diff --git a/docs/iterations/edit-project/README.md b/docs/iterations/edit-project/README.md
index 7c637ffe..3623c2af 100644
--- a/docs/iterations/edit-project/README.md
+++ b/docs/iterations/edit-project/README.md
@@ -12,7 +12,7 @@
 - **State**: Zustand slice (`editorSlice.ts`)
 - **Виртуализация**: `@tanstack/react-virtual` (уже в проекте)
 - **Fuzzy search**: `cmdk` v1.0.4 (уже в зависимостях)
-- **Новые npm-зависимости**: `@codemirror/search` (~15KB gzipped), `@radix-ui/react-context-menu` (итерация 3, контекстное меню), `simple-git` v3.32+ (итерация 5, git status). Остальное уже установлено
+- **Новые npm-зависимости**: `@codemirror/search` (итерация 1), `isbinaryfile` v5 (итерация 1, binary detection), `@radix-ui/react-context-menu` (итерация 3), `simple-git` v3.32+ (итерация 5, git status), `chokidar` v4 (итерация 5, file watcher). Остальное уже установлено
 
 ## Ключевые архитектурные решения
 
@@ -43,7 +43,7 @@
 
 ## Общая статистика
 
-- **Новые файлы**: ~35
+- **Новые файлы**: ~36
 - **Модификации**: ~18 существующих файлов
 - **Тесты**: ~15 новых тестовых файлов
 - **Итерации**: 6 (PR 0 + 5 итераций)
diff --git a/docs/iterations/edit-project/architecture.md b/docs/iterations/edit-project/architecture.md
index 2c0d81c3..60711a60 100644
--- a/docs/iterations/edit-project/architecture.md
+++ b/docs/iterations/edit-project/architecture.md
@@ -65,6 +65,7 @@ src/renderer/components/team/editor/
 ├── EditorEmptyState.tsx         # Нет открытых файлов + shortcuts шпаргалка
 ├── EditorBinaryState.tsx        # Заглушка для бинарных файлов
 ├── EditorErrorState.tsx         # Заглушка для ошибок чтения (EACCES, ENOENT)
+├── EditorErrorBoundary.tsx     # React ErrorBoundary для CM6 crashes (аналог DiffErrorBoundary)
 ├── EditorShortcutsHelp.tsx      # Модальное окно shortcuts (кнопка ?)
 └── GitStatusBadge.tsx           # M/U/A бейджи в дереве (итерация 5)
 
@@ -181,8 +182,8 @@ async function handleEditorReadFile(
     // 4. Size check
     if (stats.size > MAX_FILE_SIZE) throw new Error('File too large');
 
-    // 5. Binary check
-    const isBinary = await detectBinary(validation.normalizedPath!);
+    // 5. Binary check (isbinaryfile v5 — UTF-16, BOM, encoding hints)
+    const isBinary = await isBinaryFile(validation.normalizedPath!);
 
     // 6. Read
     const content = isBinary ? '' : await fs.readFile(validation.normalizedPath!, 'utf8');
@@ -241,7 +242,7 @@ export interface EditorSlice {
   editorOpenTabs: EditorFileTab[];
   editorActiveTabId: string | null;
 
-  openFile: (filePath: string) => Promise<void>;
+  openFile: (filePath: string) => Promise<void>;  // Dedup: если filePath уже в editorOpenTabs → setActiveTab(existing), не создавать дубликат
   closeTab: (tabId: string) => void;
   setActiveTab: (tabId: string) => void;
 
@@ -530,6 +531,7 @@ const MAX_DIR_DEPTH = 15;
 const MAX_FILENAME_LENGTH = 255;
 const MAX_PATH_LENGTH = 4096;
 
+// Единый набор — используется и в readDir, и в chokidar watcher (iter-5)
 const IGNORED_DIRS = ['.git', 'node_modules', '.next', 'dist', '__pycache__', '.cache', '.venv', '.tox', 'vendor'];
 const IGNORED_FILES = ['.DS_Store', 'Thumbs.db'];
 const BLOCKED_PATHS = ['/dev/', '/proc/', '/sys/', '\\\\.\\'];
@@ -546,7 +548,7 @@ const BLOCKED_PATHS = ['/dev/', '/proc/', '/sys/', '\\\\.\\'];
 
 Для preview-режима (2-5 MB): `readFile` возвращает `{ content: first100Lines, truncated: true, ... }`. CM6 открывается в `readOnly` режиме.
 
-Дополнительно: детектировать минификацию (строка > 10,000 chars) -- banner "Minified" + предложение line wrapping. Binary detection: null bytes в первых 8KB или расширение (.png, .wasm, .jpg, .zip и т.д.).
+Дополнительно: детектировать минификацию (строка > 10,000 chars) -- banner "Minified" + предложение line wrapping. Binary detection: `isBinaryFile()` из `isbinaryfile` v5.0.7 (UTF-16 без BOM, encoding hints, надёжнее ручного null-byte scan).
 
 ### Atomic write
 
@@ -692,6 +694,15 @@ interface TreeNode<T> {
 - ENOENT: "File was deleted. Create new? / Close tab"
 - EACCES: "Permission denied"
 
+### EditorErrorBoundary.tsx (~40-50 LOC)
+
+**Ответственность**: React ErrorBoundary, оборачивающий `CodeMirrorEditor`. Ловит runtime-ошибки CM6 (OOM, bad extension, corrupted EditorState) и показывает fallback UI вместо краша всего overlay.
+
+- Паттерн: аналог `DiffErrorBoundary.tsx` (уже в проекте)
+- Props: `filePath`, `onRetry` (сбросить EditorState и повторить)
+- Fallback UI: AlertTriangle + текст ошибки + [Retry] + [Close Tab]
+- `componentDidCatch`: логировать `filePath` + error для дебага
+
 ---
 
 ## File Tree
@@ -713,7 +724,7 @@ interface TreeNode<T> {
 
 ```typescript
 // flattenTree преобразует иерархию в плоский массив для виртуализации
-function flattenTree(tree: FileTreeEntry[], expandedDirs: Set<string>): FlatNode[] { ... }
+function flattenTree(tree: FileTreeEntry[], expandedDirs: Record<string, boolean>): FlatNode[] { ... }
 
 // В компоненте:
 const flatNodes = useMemo(() => flattenTree(tree, expandedDirs), [tree, expandedDirs]);
diff --git a/docs/iterations/edit-project/file-list.md b/docs/iterations/edit-project/file-list.md
index 3fce21a6..9db766db 100644
--- a/docs/iterations/edit-project/file-list.md
+++ b/docs/iterations/edit-project/file-list.md
@@ -92,7 +92,7 @@ Benchmark 5: Keystroke re-renders
 
 ## Полный список файлов
 
-### Новые файлы (~30)
+### Новые файлы (~36)
 
 | # | Файл | Итерация | Описание |
 |---|------|----------|----------|
@@ -101,7 +101,7 @@ Benchmark 5: Keystroke re-renders
 | 3 | `src/main/services/editor/index.ts` | 1 | Barrel export: `{ ProjectFileService }` (расширяется в итерациях 4-5) |
 | 4 | `src/main/services/editor/FileSearchService.ts` | 4 | Search in files |
 | 5 | `src/main/services/editor/GitStatusService.ts` | 5 | git status через simple-git (~80-100 LOC) |
-| 6 | `src/main/services/editor/EditorFileWatcher.ts` | 5 | FileWatcher (~250-300 LOC, burst coalescing + ENOSPC fallback) |
+| 6 | `src/main/services/editor/EditorFileWatcher.ts` | 5 | FileWatcher через chokidar v4 (~50-70 LOC) |
 | 7 | `src/main/services/editor/conflictDetection.ts` | 5 | Утилита mtime check: сравнение mtime до/после save, conflict resolution (~40 LOC) |
 | 8 | `src/main/ipc/editor.ts` | 1 | IPC handlers |
 | 9 | `src/main/ipc/ipcWrapper.ts` | 1 | Общий `createIpcWrapper()` |
@@ -122,17 +122,18 @@ Benchmark 5: Keystroke re-renders
 | 24 | `src/renderer/components/team/editor/EditorEmptyState.tsx` | 1 | Empty state |
 | 25 | `src/renderer/components/team/editor/EditorBinaryState.tsx` | 1 | Binary файлы |
 | 26 | `src/renderer/components/team/editor/EditorErrorState.tsx` | 1 | Ошибки чтения |
-| 27 | `src/renderer/components/team/editor/EditorContextMenu.tsx` | 3 | Context menu |
-| 28 | `src/renderer/components/team/editor/NewFileDialog.tsx` | 3 | Inline-input |
-| 29 | `src/renderer/components/team/editor/QuickOpenDialog.tsx` | 4 | Cmd+P dialog |
-| 30 | `src/renderer/components/team/editor/SearchInFilesPanel.tsx` | 4 | Cmd+Shift+F |
-| 31 | `src/renderer/components/team/editor/EditorBreadcrumb.tsx` | 4 | Breadcrumb |
-| 32 | `src/renderer/components/team/editor/EditorShortcutsHelp.tsx` | 4 | Shortcuts modal |
-| 33 | `src/renderer/components/team/editor/fileIcons.ts` | 4 | Иконки файлов |
-| 34 | `src/renderer/components/team/editor/GitStatusBadge.tsx` | 5 | M/U/A/C(conflict) бейджи |
-| 35 | `src/renderer/utils/editorBridge.ts` | 2 | Module-level singleton: Store ↔ CM6 refs bridge (R3) |
+| 27 | `src/renderer/components/team/editor/EditorErrorBoundary.tsx` | 1 | React ErrorBoundary для CM6 (аналог DiffErrorBoundary) |
+| 29 | `src/renderer/components/team/editor/EditorContextMenu.tsx` | 3 | Context menu |
+| 30 | `src/renderer/components/team/editor/NewFileDialog.tsx` | 3 | Inline-input |
+| 31 | `src/renderer/components/team/editor/QuickOpenDialog.tsx` | 4 | Cmd+P dialog |
+| 32 | `src/renderer/components/team/editor/SearchInFilesPanel.tsx` | 4 | Cmd+Shift+F |
+| 33 | `src/renderer/components/team/editor/EditorBreadcrumb.tsx` | 4 | Breadcrumb |
+| 34 | `src/renderer/components/team/editor/EditorShortcutsHelp.tsx` | 4 | Shortcuts modal |
+| 35 | `src/renderer/components/team/editor/fileIcons.ts` | 4 | Иконки файлов |
+| 36 | `src/renderer/components/team/editor/GitStatusBadge.tsx` | 5 | M/U/A/C(conflict) бейджи |
+| 37 | `src/renderer/utils/editorBridge.ts` | 2 | Module-level singleton: Store ↔ CM6 refs bridge (R3) |
 
-### Модификации существующих файлов (~17)
+### Модификации существующих файлов (~18)
 
 | # | Файл | Итерация | Изменение |
 |---|------|----------|-----------|
@@ -150,7 +151,7 @@ Benchmark 5: Keystroke re-renders
 | 12 | `src/renderer/api/httpClient.ts` | 1 | Stub для editor: EditorAPI (throw "not available in browser mode") |
 | 13 | `src/main/ipc/teams.ts` | follow-up | Миграция wrapTeamHandler → createIpcWrapper (40+ замен, отдельный PR) |
 | 14 | `src/shared/types/index.ts` | 1 | +`export type * from './editor'` (barrel re-export, паттерн как team/review/terminal) |
-| 15 | `src/main/index.ts` | 5 | `mainWindow.on('closed')` → `cleanupEditorState()`. `shutdownServices()` → `cleanupEditorState()` |
+| 15 | `src/main/index.ts` | 1 (расш. 5) | `mainWindow.on('closed')` → `cleanupEditorState()` (базовый reset в iter-1, watcher cleanup в iter-5) |
 | 16 | `src/renderer/index.css` | 2 | +editor CSS-переменные |
 | 17 | `src/renderer/hooks/useKeyboardShortcuts.ts` | 4 | Guard `editorOpen` для 6 конфликтующих shortcuts (R1) |
 
diff --git a/docs/iterations/edit-project/iter-1-walking-skeleton.md b/docs/iterations/edit-project/iter-1-walking-skeleton.md
index 750913eb..bfdf6b7f 100644
--- a/docs/iterations/edit-project/iter-1-walking-skeleton.md
+++ b/docs/iterations/edit-project/iter-1-walking-skeleton.md
@@ -8,7 +8,8 @@
 
 ## Новые npm-зависимости
 
-`@codemirror/search` (`pnpm add @codemirror/search`)
+- `@codemirror/search` (`pnpm add @codemirror/search`) — встроенный Cmd+F поиск в файле
+- `isbinaryfile` v5.0.7 (`pnpm add isbinaryfile`) — binary detection (33M downloads/нед, zero deps, умнее null-byte scan: UTF-16, BOM, encoding hints)
 
 ## IPC каналы
 
@@ -39,6 +40,7 @@
 | 14 | `src/renderer/components/team/editor/EditorEmptyState.tsx` | Нет открытых файлов |
 | 15 | `src/renderer/components/team/editor/EditorBinaryState.tsx` | Заглушка для бинарных файлов |
 | 16 | `src/renderer/components/team/editor/EditorErrorState.tsx` | Заглушка для ошибок чтения |
+| 17 | `src/renderer/components/team/editor/EditorErrorBoundary.tsx` | React ErrorBoundary для CM6 (аналог DiffErrorBoundary) |
 
 ## Изменения в существующих файлах
 
@@ -53,7 +55,7 @@
 | 7 | `src/renderer/components/team/TeamDetailView.tsx` | Кнопка "Open in Editor" + state для overlay |
 | 8 | `src/renderer/components/team/review/ReviewFileTree.tsx` | Рефакторинг: использовать generic FileTree + fileTreeBuilder |
 | 9 | `src/renderer/components/team/review/CodeMirrorDiffView.tsx` | Рефакторинг: импорт из codemirrorLanguages/Theme |
-| 10 | `src/main/utils/pathValidation.ts` | Добавить `validateFileName()`, `isDevicePath()`, `isGitInternalPath()`. Экспортировать `matchesSensitivePattern()` (приватная) для `isSensitive` в readDir. **B1**: Экспортировать `isPathWithinRoot()` (приватная, строка ~30) — нужна для SEC-14 write-handler guard в iter-2 |
+| 10 | `src/main/utils/pathValidation.ts` | Добавить `validateFileName()`, `isDevicePath()`, `isGitInternalPath()`. Экспортировать `matchesSensitivePattern()` (приватная) для `isSensitive` в readDir. Экспортировать `isPathWithinRoot()` (приватная, строка ~30) — нужна для SEC-15 в `editor:open` handler уже в iter-1, а также для SEC-14 write-handler guard в iter-2 |
 | 11 | `src/main/index.ts` | Добавить базовый cleanup в `mainWindow.on('closed')`: вызвать `cleanupEditorState()` (экспорт из editor.ts, сбрасывает `activeProjectRoot = null`). Без этого при Cmd+Q на macOS state "утечёт" и `editor:open` откажет при следующем открытии окна. Полный watcher cleanup — итерация 5, но базовый reset нужен с итерации 1 |
 | 12 | `src/renderer/api/httpClient.ts` | Stub для `editor: EditorAPI` — throw "Editor is not available in browser mode" (паттерн как `review`, `terminal`, `teams`) |
 | 13 | `src/renderer/store/types.ts` | `EditorSlice` в AppState |
@@ -71,7 +73,7 @@
 
 - MAX_ENTRIES_PER_DIR = 500; при превышении -- "N more files..."
 - readFile тиерная стратегия: <256KB мгновенно, 256KB-2MB progress, 2MB-5MB preview, >5MB external
-- Binary detection: null bytes в первых 8KB
+- Binary detection: `isbinaryfile` (v5.0.7) — `isBinaryFile(filePath)` вместо ручного null-byte scan
 - Дедупликация IPC: `Map<string, Promise<ReadFileResult>>` для readFile
 
 ## UX-требования
diff --git a/docs/iterations/edit-project/iter-3-multi-tab-crud.md b/docs/iterations/edit-project/iter-3-multi-tab-crud.md
index aaf544f4..46dd4f66 100644
--- a/docs/iterations/edit-project/iter-3-multi-tab-crud.md
+++ b/docs/iterations/edit-project/iter-3-multi-tab-crud.md
@@ -45,6 +45,7 @@
 1. `createFile`: `validateFileName()` -- запрет `.`, `..`, control chars, path separators, NUL, length > 255. Валидировать и `parentDir`, и `path.join(parentDir, name)` (SEC-7)
 2. `deleteFile`: `shell.trashItem()`, НЕ `fs.unlink()`. `validateFilePath()` обязательна
 3. Confirmation dialog перед удалением
+4. `createFile`, `createDir`, `deleteFile`: `isGitInternalPath()` блокирует операции внутри `.git/` (SEC-12, аналог writeFile из iter-2)
 
 ## Performance-требования
 
diff --git a/docs/iterations/edit-project/iter-5-git-watching.md b/docs/iterations/edit-project/iter-5-git-watching.md
index c4cd4f4d..d33f661d 100644
--- a/docs/iterations/edit-project/iter-5-git-watching.md
+++ b/docs/iterations/edit-project/iter-5-git-watching.md
@@ -8,7 +8,8 @@ Git status в дереве файлов. Live refresh при изменения
 
 ## Новые npm-зависимости
 
-`simple-git` v3.32+ (`pnpm add simple-git`) — обёртка над git CLI с TypeScript типами, parsed StatusResult, встроенным timeout/abort. 7.9M downloads/нед, dual ESM/CJS, не native module.
+- `simple-git` v3.32+ (`pnpm add simple-git`) — обёртка над git CLI с TypeScript типами, parsed StatusResult, встроенным timeout/abort. 7.9M downloads/нед, dual ESM/CJS, не native module
+- `chokidar` v4.0.3 (`pnpm add chokidar@4`) — file watcher (117M downloads/нед). Решает все проблемы raw `fs.watch`: нормализация событий, recursive на Linux, ENOSPC handling, symlinks. Dual CJS/ESM, Node 14+
 
 ## IPC каналы
 
@@ -22,7 +23,7 @@ Git status в дереве файлов. Live refresh при изменения
 
 | # | Файл | Описание |
 |---|------|----------|
-| 1 | `src/main/services/editor/EditorFileWatcher.ts` | FileWatcher (~250-300 LOC, не ~60!). fs.watch + burst coalescing (200ms debounce + batch) + ENOSPC fallback to polling (Linux). Фильтрация node_modules/.git/dist |
+| 1 | `src/main/services/editor/EditorFileWatcher.ts` | FileWatcher через `chokidar` v4 (~50-70 LOC). Burst coalescing, ENOSPC, recursive Linux — всё встроено. Фильтрация node_modules/.git/dist через `ignored` option |
 | 2 | `src/main/services/editor/GitStatusService.ts` | Git status через `simple-git` с `StatusResult` маппингом, кеш 5 сек. Переиспользовать `isGitRepo()` из `GitDiffFallback.ts` (~80-100 LOC) |
 | 3 | `src/main/services/editor/conflictDetection.ts` | Утилита mtime check: сравнение mtime до/после save, conflict resolution (~40 LOC) |
 | 4 | `src/renderer/components/team/editor/GitStatusBadge.tsx` | M/U/A бейджи в дереве |
@@ -57,9 +58,36 @@ Git status в дереве файлов. Live refresh при изменения
 ## Performance-требования (R4/R5)
 
 - File watcher opt-in: по умолчанию ВЫКЛЮЧЕН. Toggle "Watch for external changes". По умолчанию ручной refresh (F5)
-- `fs.watch({ recursive: true })` + фильтрация (node_modules/.git/dist) + burst coalescing 200ms
-- **macOS**: FSEvents reliable (надёжность 9/10)
-- **Linux**: inotify (надёжность 6/10). При `ENOSPC` → fallback на polling (5-10 сек). НЕ падать, деградировать
+
+### chokidar конфигурация
+
+```typescript
+// src/main/services/editor/EditorFileWatcher.ts
+import { watch, type FSWatcher } from 'chokidar';
+
+let watcher: FSWatcher | null = null;
+
+function startWatching(projectRoot: string, onChange: (event: EditorFileChangeEvent) => void) {
+  watcher = watch(projectRoot, {
+    ignored: /(node_modules|\.git|dist|__pycache__|\.cache|\.next|\.venv|\.tox|vendor)/,
+    ignoreInitial: true,
+    followSymlinks: false,
+    depth: 20,
+  });
+  watcher.on('change', path => onChange({ type: 'change', path }));
+  watcher.on('add', path => onChange({ type: 'create', path }));
+  watcher.on('unlink', path => onChange({ type: 'delete', path }));
+}
+
+function stopWatching() {
+  watcher?.close();
+  watcher = null;
+}
+```
+
+- **chokidar v4** решает все проблемы raw `fs.watch`: нормализация событий macOS, recursive на Linux, ENOSPC handling, debounce
+- **macOS**: FSEvents через chokidar (надёжность 9/10)
+- **Linux**: inotify через chokidar с автоматическим fallback (надёжность 8/10, было 6/10 с raw fs.watch)
 - Git status кешировать на 5 секунд. Invalidate по file watcher event
 
 ### simple-git конфигурация
@@ -109,7 +137,7 @@ function mapStatus(result: StatusResult): GitFileStatus[] {
 | # | Что тестировать | Файл |
 |---|----------------|------|
 | 1 | `GitStatusService` -- маппинг `simple-git` StatusResult → GitFileStatus[], кеш, graceful degradation | `test/main/services/editor/GitStatusService.test.ts` |
-| 2 | `EditorFileWatcher` -- debounce, event types | `test/main/services/editor/EditorFileWatcher.test.ts` |
+| 2 | `EditorFileWatcher` -- chokidar watcher lifecycle (start/stop), event mapping, cleanup | `test/main/services/editor/EditorFileWatcher.test.ts` |
 | 3 | `conflictDetection` -- mtime check логика | `test/main/services/editor/conflictDetection.test.ts` |
 | 4 | Manual: изменить файл в внешнем редакторе -> conflict banner | — |
 
@@ -122,5 +150,5 @@ function mapStatus(result: StatusResult): GitFileStatus[] {
 
 ## Оценка
 
-- **Надёжность решения: 8/10** (было 7/10) -- `simple-git` убирает ~120 LOC ручного парсинга, conflict/renamed detection из коробки. ENOSPC fallback и burst coalescing проработаны.
-- **Уверенность: 9/10** (было 8/10) -- simple-git 7.9M downloads/нед, TypeScript типы, встроенный timeout/abort. Риск минимален.
+- **Надёжность решения: 9/10** (было 8/10) -- `simple-git` + `chokidar` убирают ~300 LOC ручного кода: парсинг porcelain, fs.watch нормализация, ENOSPC fallback. Всё покрыто проверенными пакетами.
+- **Уверенность: 9/10** -- simple-git 7.9M + chokidar 117M downloads/нед. Оба с TypeScript, проверены в production.
diff --git a/src/main/http/utility.ts b/src/main/http/utility.ts
index efd6228a..b3aa982f 100644
--- a/src/main/http/utility.ts
+++ b/src/main/http/utility.ts
@@ -11,7 +11,7 @@
  */
 
 import { createLogger } from '@shared/utils/logger';
-import * as fs from 'fs';
+import * as fsp from 'fs/promises';
 import * as path from 'path';
 
 import {
@@ -27,14 +27,19 @@ import type { FastifyInstance } from 'fastify';
 
 const logger = createLogger('HTTP:utility');
 
+/** Cached app version — read once from package.json, not every request. */
+let cachedVersion: string | null = null;
+
 export function registerUtilityRoutes(app: FastifyInstance): void {
-  // App version
+  // App version (cached — no file I/O after first call)
   app.get('/api/version', async () => {
+    if (cachedVersion) return cachedVersion;
     try {
-      // Read version from package.json (works in both Electron and Node)
       const pkgPath = path.resolve(__dirname, '../../../package.json');
-      const pkg = JSON.parse(fs.readFileSync(pkgPath, 'utf8')) as { version: string };
-      return pkg.version;
+      const content = await fsp.readFile(pkgPath, 'utf8');
+      const pkg = JSON.parse(content) as { version: string };
+      cachedVersion = pkg.version;
+      return cachedVersion;
     } catch {
       return '0.0.0';
     }
@@ -73,7 +78,7 @@ export function registerUtilityRoutes(app: FastifyInstance): void {
     }
   });
 
-  // Read mentioned file
+  // Read mentioned file — async I/O, no TOCTOU
   app.post<{ Body: { absolutePath: string; projectRoot: string; maxTokens?: number } }>(
     '/api/read-mentioned-file',
     async (request) => {
@@ -87,16 +92,12 @@ export function registerUtilityRoutes(app: FastifyInstance): void {
 
         const safePath = validation.normalizedPath!;
 
-        if (!fs.existsSync(safePath)) {
-          return null;
-        }
-
-        const stats = fs.statSync(safePath);
+        const stats = await fsp.stat(safePath);
         if (!stats.isFile()) {
           return null;
         }
 
-        const content = fs.readFileSync(safePath, 'utf8');
+        const content = await fsp.readFile(safePath, 'utf8');
         const estimatedTokens = countTokens(content);
 
         if (estimatedTokens > maxTokens) {
diff --git a/src/main/http/validation.ts b/src/main/http/validation.ts
index 12863622..c9d9ddcd 100644
--- a/src/main/http/validation.ts
+++ b/src/main/http/validation.ts
@@ -8,7 +8,7 @@
  */
 
 import { createLogger } from '@shared/utils/logger';
-import * as fs from 'fs';
+import * as fsp from 'fs/promises';
 import * as path from 'path';
 
 import type { FastifyInstance } from 'fastify';
@@ -39,11 +39,8 @@ export function registerValidationRoutes(app: FastifyInstance): void {
           return { exists: false };
         }
 
-        if (!fs.existsSync(fullPath)) {
-          return { exists: false };
-        }
-
-        const stats = fs.statSync(fullPath);
+        // Single async stat — no TOCTOU, doesn't block the main thread
+        const stats = await fsp.stat(fullPath);
         return { exists: true, isDirectory: stats.isDirectory() };
       } catch {
         return { exists: false };
@@ -56,18 +53,24 @@ export function registerValidationRoutes(app: FastifyInstance): void {
     '/api/validate/mentions',
     async (request) => {
       const { mentions, projectPath } = request.body;
-      const results = new Map<string, boolean>();
 
-      for (const mention of mentions) {
-        const fullPath = path.join(projectPath, mention.value);
-        if (!isPathContained(fullPath, projectPath)) {
-          results.set(`@${mention.value}`, false);
-          continue;
-        }
-        results.set(`@${mention.value}`, fs.existsSync(fullPath));
-      }
+      // Validate all mentions in parallel with async I/O
+      const entries = await Promise.all(
+        mentions.map(async (mention) => {
+          const fullPath = path.join(projectPath, mention.value);
+          if (!isPathContained(fullPath, projectPath)) {
+            return [`@${mention.value}`, false] as const;
+          }
+          try {
+            await fsp.access(fullPath);
+            return [`@${mention.value}`, true] as const;
+          } catch {
+            return [`@${mention.value}`, false] as const;
+          }
+        })
+      );
 
-      return Object.fromEntries(results);
+      return Object.fromEntries(entries);
     }
   );
 
diff --git a/src/main/index.ts b/src/main/index.ts
index 1c7253f6..db9e7d37 100644
--- a/src/main/index.ts
+++ b/src/main/index.ts
@@ -9,6 +9,13 @@
  * - Manage application lifecycle
  */
 
+// Increase UV thread pool size BEFORE any async I/O.
+// Default is 4 threads which is far too few for startup:
+// binary resolution stat() calls, CLI subprocess spawning, fs.watch(),
+// and readFile/readdir from IPC handlers all compete for the pool.
+// On Windows this saturates all threads, blocking the event loop.
+process.env.UV_THREADPOOL_SIZE ??= '16';
+
 import { ChangeExtractorService } from '@main/services/team/ChangeExtractorService';
 import { FileContentResolver } from '@main/services/team/FileContentResolver';
 import { GitDiffFallback } from '@main/services/team/GitDiffFallback';
diff --git a/src/main/ipc/utility.ts b/src/main/ipc/utility.ts
index 2746fe35..2ff7642a 100644
--- a/src/main/ipc/utility.ts
+++ b/src/main/ipc/utility.ts
@@ -10,7 +10,7 @@
 
 import { createLogger } from '@shared/utils/logger';
 import { app, type IpcMain, type IpcMainInvokeEvent, shell } from 'electron';
-import * as fs from 'fs';
+import * as fsp from 'fs/promises';
 
 import {
   type ClaudeMdFileInfo,
@@ -77,9 +77,16 @@ function handleGetAppVersion(): string {
  * Handler for 'shell:showInFolder' IPC call.
  * Reveals a file in the system file manager (Finder/Explorer).
  */
-function handleShellShowInFolder(_event: IpcMainInvokeEvent, filePath: string): void {
-  if (typeof filePath === 'string' && filePath.length > 0 && fs.existsSync(filePath)) {
+async function handleShellShowInFolder(
+  _event: IpcMainInvokeEvent,
+  filePath: string
+): Promise<void> {
+  if (typeof filePath !== 'string' || filePath.length === 0) return;
+  try {
+    await fsp.access(filePath);
     shell.showItemInFolder(filePath);
+  } catch {
+    // File doesn't exist — silently ignore
   }
 }
 
@@ -137,8 +144,10 @@ async function handleShellOpenPath(
 
     const safePath = validation.normalizedPath!;
 
-    // Check if path exists
-    if (!fs.existsSync(safePath)) {
+    // Check if path exists (async to avoid blocking main thread)
+    try {
+      await fsp.access(safePath);
+    } catch {
       logger.error(`shell:openPath - path does not exist: ${safePath}`);
       return { success: false, error: 'Path does not exist' };
     }
@@ -224,19 +233,13 @@ async function handleReadMentionedFile(
 
     const safePath = validation.normalizedPath!;
 
-    // Check if file exists
-    if (!fs.existsSync(safePath)) {
-      return null;
-    }
-
-    // Check if it's a file (not directory)
-    const stats = fs.statSync(safePath);
+    // Single async stat + read — no TOCTOU, doesn't block main thread
+    const stats = await fsp.stat(safePath);
     if (!stats.isFile()) {
       return null;
     }
 
-    // Read file content
-    const content = fs.readFileSync(safePath, 'utf8');
+    const content = await fsp.readFile(safePath, 'utf8');
 
     // Calculate tokens
     const estimatedTokens = countTokens(content);
diff --git a/src/main/ipc/validation.ts b/src/main/ipc/validation.ts
index edf52760..852ddcb6 100644
--- a/src/main/ipc/validation.ts
+++ b/src/main/ipc/validation.ts
@@ -9,7 +9,7 @@
 
 import { createLogger } from '@shared/utils/logger';
 import { type IpcMain, type IpcMainInvokeEvent } from 'electron';
-import * as fs from 'fs';
+import * as fsp from 'fs/promises';
 import * as path from 'path';
 
 const logger = createLogger('IPC:validation');
@@ -75,11 +75,8 @@ async function handleValidatePath(
       return { exists: false };
     }
 
-    if (!fs.existsSync(fullPath)) {
-      return { exists: false };
-    }
-
-    const stats = fs.statSync(fullPath);
+    // Single async stat — no TOCTOU, doesn't block the main thread
+    const stats = await fsp.stat(fullPath);
     return {
       exists: true,
       isDirectory: stats.isDirectory(),
@@ -99,21 +96,27 @@ async function handleValidateMentions(
   mentions: { type: 'path'; value: string }[],
   projectPath: string
 ): Promise<Record<string, boolean>> {
-  const results = new Map<string, boolean>();
+  // Validate all mentions in parallel with async I/O
+  // (was sequential sync existsSync — blocked main thread per mention)
+  const entries = await Promise.all(
+    mentions.map(async (mention) => {
+      const fullPath = path.join(projectPath, mention.value);
 
-  for (const mention of mentions) {
-    const fullPath = path.join(projectPath, mention.value);
+      // Security: Skip paths that escape project directory
+      if (!isPathContained(fullPath, projectPath)) {
+        return [`@${mention.value}`, false] as const;
+      }
 
-    // Security: Skip paths that escape project directory
-    if (!isPathContained(fullPath, projectPath)) {
-      results.set(`@${mention.value}`, false);
-      continue;
-    }
+      try {
+        await fsp.access(fullPath);
+        return [`@${mention.value}`, true] as const;
+      } catch {
+        return [`@${mention.value}`, false] as const;
+      }
+    })
+  );
 
-    results.set(`@${mention.value}`, fs.existsSync(fullPath));
-  }
-
-  return Object.fromEntries(results);
+  return Object.fromEntries(entries);
 }
 
 /**
diff --git a/src/main/services/infrastructure/ConfigManager.ts b/src/main/services/infrastructure/ConfigManager.ts
index 64f1dca8..645213a9 100644
--- a/src/main/services/infrastructure/ConfigManager.ts
+++ b/src/main/services/infrastructure/ConfigManager.ts
@@ -13,6 +13,7 @@ import { getHomeDir, setClaudeBasePathOverride } from '@main/utils/pathDecoder';
 import { validateRegexPattern } from '@main/utils/regexValidation';
 import { createLogger } from '@shared/utils/logger';
 import * as fs from 'fs';
+import * as fsp from 'fs/promises';
 import * as path from 'path';
 
 import { DEFAULT_TRIGGERS, TriggerManager } from './TriggerManager';
@@ -352,21 +353,21 @@ export class ConfigManager {
   /**
    * Loads configuration from disk.
    * Returns default config if file doesn't exist or is invalid.
+   * Uses a single readFileSync (no TOCTOU from existsSync + readFileSync).
    */
   private loadConfig(): AppConfig {
     try {
-      if (!fs.existsSync(this.configPath)) {
-        logger.info('No config file found, using defaults');
-        return this.deepClone(DEFAULT_CONFIG);
-      }
-
       const content = fs.readFileSync(this.configPath, 'utf8');
       const parsed = JSON.parse(content) as Partial<AppConfig>;
 
       // Merge with defaults to ensure all fields exist
       return this.mergeWithDefaults(parsed);
     } catch (error) {
-      logger.error('Error loading config, using defaults:', error);
+      if ((error as NodeJS.ErrnoException).code === 'ENOENT') {
+        logger.info('No config file found, using defaults');
+      } else {
+        logger.error('Error loading config, using defaults:', error);
+      }
       return this.deepClone(DEFAULT_CONFIG);
     }
   }
@@ -384,16 +385,18 @@ export class ConfigManager {
   }
 
   /**
-   * Persists configuration to the canonical path.
+   * Persists configuration to the canonical path asynchronously.
+   * Uses async I/O to avoid blocking the main process event loop.
+   * mkdir({ recursive: true }) is idempotent — no need for an existsSync guard.
    */
   private persistConfig(config: AppConfig): void {
-    const configDir = path.dirname(this.configPath);
-    if (!fs.existsSync(configDir)) {
-      fs.mkdirSync(configDir, { recursive: true });
-    }
-
     const content = JSON.stringify(config, null, 2);
-    fs.writeFileSync(this.configPath, content, 'utf8');
+    fsp
+      .mkdir(path.dirname(this.configPath), { recursive: true })
+      .then(() => fsp.writeFile(this.configPath, content, 'utf8'))
+      .catch((error) => {
+        logger.error('Error persisting config:', error);
+      });
   }
 
   /**
diff --git a/src/main/services/infrastructure/HttpServer.ts b/src/main/services/infrastructure/HttpServer.ts
index 597675f6..f4469432 100644
--- a/src/main/services/infrastructure/HttpServer.ts
+++ b/src/main/services/infrastructure/HttpServer.ts
@@ -13,7 +13,8 @@ import { type HttpServices, registerHttpRoutes } from '@main/http';
 import { broadcastEvent } from '@main/http/events';
 import { createLogger } from '@shared/utils/logger';
 import Fastify, { type FastifyInstance } from 'fastify';
-import { existsSync, readFileSync } from 'fs';
+import { existsSync } from 'fs';
+import { readFile } from 'fs/promises';
 import { join } from 'path';
 
 const logger = createLogger('Service:HttpServer');
@@ -97,8 +98,8 @@ export class HttpServer {
     if (rendererPath) {
       logger.info(`Serving static files from: ${rendererPath}`);
 
-      // Cache index.html for SPA fallback
-      const indexHtml = readFileSync(join(rendererPath, 'index.html'), 'utf-8');
+      // Cache index.html for SPA fallback (async to avoid blocking main thread)
+      const indexHtml = await readFile(join(rendererPath, 'index.html'), 'utf-8');
 
       await this.app.register(fastifyStatic, {
         root: rendererPath,
diff --git a/src/main/services/infrastructure/NotificationManager.ts b/src/main/services/infrastructure/NotificationManager.ts
index cacf3d6f..b1f8a2bc 100644
--- a/src/main/services/infrastructure/NotificationManager.ts
+++ b/src/main/services/infrastructure/NotificationManager.ts
@@ -16,7 +16,6 @@ import { getHomeDir } from '@main/utils/pathDecoder';
 import { createLogger } from '@shared/utils/logger';
 import { type BrowserWindow, Notification } from 'electron';
 import { EventEmitter } from 'events';
-import * as fs from 'fs';
 import * as fsp from 'fs/promises';
 import * as path from 'path';
 
@@ -165,10 +164,11 @@ export class NotificationManager extends EventEmitter {
 
   /**
    * Loads notifications from disk (async to avoid blocking startup).
+   * Uses a single readFile instead of access() + readFile() to eliminate
+   * a redundant syscall and TOCTOU race condition.
    */
   private async loadNotifications(): Promise<void> {
     try {
-      await fsp.access(NOTIFICATIONS_PATH, fs.constants.F_OK);
       const data = await fsp.readFile(NOTIFICATIONS_PATH, 'utf8');
       const parsed = JSON.parse(data) as unknown;
 
@@ -188,20 +188,20 @@ export class NotificationManager extends EventEmitter {
   }
 
   /**
-   * Saves notifications to disk.
+   * Saves notifications to disk asynchronously.
+   * Uses async I/O to avoid blocking the main process event loop,
+   * which is critical on Windows where sync writes can freeze the UI.
    */
   private saveNotifications(): void {
-    try {
-      // Ensure directory exists
-      const dir = path.dirname(NOTIFICATIONS_PATH);
-      if (!fs.existsSync(dir)) {
-        fs.mkdirSync(dir, { recursive: true });
-      }
+    const data = JSON.stringify(this.notifications, null, 2);
+    const dir = path.dirname(NOTIFICATIONS_PATH);
 
-      fs.writeFileSync(NOTIFICATIONS_PATH, JSON.stringify(this.notifications, null, 2), 'utf8');
-    } catch (error) {
-      logger.error('Error saving notifications:', error);
-    }
+    fsp
+      .mkdir(dir, { recursive: true })
+      .then(() => fsp.writeFile(NOTIFICATIONS_PATH, data, 'utf8'))
+      .catch((error) => {
+        logger.error('Error saving notifications:', error);
+      });
   }
 
   /**
diff --git a/src/main/services/team/ClaudeBinaryResolver.ts b/src/main/services/team/ClaudeBinaryResolver.ts
index 90e345fd..af7d9f7b 100644
--- a/src/main/services/team/ClaudeBinaryResolver.ts
+++ b/src/main/services/team/ClaudeBinaryResolver.ts
@@ -84,24 +84,30 @@ async function resolveFromPathEnv(binaryName: string): Promise<string | null> {
   const pathParts = rawPath.split(path.delimiter);
   const binaryNames =
     process.platform === 'win32' ? expandWindowsBinaryNames(binaryName) : [binaryName];
-  for (const part of pathParts) {
-    if (!part) {
-      continue;
-    }
 
-    const cleanedPart = stripSurroundingQuotes(part);
-    if (!cleanedPart) {
-      continue;
-    }
+  // Check all PATH directories in parallel. Each directory checks all extension
+  // variants concurrently. This turns N_dirs × N_exts sequential stat() calls
+  // into a single parallel batch, dramatically reducing startup time on Windows.
+  const dirResults = await Promise.all(
+    pathParts.map(async (part) => {
+      if (!part) return null;
+      const cleanedPart = stripSurroundingQuotes(part);
+      if (!cleanedPart) return null;
 
-    for (const name of binaryNames) {
-      const candidate = path.join(cleanedPart, name);
-      if (await isExecutable(candidate)) {
-        return candidate;
-      }
-    }
-  }
-  return null;
+      const candidates = binaryNames.map((name) => path.join(cleanedPart, name));
+      const results = await Promise.all(
+        candidates.map(async (candidate) => ({
+          path: candidate,
+          ok: await isExecutable(candidate),
+        }))
+      );
+      // Return the first matching extension variant within this directory
+      return results.find((r) => r.ok)?.path ?? null;
+    })
+  );
+
+  // Return first non-null result, preserving PATH priority order
+  return dirResults.find((r) => r !== null) ?? null;
 }
 
 async function resolveFromExplicitPath(inputPath: string): Promise<string | null> {
@@ -186,11 +192,20 @@ export class ClaudeBinaryResolver {
     );
 
     const nvmCandidates = process.platform === 'win32' ? [] : await collectNvmCandidates();
-    for (const candidate of [...candidates, ...nvmCandidates]) {
-      if (await isExecutable(candidate)) {
-        cachedPath = candidate;
-        return cachedPath;
-      }
+    const allCandidates = [...candidates, ...nvmCandidates];
+
+    // Check all fallback candidates in parallel for speed
+    const results = await Promise.all(
+      allCandidates.map(async (candidate) => ({
+        path: candidate,
+        ok: await isExecutable(candidate),
+      }))
+    );
+    // Return first match, preserving candidate priority order
+    const found = results.find((r) => r.ok);
+    if (found) {
+      cachedPath = found.path;
+      return cachedPath;
     }
 
     // Don't cache null — CLI may be installed later without app restart
diff --git a/src/renderer/App.tsx b/src/renderer/App.tsx
index 1223d102..ece32b9b 100644
--- a/src/renderer/App.tsx
+++ b/src/renderer/App.tsx
@@ -23,20 +23,12 @@ export const App = (): React.JSX.Element => {
     }
   }, []);
 
-  // Defer IPC-heavy initialization to after the first paint.
-  // On Windows, firing 6+ IPC calls simultaneously at startup saturates the
-  // UV thread pool (4 threads by default), causing the app to freeze.
-  // Context system init is skipped here — local context is ready by default,
-  // and SSH context is initialized lazily when SSH connects (see below).
+  // Initialize IPC listeners and start sequential data fetch chain.
+  // No delay needed: UV_THREADPOOL_SIZE=16 prevents thread pool saturation,
+  // and the init chain fetches data sequentially to avoid concurrent I/O spikes.
   useEffect(() => {
-    let cleanup: (() => void) | undefined;
-    const timer = setTimeout(() => {
-      cleanup = initializeNotificationListeners();
-    }, 100);
-    return () => {
-      clearTimeout(timer);
-      cleanup?.();
-    };
+    const cleanup = initializeNotificationListeners();
+    return cleanup;
   }, []);
 
   // Initialize context system lazily when SSH connection state changes.
diff --git a/src/renderer/components/sidebar/DateGroupedSessions.tsx b/src/renderer/components/sidebar/DateGroupedSessions.tsx
index 56014bee..c72701fc 100644
--- a/src/renderer/components/sidebar/DateGroupedSessions.tsx
+++ b/src/renderer/components/sidebar/DateGroupedSessions.tsx
@@ -236,14 +236,26 @@ export const DateGroupedSessions = (): React.JSX.Element => {
   const [isWorktreeDropdownOpen, setIsWorktreeDropdownOpen] = useState(false);
   const worktreeDropdownRef = useRef<HTMLDivElement>(null);
 
-  // Fetch project data on mount
+  // Fetch project data on mount or when viewMode changes.
+  // Loading guards in the store actions prevent duplicate IPC calls
+  // when the centralized init chain has already started a fetch.
+  const repositoryGroupsLoading = useStore((s) => s.repositoryGroupsLoading);
+  const projectsLoading = useStore((s) => s.projectsLoading);
   useEffect(() => {
-    if (viewMode === 'grouped' && repositoryGroups.length === 0) {
+    if (viewMode === 'grouped' && repositoryGroups.length === 0 && !repositoryGroupsLoading) {
       void fetchRepositoryGroups();
-    } else if (viewMode === 'flat' && projects.length === 0) {
+    } else if (viewMode === 'flat' && projects.length === 0 && !projectsLoading) {
       void fetchProjects();
     }
-  }, [viewMode, repositoryGroups.length, projects.length, fetchRepositoryGroups, fetchProjects]);
+  }, [
+    viewMode,
+    repositoryGroups.length,
+    projects.length,
+    repositoryGroupsLoading,
+    projectsLoading,
+    fetchRepositoryGroups,
+    fetchProjects,
+  ]);
 
   // Project combobox options
   const projectComboboxOptions = useMemo((): ComboboxOption[] => {
diff --git a/src/renderer/components/sidebar/GlobalTaskList.tsx b/src/renderer/components/sidebar/GlobalTaskList.tsx
index c1248b55..36925236 100644
--- a/src/renderer/components/sidebar/GlobalTaskList.tsx
+++ b/src/renderer/components/sidebar/GlobalTaskList.tsx
@@ -128,12 +128,14 @@ export const GlobalTaskList = ({
     saveGroupingMode(mode);
   };
 
+  // Fetch tasks on mount — loading guard in the store action prevents
+  // duplicate IPC calls when the centralized init chain is already fetching.
   useEffect(() => {
-    if (!hasFetchedRef.current) {
+    if (!hasFetchedRef.current && !globalTasksLoading) {
       hasFetchedRef.current = true;
       void fetchAllTasks();
     }
-  }, [fetchAllTasks]);
+  }, [fetchAllTasks, globalTasksLoading]);
 
   // Build project combobox options from available projects/repos
   const projectFilterOptions = useMemo((): ComboboxOption[] => {
diff --git a/src/renderer/hooks/useTheme.ts b/src/renderer/hooks/useTheme.ts
index c9d2f4c9..dc6bc9f3 100644
--- a/src/renderer/hooks/useTheme.ts
+++ b/src/renderer/hooks/useTheme.ts
@@ -39,12 +39,15 @@ export function useTheme(): {
     return 'dark';
   });
 
-  // Fetch config on mount if not loaded
+  // Fetch config on mount if not loaded.
+  // The centralized init chain also calls fetchConfig — configLoading guard
+  // in the store action prevents duplicate IPC calls.
+  const configLoading = useStore((s) => s.configLoading);
   useEffect(() => {
-    if (!appConfig) {
+    if (!appConfig && !configLoading) {
       void fetchConfig();
     }
-  }, [appConfig, fetchConfig]);
+  }, [appConfig, configLoading, fetchConfig]);
 
   // Get configured theme
   const configuredTheme: Theme = appConfig?.general?.theme ?? 'dark';
diff --git a/src/renderer/store/index.ts b/src/renderer/store/index.ts
index b5eab735..6178936e 100644
--- a/src/renderer/store/index.ts
+++ b/src/renderer/store/index.ts
@@ -73,18 +73,41 @@ export function initializeNotificationListeners(): () => void {
   cleanupFns.push(() => {
     useStore.getState().unsubscribeProvisioningProgress();
   });
-  // Stagger IPC data fetches to avoid saturating the UV thread pool on Windows.
-  // Each fetch triggers file I/O in the main process; firing them all at once
-  // blocks all 4 default UV threads simultaneously, freezing the app.
-  void useStore
-    .getState()
-    .fetchTeams()
-    .finally(() => {
-      void useStore.getState().fetchNotifications();
-      if (api.cliInstaller) {
-        void useStore.getState().fetchCliStatus();
-      }
-    });
+  // Initial data fetches. Config loads first (needed for theme), then the rest
+  // run in parallel (no data dependencies between them). UV_THREADPOOL_SIZE=16
+  // prevents thread pool saturation even with concurrent I/O on Windows.
+  // Components also fire these from useEffect — loading guards in each action
+  // prevent duplicate IPC calls (whichever caller starts first wins).
+  void (async () => {
+    // Config: fast (in-memory read) — needed for theme before first paint.
+    await useStore.getState().fetchConfig();
+    // Remaining fetches have no data dependency on each other — run in parallel
+    // to avoid blocking teams/notifications behind a slow repository scan.
+    await Promise.all([
+      // Repository groups: heavy — full project directory scan for sidebar.
+      useStore.getState().fetchRepositoryGroups(),
+      // Global tasks: moderate — reads team task files for sidebar.
+      useStore.getState().fetchAllTasks(),
+      // Team summaries: moderate — reads team config files.
+      useStore.getState().fetchTeams(),
+      // Notification count: light — reads from in-memory store in main process.
+      useStore.getState().fetchNotifications(),
+    ]);
+  })();
+
+  // CLI status check is non-critical for initial render (spawns child processes
+  // + iterates PATH directories with stat() calls — heavy on Windows).
+  // Defer until the app is fully interactive.
+  let cliStatusTimer: ReturnType<typeof setTimeout> | null = null;
+  if (api.cliInstaller) {
+    cliStatusTimer = setTimeout(() => {
+      void useStore.getState().fetchCliStatus();
+      cliStatusTimer = null;
+    }, 5000);
+  }
+  cleanupFns.push(() => {
+    if (cliStatusTimer) clearTimeout(cliStatusTimer);
+  });
   const pendingSessionRefreshTimers = new Map<string, ReturnType<typeof setTimeout>>();
   const pendingProjectRefreshTimers = new Map<string, ReturnType<typeof setTimeout>>();
   let teamRefreshTimer: ReturnType<typeof setTimeout> | null = null;
@@ -179,7 +202,7 @@ export function initializeNotificationListeners(): () => void {
     }
   }
 
-  // fetchNotifications() is called in the staggered init chain above (after fetchTeams).
+  // fetchNotifications() is called in the parallel init chain above.
 
   /**
    * Check if a session is visible in any pane (not just the focused pane's active tab).
@@ -373,7 +396,7 @@ export function initializeNotificationListeners(): () => void {
     }
   }
 
-  // fetchCliStatus() is called in the staggered init chain above (after fetchTeams).
+  // fetchCliStatus() is deferred 5s after app start (heavy on Windows).
 
   // Listen for CLI installer progress events from main process
   let cliCompletedRevertTimer: ReturnType<typeof setTimeout> | null = null;
diff --git a/src/renderer/store/slices/configSlice.ts b/src/renderer/store/slices/configSlice.ts
index 0cdc5320..66122ad5 100644
--- a/src/renderer/store/slices/configSlice.ts
+++ b/src/renderer/store/slices/configSlice.ts
@@ -42,6 +42,8 @@ export const createConfigSlice: StateCreator<AppState, [], [], ConfigSlice> = (s
 
   // Fetch app configuration from main process
   fetchConfig: async () => {
+    // Guard: prevent concurrent fetches (useTheme + centralized init chain)
+    if (get().configLoading) return;
     set({ configLoading: true, configError: null });
     try {
       const config = await api.config.get();
diff --git a/src/renderer/store/slices/projectSlice.ts b/src/renderer/store/slices/projectSlice.ts
index bbcdf440..e02426e1 100644
--- a/src/renderer/store/slices/projectSlice.ts
+++ b/src/renderer/store/slices/projectSlice.ts
@@ -39,6 +39,8 @@ export const createProjectSlice: StateCreator<AppState, [], [], ProjectSlice> =
 
   // Fetch all projects from main process
   fetchProjects: async () => {
+    // Guard: prevent concurrent fetches (component mount + centralized init chain)
+    if (get().projectsLoading) return;
     set({ projectsLoading: true, projectsError: null });
     try {
       const projects = await api.getProjects();
diff --git a/src/renderer/store/slices/repositorySlice.ts b/src/renderer/store/slices/repositorySlice.ts
index f9b1b4da..d133928a 100644
--- a/src/renderer/store/slices/repositorySlice.ts
+++ b/src/renderer/store/slices/repositorySlice.ts
@@ -51,6 +51,8 @@ export const createRepositorySlice: StateCreator<AppState, [], [], RepositorySli
 
   // Fetch all repository groups (projects grouped by git repo)
   fetchRepositoryGroups: async () => {
+    // Guard: prevent concurrent fetches (component mount + centralized init chain)
+    if (get().repositoryGroupsLoading) return;
     set({ repositoryGroupsLoading: true, repositoryGroupsError: null });
     try {
       const groups = await api.getRepositoryGroups();
diff --git a/src/renderer/store/slices/teamSlice.ts b/src/renderer/store/slices/teamSlice.ts
index 12cdc62f..7ec5a138 100644
--- a/src/renderer/store/slices/teamSlice.ts
+++ b/src/renderer/store/slices/teamSlice.ts
@@ -212,6 +212,10 @@ export const createTeamSlice: StateCreator<AppState, [], [], TeamSlice> = (set,
   deletedTasksLoading: false,
 
   fetchTeams: async () => {
+    // Guard: prevent concurrent fetches (component mount + centralized init chain).
+    // Only effective during initial load (when teamsLoading is set to true below).
+    // Refreshes are already serialized by the throttle timer in onTeamChange.
+    if (get().teamsLoading) return;
     // Only show loading spinner on initial load — avoids flickering when refreshing
     const isInitialLoad = get().teams.length === 0;
     if (isInitialLoad) {
@@ -236,6 +240,8 @@ export const createTeamSlice: StateCreator<AppState, [], [], TeamSlice> = (set,
   },
 
   fetchAllTasks: async () => {
+    // Guard: prevent concurrent fetches (component mount + centralized init chain)
+    if (get().globalTasksLoading) return;
     const isInitialLoad = get().globalTasks.length === 0;
     if (isInitialLoad) {
       set({ globalTasksLoading: true, globalTasksError: null });
diff --git a/test/renderer/store/teamChangeThrottle.test.ts b/test/renderer/store/teamChangeThrottle.test.ts
index d02db025..b781c62e 100644
--- a/test/renderer/store/teamChangeThrottle.test.ts
+++ b/test/renderer/store/teamChangeThrottle.test.ts
@@ -9,6 +9,13 @@ const hoisted = vi.hoisted(() => ({
 
 vi.mock('@renderer/api', () => ({
   api: {
+    config: {
+      get: vi.fn(async () => ({
+        general: { theme: 'dark' },
+        notifications: { enabled: true, triggers: [] },
+      })),
+    },
+    getRepositoryGroups: vi.fn(async () => []),
     notifications: {
       onNew: vi.fn(() => () => undefined),
       onUpdated: vi.fn(() => () => undefined),
@@ -39,6 +46,7 @@ vi.mock('@renderer/api', () => ({
         }
       ),
       getAllTasks: vi.fn(async () => []),
+      list: vi.fn(async () => []),
     },
   },
 }));
@@ -48,7 +56,7 @@ import { initializeNotificationListeners, useStore } from '../../../src/renderer
 describe('team change throttling', () => {
   let cleanup: (() => void) | null = null;
 
-  beforeEach(() => {
+  beforeEach(async () => {
     vi.useFakeTimers();
     const fetchTeams = vi.fn(async () => undefined);
     const refreshTeamData = vi.fn(async () => undefined);
@@ -70,6 +78,10 @@ describe('team change throttling', () => {
     } as never);
 
     cleanup = initializeNotificationListeners();
+
+    // Flush microtask queue so the sequential init chain completes
+    // before test assertions start (prevents init calls from leaking into spies).
+    await vi.advanceTimersByTimeAsync(0);
   });
 
   afterEach(() => {