docs(frontend): add test hygiene plan

docs/features/frontend-test-hygiene/plan.md

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+# Frontend Test Hygiene Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Simplify and normalize the frontend test layer so helpers stay minimal, conventions stay consistent, and existing coverage remains stable.
+
+**Architecture:** This is a test-layer cleanup pass. First inspect the shared test helpers and conventions, then remove or narrow anything that is too broad or duplicated, then confirm that the remaining test setup still supports the existing suites. No new test platform is introduced and no product behavior should change.
+
+**Tech Stack:** Vitest, Testing Library, MSW, jsdom, existing frontend test helpers and conventions.
+
+---
+
+### Task 1: Inspect the current test helpers
+
+**Files:**
+- Read: `apps/frontend/src/test/setup.ts`
+- Read: `apps/frontend/src/test/server.ts`
+- Read: `apps/frontend/src/test/handlers.ts`
+- Read: `apps/frontend/src/test/test-utils.tsx`
+- Read: `apps/frontend/src/test/factories.ts`
+- Read: `apps/frontend/vitest.config.ts`
+- Read: `docs/features/frontend-test-coverage/spec.md`
+
+- [ ] **Step 1: Inventory shared helpers and wrappers**
+
+List what each shared test file does and whether it is still minimal or has grown into broad utility code.
+
+- [ ] **Step 2: Identify duplicated conventions**
+
+Check whether conventions around `QueryClient`, MSW, router setup, and auth/session wrapping are repeated in multiple places.
+
+### Task 2: Narrow the helpers
+
+**Files:**
+- Modify: `apps/frontend/src/test/test-utils.tsx`
+- Modify: `apps/frontend/src/test/factories.ts`
+- Modify: `apps/frontend/src/test/handlers.ts` only if the defaults are too broad
+- Modify: any test file that is currently compensating for an overly broad helper
+
+- [ ] **Step 1: Keep render helpers focused**
+
+Trim `renderWithProviders` or related wrappers down to the smallest shared surface needed by the existing test suite.
+
+- [ ] **Step 2: Reduce helper duplication**
+
+Move one-off setup back into the tests that need it instead of keeping it in a global helper.
+
+- [ ] **Step 3: Keep shared data factories minimal**
+
+Ensure factory data only covers the fields that are actually shared across multiple tests.
+
+### Task 3: Normalize conventions
+
+**Files:**
+- Modify: `apps/frontend/vitest.config.ts` only if the config still carries unnecessary test defaults
+- Modify: `apps/frontend/src/test/setup.ts`
+- Modify: docs that describe frontend testing conventions
+- Modify: `apps/docs/docs/frontend/overview.md` or the most relevant frontend test docs page
+
+- [ ] **Step 1: Keep the test setup explicit**
+
+Make sure global setup only contains the shared primitives that every test needs.
+
+- [ ] **Step 2: Align docs with the actual test strategy**
+
+Describe the current conventions in docs so new tests follow the same pattern instead of inventing local helpers.
+
+### Task 4: Verify coverage remains stable
+
+**Files:**
+- Read: changed test helper files and docs
+- Test: existing frontend test suite
+
+- [ ] **Step 1: Run the frontend test suite**
+
+Run:
+
+```bash
+npm run test -w apps/frontend
+```
+
+Expected: existing tests continue to pass after the hygiene cleanup.
+
+- [ ] **Step 2: Run lint and build**
+
+Run:
+
+```bash
+npm run lint -w apps/frontend
+npm run build -w apps/frontend
+```
+
+Expected: both commands pass and no runtime behavior has changed.

docs/features/frontend-test-hygiene/tasks.md

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+# Frontend Test Hygiene — tasks
+
+Статус: pending
+
+## 1. Проверить тестовые helpers
+
+- [ ] Проверить `apps/frontend/src/test/test-utils.tsx` на избыточные обёртки
+- [ ] Проверить `apps/frontend/src/test/factories.ts` на слишком широкие mock fixtures
+- [ ] Проверить `apps/frontend/src/test/handlers.ts` на лишние defaults
+
+## 2. Сузить test layer
+
+- [ ] Убрать лишнюю глобальную магию из shared test setup
+- [ ] Перенести one-off setup в конкретные тесты, если он не нужен всем
+- [ ] Оставить только действительно shared helpers
+
+## 3. Нормализовать conventions
+
+- [ ] Обновить frontend docs, описывающие test strategy и conventions
+- [ ] Убедиться, что global setup не распухает и остаётся понятным
+- [ ] Сверить conventions с `frontend-test-coverage` как отдельной фичей
+
+## 4. Финальная проверка
+
+- [ ] Запустить `npm run test -w apps/frontend`
+- [ ] Запустить `npm run lint -w apps/frontend`
+- [ ] Запустить `npm run build -w apps/frontend`
+- [ ] Убедиться, что изменения не меняют пользовательское поведение