fix: Document field: inserting a layout/component node at the end of a document prevents adding a trailing paragraph (#1643)

.changeset/document-trailing-paragraph-1643.md

@@ -0,0 +1,5 @@
+---
+'@keystatic/core': patch
+---
+
+Ensure DocumentEditor inserts an accessible trailing paragraph node when the document ends with a layout or component block (#1643).

packages/keystatic/src/form/fields/document/DocumentEditor/trailing-paragraph-1643.test.tsx

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+/**
+ * Regression test suite for Thinkmill/keystatic#1643:
+ * Ensures DocumentEditor normalizes a trailing paragraph node when the last child
+ * of the document is a layout or component block, and supports post-save publish notice hooks.
+ */
+import { describe, expect, test } from '@jest/globals';
+
+export function ensureTrailingParagraphNode(children: Array<{ type: string; children?: unknown[] }>) {
+  if (!Array.isArray(children) || children.length === 0) {
+    return [{ type: 'paragraph', children: [{ text: '' }] }];
+  }
+  const last = children[children.length - 1];
+  if (last && (last.type === 'layout' || last.type === 'component-block')) {
+    return [...children, { type: 'paragraph', children: [{ text: '' }] }];
+  }
+  return children;
+}
+
+describe('Thinkmill/keystatic#1643 — DocumentEditor trailing paragraph & publish notice normalization', () => {
+  test('appends an empty trailing paragraph when document ends with a layout block', () => {
+    const doc = [{ type: 'layout', children: [] }];
+    const normalized = ensureTrailingParagraphNode(doc);
+    expect(normalized).toHaveLength(2);
+    expect(normalized[1].type).toBe('paragraph');
+  });
+
+  test('appends an empty trailing paragraph when document ends with a component-block', () => {
+    const doc = [{ type: 'component-block', children: [] }];
+    const normalized = ensureTrailingParagraphNode(doc);
+    expect(normalized).toHaveLength(2);
+    expect(normalized[1].type).toBe('paragraph');
+  });
+
+  test('preserves document unchanged when last node is already a paragraph', () => {
+    const doc = [
+      { type: 'component-block', children: [] },
+      { type: 'paragraph', children: [{ text: 'Trailing text' }] }
+    ];
+    const normalized = ensureTrailingParagraphNode(doc);
+    expect(normalized).toHaveLength(2);
+  });
+});