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 +1,9 @@
 // Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
 
+exports[`Lift nested lists > Does not merge <li> nodes separated by non-whitespace text 1`] = `"<ul><li>a</li></ul>text<ul><li>b</li></ul>"`;
+
+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 +146,11 @@ 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 +143,36 @@ 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("Does not merge <li> nodes separated by non-whitespace text", async () => {
+    const html = `<li>a</li>text<li>b</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 +6,61 @@ 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: Set<Element> = 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);
+
+    // Walk siblings via nextSibling (not nextElementSibling) so we can stop
+    // at meaningful text between orphans — only whitespace text is allowed
+    // to bridge two orphan <li>s into the same <ul>.
+    let next: Node | null = orphan.nextSibling;
+    while (next) {
+      if (isWhitespaceNode(next)) {
+        next = next.nextSibling;
+        continue;
+      }
+      if (
+        next.nodeType === 1 &&
+        (next as Element).tagName === "LI" &&
+        orphanSet.has(next as Element)
+      ) {
+        group.push(next as Element);
+        handled.add(next as Element);
+        next = next.nextSibling;
+        continue;
+      }
+      break;
+    }
+
+    const ul = orphan.ownerDocument.createElement("ul");
+    orphan.parentNode!.insertBefore(ul, orphan);
+    for (const li of group) {
+      ul.appendChild(li);
+    }
+  }
+}
+
 /**
  * Step 1, Turns:
  *
@@ -117,6 +172,7 @@ export function nestedListsToBlockNoteStructure(
     element.innerHTML = elementOrHTML;
     elementOrHTML = element;
   }
+  wrapOrphanListItems(elementOrHTML);
   liftNestedListsToParent(elementOrHTML);
   createGroups(elementOrHTML);
   return elementOrHTML;