feat: select group children on click (#9149)

## Summary

Add a setting to select all children (nodes, reroutes, nested groups)
when clicking a group on the canvas.

## Changes

- **What**: New `LiteGraph.Group.SelectChildrenOnClick` boolean setting
(default: `false`). When enabled, selecting a group cascades `select()`
to all its `_children`, and deselecting cascades `deselect()`. Recursion
handles nested groups naturally. No double-move risk — the drag handler
already uses `skipChildren=true`. The setting is wired via `onChange` to
`canvas.groupSelectChildren`, keeping litegraph free of platform
imports.

## Review Focus

- The select/deselect cascading in `LGraphCanvas.select()` /
`deselect()` — verify no infinite recursion risk with deeply nested
groups.
- The `groupSelectChildren` property is set via the setting's `onChange`
callback on `LGraphCanvas.active_canvas` — confirm this covers canvas
re-creation scenarios.

## Screenshots (if applicable)

N/A — behavioral change behind a setting toggle.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9149-feat-select-group-children-on-click-3116d73d365081a1a7b8c82dea95b242)
by [Unito](https://www.unito.io)

---------

Co-authored-by: GitHub Action <action@github.com>

browser_tests/tests/groupSelectChildren.spec.ts

@@ -0,0 +1,123 @@
+import { expect } from '@playwright/test'
+
+import { comfyPageFixture as test } from '../fixtures/ComfyPage'
+import type { ComfyPage } from '../fixtures/ComfyPage'
+
+/**
+ * Returns the client-space position of a group's title bar (for clicking).
+ */
+async function getGroupTitlePosition(
+  comfyPage: ComfyPage,
+  title: string
+): Promise<{ x: number; y: number }> {
+  const pos = await comfyPage.page.evaluate((title) => {
+    const app = window.app!
+    const group = app.graph.groups.find(
+      (g: { title: string }) => g.title === title
+    )
+    if (!group) return null
+    const clientPos = app.canvasPosToClientPos([
+      group.pos[0] + 50,
+      group.pos[1] + 15
+    ])
+    return { x: clientPos[0], y: clientPos[1] }
+  }, title)
+  if (!pos) throw new Error(`Group "${title}" not found`)
+  return pos
+}
+
+/**
+ * Returns {selectedNodeCount, selectedGroupCount, selectedItemCount}
+ * from the canvas in the browser.
+ */
+async function getSelectionCounts(comfyPage: ComfyPage) {
+  return comfyPage.page.evaluate(() => {
+    const canvas = window.app!.canvas
+    let selectedNodeCount = 0
+    let selectedGroupCount = 0
+    for (const item of canvas.selectedItems) {
+      if ('inputs' in item || 'outputs' in item) selectedNodeCount++
+      else selectedGroupCount++
+    }
+    return {
+      selectedNodeCount,
+      selectedGroupCount,
+      selectedItemCount: canvas.selectedItems.size
+    }
+  })
+}
+
+test.describe('Group Select Children', { tag: ['@canvas', '@node'] }, () => {
+  test.afterEach(async ({ comfyPage }) => {
+    await comfyPage.canvasOps.resetView()
+  })
+
+  test('Setting enabled: clicking outer group selects nested group and inner node', async ({
+    comfyPage
+  }) => {
+    await comfyPage.settings.setSetting(
+      'LiteGraph.Group.SelectChildrenOnClick',
+      true
+    )
+    await comfyPage.workflow.loadWorkflow('groups/nested-groups-1-inner-node')
+    await comfyPage.nextFrame()
+
+    const outerPos = await getGroupTitlePosition(comfyPage, 'Outer Group')
+    await comfyPage.canvas.click({ position: outerPos })
+    await comfyPage.nextFrame()
+
+    const counts = await getSelectionCounts(comfyPage)
+    // Outer Group + Inner Group + 1 node = 3 items
+    expect(counts.selectedItemCount).toBe(3)
+    expect(counts.selectedGroupCount).toBe(2)
+    expect(counts.selectedNodeCount).toBe(1)
+  })
+
+  test('Setting disabled: clicking outer group selects only the group', async ({
+    comfyPage
+  }) => {
+    await comfyPage.settings.setSetting(
+      'LiteGraph.Group.SelectChildrenOnClick',
+      false
+    )
+    await comfyPage.workflow.loadWorkflow('groups/nested-groups-1-inner-node')
+    await comfyPage.nextFrame()
+
+    const outerPos = await getGroupTitlePosition(comfyPage, 'Outer Group')
+    await comfyPage.canvas.click({ position: outerPos })
+    await comfyPage.nextFrame()
+
+    const counts = await getSelectionCounts(comfyPage)
+    expect(counts.selectedItemCount).toBe(1)
+    expect(counts.selectedGroupCount).toBe(1)
+    expect(counts.selectedNodeCount).toBe(0)
+  })
+
+  test('Deselecting outer group deselects all children', async ({
+    comfyPage
+  }) => {
+    await comfyPage.settings.setSetting(
+      'LiteGraph.Group.SelectChildrenOnClick',
+      true
+    )
+    await comfyPage.workflow.loadWorkflow('groups/nested-groups-1-inner-node')
+    await comfyPage.nextFrame()
+
+    // Select the outer group (cascades to children)
+    const outerPos = await getGroupTitlePosition(comfyPage, 'Outer Group')
+    await comfyPage.canvas.click({ position: outerPos })
+    await comfyPage.nextFrame()
+
+    let counts = await getSelectionCounts(comfyPage)
+    expect(counts.selectedItemCount).toBe(3)
+
+    // Deselect all via page.evaluate to avoid UI overlay interception
+    await comfyPage.page.evaluate(() => {
+      window.app!.canvas.deselectAll()
+    })
+    await comfyPage.nextFrame()
+
+    counts = await getSelectionCounts(comfyPage)
+    expect(counts.selectedItemCount).toBe(0)
+  })
+})