fix(editor): keep a pinned duplicate open on close and ignore setActiveFile for a missing file (#28120)

* fix(editor): keep a pinned clean sibling open when closing its same-owner twin

Closing a document also closes clean same-owner duplicate records; a record
whose tab is pinned is now left open with its tab.

* fix(editor): ignore setActiveFile for an id with no open file

A stale tab or pane id could make a missing file active and persist it as the
workspace's active file.

src/renderer/src/store/slices/editor-close-pinned-sibling.test.ts

@@ -0,0 +1,79 @@
+import type { StoreApi } from 'zustand/vanilla'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import type { AppState } from '../types'
+import type { OpenFile } from './editor'
+import { createEditorTabsStore } from './editor-slice-test-harness'
+
+const live = vi.hoisted((): { store: StoreApi<AppState> | null } => ({ store: null }))
+vi.mock('@/store', () => ({
+  useAppStore: {
+    getState: () => {
+      if (!live.store) {
+        throw new Error('No test store')
+      }
+      return live.store.getState()
+    }
+  }
+}))
+
+let store: StoreApi<AppState>
+let file: OpenFile
+
+beforeEach(() => {
+  store = createEditorTabsStore()
+  live.store = store
+  store.getState().openFile({
+    filePath: '/repo/note.md',
+    relativePath: 'note.md',
+    worktreeId: 'wt-1',
+    language: 'markdown',
+    mode: 'edit'
+  })
+  const opened = store.getState().openFiles[0]
+  if (!opened) {
+    throw new Error('Document did not open')
+  }
+  file = opened
+})
+
+afterEach(() => {
+  live.store = null
+})
+
+// A clean same-owner twin of `file`, shown in its own tab.
+function addPinnedSibling(): OpenFile {
+  const sibling = { ...file, id: 'duplicate-record' }
+  store.setState({ openFiles: [...store.getState().openFiles, sibling] })
+  store.getState().createUnifiedTab(sibling.worktreeId, 'editor', {
+    id: 'duplicate-tab',
+    entityId: sibling.id,
+    label: 'note.md',
+    activate: false
+  })
+  store.getState().pinTab('duplicate-tab')
+  return sibling
+}
+
+describe('case 7: closing a document with a pinned clean sibling', () => {
+  it('premise: the sibling tab is pinned and both records are open', () => {
+    addPinnedSibling()
+    const tabs = store.getState().unifiedTabsByWorktree['wt-1']
+    expect(tabs.find((tab) => tab.id === 'duplicate-tab')?.isPinned).toBe(true)
+    expect(store.getState().openFiles.map((open) => open.id)).toEqual([file.id, 'duplicate-record'])
+  })
+
+  it('keeps the pinned sibling record open', () => {
+    const sibling = addPinnedSibling()
+    store.getState().closeFile(file.id)
+    expect(store.getState().openFiles).toEqual([sibling])
+  })
+
+  it('keeps the pinned sibling tab and closes only the named tab', () => {
+    addPinnedSibling()
+    store.getState().closeFile(file.id)
+    const tabs = store.getState().unifiedTabsByWorktree['wt-1'] ?? []
+    expect(tabs.map((tab) => [tab.id, tab.entityId])).toEqual([
+      ['duplicate-tab', 'duplicate-record']
+    ])
+  })
+})

src/renderer/src/store/slices/editor-set-active-file-guard.test.ts

@@ -0,0 +1,59 @@
+import type { StoreApi } from 'zustand/vanilla'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import type { AppState } from '../types'
+import { createEditorTabsStore } from './editor-slice-test-harness'
+
+const live = vi.hoisted((): { store: StoreApi<AppState> | null } => ({ store: null }))
+vi.mock('@/store', () => ({
+  useAppStore: {
+    getState: () => {
+      if (!live.store) {
+        throw new Error('No test store')
+      }
+      return live.store.getState()
+    }
+  }
+}))
+
+const GHOST_ID = 'editor:ghost-pane'
+let store: StoreApi<AppState>
+let fileId: string
+
+beforeEach(() => {
+  store = createEditorTabsStore()
+  live.store = store
+  store.getState().openFile({
+    filePath: '/repo/note.md',
+    relativePath: 'note.md',
+    worktreeId: 'wt-1',
+    language: 'markdown',
+    mode: 'edit'
+  })
+  const opened = store.getState().openFiles[0]
+  if (!opened) {
+    throw new Error('Document did not open')
+  }
+  fileId = opened.id
+})
+
+afterEach(() => {
+  live.store = null
+})
+
+describe('setActiveFile with an id that has no open file', () => {
+  it('premise: the open document is active', () => {
+    expect(store.getState().activeFileId).toBe(fileId)
+    expect(store.getState().activeFileIdByWorktree['wt-1']).toBe(fileId)
+  })
+
+  it('leaves the in-memory and per-workspace active file unchanged', () => {
+    store.getState().setActiveFile(GHOST_ID)
+    expect(store.getState().activeFileId).toBe(fileId)
+    expect(store.getState().activeFileIdByWorktree['wt-1']).toBe(fileId)
+  })
+
+  it('leaves the per-workspace active file, which is what persists, unchanged', () => {
+    store.getState().setActiveFile(GHOST_ID, 'wt-1')
+    expect(store.getState().activeFileIdByWorktree['wt-1']).toBe(fileId)
+  })
+})

src/renderer/src/store/slices/editor/actions/close-file-action.ts

@@ -88,6 +88,9 @@ export function createCloseFileAction(
                     preClose.readOnly !== true &&
                     file.readOnly !== true &&
                     isSameOwnedDocument(file, preClose) &&
+                    !get().unifiedTabsByWorktree[file.worktreeId]?.some(
+                      (tab) => tab.entityId === file.id && tab.isPinned
+                    ) &&
                     !file.isDirty &&
                     !(file.id in get().editorDrafts))
               )

src/renderer/src/store/slices/editor/actions/open-file-mutations.ts

@@ -21,6 +21,9 @@ export function createOpenFileMutations(
 > {
   return {
     setActiveFile: (fileId, targetWorktreeId) => {
+      if (!get().openFiles.some((file) => file.id === fileId)) {
+        return
+      }
       set((s) => {
         const file = s.openFiles.find((f) => f.id === fileId)
         const worktreeId = file?.worktreeId