fix(text-editor): reveal the change after undo, redo and paste

plugins/text-editor-resources/src/components/extension/__tests__/collaboration.test.ts

@@ -0,0 +1,91 @@
+//
+// Copyright © 2026 Hardcore Engineering Inc.
+//
+// Licensed under the Eclipse Public License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License. You may
+// obtain a copy of the License at https://www.eclipse.org/legal/epl-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import { type Node, Schema } from '@tiptap/pm/model'
+import { EditorState, TextSelection, type Transaction } from '@tiptap/pm/state'
+
+import { getChangedRange, revealChange } from '../collaboration'
+
+const schema = new Schema({
+  nodes: {
+    doc: { content: 'block+' },
+    text: { group: 'inline' },
+    paragraph: { group: 'block', content: 'inline*', toDOM: () => ['p', 0] }
+  }
+})
+
+function makeDoc (...paragraphs: string[]): Node {
+  return schema.node(
+    'doc',
+    undefined,
+    paragraphs.map((text) => schema.node('paragraph', undefined, text.length > 0 ? schema.text(text) : []))
+  )
+}
+
+describe('getChangedRange', () => {
+  it('returns null for equal documents', () => {
+    expect(getChangedRange(makeDoc('one', 'two'), makeDoc('one', 'two'))).toBeNull()
+  })
+
+  it('returns a collapsed range where text was removed', () => {
+    // "two!" -> "two": the removed "!" was at position 9 (after "two" in the second paragraph)
+    expect(getChangedRange(makeDoc('one', 'two!'), makeDoc('one', 'two'))).toEqual({ from: 9, to: 9 })
+  })
+
+  it('returns the inserted range in the new document', () => {
+    expect(getChangedRange(makeDoc('one', 'two'), makeDoc('one', 'two', 'three'))).toEqual({ from: 10, to: 17 })
+  })
+
+  it('handles changes next to identical content', () => {
+    expect(getChangedRange(makeDoc('aa'), makeDoc('a'))).toEqual({ from: 2, to: 2 })
+    expect(getChangedRange(makeDoc('a'), makeDoc('aa'))).toEqual({ from: 2, to: 3 })
+  })
+})
+
+describe('revealChange', () => {
+  function makeView (state: EditorState): { state: EditorState, dispatch: jest.Mock } {
+    const view = {
+      state,
+      dispatch: jest.fn((tr: Transaction) => {
+        view.state = view.state.apply(tr)
+      })
+    }
+    return view
+  }
+
+  it('moves the cursor to the changed place and scrolls it into view', () => {
+    const before = makeDoc('top', 'bottom!')
+    const doc = makeDoc('top', 'bottom')
+    const view = makeView(EditorState.create({ schema, doc, selection: TextSelection.create(doc, 1) }))
+
+    revealChange(view as any, before)
+
+    expect(view.dispatch).toHaveBeenCalledTimes(1)
+    const tr: Transaction = view.dispatch.mock.calls[0][0]
+    expect(tr.scrolledIntoView).toBe(true)
+    expect(tr.getMeta('addToHistory')).toBe(false)
+    expect(view.state.selection.from).toBe(12)
+    expect(view.state.selection.empty).toBe(true)
+  })
+
+  it('does nothing when the document did not change', () => {
+    const doc = makeDoc('top', 'bottom')
+    const view = makeView(EditorState.create({ schema, doc }))
+
+    revealChange(view as any, doc)
+
+    expect(view.dispatch).not.toHaveBeenCalled()
+  })
+})

plugins/text-editor-resources/src/components/extension/collaboration.ts

@@ -0,0 +1,80 @@
+//
+// Copyright © 2026 Hardcore Engineering Inc.
+//
+// Licensed under the Eclipse Public License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License. You may
+// obtain a copy of the License at https://www.eclipse.org/legal/epl-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import { type CommandProps } from '@tiptap/core'
+import Collaboration from '@tiptap/extension-collaboration'
+import { type Node } from '@tiptap/pm/model'
+import { Selection } from '@tiptap/pm/state'
+import { type EditorView } from '@tiptap/pm/view'
+
+/**
+ * Returns the range in `after` that differs from `before`, or null when both documents are equal.
+ */
+export function getChangedRange (before: Node, after: Node): { from: number, to: number } | null {
+  const from = before.content.findDiffStart(after.content)
+  if (from === null) return null
+
+  const end = before.content.findDiffEnd(after.content)
+  if (end === null) return { from, to: from }
+
+  // Both ends may overlap when the change is next to identical content (e.g. "aa" -> "a")
+  const overlap = from - Math.min(end.a, end.b)
+  const to = overlap > 0 ? end.b + overlap : end.b
+  return { from, to: Math.max(from, to) }
+}
+
+/**
+ * Moves the cursor to the place changed between `before` and the current document and scrolls it into view.
+ */
+export function revealChange (view: EditorView, before: Node): void {
+  const doc = view.state.doc
+  const range = getChangedRange(before, doc)
+  if (range === null) return
+
+  const selection = Selection.near(doc.resolve(range.to), -1)
+  view.dispatch(view.state.tr.setSelection(selection).scrollIntoView().setMeta('addToHistory', false))
+}
+
+// y-prosemirror restores the selection captured before the undo/redo, so a change made
+// outside the viewport stays invisible. Move the cursor to the changed place instead.
+function withRevealChange (command: () => (props: CommandProps) => boolean): (props: CommandProps) => boolean {
+  return (props) => {
+    const { view, dispatch } = props
+    if (dispatch === undefined) return command()(props)
+
+    const before = view.state.doc
+    const result = command()(props)
+    if (result) {
+      revealChange(view, before)
+    }
+    return result
+  }
+}
+
+export const CollaborationExtension = Collaboration.extend({
+  addCommands () {
+    const parent = this.parent?.()
+    if (parent === undefined) return {}
+
+    const { undo, redo } = parent
+    if (undo === undefined || redo === undefined) return parent
+
+    return {
+      ...parent,
+      undo: () => withRevealChange(undo),
+      redo: () => withRevealChange(redo)
+    }
+  }
+})

plugins/text-editor-resources/src/components/extension/shortcuts/__tests__/smartPaste.test.ts

@@ -214,6 +214,7 @@ describe('SmartPaste handlePaste transform scenarios', () => {
 
     expect(handled).toBe(true)
     expect(dispatch).toHaveBeenCalledTimes(1)
+    expect(dispatch.mock.calls[0][0].scrolledIntoView).toBe(true)
   })
 
   it('transforms when explicit markdown is present even with rich clipboard types', () => {

plugins/text-editor-resources/src/components/extension/shortcuts/smartPaste.ts

@@ -71,7 +71,7 @@ export function PasteTextAsMarkdownPlugin (): Plugin {
             const content = Node.fromJSON(view.state.schema, markupNode)
             content.check()
 
-            const transaction = view.state.tr.replaceSelectionWith(content)
+            const transaction = view.state.tr.replaceSelectionWith(content).scrollIntoView()
             view.dispatch(transaction)
             return true
           }

plugins/text-editor-resources/src/components/extension/shortcuts/tablePaste.ts

@@ -206,7 +206,7 @@ function TableMetadataPastePlugin (): Plugin {
             }
 
             const modifiedContent = rebuildNode(content)
-            const transaction = view.state.tr.replaceSelectionWith(modifiedContent)
+            const transaction = view.state.tr.replaceSelectionWith(modifiedContent).scrollIntoView()
             view.dispatch(transaction)
             return true // Handled
           }

plugins/text-editor-resources/src/kits/editor-kit.ts

@@ -34,7 +34,7 @@ import TableHeader from '@tiptap/extension-table-header'
 import 'prosemirror-codemark/dist/codemark.css'
 import 'katex/dist/katex.min.css'
 
-import Collaboration from '@tiptap/extension-collaboration'
+import { CollaborationExtension } from '../components/extension/collaboration'
 import CollaborationCursor from '@tiptap/extension-collaboration-cursor'
 import { CodeBlockHighlighExtension, codeBlockHighlightOptions } from '../components/extension/codeSnippets/codeblock'
 import { MermaidExtension, mermaidOptions } from '../components/extension/codeSnippets/mermaid'
@@ -180,7 +180,7 @@ const subKits = {
     'collaboration-kit',
     (e) =>
       ({
-        collaboration: e(Collaboration),
+        collaboration: e(CollaborationExtension),
         collaborationCursor: e(CollaborationCursor),
         inlineComments: e(InlineCommentCollaborationExtension)
       }) as const