3bc861f5 100644
--- a/packages/editor/src/extensions/block-id/block-id.ts
+++ b/packages/editor/src/extensions/block-id/block-id.ts
@@ -20,6 +20,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 import { Extension } from "@tiptap/core";
 import { Plugin } from "@tiptap/pm/state";
 import { nanoid } from "nanoid";
+import {
+  AttributeUpdate,
+  BatchAttributeStep
+} from "../../utils/batch-attribute-step.js";
 
 const NESTED_BLOCK_ID_TYPES = ["callout"];
 const BLOCK_ID_TYPES = [
@@ -74,24 +78,33 @@ export const BlockId = Extension.create({
           const isDocChanged = transactions.some((tr) => tr.docChanged);
           if (!isDocChanged) return null;
 
-          let updated = false;
+          const blockIds = new Set<string>();
+          const updates: AttributeUpdate[] = [];
           const { tr } = newState;
+
           tr.doc.forEach(function addBlockId(n, offset) {
             if (!n.isBlock || !BLOCK_ID_TYPES.includes(n.type.name)) return;
-            if (!n.attrs.blockId) {
-              const id = nanoid(8);
-              // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-              // @ts-ignore we can't use tr.setNodeMarkup as that creates
-              // a new transaction for every single node update causing
-              // significant performance issues
-              n.attrs.blockId = id;
-              updated = true;
+
+            const currentId = n.attrs.blockId;
+            const shouldUpdateId = !currentId || blockIds.has(currentId);
+            const finalId = shouldUpdateId ? nanoid(8) : currentId;
+
+            if (shouldUpdateId) {
+              updates.push({
+                pos: offset,
+                attrName: "blockId",
+                value: finalId
+              });
             }
 
+            blockIds.add(finalId);
+
             if (NESTED_BLOCK_ID_TYPES.includes(n.type.name))
               n.forEach((n, pos) => addBlockId(n, offset + pos + 1));
           });
-          if (updated) {
+
+          if (updates.length > 0) {
+            tr.step(new BatchAttributeStep(updates));
             tr.setMeta("ignoreEdit", true);
             return tr;
           }
diff --git a/packages/editor/src/extensions/heading/heading.ts b/packages/editor/src/extensions/heading/heading.ts
index a16efc0ae..7ad39e7f0 100644
--- a/packages/editor/src/extensions/heading/heading.ts
+++ b/packages/editor/src/extensions/heading/heading.ts
@@ -30,7 +30,10 @@ import {
   changedDescendants,
   findParentNodeOfTypeClosestToPos
 } from "../../utils/prosemirror.js";
-import { AttributeUpdate, BatchAttributeStep } from "./batch-attribute-step.js";
+import {
+  AttributeUpdate,
+  BatchAttributeStep
+} from "../../utils/batch-attribute-step.js";
 
 const COLLAPSIBLE_BLOCK_TYPES = [
   "paragraph",
diff --git a/packages/editor/src/extensions/heading/batch-attribute-step.ts b/packages/editor/src/utils/batch-attribute-step.ts
similarity index 100%
rename from packages/editor/src/extensions/heading/batch-attribute-step.ts
rename to packages/editor/src/utils/batch-attribute-step.ts