[pull] main from facebook:main

packages/lexical/src/LexicalDOMSlot.ts

@@ -431,11 +431,23 @@ export class ElementDOMSlot<
     lineBreakType: null | 'empty' | 'line-break' | 'decorator',
   ): void {
     const element: HTMLElement & LexicalPrivateDOM = this.element;
-    element.__lexicalLastChildKind = lineBreakType;
-    if (lineBreakType === null) {
+    // Slot containers are a contiguous prefix of the managed range, so only
+    // its first node needs to be inspected. This also excludes containers
+    // outside an `after` boundary.
+    const firstNode =
+      this.after === null ? element.firstChild : this.after.nextSibling;
+    const nextLineBreakType =
+      lineBreakType === 'empty' && isSlotContainerDOM(firstNode)
+        ? null
+        : lineBreakType;
+    if (element.__lexicalLastChildKind === nextLineBreakType) {
+      return;
+    }
+    element.__lexicalLastChildKind = nextLineBreakType;
+    if (nextLineBreakType === null) {
       this.removeManagedLineBreak();
     } else {
-      const webkitHack = lineBreakType === 'decorator' && IS_WEBKIT_BROWSER;
+      const webkitHack = nextLineBreakType === 'decorator' && IS_WEBKIT_BROWSER;
       this.insertManagedLineBreak(webkitHack);
     }
   }

packages/lexical/src/LexicalReconciler.ts

@@ -911,12 +911,7 @@ function $isLastChildLineBreakOrDecorator(
             : null;
       }
     }
-    // A host with slots but no linked-list children is not empty (the slots
-    // carry its content). The 'empty' line break exists to give a truly empty
-    // block a caret target; on a slots-only host that <br> would instead be a
-    // stray caret target in the host's own child area, after the slot
-    // containers — text typed there leaks out of the slot. Skip it.
-    return $readSlots(element).size > 0 ? null : 'empty';
+    return 'empty';
   }
   return null;
 }
@@ -962,20 +957,14 @@ function $reconcileElementTerminatingLineBreak(
   nextElement: ElementNode,
   dom: HTMLElement & LexicalPrivateDOM,
 ): void {
-  // Read previous render's last-child kind from the slot element's cache
-  // so the prev-state DecoratorNode reference's isInline() (which routes
-  // through getLatest() and would throw once the key is detached from the
-  // active node map) is never called.
   const slot = $getDOMSlot(nextElement, dom, activeEditor);
-  const slotElement: HTMLElement & LexicalPrivateDOM = slot.element;
-  const prevLineBreak = slotElement.__lexicalLastChildKind ?? null;
   const nextLineBreak = $isLastChildLineBreakOrDecorator(
     nextElement,
     activeNextNodeMap,
   );
-  if (prevLineBreak !== nextLineBreak) {
-    slot.setManagedLineBreak(nextLineBreak);
-  }
+  // ElementDOMSlot normalizes the empty state against the actual content
+  // range, including named-slot containers, and caches the result.
+  slot.setManagedLineBreak(nextLineBreak);
 }
 
 function reconcileTextFormat(element: ElementNode): void {

packages/lexical/src/__tests__/unit/LexicalDOMSlot.test.tsx

@@ -125,6 +125,19 @@ describe('ElementDOMSlot class', () => {
     expect(updated).toBe(original);
   });
 
+  test('setManagedLineBreak ignores slot containers before the managed range', () => {
+    const el = makeElement();
+    const slotContainer = document.createElement('div');
+    slotContainer.setAttribute('data-lexical-slot', 'title');
+    const after = document.createElement('span');
+    el.append(slotContainer, after);
+    const slot = new ElementDOMSlot(el, null, after);
+
+    inEditor(() => slot.setManagedLineBreak('empty'));
+
+    expect(slot.getManagedLineBreak()).not.toBe(null);
+  });
+
   test('insertChild appends when before is null', () => {
     const el = makeElement();
     const slot = new ElementDOMSlot(el);

packages/lexical/src/__tests__/unit/LexicalSlot.test.ts

@@ -143,6 +143,30 @@ class ReservedDeclaredHostNode extends ElementNode {
   }
 }
 
+class WrappedSlotHostNode extends ElementNode {
+  $config() {
+    return this.config('wrapped_slot_host', {
+      extends: ElementNode,
+      slots: ['title'],
+    });
+  }
+  createDOM() {
+    const host = document.createElement('div');
+    const content = document.createElement('span');
+    content.dataset.content = 'true';
+    host.appendChild(content);
+    return host;
+  }
+  updateDOM() {
+    return false;
+  }
+  getDOMSlot(dom: HTMLElement) {
+    return super
+      .getDOMSlot(dom)
+      .withElement(dom.querySelector<HTMLElement>('[data-content]') ?? dom);
+  }
+}
+
 const mountedRoots: HTMLElement[] = [];
 afterEach(() => {
   while (mountedRoots.length > 0) {
@@ -170,6 +194,7 @@ function createSlotEditor(): LexicalEditorWithDispose {
         ReorderedHostNode,
         DupDeclaredHostNode,
         ReservedDeclaredHostNode,
+        WrappedSlotHostNode,
       ],
     }),
   );
@@ -182,6 +207,35 @@ function createSlotEditor(): LexicalEditorWithDispose {
 }
 
 describe('named-slots: core foundation', () => {
+  test('an empty wrapped child area gets a managed line break', () => {
+    using editor = createSlotEditor();
+    let hostKey = '';
+
+    editor.update(
+      () => {
+        const host = $create(WrappedSlotHostNode).append(
+          $createTextNode('Body'),
+        );
+        $getRoot().append(host);
+        $setSlot(host, 'title', $slotContainer('Title'));
+        hostKey = host.getKey();
+      },
+      {discrete: true},
+    );
+    editor.update(
+      () => {
+        $assertNodeType($getNodeByKey(hostKey), $isElementNode).clear();
+      },
+      {discrete: true},
+    );
+
+    const hostDom = editor.getElementByKey(hostKey)!;
+    const content = hostDom.querySelector('[data-content]')!;
+    expect(
+      content.querySelector('[data-lexical-managed-linebreak="true"]'),
+    ).not.toBe(null);
+  });
+
   test('a slotted node is reachable, parentless, and attached', () => {
     using editor = createSlotEditor();
     let hostKey = '';
@@ -1398,6 +1452,29 @@ describe('named-slots: core foundation', () => {
     // A truly empty host (no slots, no children) still gets the br — the
     // gate is scoped to slots-only hosts.
     expect(directBr(editor.getElementByKey(emptyHostKey)!)).not.toBe(undefined);
+
+    editor.update(
+      () => {
+        $removeSlot(
+          $assertNodeType($getNodeByKey(slotHostKey), $isElementNode),
+          'title',
+        );
+      },
+      {discrete: true},
+    );
+    expect(directBr(editor.getElementByKey(slotHostKey)!)).not.toBe(undefined);
+
+    editor.update(
+      () => {
+        $setSlot(
+          $assertNodeType($getNodeByKey(slotHostKey), $isElementNode),
+          'title',
+          $slotContainer('New title'),
+        );
+      },
+      {discrete: true},
+    );
+    expect(directBr(editor.getElementByKey(slotHostKey)!)).toBeUndefined();
   });
 
   test('descendant navigation stays children-only (slots stay out of selection)', () => {