feat(native-chat): attach several files from one picker selection (#23956)

* feat(native-chat): attach several files from one picker selection

Picks over 256 files are rejected whole, matching the drop limit.

Fixes #23905

* refactor(native-chat): name the composer action for the files it now attaches

The hook still returned `pickAttachment` after it started attaching a
whole selection. Also records why the plural IPC handler sits next to the
singular one, matching its siblings in the same file.

* test(native-chat): cover the paperclip forwarding every picked path

The one line that makes the feature work — the composer handing the whole
picker result to attachExternalPaths — had no test; reverting it to
paths[0] kept every existing test green. Adds a hook test for the
multi-path, canceled, and wrong-pane cases, plus the missing canceled
case for the shell:pickAttachments handler.

* test(native-chat): exercise multi-pick through renderHook

* test(settings): preserve label fallback and verify Spanish copy

Keep latest main's missing-label fixture and restore its translation namespace after cleanup, so later tests still load real catalogs. Independently assert the shipped Spanish resource and rendered supported-agents label.

---------

Co-authored-by: Neil <neil@stably.ai>
Co-authored-by: Neil <4138956+nwparker@users.noreply.github.com>
Co-authored-by: Brennan Benson <79079362+brennanb2025@users.noreply.github.com>

src/main/ipc/shell.test.ts

@@ -170,6 +170,32 @@ describe('registerShellHandlers', () => {
     })
   })
 
+  it('picks several attachment files in one native dialog', async () => {
+    showOpenDialogMock.mockResolvedValue({
+      canceled: false,
+      filePaths: ['/Users/kaylee/notes.md', '/Users/kaylee/diagram.png']
+    })
+
+    const handler = getHandler('shell:pickAttachments')
+    await expect(handler({})).resolves.toEqual([
+      '/Users/kaylee/notes.md',
+      '/Users/kaylee/diagram.png'
+    ])
+    expect(showOpenDialogMock).toHaveBeenCalledWith({
+      properties: ['openFile', 'multiSelections']
+    })
+  })
+
+  it('returns no attachment paths when multi-file picking is canceled', async () => {
+    showOpenDialogMock.mockResolvedValue({
+      canceled: true,
+      filePaths: ['/Users/kaylee/notes.md']
+    })
+
+    const handler = getHandler('shell:pickAttachments')
+    await expect(handler({})).resolves.toEqual([])
+  })
+
   describe('shell:openPath', () => {
     it('ignores relative paths', async () => {
       const handler = getHandler('shell:openPath')

src/main/ipc/shell.ts

@@ -242,6 +242,15 @@ export function registerShellHandlers(store: Store): void {
     return result.filePaths[0]
   })
 
+  // Why: a separate plural handler, like repos:pickFolder/pickFolders — callers that
+  // must take exactly one file (the notebook interpreter picker) keep pickAttachment.
+  ipcMain.handle('shell:pickAttachments', async (): Promise<string[]> => {
+    const result = await dialog.showOpenDialog({
+      properties: ['openFile', 'multiSelections']
+    })
+    return result.canceled ? [] : result.filePaths
+  })
+
   // Why: window.prompt() and <input type="file"> are unreliable in Electron,
   // so we use the native OS dialog to let the user pick an image file.
   ipcMain.handle('shell:pickImage', async (): Promise<string | null> => {

src/preload/api/shell-api.ts

@@ -22,6 +22,7 @@ export type ShellApi = {
   pathsExist?: (paths: string[]) => Promise<boolean[]>
   pathExists: (path: string) => Promise<boolean>
   pickAttachment: () => Promise<string | null>
+  pickAttachments: () => Promise<string[]>
   pickImage: () => Promise<string | null>
   pickRepoIconImage: () => Promise<{
     dataUrl: string

src/preload/api/shell-bridge.ts

@@ -29,6 +29,8 @@ export const shellApi = {
 
   pickAttachment: (): Promise<string | null> => ipcRenderer.invoke('shell:pickAttachment'),
 
+  pickAttachments: (): Promise<string[]> => ipcRenderer.invoke('shell:pickAttachments'),
+
   pickImage: (): Promise<string | null> => ipcRenderer.invoke('shell:pickImage'),
 
   pickRepoIconImage: (): Promise<{ dataUrl: string; fileName: string } | null> =>

src/renderer/src/components/native-chat/NativeChatComposer.tsx

@@ -218,7 +218,7 @@ const NativeChatComposerPane = forwardRef<NativeChatComposerHandle, NativeChatCo
       setNotice
     })
 
-    const { pickAttachment } = useNativeChatFileAttachmentActions(paneKey, attachExternalPaths)
+    const { pickAttachments } = useNativeChatFileAttachmentActions(paneKey, attachExternalPaths)
     const dictation = useNativeChatDictation(textareaRef)
     const { dispatch: dispatchSessionOptionCommand, isDispatching: isDispatchingSessionOption } =
       useNativeChatSessionOptionCommand({
@@ -411,7 +411,7 @@ const NativeChatComposerPane = forwardRef<NativeChatComposerHandle, NativeChatCo
           requestAnimationFrame(() => textarea?.setSelectionRange(result.caret, result.caret))
         }}
         onRemoveImageAttachment={(id) => removeImageAttachment(id)}
-        onAttach={pickAttachment}
+        onAttach={pickAttachments}
         onDictationToggle={dictation.toggleDictation}
         onDictationHoldStart={dictation.startHoldDictation}
         onDictationHoldEnd={dictation.stopHoldDictation}

src/renderer/src/components/native-chat/native-chat-attachment-upload.ts

@@ -10,6 +10,7 @@ import { getConnectionIdFromState } from '@/lib/connection-context'
 import { getRuntimeEnvironmentIdForWorktree } from '@/lib/worktree-runtime-owner'
 import type { AppState } from '@/store/types'
 import { reportTerminalDropUploadSkipsAndFailures } from '../terminal-pane/terminal-drop-upload-report'
+import { NATIVE_FILE_DROP_MAX_PATHS } from '../../../../shared/native-file-drop'
 import {
   findTerminalTabWorktreeId,
   resolveNativeChatFileLinkContext
@@ -117,6 +118,14 @@ export function nativeChatAttachmentUnreadableNotice(): string {
   )
 }
 
+export function nativeChatTooManyAttachmentsNotice(): string {
+  return translate(
+    'components.native-chat.composer.tooManyAttachments',
+    'Attach {{value0}} or fewer files at a time.',
+    { value0: NATIVE_FILE_DROP_MAX_PATHS }
+  )
+}
+
 export function nativeChatLocalAttachmentUnsupportedNotice(): string {
   return translate(
     'components.native-chat.composer.localAttachmentUnsupported',

src/renderer/src/components/native-chat/use-native-chat-external-attachments.test.tsx

@@ -61,6 +61,9 @@ function Probe({
   return null
 }
 
+// One past NATIVE_FILE_DROP_MAX_PATHS.
+const pathsOverDropLimit = Array.from({ length: 257 }, (_, index) => `/external/${index}.png`)
+
 let root: Root | null = null
 
 async function renderProbe(args: {
@@ -141,6 +144,31 @@ describe('useNativeChatExternalAttachments', () => {
     expect(mocks.uploadNativeChatAttachmentPaths).not.toHaveBeenCalled()
   })
 
+  it('rejects a whole batch over the drop path limit, like a drop does', async () => {
+    mocks.resolveNativeChatAttachmentOwner.mockReturnValue({ kind: 'local' })
+    const attachResolvedPaths = vi.fn()
+    const setNotice = vi.fn()
+    const probe = await renderProbe({ attachResolvedPaths, setNotice })
+    await act(async () => {
+      probe.latest().attachExternalPaths(pathsOverDropLimit)
+    })
+    expect(setNotice).toHaveBeenCalledExactlyOnceWith('Attach 256 or fewer files at a time.')
+    expect(mocks.stat).not.toHaveBeenCalled()
+    expect(attachResolvedPaths).not.toHaveBeenCalled()
+  })
+
+  it('reports a remote runtime before the path limit, since trimming would not help', async () => {
+    mocks.resolveNativeChatAttachmentOwner.mockReturnValue({ kind: 'runtime' })
+    const setNotice = vi.fn()
+    const probe = await renderProbe({ attachResolvedPaths: vi.fn(), setNotice })
+    await act(async () => {
+      probe.latest().attachExternalPaths(pathsOverDropLimit)
+    })
+    expect(setNotice).toHaveBeenCalledExactlyOnceWith(
+      'Local attachments are not available for remote sessions.'
+    )
+  })
+
   it('waits for the local file check and skips rejected paths without blocking other files', async () => {
     mocks.resolveNativeChatAttachmentOwner.mockReturnValue({ kind: 'local' })
     const fileCheck = deferred<void>()

src/renderer/src/components/native-chat/use-native-chat-external-attachments.ts

@@ -1,10 +1,12 @@
 import { useCallback, useLayoutEffect, useRef } from 'react'
 import { useAppStore } from '@/store'
+import { NATIVE_FILE_DROP_MAX_PATHS } from '../../../../shared/native-file-drop'
 import { nativeChatAttachmentOwnerUnchanged } from './native-chat-resolved-path-ownership'
 import {
   nativeChatAttachmentOwnerChangedNotice,
   nativeChatAttachmentUnreadableNotice,
   nativeChatLocalAttachmentUnsupportedNotice,
+  nativeChatTooManyAttachmentsNotice,
   nativeChatWorktreeNotReadyNotice,
   resolveNativeChatAttachmentOwner,
   resolveNativeChatAttachmentOwnerForWorktree,
@@ -84,6 +86,11 @@ export function useNativeChatExternalAttachments({
         setNotice(nativeChatLocalAttachmentUnsupportedNotice())
         return
       }
+      // The picker has no native cap, so it gets the same all-or-nothing limit as a drop.
+      if (paths.length > NATIVE_FILE_DROP_MAX_PATHS) {
+        setNotice(nativeChatTooManyAttachmentsNotice())
+        return
+      }
       // Why every exit reports: a drop that reaches here and produces nothing is
       // the silent-failure complaint in #15782. Only a disabled composer stays
       // quiet — it is being torn down or guarded, and has no notice surface.

src/renderer/src/components/native-chat/use-native-chat-file-attachment-actions.test.tsx

@@ -0,0 +1,94 @@
+// @vitest-environment happy-dom
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { act } from 'react'
+import { cleanup, renderHook } from '@testing-library/react'
+import {
+  NATIVE_FILE_DROP_TARGET,
+  type NativeFileDropPayload
+} from '../../../../shared/native-file-drop'
+import { useNativeChatFileAttachmentActions } from './use-native-chat-file-attachment-actions'
+
+const SCOPE_KEY = 'pane-1'
+
+let pickAttachments: ReturnType<typeof vi.fn>
+type DropListener = (payload: NativeFileDropPayload) => void
+
+let dropListeners: DropListener[] = []
+function renderProbe(
+  attachExternalPaths: (paths: string[]) => void
+): () => { pickAttachments: () => void } {
+  const { result } = renderHook(() =>
+    useNativeChatFileAttachmentActions(SCOPE_KEY, attachExternalPaths)
+  )
+  return () => result.current
+}
+
+describe('useNativeChatFileAttachmentActions', () => {
+  beforeEach(() => {
+    dropListeners = []
+    pickAttachments = vi.fn()
+    Object.defineProperty(window, 'api', {
+      configurable: true,
+      value: {
+        shell: { pickAttachments },
+        ui: {
+          onFileDrop: (listener: DropListener) => {
+            dropListeners.push(listener)
+            return () => {
+              dropListeners = dropListeners.filter((entry) => entry !== listener)
+            }
+          }
+        }
+      }
+    })
+  })
+
+  afterEach(cleanup)
+
+  it('attaches every path the picker returns, not just the first', async () => {
+    pickAttachments.mockResolvedValue(['/picked/notes.md', '/picked/diagram.png'])
+    const attachExternalPaths = vi.fn()
+    const latest = renderProbe(attachExternalPaths)
+    await act(async () => {
+      latest().pickAttachments()
+    })
+    expect(attachExternalPaths).toHaveBeenCalledExactlyOnceWith([
+      '/picked/notes.md',
+      '/picked/diagram.png'
+    ])
+  })
+
+  it('attaches nothing when the picker is canceled', async () => {
+    pickAttachments.mockResolvedValue([])
+    const attachExternalPaths = vi.fn()
+    const latest = renderProbe(attachExternalPaths)
+    await act(async () => {
+      latest().pickAttachments()
+    })
+    // Whether the empty batch is forwarded or dropped here, no file may attach.
+    expect(attachExternalPaths.mock.calls.flatMap(([paths]) => paths)).toEqual([])
+  })
+
+  it('only attaches a drop aimed at this pane', async () => {
+    const attachExternalPaths = vi.fn()
+    renderProbe(attachExternalPaths)
+    await act(async () => {
+      for (const listener of dropListeners) {
+        listener({
+          target: NATIVE_FILE_DROP_TARGET.composer,
+          scopeKey: 'other-pane',
+          paths: ['/dropped/a.png']
+        })
+        listener({
+          target: NATIVE_FILE_DROP_TARGET.composer,
+          scopeKey: SCOPE_KEY,
+          paths: ['/dropped/a.png', '/dropped/b.png']
+        })
+      }
+    })
+    expect(attachExternalPaths).toHaveBeenCalledExactlyOnceWith([
+      '/dropped/a.png',
+      '/dropped/b.png'
+    ])
+  })
+})

src/renderer/src/components/native-chat/use-native-chat-file-attachment-actions.ts

@@ -5,7 +5,7 @@ export function useNativeChatFileAttachmentActions(
   /** Pane identity published as `data-composer-scope-key` on the drop target. */
   scopeKey: string,
   attachExternalPaths: (paths: string[]) => void
-): { pickAttachment: () => void } {
+): { pickAttachments: () => void } {
   useEffect(
     () =>
       window.api.ui.onFileDrop((payload) => {
@@ -18,14 +18,11 @@ export function useNativeChatFileAttachmentActions(
     [attachExternalPaths, scopeKey]
   )
 
-  const pickAttachment = useCallback(() => {
+  const pickAttachments = useCallback(() => {
     void (async () => {
-      const filePath = await window.api.shell.pickAttachment()
-      if (filePath) {
-        attachExternalPaths([filePath])
-      }
+      attachExternalPaths(await window.api.shell.pickAttachments())
     })()
   }, [attachExternalPaths])
 
-  return { pickAttachment }
+  return { pickAttachments }
 }

src/renderer/src/i18n/locales/en.json

@@ -17991,7 +17991,8 @@
         "imagePreviewUnavailable": "Preview unavailable",
         "workspaceAttachmentMismatch": "Files can only be attached to their source workspace.",
         "attachmentOwnerChanged": "This workspace changed hosts while attaching — drop the files again.",
-        "attachmentUnreadable": "Couldn't read the dropped files."
+        "attachmentUnreadable": "Couldn't read the dropped files.",
+        "tooManyAttachments": "Attach {{value0}} or fewer files at a time."
       },
       "tool": {
         "exitCode": "exit {{value0}}",

src/renderer/src/i18n/locales/es.json

@@ -17731,7 +17731,8 @@
         "imagePreview": "Vista previa de la imagen a tamaño completo",
         "workspaceAttachmentMismatch": "Los archivos solo se pueden adjuntar a su espacio de trabajo de origen.",
         "attachmentOwnerChanged": "Este espacio de trabajo cambió de host durante la conexión; vuelve a soltar los archivos.",
-        "attachmentUnreadable": "No se pudieron leer los archivos soltados."
+        "attachmentUnreadable": "No se pudieron leer los archivos soltados.",
+        "tooManyAttachments": "Adjunta {{value0}} archivos o menos a la vez."
       },
       "tool": {
         "running": "Ejecutando…",

src/renderer/src/i18n/locales/fr.json

@@ -17830,7 +17830,8 @@
         "imagePreviewUnavailable": "Aperçu indisponible",
         "workspaceAttachmentMismatch": "Les fichiers ne peuvent être joints qu'à leur espace de travail source.",
         "attachmentOwnerChanged": "Cet espace de travail a changé d'hôte lors de la connexion : supprimez à nouveau les fichiers.",
-        "attachmentUnreadable": "Impossible de lire les fichiers supprimés."
+        "attachmentUnreadable": "Impossible de lire les fichiers supprimés.",
+        "tooManyAttachments": "Joignez {{value0}} fichiers maximum à la fois."
       },
       "tool": {
         "running": "En cours…",

src/renderer/src/i18n/locales/ja.json

@@ -17766,7 +17766,8 @@
         "imagePreviewUnavailable": "プレビューは利用できません",
         "workspaceAttachmentMismatch": "ファイルはソースワークスペースにのみ添付できます。",
         "attachmentOwnerChanged": "このワークスペースは接続中にホストを変更しました。ファイルを再度ドロップしてください。",
-        "attachmentUnreadable": "ドロップされたファイルを読み取れませんでした。"
+        "attachmentUnreadable": "ドロップされたファイルを読み取れませんでした。",
+        "tooManyAttachments": "一度に添付できるファイルは {{value0}} 個以下です。"
       },
       "tool": {
         "running": "実行中…",

src/renderer/src/i18n/locales/ko.json

@@ -17766,7 +17766,8 @@
         "imagePreviewUnavailable": "미리보기를 사용할 수 없습니다.",
         "workspaceAttachmentMismatch": "파일은 소스 워크스페이스에만 첨부할 수 있습니다.",
         "attachmentOwnerChanged": "이 워크스페이스는 첨부하는 동안 호스트를 변경했습니다. 파일을 다시 삭제하세요.",
-        "attachmentUnreadable": "삭제된 파일을 읽을 수 없습니다."
+        "attachmentUnreadable": "삭제된 파일을 읽을 수 없습니다.",
+        "tooManyAttachments": "한 번에 {{value0}}개 이하의 파일을 첨부하세요."
       },
       "tool": {
         "running": "실행 중…",

src/renderer/src/i18n/locales/zh.json

@@ -17731,7 +17731,8 @@
         "imagePreviewUnavailable": "预览不可用",
         "workspaceAttachmentMismatch": "文件只能附加到其源工作区。",
         "attachmentOwnerChanged": "此工作区在附加时更改了主机 - 再次删除文件。",
-        "attachmentUnreadable": "无法读取删除的文件。"
+        "attachmentUnreadable": "无法读取删除的文件。",
+        "tooManyAttachments": "每次最多附加 {{value0}} 个文件。"
       },
       "tool": {
         "running": "正在运行…",

src/renderer/src/web/preload-api/web-shell-api.ts

@@ -25,6 +25,7 @@ export function createShellApi(): NonNullable<Partial<PreloadApi>['shell']> {
     // Without this the fallback proxy answers `undefined` and the caller's batch rejects.
     pathsExist: (paths) => Promise.all(paths.map((path) => pathExistsOnRuntime(path))),
     pickAttachment: () => Promise.resolve(null),
+    pickAttachments: () => Promise.resolve([]),
     pickImage: () => Promise.resolve(null),
     pickRepoIconImage: () => Promise.resolve(null),
     pickAudio: () => Promise.resolve(null),