fix(core): preserve list item type when pasting into empty list items

packages/core/src/api/parsers/html/util/__snapshots__/nestedLists.test.ts.snap

@@ -1,5 +1,7 @@
 // Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
 
+exports[`Lift nested lists > Leaves <li>s already inside a <ul> alone 1`] = `"<ul><li>existing</li></ul><ul><li>orphan</li></ul>"`;
+
 exports[`Lift nested lists > Lifts multiple bullet lists 1`] = `
 "<ul>
     <div><li>
@@ -142,3 +144,11 @@ exports[`Lift nested lists > Lifts nested numbered lists 1`] = `
     </li>
  </ol>"
 `;
+
+exports[`Lift nested lists > Wraps a single bare <li> in a <ul> 1`] = `"<ul><li>only</li></ul>"`;
+
+exports[`Lift nested lists > Wraps bare <li>s mixed with other top-level content 1`] = `"<p>before</p><ul><li>x</li><li>y</li></ul><p>after</p>"`;
+
+exports[`Lift nested lists > Wraps consecutive bare <li> elements in a <ul> 1`] = `"<ul><li>a</li><li>b</li></ul>"`;
+
+exports[`Lift nested lists > Wraps nested orphan <li>s as inner lists 1`] = `"<ul><li>outer</li><li>inner</li></ul>"`;

packages/core/src/api/parsers/html/util/nestedLists.test.ts

@@ -143,6 +143,31 @@ describe("Lift nested lists", () => {
     await testHTML(html);
   });
 
+  it("Wraps consecutive bare <li> elements in a <ul>", async () => {
+    const html = `<li>a</li><li>b</li>`;
+    await testHTML(html);
+  });
+
+  it("Wraps a single bare <li> in a <ul>", async () => {
+    const html = `<li>only</li>`;
+    await testHTML(html);
+  });
+
+  it("Wraps bare <li>s mixed with other top-level content", async () => {
+    const html = `<p>before</p><li>x</li><li>y</li><p>after</p>`;
+    await testHTML(html);
+  });
+
+  it("Leaves <li>s already inside a <ul> alone", async () => {
+    const html = `<ul><li>existing</li></ul><li>orphan</li>`;
+    await testHTML(html);
+  });
+
+  it("Wraps nested orphan <li>s as inner lists", async () => {
+    const html = `<li>outer<li>inner</li></li>`;
+    await testHTML(html);
+  });
+
   it("Lifts nested mixed lists", async () => {
     const html = `<ol>
     <li>

packages/core/src/api/parsers/html/util/nestedLists.ts

@@ -6,6 +6,46 @@ function isWhitespaceNode(node: Node) {
   return node.nodeType === 3 && !/\S/.test(node.nodeValue || "");
 }
 
+/**
+ * Step 0, wraps any `<li>` element that is not inside a `<ul>`/`<ol>` in a
+ * fresh `<ul>` so the existing parse rules (which require an `<ul>`/`<ol>`
+ * parent) match. Consecutive orphan `<li>` siblings are grouped under a
+ * single `<ul>`.
+ *
+ * Without this, pasting bare `<li>a</li><li>b</li>` HTML would parse as two
+ * paragraphs because the BulletListItem parse rule only matches `<li>`
+ * whose parent is `<ul>`.
+ */
+function wrapOrphanListItems(element: HTMLElement) {
+  const orphans = Array.from(element.querySelectorAll("li")).filter(
+    (li) => li.closest("ul, ol") === null,
+  );
+  const orphanSet = new Set(orphans);
+  const handled = new Set<Element>();
+
+  for (const orphan of orphans) {
+    if (handled.has(orphan)) {
+      continue;
+    }
+
+    const group: Element[] = [orphan];
+    handled.add(orphan);
+
+    let next = orphan.nextElementSibling;
+    while (next && next.tagName === "LI" && orphanSet.has(next as HTMLElement)) {
+      group.push(next);
+      handled.add(next);
+      next = next.nextElementSibling;
+    }
+
+    const ul = orphan.ownerDocument.createElement("ul");
+    orphan.parentNode!.insertBefore(ul, orphan);
+    for (const li of group) {
+      ul.appendChild(li);
+    }
+  }
+}
+
 /**
  * Step 1, Turns:
  *
@@ -117,6 +157,7 @@ export function nestedListsToBlockNoteStructure(
     element.innerHTML = elementOrHTML;
     elementOrHTML = element;
   }
+  wrapOrphanListItems(elementOrHTML);
   liftNestedListsToParent(elementOrHTML);
   createGroups(elementOrHTML);
   return elementOrHTML;

packages/core/src/editor/transformPasted.test.ts

@@ -0,0 +1,285 @@
+import { TextSelection } from "@tiptap/pm/state";
+import { describe, expect, it } from "vitest";
+
+import { BlockNoteEditor } from "./BlockNoteEditor.js";
+
+/**
+ * @vitest-environment jsdom
+ */
+
+function mountEditor(editor: BlockNoteEditor<any, any, any>) {
+  editor.mount(document.createElement("div"));
+}
+
+function selectStartOfFirstBlock(editor: BlockNoteEditor) {
+  editor.transact((tr) => {
+    let pos: number | undefined;
+    tr.doc.descendants((node, nodePos) => {
+      if (node.type.spec.group === "blockContent") {
+        pos = nodePos + 1;
+        return false;
+      }
+      return pos === undefined;
+    });
+    tr.setSelection(TextSelection.create(tr.doc, pos!));
+  });
+}
+
+describe("paste into empty inline-content block", () => {
+  it.each(["bulletListItem", "numberedListItem", "checkListItem"] as const)(
+    "pastes a paragraph into an empty %s without replacing it",
+    (type) => {
+      const editor = BlockNoteEditor.create({
+        initialContent: [{ type, content: "" }],
+      });
+      mountEditor(editor);
+      selectStartOfFirstBlock(editor);
+
+      editor.pasteHTML(`<p>Pasted</p>`);
+
+      const blocks = editor.document;
+      expect(blocks[0].type).toBe(type);
+      expect(blocks[0].content).toEqual([
+        { type: "text", text: "Pasted", styles: {} },
+      ]);
+    },
+  );
+
+  it("inserts paragraph content into an empty list item without dropping marks", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "" }],
+    });
+    mountEditor(editor);
+    selectStartOfFirstBlock(editor);
+
+    editor.pasteHTML(`<p>Hello <strong>world</strong></p>`);
+
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("bulletListItem");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "Hello ", styles: {} },
+      { type: "text", text: "world", styles: { bold: true } },
+    ]);
+  });
+
+  it("merges leading paragraph into empty list item and inserts rest as siblings", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "" }],
+    });
+    mountEditor(editor);
+    selectStartOfFirstBlock(editor);
+
+    editor.pasteHTML(`<p>First</p><p>Second</p>`);
+
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("bulletListItem");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "First", styles: {} },
+    ]);
+    expect(blocks[1].type).toBe("paragraph");
+    expect(blocks[1].content).toEqual([
+      { type: "text", text: "Second", styles: {} },
+    ]);
+  });
+
+  it("replaces an empty list item with a heading when pasting a heading", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "" }],
+    });
+    mountEditor(editor);
+    selectStartOfFirstBlock(editor);
+
+    editor.pasteHTML(`<h1>Heading</h1>`);
+
+    // The empty list item is replaced by the heading rather than absorbing
+    // its inline content. Headings carry semantic meaning the user explicitly
+    // chose, so we keep them as-is.
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("heading");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "Heading", styles: {} },
+    ]);
+  });
+
+  it("keeps the list item but discards the heading wrapper when a paragraph follows the heading", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "" }],
+    });
+    mountEditor(editor);
+    selectStartOfFirstBlock(editor);
+
+    // Heading first means the leading block is not a paragraph, so the
+    // unwrap/retype rule doesn't apply: the empty list item gets replaced
+    // by the pasted heading and the trailing paragraph follows as a sibling.
+    editor.pasteHTML(`<h1>Heading</h1><p>Body</p>`);
+
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("heading");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "Heading", styles: {} },
+    ]);
+    expect(blocks[1].type).toBe("paragraph");
+    expect(blocks[1].content).toEqual([
+      { type: "text", text: "Body", styles: {} },
+    ]);
+  });
+
+  it("still replaces the empty list item when pasting another list item", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "" }],
+    });
+    mountEditor(editor);
+    selectStartOfFirstBlock(editor);
+
+    editor.pasteHTML(`<ul><li>Pasted item</li></ul>`);
+
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("bulletListItem");
+    // The empty list item should be replaced (not have inline content
+    // appended in-place), which matches the existing behavior.
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "Pasted item", styles: {} },
+    ]);
+  });
+
+  it("pastes a paragraph into a non-empty list item without replacing it", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "abc" }],
+    });
+    mountEditor(editor);
+    editor.setTextCursorPosition(editor.document[0].id, "end");
+
+    editor.pasteHTML(`<p>hello</p>`);
+
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("bulletListItem");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "abchello", styles: {} },
+    ]);
+  });
+
+  it("pastes bare <li>a</li><li>b</li> into an empty list item as two list items", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "" }],
+    });
+    mountEditor(editor);
+    selectStartOfFirstBlock(editor);
+
+    editor.pasteHTML(`<li>a</li><li>b</li>`);
+
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("bulletListItem");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "a", styles: {} },
+    ]);
+    expect(blocks[1].type).toBe("bulletListItem");
+    expect(blocks[1].content).toEqual([
+      { type: "text", text: "b", styles: {} },
+    ]);
+  });
+
+  it("pastes bare <li>a</li><li>b</li> into a non-empty list item, splicing the first into the cursor", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "X" }],
+    });
+    mountEditor(editor);
+    editor.setTextCursorPosition(editor.document[0].id, "end");
+
+    editor.pasteHTML(`<li>a</li><li>b</li>`);
+
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("bulletListItem");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "Xa", styles: {} },
+    ]);
+    expect(blocks[1].type).toBe("bulletListItem");
+    expect(blocks[1].content).toEqual([
+      { type: "text", text: "b", styles: {} },
+    ]);
+  });
+
+  it("pastes two list items into an empty list item as two siblings", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "" }],
+    });
+    mountEditor(editor);
+    selectStartOfFirstBlock(editor);
+
+    editor.pasteHTML(`<ul><li>a</li><li>b</li></ul>`);
+
+    // The empty list item is replaced by the two pasted list items.
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("bulletListItem");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "a", styles: {} },
+    ]);
+    expect(blocks[1].type).toBe("bulletListItem");
+    expect(blocks[1].content).toEqual([
+      { type: "text", text: "b", styles: {} },
+    ]);
+  });
+
+  it("pastes two list items into a non-empty list item, splicing the first into the cursor", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "X" }],
+    });
+    mountEditor(editor);
+    editor.setTextCursorPosition(editor.document[0].id, "end");
+
+    editor.pasteHTML(`<ul><li>a</li><li>b</li></ul>`);
+
+    // The first list item's inline content is spliced at the cursor (the
+    // existing list item becomes "Xa") and the second list item becomes a
+    // new sibling.
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("bulletListItem");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "Xa", styles: {} },
+    ]);
+    expect(blocks[1].type).toBe("bulletListItem");
+    expect(blocks[1].content).toEqual([
+      { type: "text", text: "b", styles: {} },
+    ]);
+  });
+
+  it("preserves nested list structure when pasting a nested list into an empty list item", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "bulletListItem", content: "" }],
+    });
+    mountEditor(editor);
+    selectStartOfFirstBlock(editor);
+
+    // Pasting a list with nested children: the leading block is a list item,
+    // so the unwrap/retype rule does not apply and the existing slice-level
+    // list-nesting fix in `transformPasted` keeps the nested structure
+    // intact.
+    editor.pasteHTML(`<ul><li>Outer<ul><li>Inner</li></ul></li></ul>`);
+
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("bulletListItem");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "Outer", styles: {} },
+    ]);
+    expect(blocks[0].children).toHaveLength(1);
+    expect(blocks[0].children[0].type).toBe("bulletListItem");
+    expect(blocks[0].children[0].content).toEqual([
+      { type: "text", text: "Inner", styles: {} },
+    ]);
+  });
+
+  it("preserves the existing paragraph behavior when pasting into a non-empty paragraph", () => {
+    const editor = BlockNoteEditor.create({
+      initialContent: [{ type: "paragraph", content: "Existing " }],
+    });
+    mountEditor(editor);
+    editor.setTextCursorPosition(editor.document[0].id, "end");
+
+    editor.pasteHTML(`<p>added</p>`);
+
+    const blocks = editor.document;
+    expect(blocks[0].type).toBe("paragraph");
+    expect(blocks[0].content).toEqual([
+      { type: "text", text: "Existing added", styles: {} },
+    ]);
+  });
+});