FIX - support folder dragging across scaling (#41)

frontend/src/components/HomeFolderInteraction.contract.test.ts

@@ -26,6 +26,10 @@ const mainCss = readFileSync(
   new URL('../assets/main.css', import.meta.url),
   'utf8',
 )
+const openedFolderAppBlocks =
+  overlaySource.match(/<AppIcon\b[\s\S]*?\/>/g) ?? []
+const homeFolderIconBlocks =
+  springboardSource.match(/<HomeFolderIcon\b[\s\S]*?\/>/g) ?? []
 
 describe('Home folder interaction contract', () => {
   it('opens folders from edit mode and starts dragging only after movement', () => {
@@ -36,7 +40,7 @@ describe('Home folder interaction contract', () => {
     expect(iconSource).not.toContain('props.editMode || suppressClick.value')
   })
 
-  it('keeps folder app dragging aligned at every phone scale', () => {
+  it('keeps whole-folder dragging aligned at every phone scale', () => {
     expect(dragSource).toContain("'.springboard-page, .home-folder-panel'")
     expect(dragSource).toContain('viewportWidth: bounds.width')
     expect(dragSource).not.toContain("getPropertyValue('zoom')")
@@ -47,6 +51,60 @@ describe('Home folder interaction contract', () => {
     )
   })
 
+  it('routes whole folders from both the grid and dock through the shared drag portal', () => {
+    expect(homeFolderIconBlocks).toHaveLength(2)
+    for (const area of ['grid', 'dock'] as const) {
+      const block = homeFolderIconBlocks.find((candidate) =>
+        candidate.includes(`data-home-area="${area}"`),
+      )
+
+      expect(block).toBeDefined()
+      expect(block).toContain(':external-drag-visual="homeDragVisualActive"')
+      expect(block).toContain('@dragcancel="stopHomeDrag"')
+      expect(block).toContain('@dragend="finishHomeDrag"')
+      expect(block).toContain('@dragmove="moveHomeDrag"')
+      expect(block).toContain(`@dragstart="startHomeDrag('${area}',`)
+    }
+  })
+
+  it('uses the external viewport visual for apps dragged from an opened folder', () => {
+    expect(openedFolderAppBlocks).toHaveLength(1)
+    expect(overlaySource).toMatch(/externalDragVisual\??:\s*boolean/)
+    expect(openedFolderAppBlocks[0]).toContain(
+      ':external-drag-visual="externalDragVisual"',
+    )
+    expect(appIconSource).toContain('externalDragVisual?: boolean')
+    expect(appIconSource).toContain('app-icon-item--drag-source')
+  })
+
+  it('forwards opened-folder pointer start, move, and cancellation to the parent session', () => {
+    expect(overlaySource).toMatch(
+      /function startFolderAppDrag\(index: number, event: PointerEvent\)/,
+    )
+    expect(overlaySource).toContain("emit('dragstart', index, event)")
+    expect(overlaySource).toContain("emit('dragmove', event)")
+    expect(overlaySource).toContain("emit('dragcancel')")
+    expect(openedFolderAppBlocks[0]).toContain(
+      '@dragstart="startFolderAppDrag(entry.index, $event)"',
+    )
+    expect(openedFolderAppBlocks[0]).toContain('@dragmove="moveFolderAppDrag"')
+    expect(openedFolderAppBlocks[0]).toContain(
+      '@dragcancel="stopFolderAppDrag"',
+    )
+  })
+
+  it('hit-tests the opened folder panel and app targets in normalized viewport coordinates', () => {
+    expect(overlaySource).toContain('readPhoneViewportGeometry')
+    expect(overlaySource).toContain('phoneViewportRectContainsPoint')
+    expect(overlaySource).toContain('folderDragViewportRect(panel)')
+    expect(overlaySource).toContain('folderDragViewportRect(element)')
+    expect(overlaySource).toMatch(/geometry\?\.rect\(element\)/)
+    expect(overlaySource).not.toContain(
+      'panelElement.value?.getBoundingClientRect()',
+    )
+    expect(overlaySource).not.toContain('document.elementsFromPoint')
+  })
+
   it('edits the folder name inline with Sky UI controls', () => {
     expect(overlaySource).toContain('<SkyField')
     expect(overlaySource).toContain('home-folder-heading--editing')
@@ -63,8 +121,9 @@ describe('Home folder interaction contract', () => {
     expect(springboardSource).toContain(
       '@drag-outside-change="folderDraggingOutside = $event"',
     )
+    expect(overlaySource).toContain('if (draggingIndex.value === null) return')
     expect(overlaySource).toContain(
-      'if (draggingIndex.value === null || draggingOutside.value) return',
+      'if (!draggingOutside.value && !isPointerInsidePanel(event))',
     )
     expect(overlaySource).toContain(
       'draggingOutside.value || !isPointerInsidePanel(event)',

frontend/src/components/HomeFolderOverlay.vue

@@ -1,6 +1,6 @@
 <script setup lang="ts">
 import { Check, Pencil, X } from 'lucide-vue-next'
-import { computed, nextTick, ref, watch } from 'vue'
+import { computed, nextTick, onBeforeUnmount, ref, watch } from 'vue'
 
 import AppIcon from '@/components/AppIcon.vue'
 import { usePhoneStore } from '@/stores/phone'
@@ -11,20 +11,35 @@ import {
   HOME_FOLDER_PAGE_SIZE,
   type HomeFolder,
 } from '@/utils/homeLayout'
+import {
+  phoneViewportRectContainsPoint,
+  readPhoneViewportGeometry,
+  type PhoneViewportGeometry,
+  type PhoneViewportRect,
+} from '@/utils/phoneViewportGeometry'
 
 type FolderAppEntry = {
   app: PhoneAppDefinition
   index: number
 }
 
-const props = defineProps<{
-  apps: FolderAppEntry[]
-  editMode: boolean
-  folder: HomeFolder
-  renameOnOpen: boolean
-}>()
+const props = withDefaults(
+  defineProps<{
+    apps: FolderAppEntry[]
+    editMode: boolean
+    externalDragVisual?: boolean
+    folder: HomeFolder
+    renameOnOpen: boolean
+  }>(),
+  {
+    externalDragVisual: false,
+  },
+)
 const emit = defineEmits<{
   close: []
+  dragcancel: []
+  dragmove: [event: PointerEvent]
+  dragstart: [index: number, event: PointerEvent]
   'drag-outside-change': [outside: boolean]
   edit: []
   extract: [index: number, event: PointerEvent]
@@ -43,6 +58,7 @@ const renameOpened = ref(false)
 const renameDraft = ref('')
 let pagePointerStart = 0
 let pagePointerId: number | null = null
+let dragGeometry: PhoneViewportGeometry | null = null
 
 const folderName = computed(
   () => props.folder.name || phone.t('Home.folders.defaultName'),
@@ -113,25 +129,48 @@ function saveRename(): void {
   renameOpened.value = false
 }
 
-function startFolderAppDrag(index: number): void {
+function startFolderAppDrag(index: number, event: PointerEvent): void {
   draggingIndex.value = index
+  dragGeometry = readPhoneViewportGeometry(panelElement.value)
   setDraggingOutside(false)
+  emit('dragstart', index, event)
+}
+
+function fallbackViewportRect(element: Element): PhoneViewportRect {
+  const bounds = element.getBoundingClientRect()
+  return {
+    bottom: bounds.bottom,
+    height: bounds.height,
+    left: bounds.left,
+    right: bounds.right,
+    top: bounds.top,
+    width: bounds.width,
+  }
+}
+
+function folderDragViewportRect(element: Element): PhoneViewportRect {
+  const geometry = dragGeometry ?? readPhoneViewportGeometry(element)
+  return geometry?.rect(element) ?? fallbackViewportRect(element)
 }
 
 function isPointerInsidePanel(event: PointerEvent): boolean {
-  const panelBounds = panelElement.value?.getBoundingClientRect()
-  if (!panelBounds) return false
+  const panel = panelElement.value
   return (
-    event.clientX >= panelBounds.left &&
-    event.clientX <= panelBounds.right &&
-    event.clientY >= panelBounds.top &&
-    event.clientY <= panelBounds.bottom
+    panel !== null &&
+    phoneViewportRectContainsPoint(
+      folderDragViewportRect(panel),
+      event.clientX,
+      event.clientY,
+    )
   )
 }
 
 function moveFolderAppDrag(event: PointerEvent): void {
-  if (draggingIndex.value === null || draggingOutside.value) return
-  if (!isPointerInsidePanel(event)) setDraggingOutside(true)
+  if (draggingIndex.value === null) return
+  if (!draggingOutside.value && !isPointerInsidePanel(event)) {
+    setDraggingOutside(true)
+  }
+  emit('dragmove', event)
 }
 
 function setDraggingOutside(outside: boolean): void {
@@ -145,31 +184,52 @@ function finishFolderAppDrag(event: PointerEvent): void {
   const shouldExtract = draggingOutside.value || !isPointerInsidePanel(event)
   draggingIndex.value = null
   if (sourceIndex === null) {
+    dragGeometry = null
     setDraggingOutside(false)
+    emit('dragcancel')
     return
   }
   if (shouldExtract) {
     emit('extract', sourceIndex, event)
+    dragGeometry = null
     setDraggingOutside(false)
     return
   }
   setDraggingOutside(false)
 
-  const target = document
-    .elementsFromPoint(event.clientX, event.clientY)
-    .map((element) => element.closest<HTMLElement>('[data-folder-app-index]'))
-    .find(
-      (element) =>
-        element && Number(element.dataset.folderAppIndex) !== sourceIndex,
-    )
-  if (!target) return
+  const target = Array.from(
+    panelElement.value?.querySelectorAll<HTMLElement>(
+      '[data-folder-app-index]',
+    ) ?? [],
+  ).find(
+    (element) =>
+      Number(element.dataset.folderAppIndex) !== sourceIndex &&
+      phoneViewportRectContainsPoint(
+        folderDragViewportRect(element),
+        event.clientX,
+        event.clientY,
+      ),
+  )
+  if (!target) {
+    dragGeometry = null
+    emit('dragcancel')
+    return
+  }
   const targetIndex = Number(target.dataset.folderAppIndex)
-  if (Number.isInteger(targetIndex)) emit('move', sourceIndex, targetIndex)
+  dragGeometry = null
+  if (!Number.isInteger(targetIndex)) {
+    emit('dragcancel')
+    return
+  }
+  emit('move', sourceIndex, targetIndex)
 }
 
 function stopFolderAppDrag(): void {
+  const wasDragging = draggingIndex.value !== null
   draggingIndex.value = null
+  dragGeometry = null
   setDraggingOutside(false)
+  if (wasDragging) emit('dragcancel')
 }
 
 function goToPage(page: number): void {
@@ -195,6 +255,11 @@ function finishPageSwipe(event: PointerEvent): void {
   }
   pagePointerId = null
 }
+
+onBeforeUnmount(() => {
+  stopFolderAppDrag()
+  pagePointerId = null
+})
 </script>
 
 <template>
@@ -290,10 +355,11 @@ function finishPageSwipe(event: PointerEvent): void {
                 :app="entry.app"
                 :data-folder-app-index="entry.index"
                 :edit-mode="editMode"
+                :external-drag-visual="externalDragVisual"
                 @dragcancel="stopFolderAppDrag"
                 @dragend="finishFolderAppDrag"
                 @dragmove="moveFolderAppDrag"
-                @dragstart="startFolderAppDrag(entry.index)"
+                @dragstart="startFolderAppDrag(entry.index, $event)"
                 @edit="emit('edit')"
               />
             </div>

frontend/src/stores/app-store.test.ts

@@ -474,6 +474,41 @@ describe('app store', () => {
     expect(mocks.phone.saveDeviceNamespace).toHaveBeenCalledTimes(5)
   })
 
+  it('materializes a trailing page only for a successful folder extraction', () => {
+    const apps = useAppStoreStore()
+    apps.hydrate(null)
+
+    const notesIndex = apps.homeLayout.grid.indexOf('notes')
+    const settingsIndex = apps.homeLayout.grid.indexOf('settings')
+    const folderId = apps.createHomeFolder(
+      'grid',
+      notesIndex,
+      'grid',
+      settingsIndex,
+      'Utilities',
+    )
+    expect(folderId).toBeTruthy()
+
+    const originalPageCount = apps.homeLayout.pageCount
+    const targetPage = originalPageCount + 1
+    const targetIndex = originalPageCount * HOME_GRID_PAGE_SIZE
+    expect(apps.homeLayout.grid[targetIndex]).toBeUndefined()
+
+    expect(
+      apps.extractHomeFolderApp('missing-folder', 0, 'grid', targetIndex),
+    ).toBe(false)
+    expect(apps.homeLayout.pageCount).toBe(originalPageCount)
+    expect(apps.homeLayout.grid[targetIndex]).toBeUndefined()
+
+    mocks.phone.saveDeviceNamespace.mockClear()
+    expect(apps.extractHomeFolderApp(folderId!, 0, 'grid', targetIndex)).toBe(
+      true,
+    )
+    expect(apps.homeLayout.pageCount).toBe(targetPage)
+    expect(apps.homeLayout.grid[targetIndex]).toBe('settings')
+    expect(mocks.phone.saveDeviceNamespace).toHaveBeenCalledTimes(1)
+  })
+
   it('does not commit an installation to a different phone', () => {
     vi.useFakeTimers()
     const apps = useAppStoreStore()

frontend/src/stores/app-store.ts

@@ -19,6 +19,7 @@ import {
   createDefaultHomeLayout,
   deleteHomePage,
   extractHomeFolderApp,
+  HOME_GRID_PAGE_SIZE,
   moveHomeFolderApp,
   moveHomeApp,
   moveHomeAppToGridPage,
@@ -519,14 +520,23 @@ export const useAppStoreStore = defineStore('app-store', {
       to: HomeArea,
       targetIndex: number,
     ): boolean {
+      let sourceLayout = this.homeLayout
+      if (to === 'grid' && Number.isInteger(targetIndex) && targetIndex >= 0) {
+        const targetPage = Math.floor(targetIndex / HOME_GRID_PAGE_SIZE) + 1
+        while (sourceLayout.pageCount < targetPage) {
+          const expanded = addHomePage(sourceLayout)
+          if (expanded === sourceLayout) return false
+          sourceLayout = expanded
+        }
+      }
       const next = extractHomeFolderApp(
-        this.homeLayout,
+        sourceLayout,
         folderId,
         sourceIndex,
         to,
         targetIndex,
       )
-      if (next === this.homeLayout) return false
+      if (next === sourceLayout) return false
       this.homeLayout = next
       this.persist()
       return true

frontend/src/utils/phoneViewportGeometry.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, it } from 'vitest'
 
 import {
   normalizePhoneViewportRect,
+  phoneViewportRectContainsPoint,
   readPhoneViewportGeometry,
   type PhoneViewportRect,
 } from '@/utils/phoneViewportGeometry'
@@ -63,7 +64,78 @@ function createGeometryFixture(options: {
   }
 }
 
+const PHONE_BASE_ZOOM = 0.69 * 1.2
+const PHONE_HEIGHT = 844
+const PHONE_WIDTH = 390
+const REFERENCE_VIEWPORT_HEIGHT = 1080
+const REFERENCE_VIEWPORT_WIDTH = 1920
+
+const displayCases = [
+  { height: 1080, label: '1080p 16:9', width: 1920 },
+  { height: 2160, label: '4K 16:9', width: 3840 },
+  { height: 1440, label: '21:9', width: 3440 },
+  { height: 1440, label: '32:9', width: 5120 },
+  { height: 1600, label: '16:10', width: 2560 },
+] as const
+
+const phoneScales = [80, 100, 120] as const
+
+function productionPhoneZoom(
+  viewportWidth: number,
+  viewportHeight: number,
+  phoneScale: number,
+): number {
+  const viewportScale = Math.min(
+    viewportWidth / REFERENCE_VIEWPORT_WIDTH,
+    viewportHeight / REFERENCE_VIEWPORT_HEIGHT,
+  )
+  const preferred = PHONE_BASE_ZOOM * viewportScale * (phoneScale / 100)
+  const edgeGap = 24 * viewportScale
+  const viewportMaximum = Math.max(
+    0,
+    Math.min(
+      (viewportWidth - edgeGap) / PHONE_WIDTH,
+      (viewportHeight - edgeGap) / PHONE_HEIGHT,
+    ),
+  )
+
+  return Math.min(viewportMaximum, Math.max(260 / PHONE_WIDTH, preferred))
+}
+
+const cefDisplayMatrix = displayCases.flatMap((display) =>
+  phoneScales.map((phoneScale) => ({ display, phoneScale })),
+)
+
 describe('phone viewport geometry', () => {
+  it('treats every rectangle boundary as inside and rejects points beyond it', () => {
+    const rect: PhoneViewportRect = {
+      bottom: 260,
+      height: 160,
+      left: 120,
+      right: 360,
+      top: 100,
+      width: 240,
+    }
+
+    expect(phoneViewportRectContainsPoint(rect, 240, 180)).toBe(true)
+    expect(phoneViewportRectContainsPoint(rect, rect.left, rect.top)).toBe(true)
+    expect(phoneViewportRectContainsPoint(rect, rect.right, rect.bottom)).toBe(
+      true,
+    )
+    expect(phoneViewportRectContainsPoint(rect, rect.left - 0.001, 180)).toBe(
+      false,
+    )
+    expect(phoneViewportRectContainsPoint(rect, rect.right + 0.001, 180)).toBe(
+      false,
+    )
+    expect(phoneViewportRectContainsPoint(rect, 240, rect.top - 0.001)).toBe(
+      false,
+    )
+    expect(phoneViewportRectContainsPoint(rect, 240, rect.bottom + 0.001)).toBe(
+      false,
+    )
+  })
+
   it('leaves modern Chrome measurements unchanged when the canvas BCR is already rendered', () => {
     const wrapper = measuredRect(1573.09, 126.25, 322.92, 698.832)
     const layer = measuredRect(1589.783336, 177.75, 289.533328, 603.2)
@@ -124,6 +196,76 @@ describe('phone viewport geometry', () => {
     },
   )
 
+  it.each(cefDisplayMatrix)(
+    'keeps an opened folder panel hit-test exact at $phoneScale% on $display.label',
+    ({ display, phoneScale }) => {
+      const viewportScale = Math.min(
+        display.width / REFERENCE_VIEWPORT_WIDTH,
+        display.height / REFERENCE_VIEWPORT_HEIGHT,
+      )
+      const zoom = productionPhoneZoom(
+        display.width,
+        display.height,
+        phoneScale,
+      )
+      const edgeGap = 24 * viewportScale
+      const wrapper = measuredRect(
+        display.width - edgeGap - PHONE_WIDTH * zoom,
+        display.height - edgeGap - PHONE_HEIGHT * zoom,
+        PHONE_WIDTH * zoom,
+        PHONE_HEIGHT * zoom,
+      )
+      // Live CEF 103 can report the zoomed canvas in a different coordinate
+      // space from pointer events. Preserve that mismatch in this fixture.
+      const rawCanvas = measuredRect(
+        display.width + 117.375,
+        83.625,
+        PHONE_WIDTH,
+        PHONE_HEIGHT,
+      )
+      const rawPanel = measuredRect(
+        rawCanvas.left + 23.25,
+        rawCanvas.top + 246.75,
+        343.5,
+        324.25,
+      )
+      const panel = normalizePhoneViewportRect(rawPanel, rawCanvas, wrapper)
+      const expected = {
+        bottom: wrapper.top + (246.75 + 324.25) * zoom,
+        height: 324.25 * zoom,
+        left: wrapper.left + 23.25 * zoom,
+        right: wrapper.left + (23.25 + 343.5) * zoom,
+        top: wrapper.top + 246.75 * zoom,
+        width: 343.5 * zoom,
+      }
+
+      expectRectClose(panel, expected)
+      expect(
+        phoneViewportRectContainsPoint(
+          panel,
+          panel.left + panel.width / 2,
+          panel.top + panel.height / 2,
+        ),
+      ).toBe(true)
+      expect(phoneViewportRectContainsPoint(panel, panel.left, panel.top)).toBe(
+        true,
+      )
+      expect(
+        phoneViewportRectContainsPoint(panel, panel.right, panel.bottom),
+      ).toBe(true)
+      expect(
+        phoneViewportRectContainsPoint(panel, panel.left - 0.25, panel.top),
+      ).toBe(false)
+      expect(
+        phoneViewportRectContainsPoint(panel, panel.right + 0.25, panel.bottom),
+      ).toBe(false)
+      expect(panel.left).toBeGreaterThanOrEqual(0)
+      expect(panel.right).toBeLessThanOrEqual(display.width)
+      expect(panel.top).toBeGreaterThanOrEqual(0)
+      expect(panel.bottom).toBeLessThanOrEqual(display.height)
+    },
+  )
+
   it('reads visual scale and normalized element rects from a canvas anchor', () => {
     const fixture = createGeometryFixture({
       canvasOffsetHeight: 844,

frontend/src/utils/phoneViewportGeometry.ts

@@ -7,6 +7,14 @@ export type PhoneViewportRect = {
   width: number
 }
 
+export function phoneViewportRectContainsPoint(
+  rect: PhoneViewportRect,
+  x: number,
+  y: number,
+): boolean {
+  return x >= rect.left && x <= rect.right && y >= rect.top && y <= rect.bottom
+}
+
 type RectMeasurement = Pick<
   DOMRectReadOnly,
   'height' | 'left' | 'top' | 'width'

frontend/src/views/SpringboardView.contract.test.ts

@@ -31,6 +31,22 @@ const builtInWallpaperCss = mainCss.slice(
   mainCss.indexOf('.wallpaper--midnight'),
   mainCss.indexOf('.wallpaper--custom'),
 )
+const folderOverlayBlock =
+  viewSource.match(/<HomeFolderOverlay\b[\s\S]*?\/>/)?.[0] ?? ''
+
+function handlerName(block: string, event: string): string {
+  return (
+    block.match(new RegExp(`@${event}="([A-Za-z][A-Za-z0-9_]*)"`))?.[1] ?? ''
+  )
+}
+
+function functionSource(name: string): string {
+  if (!name) return ''
+  const start = viewSource.indexOf(`function ${name}(`)
+  if (start < 0) return ''
+  const next = viewSource.indexOf('\nfunction ', start + 1)
+  return viewSource.slice(start, next < 0 ? viewSource.length : next)
+}
 
 describe('Springboard page swipe contract', () => {
   it('keeps app and widget labels on the larger shared home typography', () => {
@@ -136,7 +152,7 @@ describe('Springboard page swipe contract', () => {
     )
     expect(
       viewSource.match(/:external-drag-visual="homeDragVisualActive"/g),
-    ).toHaveLength(4)
+    ).toHaveLength(5)
     expect(viewSource).toContain('updateHomeDragGhost(event)')
     expect(viewSource).toContain('const dropGhost = homeDragGhost')
     expect(viewSource).toContain('const dropOrigin = homeDragPreviewBounds')
@@ -160,6 +176,65 @@ describe('Springboard page swipe contract', () => {
     )
   })
 
+  it('owns one external drag session for an app leaving an opened folder', () => {
+    expect(folderOverlayBlock).toContain(
+      ':external-drag-visual="homeDragVisualActive"',
+    )
+
+    const startSource = functionSource(
+      handlerName(folderOverlayBlock, 'dragstart'),
+    )
+    const moveSource = functionSource(
+      handlerName(folderOverlayBlock, 'dragmove'),
+    )
+    const cancelSource = functionSource(
+      handlerName(folderOverlayBlock, 'dragcancel'),
+    )
+
+    expect(startSource).toContain('createHomeDragGhost(event)')
+    expect(startSource).toMatch(/\.value\s*=\s*\{[\s\S]*?sourceIndex/)
+    expect(moveSource).toContain('updateHomeDragGhost(event)')
+    expect(moveSource).toContain('folderDraggingOutside.value')
+    expect(moveSource).toContain('resolveHomeEdgeTurn(event)')
+    expect(moveSource).toContain("queueEdgePageTurn(event, 'app')")
+    expect(viewSource).toContain(
+      '(draggingHomeApp.value || draggingFolderApp.value)',
+    )
+    expect(cancelSource).toContain('clearHomeDragGhost()')
+    expect(cancelSource).toContain('clearTemporaryHomePage()')
+  })
+
+  it('settles an extracted folder app from the tracked viewport preview', () => {
+    const extractSource = functionSource('extractOpenedFolderApp')
+    const targetSource = functionSource('folderExtractionDropTarget')
+
+    expect(extractSource).toContain('const dropGhost = homeDragGhost')
+    expect(extractSource).toContain('homeDragPreviewBounds')
+    expect(targetSource).toContain('page > appStore.homeLayout.pageCount')
+    expect(extractSource).not.toContain('sourceElement')
+    expect(extractSource).not.toContain('getBoundingClientRect()')
+    expect(extractSource).toMatch(
+      /animateHomeItemDrop\([\s\S]*?dropOrigin[\s\S]*?\)\.finally\(/,
+    )
+    expect(extractSource).toContain('clearHomeDragGhost(dropGhost)')
+    expect(extractSource).toMatch(
+      /if \(!target\) \{[\s\S]*?clearHomeDragGhost\(\)/,
+    )
+  })
+
+  it('cleans the opened-folder drag preview after an internal move, cancellation, or unmount', () => {
+    const moveSource = functionSource('moveOpenedFolderApp')
+    const cancelSource = functionSource(
+      handlerName(folderOverlayBlock, 'dragcancel'),
+    )
+
+    expect(moveSource).toContain('stopOpenedFolderAppDrag()')
+    expect(cancelSource).toContain('clearHomeDragGhost()')
+    expect(viewSource).toMatch(
+      /onBeforeUnmount\(\(\) => \{[\s\S]*?clearHomeDragGhost\(\)/,
+    )
+  })
+
   it('cleans up the external drag visual on every terminal path', () => {
     expect(
       viewSource.match(

frontend/src/views/SpringboardView.vue

@@ -42,6 +42,7 @@ import {
 } from '@/utils/homeLayout'
 import type { ReorderDirection } from '@/utils/keyboard'
 import {
+  phoneViewportRectContainsPoint,
   readPhoneViewportGeometry,
   type PhoneViewportGeometry,
   type PhoneViewportRect,
@@ -111,6 +112,11 @@ const draggingHomeApp = ref<{
   area: HomeArea
   index: number
 } | null>(null)
+const draggingFolderApp = ref<{
+  appId: LaunchablePhoneAppId
+  folderId: string
+  sourceIndex: number
+} | null>(null)
 const homeDragLayer = ref<HTMLElement | null>(null)
 const homeDragVisualActive = ref(false)
 const temporaryHomePage = ref<number | null>(null)
@@ -610,7 +616,11 @@ function queueEdgePageTurn(
     edgePageTimer = undefined
     edgePageDirection = direction
     edgePageLocked = dragType === 'widget'
-    if (dragType === 'app' && lastHomePointer && draggingHomeApp.value) {
+    if (
+      dragType === 'app' &&
+      lastHomePointer &&
+      (draggingHomeApp.value || draggingFolderApp.value)
+    ) {
       queueEdgePageTurn(lastHomePointer, 'app')
     }
   }, HOME_EDGE_PAGE_TURN_DELAY)
@@ -814,7 +824,7 @@ function updateHomeDragGhost(event: {
   )
 }
 
-function createHomeDragGhost(event: PointerEvent): void {
+function createHomeDragGhost(event: PointerEvent): HTMLElement | null {
   clearHomeDragGhost()
   const eventTarget =
     event.currentTarget instanceof Element
@@ -827,7 +837,7 @@ function createHomeDragGhost(event: PointerEvent): void {
   const springboard = source?.closest<HTMLElement>('.springboard')
   const portal = layer?.closest<HTMLElement>('.phone-home-drag-portal')
   const geometry = readPhoneViewportGeometry(source ?? null)
-  if (!source || !layer || !springboard || !portal || !geometry) return
+  if (!source || !layer || !springboard || !portal || !geometry) return null
 
   const portalBounds = portal.getBoundingClientRect()
   const clipBounds = geometry.rect(springboard)
@@ -838,7 +848,7 @@ function createHomeDragGhost(event: PointerEvent): void {
     sourceBounds.width <= 0 ||
     sourceBounds.height <= 0
   ) {
-    return
+    return null
   }
 
   layer.style.left = `${clipBounds.left - portalBounds.left}px`
@@ -865,7 +875,12 @@ function createHomeDragGhost(event: PointerEvent): void {
   for (const element of [ghost, ...Array.from(ghost.querySelectorAll('*'))]) {
     element.removeAttribute('id')
     for (const attribute of element.getAttributeNames()) {
-      if (attribute.startsWith('data-home-')) element.removeAttribute(attribute)
+      if (
+        attribute.startsWith('data-home-') ||
+        attribute.startsWith('data-folder-')
+      ) {
+        element.removeAttribute(attribute)
+      }
     }
   }
   for (const control of ghost.querySelectorAll<HTMLElement>(
@@ -894,6 +909,7 @@ function createHomeDragGhost(event: PointerEvent): void {
   layer.appendChild(position)
   homeDragVisualActive.value = true
   updateHomeDragGhost(event)
+  return position
 }
 
 function startHomeDrag(
@@ -1190,6 +1206,98 @@ function nearestDockDropTarget(event: {
   return closestIndex === null ? null : slots[closestIndex]
 }
 
+function folderExtractionDropTarget(event: {
+  clientX: number
+  clientY: number
+}):
+  | { area: 'dock'; index: number }
+  | { area: 'grid'; index: number; page: number }
+  | null {
+  const geometry = homeDragGeometry
+  if (!geometry) return null
+
+  const dock = document.querySelector<HTMLElement>('.app-dock')
+  if (dock) {
+    const dockBounds = homeDragViewportRect(dock, geometry)
+    if (
+      phoneViewportRectContainsPoint(dockBounds, event.clientX, event.clientY)
+    ) {
+      const slots = Array.from(
+        dock.querySelectorAll<HTMLElement>(
+          '[data-home-area="dock"][data-home-index]',
+        ),
+      ).filter((slot) => {
+        const index = Number(slot.dataset.homeIndex)
+        return (
+          Number.isInteger(index) && appStore.homeLayout.dock[index] === null
+        )
+      })
+      const closestIndex = nearestSpringboardRectIndex(
+        event.clientX,
+        event.clientY,
+        slots.map((slot) => homeDragViewportRect(slot, geometry)),
+      )
+      if (closestIndex === null) return null
+      const index = Number(slots[closestIndex]?.dataset.homeIndex)
+      return Number.isInteger(index) ? { area: 'dock', index } : null
+    }
+  }
+
+  const page = phone.currentPage
+  if (page < 1 || page > appPages.value.length) return null
+  const grid = document.querySelector<HTMLElement>(
+    `.springboard-page--apps[data-home-page="${page}"] .app-grid`,
+  )
+  const pageElement = grid?.closest<HTMLElement>('.springboard-page')
+  const springboard = grid?.closest<HTMLElement>('.springboard')
+  if (!grid || !pageElement || !springboard) return null
+
+  const pageBounds = homeDragViewportRect(pageElement, geometry)
+  const springboardBounds = homeDragViewportRect(springboard, geometry)
+  const rawGridBounds = homeDragViewportRect(grid, geometry)
+  const gridBounds = viewportRectAt(
+    springboardBounds.left + (rawGridBounds.left - pageBounds.left),
+    springboardBounds.top + (rawGridBounds.top - pageBounds.top),
+    rawGridBounds.width,
+    rawGridBounds.height,
+  )
+  if (
+    !phoneViewportRectContainsPoint(gridBounds, event.clientX, event.clientY)
+  ) {
+    return null
+  }
+
+  const slots = Array.from(
+    grid.querySelectorAll<HTMLElement>(
+      '[data-home-area="grid"][data-home-index]',
+    ),
+  ).filter((slot) => {
+    const index = Number(slot.dataset.homeIndex)
+    const item = appStore.homeLayout.grid[index]
+    return (
+      Number.isInteger(index) &&
+      (item === null ||
+        (item === undefined && page > appStore.homeLayout.pageCount))
+    )
+  })
+  const closestIndex = nearestSpringboardRectIndex(
+    event.clientX,
+    event.clientY,
+    slots.map((slot) => {
+      const bounds = homeDragViewportRect(slot, geometry)
+      return {
+        height: bounds.height,
+        left: springboardBounds.left + (bounds.left - pageBounds.left),
+        top: springboardBounds.top + (bounds.top - pageBounds.top),
+        width: bounds.width,
+      }
+    }),
+  )
+  if (closestIndex === null) return null
+  const index = Number(slots[closestIndex]?.dataset.homeIndex)
+  return Number.isInteger(index) ? { area: 'grid', index, page } : null
+}
+
 function finishHomeDrag(event: PointerEvent): void {
   clearEdgePageTurn()
   clearFolderHover()
@@ -1324,16 +1432,83 @@ function folderPreviewApps(folder: HomeFolder): PhoneAppDefinition[] {
   return apps
 }
 
+function currentOpenedFolderDragSession(sourceIndex?: number) {
+  const session = draggingFolderApp.value
+  const folder = openedFolder.value
+  if (
+    !session ||
+    !folder ||
+    folder.id !== session.folderId ||
+    (sourceIndex !== undefined && sourceIndex !== session.sourceIndex) ||
+    folder.apps[session.sourceIndex] !== session.appId
+  ) {
+    return null
+  }
+  return session
+}
+
+function startOpenedFolderAppDrag(
+  sourceIndex: number,
+  event: PointerEvent,
+): void {
+  stopOpenedFolderAppDrag()
+  const folder = openedFolder.value
+  if (
+    !folder ||
+    !Number.isInteger(sourceIndex) ||
+    sourceIndex < 0 ||
+    sourceIndex >= folder.apps.length
+  ) {
+    return
+  }
+  const appId = folder.apps[sourceIndex]
+  if (!appId || !installedAppsById.value.has(appId)) return
+  if (!createHomeDragGhost(event)) {
+    clearHomeDragGhost()
+    return
+  }
+  draggingFolderApp.value = { appId, folderId: folder.id, sourceIndex }
+  lastHomePointer = { clientX: event.clientX, clientY: event.clientY }
+}
+
+function moveOpenedFolderAppDrag(event: PointerEvent): void {
+  if (!currentOpenedFolderDragSession()) {
+    stopOpenedFolderAppDrag()
+    return
+  }
+  lastHomePointer = { clientX: event.clientX, clientY: event.clientY }
+  updateHomeDragGhost(event)
+  if (folderDraggingOutside.value && resolveHomeEdgeTurn(event)) {
+    queueEdgePageTurn(event, 'app')
+    return
+  }
+  clearEdgePageTurn()
+}
+
+function stopOpenedFolderAppDrag(): void {
+  clearEdgePageTurn()
+  draggingFolderApp.value = null
+  lastHomePointer = null
+  clearHomeDragGhost()
+  clearTemporaryHomePage()
+}
+
+function resetOpenedFolderState(): void {
+  folderDraggingOutside.value = false
+  openedFolderId.value = null
+  renameFolderOnOpenId.value = null
+}
+
 function openFolder(folderId: string): void {
+  stopOpenedFolderAppDrag()
   pageTransitioning.value = false
   folderDraggingOutside.value = false
   openedFolderId.value = folderId
 }
 
 function closeFolder(): void {
-  folderDraggingOutside.value = false
-  openedFolderId.value = null
-  renameFolderOnOpenId.value = null
+  stopOpenedFolderAppDrag()
+  resetOpenedFolderState()
 }
 
 function renameOpenedFolder(name: string): void {
@@ -1342,71 +1517,68 @@ function renameOpenedFolder(name: string): void {
 }
 
 function moveOpenedFolderApp(sourceIndex: number, targetIndex: number): void {
-  if (!openedFolderId.value) return
-  appStore.moveHomeFolderApp(openedFolderId.value, sourceIndex, targetIndex)
+  const session = currentOpenedFolderDragSession(sourceIndex)
+  stopOpenedFolderAppDrag()
+  if (!session) return
+  appStore.moveHomeFolderApp(session.folderId, sourceIndex, targetIndex)
 }
 
 function extractOpenedFolderApp(
   sourceIndex: number,
   event: PointerEvent,
 ): void {
-  const folder = openedFolder.value
-  if (!folder) return
-  const appId = folder.apps[sourceIndex]
-  const sourceElement = document
-    .querySelector<HTMLElement>(
-      `.home-folder-panel [data-folder-app-index="${sourceIndex}"]`,
-    )
-    ?.closest<HTMLElement>('.app-icon-item')
-  const geometry = readPhoneViewportGeometry(sourceElement ?? null)
-  const sourceBounds = sourceElement
-    ? homeDragViewportRect(sourceElement, geometry)
-    : null
-  const candidates = Array.from(
-    document.querySelectorAll<HTMLElement>('[data-home-index][data-home-area]'),
-  ).filter((element) => {
-    const area = element.dataset.homeArea as HomeArea
-    const index = Number(element.dataset.homeIndex)
-    return (
-      (area === 'grid' || area === 'dock') &&
-      Number.isInteger(index) &&
-      appStore.homeLayout[area][index] === null
-    )
-  })
-  const target = candidates.reduce<HTMLElement | null>((closest, candidate) => {
-    if (!closest) return candidate
-    const bounds = homeDragViewportRect(candidate, geometry)
-    const closestBounds = homeDragViewportRect(closest, geometry)
-    const distance = Math.hypot(
-      event.clientX - (bounds.left + bounds.width / 2),
-      event.clientY - (bounds.top + bounds.height / 2),
-    )
-    const closestDistance = Math.hypot(
-      event.clientX - (closestBounds.left + closestBounds.width / 2),
-      event.clientY - (closestBounds.top + closestBounds.height / 2),
-    )
-    return distance < closestDistance ? candidate : closest
-  }, null)
-  if (!target) {
+  const session = currentOpenedFolderDragSession(sourceIndex)
+  if (!session) {
     closeFolder()
     return
   }
+  updateHomeDragGhost(event)
+  const dropGhost = homeDragGhost
+  const dropOrigin = homeDragPreviewBounds ? { ...homeDragPreviewBounds } : null
+  if (!dropGhost || !dropOrigin) {
+    closeFolder()
+    return
+  }
+  const target = folderExtractionDropTarget(event)
+  if (!target) {
+    clearEdgePageTurn()
+    draggingFolderApp.value = null
+    lastHomePointer = null
+    clearHomeDragGhost()
+    clearTemporaryHomePage()
+    resetOpenedFolderState()
+    return
+  }
 
-  const area = target.dataset.homeArea as HomeArea
-  const targetIndex = Number(target.dataset.homeIndex)
+  const { area, index: targetIndex } = target
   if (
-    !appStore.extractHomeFolderApp(folder.id, sourceIndex, area, targetIndex)
+    !appStore.extractHomeFolderApp(
+      session.folderId,
+      session.sourceIndex,
+      area,
+      targetIndex,
+    )
   ) {
     closeFolder()
     return
   }
-  closeFolder()
-  if (sourceBounds) {
-    const extractedIndex = findHomeItemIndex(appId, area, targetIndex)
-    if (extractedIndex !== null) {
-      void animateHomeItemDrop(appId, area, extractedIndex, sourceBounds)
-    }
+
+  clearEdgePageTurn()
+  draggingFolderApp.value = null
+  lastHomePointer = null
+  clearTemporaryHomePage(area === 'grid')
+  resetOpenedFolderState()
+  const extractedIndex = findHomeItemIndex(session.appId, area, targetIndex)
+  if (extractedIndex === null) {
+    clearHomeDragGhost(dropGhost)
+    return
   }
+  void animateHomeItemDrop(
+    session.appId,
+    area,
+    extractedIndex,
+    dropOrigin,
+  ).finally(() => clearHomeDragGhost(dropGhost))
 }
 
 function clearSearch(): void {
@@ -1426,11 +1598,12 @@ watch(isEditablePage, (visible) => {
 watch(editMode, (editing) => {
   emit('editModeChange', editing)
   if (editing) return
+  stopOpenedFolderAppDrag()
   stopHomeDrag()
   stopWidgetDrag()
 })
 watch(openedFolder, (folder) => {
-  if (!folder) closeFolder()
+  if (!folder && openedFolderId.value !== null) closeFolder()
 })
 onBeforeUnmount(() => {
   emit('editModeChange', false)
@@ -1445,6 +1618,7 @@ onBeforeUnmount(() => {
   clearHomeDragGhost()
   temporaryHomePage.value = null
   draggingHomeApp.value = null
+  draggingFolderApp.value = null
   draggingWidgetId.value = null
 })
 </script>
@@ -1858,9 +2032,13 @@ onBeforeUnmount(() => {
         v-if="openedFolder"
         :apps="openedFolderApps"
         :edit-mode="editMode"
+        :external-drag-visual="homeDragVisualActive"
         :folder="openedFolder"
         :rename-on-open="renameFolderOnOpenId === openedFolder.id"
         @close="closeFolder"
+        @dragcancel="stopOpenedFolderAppDrag"
+        @dragmove="moveOpenedFolderAppDrag"
+        @dragstart="startOpenedFolderAppDrag"
         @drag-outside-change="folderDraggingOutside = $event"
         @edit="enterEditMode"
         @extract="extractOpenedFolderApp"