Include styleRuns in text edit undo

styleRuns were updated on the graph during editing (via syncText) but
commitTextEdit only captured text changes. Now both text and styleRuns
are snapshotted at startTextEditing and restored on undo.

packages/core/src/editor/text.ts

@@ -1,7 +1,9 @@
+import type { SceneNode } from '../scene-graph'
 import type { EditorContext } from './types'
 
 export function createTextActions(ctx: EditorContext) {
   let textBeforeEdit: string | null = null
+  let styleRunsBeforeEdit: SceneNode['styleRuns'] | null = null
 
   function startTextEditing(nodeId: string) {
     const te = ctx.getTextEditor()
@@ -9,6 +11,7 @@ export function createTextActions(ctx: EditorContext) {
     const node = ctx.graph.getNode(nodeId)
     if (!node) return
     textBeforeEdit = node.text
+    styleRunsBeforeEdit = structuredClone(node.styleRuns)
     ctx.state.editingTextId = nodeId
     if (te) {
       te.setRenderer(ctx.getRenderer())
@@ -22,28 +25,37 @@ export function createTextActions(ctx: EditorContext) {
     if (!te?.isActive) {
       ctx.state.editingTextId = null
       textBeforeEdit = null
+      styleRunsBeforeEdit = null
       return
     }
     const result = te.stop()
     if (!result) {
       ctx.state.editingTextId = null
       textBeforeEdit = null
+      styleRunsBeforeEdit = null
       ctx.requestRender()
       return
     }
     const prevText = textBeforeEdit ?? ''
+    const prevRuns = styleRunsBeforeEdit ?? []
     const newText = result.text
-    ctx.graph.updateNode(result.nodeId, { text: newText })
+    const node = ctx.graph.getNode(result.nodeId)
+    const newRuns = node ? structuredClone(node.styleRuns) : []
+    ctx.graph.updateNode(result.nodeId, { text: newText, styleRuns: newRuns })
     ctx.state.editingTextId = null
     textBeforeEdit = null
-    if (prevText !== newText) {
+    styleRunsBeforeEdit = null
+
+    const textChanged = prevText !== newText
+    const runsChanged = JSON.stringify(prevRuns) !== JSON.stringify(newRuns)
+    if (textChanged || runsChanged) {
       ctx.undo.push({
         label: 'Edit text',
         forward: () => {
-          ctx.graph.updateNode(result.nodeId, { text: newText })
+          ctx.graph.updateNode(result.nodeId, { text: newText, styleRuns: newRuns })
         },
         inverse: () => {
-          ctx.graph.updateNode(result.nodeId, { text: prevText })
+          ctx.graph.updateNode(result.nodeId, { text: prevText, styleRuns: prevRuns })
         }
       })
     }

tests/engine/text-edit-undo.test.ts

@@ -3,6 +3,7 @@ import { describe, test, expect } from 'bun:test'
 import { SceneGraph, TextEditor, UndoManager } from '@open-pencil/core'
 import { createTextActions } from '@open-pencil/core/editor'
 
+import type { StyleRun } from '@open-pencil/core'
 import type { EditorContext, EditorState } from '@open-pencil/core/editor'
 
 function setup() {
@@ -117,4 +118,58 @@ describe('text edit undo', () => {
     undo.undo()
     expect(graph.getNode(textNode.id)!.text).toBe('Hello')
   })
+
+  test('undo restores styleRuns when they changed during editing', () => {
+    const { graph, undo, textEditor, textNode, actions } = setup()
+
+    const boldRun: StyleRun = { start: 0, length: 5, style: { fontWeight: 700 } }
+    graph.updateNode(textNode.id, { styleRuns: [boldRun] })
+
+    actions.startTextEditing(textNode.id)
+
+    textEditor.insert(' World', textNode)
+    const newRuns: StyleRun[] = [
+      { start: 0, length: 5, style: { fontWeight: 700 } },
+      { start: 5, length: 6, style: { fontWeight: 400 } },
+    ]
+    graph.updateNode(textNode.id, { text: textEditor.state!.text, styleRuns: newRuns })
+
+    actions.commitTextEdit()
+
+    expect(graph.getNode(textNode.id)!.styleRuns).toEqual(newRuns)
+    expect(undo.canUndo).toBe(true)
+
+    undo.undo()
+    expect(graph.getNode(textNode.id)!.text).toBe('Hello')
+    expect(graph.getNode(textNode.id)!.styleRuns).toEqual([boldRun])
+
+    undo.redo()
+    expect(graph.getNode(textNode.id)!.text).toBe('Hello World')
+    expect(graph.getNode(textNode.id)!.styleRuns).toEqual(newRuns)
+  })
+
+  test('undo entry is pushed when only styleRuns changed', () => {
+    const { graph, undo, textNode, actions } = setup()
+
+    actions.startTextEditing(textNode.id)
+
+    const newRuns: StyleRun[] = [{ start: 0, length: 5, style: { fontWeight: 700 } }]
+    graph.updateNode(textNode.id, { styleRuns: newRuns })
+
+    actions.commitTextEdit()
+
+    expect(undo.canUndo).toBe(true)
+
+    undo.undo()
+    expect(graph.getNode(textNode.id)!.styleRuns).toEqual([])
+  })
+
+  test('no undo entry when neither text nor styleRuns changed', () => {
+    const { undo, actions, textNode } = setup()
+
+    actions.startTextEditing(textNode.id)
+    actions.commitTextEdit()
+
+    expect(undo.canUndo).toBe(false)
+  })
 })