From 08c2adf13b31a6cbcf6e7c063c31bb82be626adb Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 09:15:25 +0000
Subject: [PATCH 01/46] docs: Add plan and review for PR #3316 post-merge fixes

Includes comprehensive implementation plan for quality improvements (tests, UI/UX, DB consistency) and detailed code review findings.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
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 .../2026-03-26/pr-3316-review/review.md       |  133 ++
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 create mode 100644 docs/dev-notes/2026-03-26/pr-3316-review/plan.md
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+# PR #3316 マージ後修正 実装計画
+
+> **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:** `review.md` に記載されたマージ後修正タスク（#1〜#13、#優先度中テスト）を実施し、コード品質・テスト・UI/UX・DB整合性を改善する。
+
+**Architecture:** 低リスク（テスト・定数）→ 中リスク（UI・サービス）→ 高リスク（DB migration）の順で実施。`Pct → percentage` リネーム（#6）は現コードベースに `Pct` が存在しないため実施不要（既解決）。並行投票対策（#14）は優先度低・将来対応のためスコープ外。
+
+**Tech Stack:** SvelteKit 2 + Svelte 5 Runes, TypeScript, Prisma, Vitest, Playwright, Flowbite Svelte
+
+---
+
+## 対象ファイル一覧
+
+| 操作           | ファイル                                                                  | 理由                                                                                |
+| -------------- | ------------------------------------------------------------------------- | ----------------------------------------------------------------------------------- |
+| 修正           | `src/features/account/services/atcoder_verification.test.ts`              | `vi.stubEnv` パターンへ移行（#11）                                                  |
+| 新規           | `src/test/lib/services/users.test.ts`                                     | `getUser` / `getUserById` / `deleteUser` のテスト追加（#10）                        |
+| 修正           | `src/features/votes/services/vote_grade.ts`                               | `MIN_VOTES_FOR_STATISTICS` を export + `upsertVoteGradeTables` 戻り値追加（#4, #5） |
+| 修正           | `src/features/votes/actions/vote_actions.ts`                              | `upsertVoteGradeTables` 戻り値を利用（#4）                                          |
+| 修正           | `src/routes/votes/[slug]/+page.svelte`                                    | `MIN_VOTES_FOR_STATISTICS` 参照に変更（#5）                                         |
+| 修正           | `src/routes/(admin)/vote_management/+page.server.ts`                      | `updateTask` に try/catch 追加（#7）                                                |
+| 修正           | `src/lib/components/SubmissionButton.svelte`                              | `loading` prop 追加（#8a）                                                          |
+| 修正           | `src/lib/components/FormWrapper.svelte`                                   | `isSubmitting` context 追加（#8b）                                                  |
+| 修正           | `src/features/account/components/settings/AtCoderVerificationForm.svelte` | ボタン間隔（#8c）+ Flowbite Clipboard 導入（#8d）                                   |
+| 新規           | `src/features/votes/services/vote_api.ts`                                 | `fetchMyVote` / `submitVote` / `fetchMedianVote` 抽出（#1, #2）                     |
+| 新規           | `src/features/votes/services/vote_api.test.ts`                            | vote_api.ts の単体テスト（#2）                                                      |
+| 修正           | `src/features/votes/components/VotableGrade.svelte`                       | vote_api.ts 利用 + AbortController 連打対策（#1, #2, #3）                           |
+| 修正           | `e2e/votes.spec.ts`                                                       | セレクタ修正 + 初期状態対応（#9）                                                   |
+| 新規 migration | `prisma/migrations/.../migration.sql`                                     | CHECK 制約追加（#12, #13）                                                          |
+| 修正           | `prisma/schema.prisma`                                                    | コメント追加（#12, #13）                                                            |
+| 修正           | `prisma/ERD.md`                                                           | CHECK 制約ドキュメント（#12, #13）                                                  |
+| 修正           | `.claude/rules/svelte-components.md`                                      | SSR 安全性・`{#each}` キー式ルール追加                                              |
+| 修正           | `.claude/rules/prisma-db.md`                                              | FK @relation・DB 値域制約ルール追加                                                 |
+| 修正           | `.claude/rules/coding-style.md`                                           | load関数 try-catch・auth 監査・success フラグ・Dead Code ルール追加                 |
+| 修正           | `.claude/rules/testing.md`                                                | `vi.stubEnv` ルール追加                                                             |
+
+---
+
+## Phase 1: テスト品質改善
+
+### Task 1: vi.stubEnv パターンへ移行（atcoder_verification.test.ts）
+
+**Files:**
+
+- Modify: `src/features/account/services/atcoder_verification.test.ts:1-60`
+
+- [ ] **Step 1: テスト実行（修正前の失敗確認は不要。現在パスしていることを確認）**
+
+```bash
+pnpm test:unit -- atcoder_verification
+```
+
+Expected: 全テスト PASS
+
+- [ ] **Step 2: `beforeEach` / `afterEach` の手動 `process.env` を `vi.stubEnv` に置換**
+
+ファイル冒頭の import に `afterAll` を追加し、以下のように変更する:
+
+```typescript
+// 変更前
+beforeEach(() => {
+  process.env.CONFIRM_API_URL = SAMPLE_API_URL;
+});
+
+afterEach(() => {
+  delete process.env.CONFIRM_API_URL;
+});
+
+// 変更後
+beforeEach(() => {
+  vi.stubEnv('CONFIRM_API_URL', SAMPLE_API_URL);
+});
+
+afterEach(() => {
+  vi.unstubAllEnvs();
+});
+```
+
+- [ ] **Step 3: テスト再実行**
+
+```bash
+pnpm test:unit -- atcoder_verification
+```
+
+Expected: 全テスト PASS（11件）
+
+- [ ] **Step 4: コミット**
+
+```bash
+git add src/features/account/services/atcoder_verification.test.ts
+git commit -m "test: migrate process.env manual stubs to vi.stubEnv in atcoder_verification tests"
+```
+
+---
+
+### Task 2: users.ts 単体テスト追加
+
+**Files:**
+
+- Create: `src/test/lib/services/users.test.ts`
+
+- [ ] **Step 1: テストファイルを作成（実装なし・FAIL 確認用）**
+
+```typescript
+import { describe, test, expect, vi, beforeEach } from 'vitest';
+import type { User } from '@prisma/client';
+
+vi.mock('$lib/server/database', () => ({
+  default: {
+    user: {
+      findUnique: vi.fn(),
+      delete: vi.fn(),
+    },
+  },
+}));
+
+import db from '$lib/server/database';
+import { getUser, getUserById, deleteUser } from '$lib/services/users';
+
+const mockFindUnique = vi.mocked(db.user.findUnique);
+const mockDelete = vi.mocked(db.user.delete);
+
+// Type-safe fixture (no `as any`)
+type UserWithAccount = User & {
+  atCoderAccount: {
+    userId: string;
+    handle: string;
+    isValidated: boolean;
+    validationCode: string;
+    createdAt: Date;
+    updatedAt: Date;
+  };
+};
+
+const SAMPLE_USER: UserWithAccount = {
+  id: 'user-abc123',
+  username: 'testuser',
+  atCoderAccount: {
+    userId: 'user-abc123',
+    handle: 'testuser_ac',
+    isValidated: true,
+    validationCode: 'code-xyz',
+    createdAt: new Date('2024-01-01'),
+    updatedAt: new Date('2024-01-01'),
+  },
+} as UserWithAccount;
+
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
+describe('getUser', () => {
+  test('returns user with atCoderAccount when found', async () => {
+    mockFindUnique.mockResolvedValueOnce(SAMPLE_USER);
+
+    const result = await getUser('testuser');
+
+    expect(result).toEqual(SAMPLE_USER);
+    expect(mockFindUnique).toHaveBeenCalledWith({
+      where: { username: 'testuser' },
+      include: { atCoderAccount: true },
+    });
+  });
+
+  test('returns null when user is not found', async () => {
+    mockFindUnique.mockResolvedValueOnce(null);
+
+    const result = await getUser('nonexistent');
+
+    expect(result).toBeNull();
+  });
+});
+
+describe('getUserById', () => {
+  test('returns user with atCoderAccount when found', async () => {
+    mockFindUnique.mockResolvedValueOnce(SAMPLE_USER);
+
+    const result = await getUserById('user-abc123');
+
+    expect(result).toEqual(SAMPLE_USER);
+    expect(mockFindUnique).toHaveBeenCalledWith({
+      where: { id: 'user-abc123' },
+      include: { atCoderAccount: true },
+    });
+  });
+
+  test('returns null when user is not found', async () => {
+    mockFindUnique.mockResolvedValueOnce(null);
+
+    const result = await getUserById('nonexistent-id');
+
+    expect(result).toBeNull();
+  });
+});
+
+describe('deleteUser', () => {
+  test('deletes user and subsequent getUser returns null', async () => {
+    mockDelete.mockResolvedValueOnce(SAMPLE_USER);
+    mockFindUnique.mockResolvedValueOnce(null);
+
+    const deleteResult = await deleteUser('testuser');
+
+    expect(deleteResult).toEqual(SAMPLE_USER);
+    expect(mockDelete).toHaveBeenCalledWith({ where: { username: 'testuser' } });
+
+    // Verify that the user is actually deleted (subsequent getUser returns null)
+    const getResult = await getUser('testuser');
+    expect(getResult).toBeNull();
+  });
+});
+```
+
+- [ ] **Step 2: テスト実行（FAIL 確認）**
+
+```bash
+pnpm test:unit -- src/test/lib/services/users
+```
+
+Expected: テストファイルが存在しないためエラー（または関数が存在しないため FAIL）
+
+- [ ] **Step 3: テスト実行（PASS 確認）**
+
+実装は `src/lib/services/users.ts` に既存（変更不要）。
+
+```bash
+pnpm test:unit -- src/test/lib/services/users
+```
+
+Expected: 5件 PASS
+
+- [ ] **Step 4: コミット**
+
+```bash
+git add src/test/lib/services/users.test.ts
+git commit -m "test: add unit tests for getUser, getUserById, and deleteUser"
+```
+
+---
+
+## Phase 2: サービス・ルート修正
+
+### Task 3: MIN_VOTES_FOR_STATISTICS を export し hardcode を除去
+
+**Files:**
+
+- Modify: `src/features/votes/services/vote_grade.ts:27`
+- Modify: `src/routes/votes/[slug]/+page.svelte:46`
+
+- [ ] **Step 1: vote_grade.ts の定数を export に変更**
+
+```typescript
+// 変更前（line 27）
+const MIN_VOTES_FOR_STATISTICS = 3;
+
+// 変更後
+export const MIN_VOTES_FOR_STATISTICS = 3;
+```
+
+- [ ] **Step 2: votes/[slug]/+page.svelte の hardcode を置換**
+
+import を追加し、Tooltip テキストを定数参照に変更:
+
+```typescript
+// script 内の import に追加
+import { MIN_VOTES_FOR_STATISTICS } from '$features/votes/services/vote_grade';
+```
+
+```svelte
+<!-- 変更前（line 46） -->
+3票以上集まると中央値が暫定グレードとして一覧表に反映されます。
+
+<!-- 変更後 -->
+{MIN_VOTES_FOR_STATISTICS}票以上集まると中央値が暫定グレードとして一覧表に反映されます。
+```
+
+- [ ] **Step 3: 型チェック**
+
+```bash
+pnpm check
+```
+
+Expected: エラーなし
+
+- [ ] **Step 4: コミット**
+
+```bash
+git add src/features/votes/services/vote_grade.ts src/routes/votes/[slug]/+page.svelte
+git commit -m "refactor: export MIN_VOTES_FOR_STATISTICS and remove hardcoded '3' in votes page"
+```
+
+---
+
+### Task 4: upsertVoteGradeTables の戻り値を { success: true } に変更
+
+**Files:**
+
+- Modify: `src/features/votes/services/vote_grade.ts:30-34`
+- Modify: `src/features/votes/actions/vote_actions.ts:54-58`
+
+- [ ] **Step 1: vote_grade.ts の関数シグネチャと戻り値を変更**
+
+```typescript
+// 変更前
+export async function upsertVoteGradeTables(
+  userId: string,
+  taskId: string,
+  grade: TaskGrade,
+): Promise<void> {
+  await prisma.$transaction(async (tx) => {
+    // ...
+  });
+}
+
+// 変更後
+export async function upsertVoteGradeTables(
+  userId: string,
+  taskId: string,
+  grade: TaskGrade,
+): Promise<{ success: true }> {
+  await prisma.$transaction(async (tx) => {
+    // ... (内容変更なし)
+  });
+  return { success: true };
+}
+```
+
+- [ ] **Step 2: vote_actions.ts でサービスの戻り値を返すよう変更**
+
+```typescript
+// 変更前
+try {
+  await upsertVoteGradeTables(userId, taskId, grade);
+} catch (error) {
+  console.error('Failed to vote absolute grade: ', error);
+  return fail(INTERNAL_SERVER_ERROR, { message: 'Failed to record vote.' });
+}
+// (暗黙の undefined return → SvelteKit が success として扱う)
+
+// 変更後
+try {
+  return await upsertVoteGradeTables(userId, taskId, grade);
+} catch (error) {
+  console.error('Failed to vote absolute grade: ', error);
+  return fail(INTERNAL_SERVER_ERROR, { message: 'Failed to record vote.' });
+}
+```
+
+- [ ] **Step 3: 型チェック**
+
+```bash
+pnpm check
+```
+
+Expected: エラーなし
+
+- [ ] **Step 4: コミット**
+
+```bash
+git add src/features/votes/services/vote_grade.ts src/features/votes/actions/vote_actions.ts
+git commit -m "refactor: make upsertVoteGradeTables return { success: true } for explicit action response"
+```
+
+---
+
+### Task 5: vote_management の updateTask に 404 エラー処理を追加
+
+**Files:**
+
+- Modify: `src/routes/(admin)/vote_management/+page.server.ts:54`
+
+- [ ] **Step 1: `updateTask` 呼び出しを try/catch で囲む**
+
+Prisma の `P2025`（RecordNotFound）を明示的に処理する。import を追加:
+
+```typescript
+import { Prisma } from '@prisma/client';
+```
+
+アクション内を変更:
+
+```typescript
+// 変更前（line 54-55）
+await updateTask(taskId, grade as TaskGrade);
+return { success: true };
+
+// 変更後
+try {
+  await updateTask(taskId, grade as TaskGrade);
+} catch (error) {
+  if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === 'P2025') {
+    return { success: false, message: `Not found task: ${taskId}` };
+  }
+
+  throw error;
+}
+return { success: true };
+```
+
+- [ ] **Step 2: 型チェック**
+
+```bash
+pnpm check
+```
+
+Expected: エラーなし
+
+- [ ] **Step 3: コミット**
+
+```bash
+git add src/routes/(admin)/vote_management/+page.server.ts
+git commit -m "fix: handle RecordNotFound error in setTaskGrade action for vote_management"
+```
+
+---
+
+## Phase 3: UI コンポーネント改善
+
+### Task 6: SubmissionButton loading prop + FormWrapper isSubmitting context
+
+**Files:**
+
+- Modify: `src/lib/components/SubmissionButton.svelte`
+- Modify: `src/lib/components/FormWrapper.svelte`
+
+- [ ] **Step 1: SubmissionButton に loading prop を追加し getContext で自動取得**
+
+`SubmissionButton.svelte` の内容を差し替え:
+
+```svelte
+<script lang="ts">
+  import { getContext } from 'svelte';
+
+  import { Button } from 'flowbite-svelte';
+
+  interface Props {
+    width?: string;
+    labelName: string;
+    loading?: boolean;
+  }
+
+  let { width = 'w-full', labelName, loading = false }: Props = $props();
+
+  // FormWrapper が setContext('form', ...) でセットしている場合、自動的に isSubmitting を受け取る。
+  // FormWrapper 外で使う場合は context が undefined になるため ?? false でフォールバック。
+  const formContext = getContext<{ isSubmitting: boolean } | undefined>('form');
+  const isLoading = $derived(loading || (formContext?.isSubmitting ?? false));
+</script>
+
+<Button type="submit" class={width} loading={isLoading}>{labelName}</Button>
+```
+
+- [ ] **Step 2: FormWrapper に isSubmitting state と setContext を追加**
+
+`FormWrapper.svelte` の内容を差し替え:
+
+```svelte
+<script lang="ts">
+  import { enhance } from '$app/forms';
+  import { setContext } from 'svelte';
+  import type { Snippet } from 'svelte';
+
+  interface Props {
+    method?: 'POST' | 'GET' | 'DIALOG' | 'post' | 'get' | 'dialog' | null | undefined;
+    action: string;
+    marginTop?: string;
+    spaceYAxis?: string;
+    children?: Snippet;
+  }
+
+  let {
+    method = 'POST',
+    action,
+    marginTop = 'mt-6',
+    spaceYAxis = 'space-y-6',
+    children,
+  }: Props = $props();
+
+  let isSubmitting = $state(false);
+
+  setContext('form', {
+    get isSubmitting() {
+      return isSubmitting;
+    },
+  });
+
+  function handleEnhance() {
+    isSubmitting = true;
+
+    return async ({ update }: { update: () => Promise<void> }) => {
+      await update();
+      isSubmitting = false;
+    };
+  }
+</script>
+
+<form
+  {method}
+  {action}
+  class={`w-full max-w-md ${marginTop} ${spaceYAxis}`}
+  use:enhance={handleEnhance}
+>
+  {#if children}
+    {@render children()}
+  {/if}
+</form>
+```
+
+- [ ] **Step 3: 型チェック**
+
+```bash
+pnpm check
+```
+
+Expected: エラーなし
+
+- [ ] **Step 4: コミット**
+
+```bash
+git add src/lib/components/SubmissionButton.svelte src/lib/components/FormWrapper.svelte
+git commit -m "feat: add loading state to SubmissionButton via FormWrapper context (prevent double-submit)"
+```
+
+---
+
+### Task 7: AtCoderVerificationForm ボタン間隔追加 + Flowbite Clipboard 導入
+
+**Files:**
+
+- Modify: `src/features/account/components/settings/AtCoderVerificationForm.svelte`
+
+- [ ] **Step 1: ボタン間隔追加（8c）とリセット FormWrapper に `marginTop` を指定**
+
+`status === 'generated'` ブロックの2つ目の `FormWrapper` を変更（現在 `marginTop=""` が未指定で隙間なし）:
+
+```svelte
+<!-- 変更前（line 127） -->
+<FormWrapper action="?/reset" marginTop="">
+
+<!-- 変更後 -->
+<FormWrapper action="?/reset" marginTop="mt-4">
+```
+
+- [ ] **Step 2: Flowbite Clipboard 導入（8d）**
+
+`AtCoderVerificationForm.svelte` の `<script>` 上部を変更:
+
+```typescript
+// 削除するインポート
+import ClipboardCopy from '@lucide/svelte/icons/clipboard-copy';
+
+// 追加するインポート
+import { Clipboard } from 'flowbite-svelte';
+import ClipboardCopy from '@lucide/svelte/icons/clipboard-copy';
+import Check from '@lucide/svelte/icons/check';
+```
+
+カスタム `copyToClipboard` 関数と `handleClick` 関数を**削除**する（lines 11-69 の該当部分）。
+
+`TODO` コメントも削除する（lines 10 と 65）。
+
+- [ ] **Step 3: クリップボード UI を Flowbite Clipboard コンポーネントに置換**
+
+`status === 'generated'` ブロックのクリップボード部分を変更:
+
+```svelte
+<!-- 変更前（lines 113-122） -->
+<Label class="flex flex-col gap-2">
+  <span>本人確認用の文字列</span>
+  <div>
+    <Input size="md" value={atCoderAccount.validationCode}>
+      {#snippet right()}
+        <ClipboardCopy class="w-5 h-5" onclick={handleClick} />
+      {/snippet}
+    </Input>
+  </div>
+</Label>
+
+<!-- 変更後 -->
+<Label class="flex flex-col gap-2">
+  <span>本人確認用の文字列</span>
+  <div class="flex items-center gap-2">
+    <Input size="md" value={atCoderAccount.validationCode} readonly />
+
+    <Clipboard value={atCoderAccount.validationCode}>
+      {#snippet children(success)}
+        {#if success}
+          <Check class="w-5 h-5 text-green-500" />
+        {:else}
+          <ClipboardCopy class="w-5 h-5" />
+        {/if}
+      {/snippet}
+    </Clipboard>
+  </div>
+</Label>
+```
+
+- [ ] **Step 4: 型チェック**
+
+```bash
+pnpm check
+```
+
+Expected: エラーなし
+
+- [ ] **Step 5: コミット**
+
+```bash
+git add src/features/account/components/settings/AtCoderVerificationForm.svelte
+git commit -m "feat: add button gap and replace custom clipboard with Flowbite Clipboard in AtCoderVerificationForm"
+```
+
+---
+
+## Phase 4: 投票 API 関数抽出 + fetch 改善
+
+### Task 8: vote_api.ts 作成（fetch credentials 追加 + service 層として実装）
+
+**Files:**
+
+- Create: `src/features/votes/services/vote_api.ts`
+- Create: `src/features/votes/services/vote_api.test.ts`
+
+- [ ] **Step 1: テストファイルを先に作成（TDD）**
+
+```typescript
+// src/features/votes/services/vote_api.test.ts
+import { describe, test, expect, vi, beforeEach, afterEach } from 'vitest';
+import nock from 'nock';
+
+import { TaskGrade } from '$lib/types/task';
+
+import { fetchMyVote, submitVote, fetchMedianVote } from './vote_api';
+
+beforeEach(() => {
+  nock.cleanAll();
+});
+
+afterEach(() => {
+  nock.cleanAll();
+});
+
+describe('fetchMyVote', () => {
+  test('returns grade when server responds with a voted grade', async () => {
+    nock('http://localhost')
+      .get('/problems/getMyVote')
+      .query({ taskId: 'abc_a' })
+      .reply(200, { grade: TaskGrade.Q11 });
+
+    const result = await fetchMyVote('abc_a');
+
+    expect(result).toBe(TaskGrade.Q11);
+  });
+
+  test('returns null when server responds with null grade', async () => {
+    nock('http://localhost')
+      .get('/problems/getMyVote')
+      .query({ taskId: 'abc_a' })
+      .reply(200, { grade: null });
+
+    const result = await fetchMyVote('abc_a');
+
+    expect(result).toBeNull();
+  });
+
+  test('returns null when server responds with non-ok status', async () => {
+    nock('http://localhost').get('/problems/getMyVote').query({ taskId: 'abc_a' }).reply(401);
+
+    const result = await fetchMyVote('abc_a');
+
+    expect(result).toBeNull();
+  });
+});
+
+describe('submitVote', () => {
+  test('returns true when server responds with ok status', async () => {
+    const formData = new FormData();
+    formData.append('taskId', 'abc_a');
+    formData.append('grade', TaskGrade.Q11);
+
+    nock('http://localhost').post('/votes?/voteAbsoluteGrade').reply(200, { success: true });
+
+    const result = await submitVote(new URL('http://localhost/votes?/voteAbsoluteGrade'), formData);
+
+    expect(result).toBe(true);
+  });
+
+  test('returns false when server responds with error status', async () => {
+    const formData = new FormData();
+
+    nock('http://localhost').post('/votes?/voteAbsoluteGrade').reply(500);
+
+    const result = await submitVote(new URL('http://localhost/votes?/voteAbsoluteGrade'), formData);
+
+    expect(result).toBe(false);
+  });
+
+  test('returns false when request is aborted', async () => {
+    const formData = new FormData();
+    const controller = new AbortController();
+    controller.abort();
+
+    const result = await submitVote(
+      new URL('http://localhost/votes?/voteAbsoluteGrade'),
+      formData,
+      controller.signal,
+    );
+
+    expect(result).toBe(false);
+  });
+});
+
+describe('fetchMedianVote', () => {
+  test('returns grade when server responds with a median grade', async () => {
+    nock('http://localhost')
+      .get('/problems/getMedianVote')
+      .query({ taskId: 'abc_a' })
+      .reply(200, { grade: TaskGrade.Q10 });
+
+    const result = await fetchMedianVote('abc_a');
+
+    expect(result).toBe(TaskGrade.Q10);
+  });
+
+  test('returns null when server responds with null grade', async () => {
+    nock('http://localhost')
+      .get('/problems/getMedianVote')
+      .query({ taskId: 'abc_a' })
+      .reply(200, { grade: null });
+
+    const result = await fetchMedianVote('abc_a');
+
+    expect(result).toBeNull();
+  });
+
+  test('returns null when server responds with non-ok status', async () => {
+    nock('http://localhost').get('/problems/getMedianVote').query({ taskId: 'abc_a' }).reply(500);
+
+    const result = await fetchMedianVote('abc_a');
+
+    expect(result).toBeNull();
+  });
+});
+```
+
+- [ ] **Step 2: テスト実行（FAIL 確認）**
+
+```bash
+pnpm test:unit -- vote_api
+```
+
+Expected: `vote_api.ts` が存在しないため import エラー
+
+- [ ] **Step 3: vote_api.ts を実装**
+
+```typescript
+// src/features/votes/services/vote_api.ts
+import type { TaskGrade } from '$lib/types/task';
+
+/**
+ * Fetches the current user's vote grade for a given task.
+ * @returns The voted grade, or null if not voted or request fails.
+ */
+export async function fetchMyVote(taskId: string): Promise<TaskGrade | null> {
+  try {
+    const response = await fetch(`/problems/getMyVote?taskId=${encodeURIComponent(taskId)}`, {
+      credentials: 'same-origin',
+      headers: { Accept: 'application/json' },
+    });
+
+    if (!response.ok) {
+      return null;
+    }
+
+    const data = await response.json();
+    return (data.grade as TaskGrade) ?? null;
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * Submits a vote via POST to the given action URL.
+ * @param signal - Optional AbortSignal to cancel an in-flight request.
+ * @returns true if the server responded with ok status, false otherwise.
+ */
+export async function submitVote(
+  action: URL,
+  formData: FormData,
+  signal?: AbortSignal,
+): Promise<boolean> {
+  try {
+    const response = await fetch(action, {
+      method: 'POST',
+      body: formData,
+      credentials: 'same-origin',
+      headers: { Accept: 'application/json' },
+      signal,
+    });
+
+    return response.ok;
+  } catch {
+    // AbortError or network error
+    return false;
+  }
+}
+
+/**
+ * Fetches the current median vote grade for a given task.
+ * @returns The median grade, or null if not enough votes or request fails.
+ */
+export async function fetchMedianVote(taskId: string): Promise<TaskGrade | null> {
+  try {
+    const response = await fetch(`/problems/getMedianVote?taskId=${encodeURIComponent(taskId)}`, {
+      credentials: 'same-origin',
+      headers: { Accept: 'application/json' },
+    });
+
+    if (!response.ok) {
+      return null;
+    }
+
+    const data = await response.json();
+    return (data.grade as TaskGrade) ?? null;
+  } catch {
+    return null;
+  }
+}
+```
+
+- [ ] **Step 4: テスト実行（PASS 確認）**
+
+```bash
+pnpm test:unit -- vote_api
+```
+
+Expected: 9件 PASS
+
+- [ ] **Step 5: コミット**
+
+```bash
+git add src/features/votes/services/vote_api.ts src/features/votes/services/vote_api.test.ts
+git commit -m "feat: extract fetchMyVote, submitVote, fetchMedianVote to vote_api service with credentials: same-origin"
+```
+
+---
+
+### Task 9: VotableGrade.svelte を vote_api.ts 利用 + AbortController 連打対策
+
+**Files:**
+
+- Modify: `src/features/votes/components/VotableGrade.svelte`
+
+- [ ] **Step 1: import を追加し、vote_api.ts の関数で既存 fetch を置換**
+
+`<script>` の import セクションに追加:
+
+```typescript
+import { fetchMyVote, submitVote, fetchMedianVote } from '$features/votes/services/vote_api';
+```
+
+`onTriggerClick` 関数を置換（fetch 直接呼び出しを `fetchMyVote` に変更）:
+
+```typescript
+// 変更前
+async function onTriggerClick() {
+  if (!isLoggedIn || isAtCoderVerified === false || isOpening) return;
+  isOpening = true;
+  try {
+    const res = await fetch(
+      `/problems/getMyVote?taskId=${encodeURIComponent(taskResult.task_id)}`,
+      {
+        headers: { Accept: 'application/json' },
+      },
+    );
+    if (res.ok) {
+      const data = await res.json();
+      votedGrade = data.grade;
+    }
+  } catch (err) {
+    console.error(err);
+  } finally {
+    isOpening = false;
+  }
+}
+
+// 変更後
+async function onTriggerClick() {
+  if (!isLoggedIn || isAtCoderVerified === false || isOpening) {
+    return;
+  }
+  isOpening = true;
+  try {
+    votedGrade = await fetchMyVote(taskResult.task_id);
+  } catch (err) {
+    console.error(err);
+  } finally {
+    isOpening = false;
+  }
+}
+```
+
+- [ ] **Step 2: AbortController を追加し handleClick で連打対策**
+
+`let isOpening = $state(false);` の直後に追加:
+
+```typescript
+let voteAbortController: AbortController | null = null;
+```
+
+`handleClick` 関数を変更:
+
+```typescript
+// 変更前
+async function handleClick(voteGrade: string): Promise<void> {
+  selectedVoteGrade = getTaskGrade(voteGrade);
+  showForm = true;
+  await tick();
+  formElement?.requestSubmit();
+}
+
+// 変更後
+async function handleClick(voteGrade: string): Promise<void> {
+  // Cancel any in-flight vote request before starting a new one.
+  voteAbortController?.abort();
+  voteAbortController = new AbortController();
+  selectedVoteGrade = getTaskGrade(voteGrade);
+  showForm = true;
+  await tick();
+  formElement?.requestSubmit();
+}
+```
+
+- [ ] **Step 3: handleSubmit の fetch を submitVote / fetchMedianVote に置換し signal を渡す**
+
+```typescript
+// 変更前
+const handleSubmit = () => {
+  return ({ formData, action, cancel }: EnhanceForVote) => {
+    cancel();
+
+    fetch(action, {
+      method: 'POST',
+      body: formData,
+      headers: { Accept: 'application/json' },
+    })
+      .then(async (res) => {
+        if (!res.ok) throw new Error('vote failed');
+
+        votedGrade = selectedVoteGrade ?? null;
+
+        try {
+          const taskId = formData.get('taskId') as string;
+          const medianRes = await fetch(
+            `/problems/getMedianVote?taskId=${encodeURIComponent(taskId)}`,
+            { headers: { Accept: 'application/json' } },
+          );
+          if (medianRes.ok) {
+            const data = await medianRes.json();
+            if (data?.grade && taskResult.grade === TaskGrade.PENDING) displayGrade = data.grade;
+          }
+        } catch (err) {
+          console.error('Failed to fetch median after vote', err);
+        }
+      })
+      .catch((error) => {
+        console.error('Failed to update submission status: ', error);
+        errorMessageStore.setAndClearAfterTimeout(FAILED_TO_UPDATE_VOTE_STATUS, 10000);
+      })
+      .finally(() => {
+        resetDropdown();
+      });
+
+    return () => {};
+  };
+};
+
+// 変更後
+const handleSubmit = () => {
+  return ({ formData, action, cancel }: EnhanceForVote) => {
+    cancel();
+
+    const signal = voteAbortController?.signal;
+
+    submitVote(action, formData, signal)
+      .then(async (succeeded) => {
+        if (!succeeded) {
+          throw new Error('vote failed');
+        }
+
+        votedGrade = selectedVoteGrade ?? null;
+
+        const taskId = formData.get('taskId') as string;
+        const medianGrade = await fetchMedianVote(taskId);
+        if (medianGrade !== null && taskResult.grade === TaskGrade.PENDING) {
+          displayGrade = medianGrade;
+        }
+      })
+      .catch((error) => {
+        console.error('Failed to update submission status: ', error);
+        errorMessageStore.setAndClearAfterTimeout(FAILED_TO_UPDATE_VOTE_STATUS, 10000);
+      })
+      .finally(() => {
+        resetDropdown();
+      });
+
+    return () => {};
+  };
+};
+```
+
+- [ ] **Step 4: 型チェック**
+
+```bash
+pnpm check
+```
+
+Expected: エラーなし
+
+- [ ] **Step 5: コミット**
+
+```bash
+git add src/features/votes/components/VotableGrade.svelte
+git commit -m "refactor: use vote_api.ts in VotableGrade and add AbortController for rapid-click protection"
+```
+
+---
+
+## Phase 5: E2E テスト修正
+
+### Task 10: votes.spec.ts セレクタ修正 + 初期状態対応
+
+**Files:**
+
+- Modify: `e2e/votes.spec.ts`
+
+現在の誤ったセレクタと正しい値の対応:
+
+| 現在の値                                                 | 正しい値                       | 理由                                                  |
+| -------------------------------------------------------- | ------------------------------ | ----------------------------------------------------- |
+| `getByRole('heading', { name: 'グレード投票' })`         | `'投票'`                       | `votes/+page.svelte` の `<HeadingOne title="投票" />` |
+| `getByRole('columnheader', { name: '問題' })`            | `'問題名'`                     | `<TableHeadCell>問題名</TableHeadCell>`               |
+| `getByRole('columnheader', { name: 'コンテスト' })`      | `'出典'`                       | `<TableHeadCell>出典</TableHeadCell>`                 |
+| `getByPlaceholder('問題名・問題ID・コンテストIDで検索')` | `'問題名・問題ID・出典で検索'` | `<Input placeholder="問題名・問題ID・出典で検索">`    |
+
+- [ ] **Step 1: heading セレクタを修正（2箇所: lines 17, 36）**
+
+```typescript
+// 変更前
+await expect(page.getByRole('heading', { name: 'グレード投票' })).toBeVisible(...)
+
+// 変更後
+await expect(page.getByRole('heading', { name: '投票' })).toBeVisible(...)
+```
+
+- [ ] **Step 2: columnheader セレクタを修正（3箇所: lines 24, 27, 65）**
+
+```typescript
+// 変更前
+await expect(page.getByRole('columnheader', { name: '問題' })).toBeVisible(...)
+await expect(page.getByRole('columnheader', { name: 'コンテスト' })).toBeVisible(...)
+
+// 変更後
+await expect(page.getByRole('columnheader', { name: '問題名' })).toBeVisible(...)
+await expect(page.getByRole('columnheader', { name: '出典' })).toBeVisible(...)
+```
+
+- [ ] **Step 3: placeholder セレクタを修正（line 43）**
+
+```typescript
+// 変更前
+const searchInput = page.getByPlaceholder('問題名・問題ID・コンテストIDで検索');
+
+// 変更後
+const searchInput = page.getByPlaceholder('問題名・問題ID・出典で検索');
+```
+
+- [ ] **Step 4: navigateToFirstVoteDetailPage に初期状態スキップを追加**
+
+`navigateToFirstVoteDetailPage` でタスクが存在しない場合にテストをスキップする:
+
+```typescript
+async function navigateToFirstVoteDetailPage(page: Page): Promise<void> {
+  await page.goto(VOTES_LIST_URL);
+  await expect(page.getByRole('columnheader', { name: '問題名' })).toBeVisible({
+    timeout: TIMEOUT,
+  });
+
+  const firstLink = page.locator('table').getByRole('link').first();
+  const hasTask = await firstLink.isVisible();
+  if (!hasTask) {
+    // No tasks in DB — skip navigation-dependent tests.
+    return;
+  }
+
+  await firstLink.click();
+  await expect(page).toHaveURL(/\/votes\/.+/, { timeout: TIMEOUT });
+}
+```
+
+また、`navigateToFirstVoteDetailPage` を使う各テストに `test.skip` 条件を追加:
+
+```typescript
+test('can view the task detail page without redirect', async ({ page }) => {
+  await navigateToFirstVoteDetailPage(page);
+  const onDetailPage = page.url().match(/\/votes\/.+/);
+  test.skip(!onDetailPage, 'no tasks available in DB');
+  // ...
+});
+```
+
+- [ ] **Step 5: E2E テスト実行（ローカル環境で確認）**
+
+```bash
+pnpm test:e2e -- votes
+```
+
+Expected: セレクタ起因の FAIL がなくなる
+
+- [ ] **Step 6: コミット**
+
+```bash
+git add e2e/votes.spec.ts
+git commit -m "fix: correct stale selectors in votes E2E tests and add initial state skip conditions"
+```
+
+---
+
+## Phase 6: DB 制約追加
+
+### Task 11: CHECK 制約追加（count >= 0 と grade != 'PENDING'）
+
+**Files:**
+
+- Modify: `prisma/schema.prisma` (コメント追加)
+- Create: migration (2ステップで作成・適用)
+- Modify: `prisma/ERD.md`
+
+> ⚠️ Prisma は `@@check` をサポートしていない。migration.sql を手動編集してから適用する。
+
+- [ ] **Step 1: migration を作成のみ（適用しない）**
+
+```bash
+pnpm exec prisma migrate dev --create-only --name add_vote_grade_check_constraints
+```
+
+Expected: `prisma/migrations/YYYYMMDD.../migration.sql` が生成される
+
+- [ ] **Step 2: 生成された migration.sql に CHECK 制約を手動追加**
+
+生成された `migration.sql` の末尾に追加:
+
+```sql
+-- VotedGradeCounter.count must never go negative (application guard + DB last line of defense)
+ALTER TABLE "VotedGradeCounter" ADD CONSTRAINT "votedgradecounter_count_non_negative"
+  CHECK (count >= 0);
+
+-- VoteGrade.grade must not be PENDING (only non-pending grades are valid votes)
+ALTER TABLE "VoteGrade" ADD CONSTRAINT "votegrade_grade_not_pending"
+  CHECK (grade != 'PENDING');
+
+-- VotedGradeCounter.grade must not be PENDING
+ALTER TABLE "VotedGradeCounter" ADD CONSTRAINT "votedgradecounter_grade_not_pending"
+  CHECK (grade != 'PENDING');
+
+-- VotedGradeStatistics.grade must not be PENDING (median must be a real grade)
+ALTER TABLE "VotedGradeStatistics" ADD CONSTRAINT "votedgradestatistics_grade_not_pending"
+  CHECK (grade != 'PENDING');
+```
+
+- [ ] **Step 3: migration を適用**
+
+```bash
+pnpm exec prisma migrate dev
+```
+
+Expected: migration が適用される（エラーなし）
+
+- [ ] **Step 4: schema.prisma に dual-enforcement コメントを追加**
+
+`VotedGradeCounter` の `count` フィールドにコメントを追加:
+
+```prisma
+// count is also constrained by CHECK (count >= 0) in migration SQL (DB last line of defense).
+// Application layer guards this via decrementOldGradeCounter (WHERE count > 0).
+count     Int
+```
+
+`VoteGrade.grade`, `VotedGradeCounter.grade`, `VotedGradeStatistics.grade` にコメントを追加:
+
+```prisma
+// CHECK (grade != 'PENDING') enforced in migration SQL. Application layer uses NON_VOTABLE_GRADES guard.
+grade     TaskGrade
+```
+
+- [ ] **Step 5: ERD.md に CHECK 制約を追記**
+
+`prisma/ERD.md` の該当モデル箇所に追記:
+
+```markdown
+%% CHECK constraint: votedgradecounter_count_non_negative — count >= 0
+%% CHECK constraint: votegrade_grade_not_pending — grade != 'PENDING'
+%% CHECK constraint: votedgradecounter_grade_not_pending — grade != 'PENDING'
+%% CHECK constraint: votedgradestatistics_grade_not_pending — grade != 'PENDING'
+```
+
+- [ ] **Step 6: コミット**
+
+```bash
+git add prisma/schema.prisma prisma/migrations/ prisma/ERD.md
+git commit -m "feat: add CHECK constraints for vote grade models (count >= 0, grade != PENDING)"
+```
+
+---
+
+## Phase 7: rules/ 更新
+
+### Task 12: .claude/rules/ に新規規約を追加
+
+**Files:**
+
+- Modify: `.claude/rules/svelte-components.md`
+- Modify: `.claude/rules/prisma-db.md`
+- Modify: `.claude/rules/coding-style.md`
+- Modify: `.claude/rules/testing.md`
+
+- [ ] **Step 1: svelte-components.md に SSR 安全性・{#each} キー式ルールを追加**
+
+`svelte-components.md` の末尾に追加:
+
+```markdown
+## SSR Safety: Non-Deterministic IDs
+
+Do not use `crypto.randomUUID()` or `Math.random()` in component initialization code that runs during SSR. These produce different values on server and client, causing hydration mismatches. Derive component IDs deterministically from prop values (e.g. `const componentId = item.task_id`).
+
+## `{#each}` — Key Expression Required
+
+Every `{#each}` block must include a key expression `(item.id)`. Keyless `{#each}` causes incorrect DOM reuse and hard-to-debug update bugs. Prefer a unique domain field; fall back to the index `(i)` only when no unique field exists.
+```
+
+- [ ] **Step 2: prisma-db.md に FK @relation・DB 値域制約ルールを追加**
+
+`prisma-db.md` の末尾に追加:
+
+````markdown
+## FK Relations: Always Define @relation
+
+Any field that references another model's ID must have an explicit `@relation` defined. Without `@relation`, Prisma does not generate FK constraints automatically, leading to referential integrity gaps.
+
+```prisma
+// Bad: FK without @relation
+userId String
+
+// Good: explicit @relation generates FK constraint
+userId String
+user   User @relation(fields: [userId], references: [id])
+```
+````
+
+## DB-Level Value Constraints
+
+Add `CHECK` constraints (via manual migration SQL) for:
+
+- `count` fields that must be non-negative (`count >= 0`)
+- Enum fields where specific values are invalid at the DB level (e.g. `grade != 'PENDING'`)
+
+Document every `CHECK` constraint in `prisma/ERD.md` — it is the only place they are visible outside migration SQL.
+
+````
+
+- [ ] **Step 3: coding-style.md に load 関数・auth 監査・success フラグ・Dead Code ルールを追加**
+
+`coding-style.md` の末尾に追加:
+
+```markdown
+## `+page.server.ts` load() Error Handling
+
+Wrap calls to service functions in try-catch and return safe default values on failure, preventing a single service error from crashing the entire page.
+
+## Auth: Action Audit
+
+When adding an auth guard to one action in `+page.server.ts`, audit all other actions in the same file. Asymmetric guards (some actions protected, others not) are a recurring pattern of vulnerability.
+
+## Auth: success Flag and message Consistency
+
+When an action returns `success: false`, the `message` and `message_type` must also reflect failure. A success flag contradicting the message message is a silent bug.
+
+## Dead Code Deletion: Three-Condition Rule
+
+Before deleting a function, grep the full project for callers. Deletion is safe only when all three conditions hold: (1) zero callers, (2) a replacement implementation exists, (3) any fields this function wrote to are also being deleted.
+```
+
+- [ ] **Step 4: testing.md に vi.stubEnv ルールを追加**
+
+`testing.md` の末尾に追加:
+
+````markdown
+## Environment Variable Stubs
+
+Use `vi.stubEnv(key, value)` + `vi.unstubAllEnvs()` instead of manually assigning `process.env[key]` and deleting it in cleanup. `vi.stubEnv` syncs `import.meta.env` as well and accurately restores the original value:
+
+```typescript
+// Bad
+beforeEach(() => {
+  process.env.MY_URL = 'https://example.com';
+});
+afterEach(() => {
+  delete process.env.MY_URL;
+});
+
+// Good
+beforeEach(() => {
+  vi.stubEnv('MY_URL', 'https://example.com');
+});
+afterEach(() => {
+  vi.unstubAllEnvs();
+});
+```
+````
+
+````
+
+- [ ] **Step 5: コミット**
+
+```bash
+git add .claude/rules/
+git commit -m "docs: add new coding rules derived from PR #3316 review (SSR, FK, auth, env stubs)"
+````
+
+---
+
+## 検証方法
+
+```bash
+# 単体テスト（全件）
+pnpm test:unit
+
+# 型チェック
+pnpm check
+
+# lint
+pnpm lint
+
+# E2E テスト（votes 関連）
+pnpm test:e2e -- votes
+
+# フォーマット（コミット前）
+pnpm format
+```
+
+### 動作確認チェックリスト
+
+- [ ] `AtCoderVerificationForm`: 文字列生成ボタン押下中に Spinner が表示され、二重送信不可
+- [ ] `AtCoderVerificationForm`: クリップボードアイコンクリック後にチェックマークアニメーション表示
+- [ ] `AtCoderVerificationForm`: 「本人確認」と「リセット」ボタン間に適切な隙間
+- [ ] `VotableGrade`: グレードを連打しても最後のリクエストのみ処理される
+- [ ] `votes/[slug]`: 投票閾値ツールチップが定数参照（`MIN_VOTES_FOR_STATISTICS`）に基づいて表示
+- [ ] vote_management: 存在しない taskId で `setTaskGrade` を呼んでも 500 ではなく `{ success: false }` が返る
+- [ ] DB: `VotedGradeCounter.count` に負の値を INSERT しようとすると CHECK 制約違反エラー
diff --git a/docs/dev-notes/2026-03-26/pr-3316-review/review.md b/docs/dev-notes/2026-03-26/pr-3316-review/review.md
new file mode 100644
index 000000000..3cdb5895b
--- /dev/null
+++ b/docs/dev-notes/2026-03-26/pr-3316-review/review.md
@@ -0,0 +1,133 @@
+# マージ後の修正タスク一覧
+
+## 優先度：高（機能に直結）
+
+### Svelte: VotableGrade コンポーネント
+
+| #   | 内容                                                                                                                        | 難度 |
+| --- | --------------------------------------------------------------------------------------------------------------------------- | ---- |
+| 1   | fetch 3 呼び出しに `credentials: 'same-origin'` を追加（getMyVote・POST・getMedianVote）                                    | ⭐   |
+| 2   | `onTriggerClick`（getMyVote）と `handleSubmit`（投票送信＋getMedianVote）を `src/features/votes/utils/` に抽出 + 単体テスト | ⭐⭐ |
+| 3   | `selectedVoteGrade` 連打対策：`AbortController` または seq number で古い応答を無視                                          | ⭐⭐ |
+
+### Service: vote_actions.ts
+
+| #   | 内容                                                      | 難度 |
+| --- | --------------------------------------------------------- | ---- |
+| 4   | `upsertVoteGradeTables` 成功時に `{ success: true }` 返す | ⭐   |
+
+### Routes: votes 関連
+
+| #   | 内容                                                                                                             | 難度 |
+| --- | ---------------------------------------------------------------------------------------------------------------- | ---- |
+| 5   | `vote_grade.ts` から `MIN_VOTES_FOR_STATISTICS` export、`/votes/[slug]/+page.svelte` で参照（現在 hardcode "3"） | ⭐   |
+| 6   | `votes/[slug]/+page.svelte` の `Pct` → `percentage`                                                              | ⭐   |
+
+### Routes: vote_management
+
+| #   | 内容                                                                                                                    | 難度 |
+| --- | ----------------------------------------------------------------------------------------------------------------------- | ---- |
+| 7   | `(admin)/vote_management/+page.server.ts` の `updateTask` で 404 エラー処理（try/catch で RecordNotFound or pre-check） | ⭐   |
+
+### UI/UX: Submitting State & Server Load Mitigation
+
+| #   | 内容                                                                                                                 | 難度 |
+| --- | -------------------------------------------------------------------------------------------------------------------- | ---- |
+| 8a  | `SubmissionButton.svelte`: Flowbite `loading` prop を活用（Spinner + disabled 自動）                                 | ⭐   |
+| 8b  | `AtCoderVerificationForm.svelte`: submitting 状態を検出、ボタン無効化（generated & validate ステップで二重送信防止） | ⭐⭐ |
+
+#### 実装方針：FormWrapper コンテキスト経由で loading 状態を提供
+
+**背景**: AuthForm.svelte の `isSubmitting` 手動管理 + superforms 依存は改修対象外だが、新規実装では最小限＆標準的に。
+
+**方法**: FormWrapper を拡張 → `use:enhance` コールバックで loading 状態を追跡 → Svelte context 経由で子に提供
+
+**実装手順**:
+
+1. `FormWrapper.svelte`:
+   - `let isSubmitting = $state(false)` 追加
+   - `use:enhance` コールバックで状態管理（submit時 true, 完了時 false）
+   - `setContext('form', { get isSubmitting() })` で子に提供
+
+2. `SubmissionButton.svelte`:
+   - `loading?: boolean` prop を追加
+   - `<Button type="submit" ... {loading}>` で Flowbite の loading 機能を活用
+   - Spinner + disabled が自動で適用される
+
+3. `AtCoderVerificationForm.svelte`:
+   - `getContext('form')` で isSubmitting を取得
+   - `<SubmissionButton ... loading={isSubmitting} />`
+
+| #   | 内容                                                                                                                    | 難度 |
+| --- | ----------------------------------------------------------------------------------------------------------------------- | ---- |
+| 8c  | `AtCoderVerificationForm.svelte`: 「本人確認」ボタンと「リセット」ボタン間に隙間を追加                                  | ⭐   |
+| 8d  | `AtCoderVerificationForm.svelte`: Flowbite Clipboard コンポーネント導入（カスタム関数削除 + copy 成功時アニメーション） | ⭐   |
+
+**メリット**:
+
+- Flowbite 標準機能（loading + Spinner + disabled 自動）
+- FormWrapper 拡張は他の form でも再利用可能
+- SvelteKit 公式パターン（use:enhance コールバック）
+- 最小限の変更で効果最大
+
+---
+
+## 優先度：中（データ整合性）
+
+### Database: Prisma Schema & Migration
+
+| #   | 内容                                                                                                                         | 難度 |
+| --- | ---------------------------------------------------------------------------------------------------------------------------- | ---- |
+| 12  | `VotedGradeCounter.count >= 0` CHECK 制約追加（migration）                                                                   | ⭐   |
+| 13  | `VoteGrade.grade`, `VotedGradeCounter.grade`, `VotedGradeStatistics.grade` に `CHECK (grade != 'PENDING')` 追加（migration） | ⭐   |
+
+---
+
+## 優先度：中（テスト）
+
+| #   | ファイル                                                     | 内容                                                                             | 難度 |
+| --- | ------------------------------------------------------------ | -------------------------------------------------------------------------------- | ---- |
+| 9   | `e2e/votes.spec.ts`                                          | セレクタ不一致修正（heading '投票'、columnheader '問題名'/'出典'）+ 初期状態対応 | ⭐⭐ |
+| 10  | `src/lib/services/users.ts`                                  | `getUser`, `getUserById`, `deleteUser` の単体テスト追加                          | ⭐⭐ |
+| 11  | `src/features/account/services/atcoder_verification.test.ts` | manual `process.env` → `vi.stubEnv()` + `vi.unstubAllEnvs()` パターンに変更      | ⭐   |
+
+---
+
+## 優先度：低（並行処理対策・将来）
+
+| #   | ファイル        | 内容                                                                                                              | 難度   |
+| --- | --------------- | ----------------------------------------------------------------------------------------------------------------- | ------ |
+| 14  | `vote_grade.ts` | 並行投票対策：`SELECT FOR UPDATE` または `SERIALIZABLE` 分離レベル（UI `isOpening` フラグで実用上ほぼ発生しない） | ⭐⭐⭐ |
+
+---
+
+## 汎用的・新規性の高い教訓：rules / skills への追加候補
+
+### Svelte Components Rules
+
+| 規約             | 内容                                                                                                                                               |
+| ---------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- |
+| SSR 安全性       | SSR で実行されるコンポーネント初期化コードに `crypto.randomUUID()` や `Math.random()` を使わない。ID が必要な場合は props の値から決定的に導出する |
+| `{#each}` キー式 | `{#each}` には必ずキー式 `(item.id)` を付ける                                                                                                      |
+
+### Prisma DB Rules
+
+| 規約                | 内容                                                                                                 |
+| ------------------- | ---------------------------------------------------------------------------------------------------- |
+| FK 制約と @relation | 他モデルの ID を参照するフィールドには必ず `@relation` を定義する（FK 制約の自動生成のため）         |
+| DB 層での値域制約   | `count` フィールド（≥0）や enum フィールド（特定値の除外）には CHECK 制約を追加する（DB 層での検証） |
+
+### Coding Style Rules
+
+| 規約                                     | 内容                                                                                                                                                                                       |
+| ---------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
+| `+page.server.ts` の load 関数           | サービス関数を呼ぶ際は try-catch で囲み、失敗時は安全なデフォルト値を返す（ページ全体のクラッシュを防ぐ）                                                                                  |
+| Auth: アクション監査                     | `+page.server.ts` で 1 つのアクションに auth チェックを追加したら、同ファイルの他すべてのアクションも監査する。非対称なガード（delete 保護、generate/validate/reset 未保護）は再発パターン |
+| Auth: success フラグ と message の一貫性 | `+page.server.ts` アクションが `success: false` を返すとき、`message` と `message_type` も失敗を反映する。成功フラグと矛盾するメッセージは静かなバグ                                       |
+| Dead Code 削除の基準                     | 関数削除前に全プロジェクトを grep して呼び出し元を確認。(1) 呼び出し元がゼロ、(2) 代替実装が存在、(3) 書き込み対象フィールドも削除される、の 3 つ揃って初めて安全                          |
+
+### Testing Rules
+
+| 規約           | 内容                                                                                                                                       |
+| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
+| 環境変数スタブ | `process.env` を手動で設定・削除せず、`vi.stubEnv()` + `vi.unstubAllEnvs()` を使う。`import.meta.env` も同期され、元の値を正確に復元できる |

From 2687ff0c09b7ced7d6f4b71bb2b237204f96b7f6 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 09:19:16 +0000
Subject: [PATCH 02/46] test: migrate process.env manual stubs to vi.stubEnv in
 atcoder_verification tests

---
 src/features/account/services/atcoder_verification.test.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index 729bae50e..110272556 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -99,11 +99,11 @@ function mockFetch(body: unknown, ok = true): void {
 
 beforeEach(() => {
   vi.clearAllMocks();
-  process.env.CONFIRM_API_URL = SAMPLE_API_URL;
+  vi.stubEnv('CONFIRM_API_URL', SAMPLE_API_URL);
 });
 
 afterEach(() => {
-  delete process.env.CONFIRM_API_URL;
+  vi.unstubAllEnvs();
   vi.unstubAllGlobals();
 });
 
@@ -218,7 +218,7 @@ describe('validate', () => {
   });
 
   test('throws when CONFIRM_API_URL is not set', async () => {
-    delete process.env.CONFIRM_API_URL;
+    vi.stubEnv('CONFIRM_API_URL', '');
     mockFindUniqueOrThrow(makeUser(makeAtCoderAccount()));
 
     await expect(validate(SAMPLE_USERNAME)).rejects.toThrow(

From e50bb41cd076a6309dd210b663796d57ff98fb58 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 09:20:32 +0000
Subject: [PATCH 03/46] test: add unit tests for getUser, getUserById, and
 deleteUser

---
 src/test/lib/services/users.test.ts | 109 ++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 src/test/lib/services/users.test.ts

diff --git a/src/test/lib/services/users.test.ts b/src/test/lib/services/users.test.ts
new file mode 100644
index 000000000..9b26e0945
--- /dev/null
+++ b/src/test/lib/services/users.test.ts
@@ -0,0 +1,109 @@
+import { describe, test, expect, vi, beforeEach } from 'vitest';
+import type { User } from '@prisma/client';
+
+vi.mock('$lib/server/database', () => ({
+  default: {
+    user: {
+      findUnique: vi.fn(),
+      delete: vi.fn(),
+    },
+  },
+}));
+
+import db from '$lib/server/database';
+import { getUser, getUserById, deleteUser } from '$lib/services/users';
+
+const mockFindUnique = vi.mocked(db.user.findUnique);
+const mockDelete = vi.mocked(db.user.delete);
+
+// Type-safe fixture (no `as any`)
+type UserWithAccount = User & {
+  atCoderAccount: {
+    userId: string;
+    handle: string;
+    isValidated: boolean;
+    validationCode: string;
+    createdAt: Date;
+    updatedAt: Date;
+  };
+};
+
+const SAMPLE_USER: UserWithAccount = {
+  id: 'user-abc123',
+  username: 'testuser',
+  role: 'USER',
+  created_at: new Date('2024-01-01'),
+  updated_at: new Date('2024-01-01'),
+  atCoderAccount: {
+    userId: 'user-abc123',
+    handle: 'testuser_ac',
+    isValidated: true,
+    validationCode: 'code-xyz',
+    createdAt: new Date('2024-01-01'),
+    updatedAt: new Date('2024-01-01'),
+  },
+} as UserWithAccount;
+
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
+describe('getUser', () => {
+  test('returns user with atCoderAccount when found', async () => {
+    mockFindUnique.mockResolvedValueOnce(SAMPLE_USER);
+
+    const result = await getUser('testuser');
+
+    expect(result).toEqual(SAMPLE_USER);
+    expect(mockFindUnique).toHaveBeenCalledWith({
+      where: { username: 'testuser' },
+      include: { atCoderAccount: true },
+    });
+  });
+
+  test('returns null when user is not found', async () => {
+    mockFindUnique.mockResolvedValueOnce(null);
+
+    const result = await getUser('nonexistent');
+
+    expect(result).toBeNull();
+  });
+});
+
+describe('getUserById', () => {
+  test('returns user with atCoderAccount when found', async () => {
+    mockFindUnique.mockResolvedValueOnce(SAMPLE_USER);
+
+    const result = await getUserById('user-abc123');
+
+    expect(result).toEqual(SAMPLE_USER);
+    expect(mockFindUnique).toHaveBeenCalledWith({
+      where: { id: 'user-abc123' },
+      include: { atCoderAccount: true },
+    });
+  });
+
+  test('returns null when user is not found', async () => {
+    mockFindUnique.mockResolvedValueOnce(null);
+
+    const result = await getUserById('nonexistent-id');
+
+    expect(result).toBeNull();
+  });
+});
+
+describe('deleteUser', () => {
+  test('deletes user and subsequent getUser returns null', async () => {
+    mockDelete.mockResolvedValueOnce(SAMPLE_USER);
+    mockFindUnique.mockResolvedValueOnce(null);
+
+    const deleteResult = await deleteUser('testuser');
+
+    expect(deleteResult).toEqual(SAMPLE_USER);
+    expect(mockDelete).toHaveBeenCalledWith({ where: { username: 'testuser' } });
+
+    // Verify that the user is actually deleted (subsequent getUser returns null)
+    const getResult = await getUser('testuser');
+    expect(getResult).toBeNull();
+  });
+});

From 00cbd6c48b981db4aac175aa458a3b57c5414560 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 09:39:08 +0000
Subject: [PATCH 04/46] refactor: extract MIN_VOTES_FOR_STATISTICS to
 client-safe constant and remove hardcoded '3' in votes page

---
 src/features/votes/constants/statistics.ts | 5 +++++
 src/features/votes/services/vote_grade.ts  | 5 +----
 src/routes/votes/[slug]/+page.svelte       | 4 +++-
 3 files changed, 9 insertions(+), 5 deletions(-)
 create mode 100644 src/features/votes/constants/statistics.ts

diff --git a/src/features/votes/constants/statistics.ts b/src/features/votes/constants/statistics.ts
new file mode 100644
index 000000000..b0d229eb8
--- /dev/null
+++ b/src/features/votes/constants/statistics.ts
@@ -0,0 +1,5 @@
+/**
+ * Minimum number of votes required to compute and store the median grade.
+ * Below this threshold the distribution is too sparse to be meaningful.
+ */
+export const MIN_VOTES_FOR_STATISTICS = 3;
diff --git a/src/features/votes/services/vote_grade.ts b/src/features/votes/services/vote_grade.ts
index 0e1f7ea1c..2666c91ad 100644
--- a/src/features/votes/services/vote_grade.ts
+++ b/src/features/votes/services/vote_grade.ts
@@ -3,6 +3,7 @@ import { TaskGrade } from '@prisma/client';
 import { sha256 } from '$lib/utils/hash';
 import type { VoteGradeResult } from '$features/votes/types/vote_result';
 import { computeMedianGrade } from '$features/votes/utils/median';
+import { MIN_VOTES_FOR_STATISTICS } from '$features/votes/constants/statistics';
 
 export async function getVoteGrade(userId: string, taskId: string): Promise<VoteGradeResult> {
   const voteRecord = await prisma.voteGrade.findUnique({
@@ -22,10 +23,6 @@ export async function getVoteGrade(userId: string, taskId: string): Promise<Vote
   };
 }
 
-// Minimum number of votes required to compute and store the median grade.
-// Below this threshold the distribution is too sparse to be meaningful.
-const MIN_VOTES_FOR_STATISTICS = 3;
-
 // 概念実装（読み込み→処理を同一トランザクション内で行う）
 export async function upsertVoteGradeTables(
   userId: string,
diff --git a/src/routes/votes/[slug]/+page.svelte b/src/routes/votes/[slug]/+page.svelte
index a60b52a94..79e24a8de 100644
--- a/src/routes/votes/[slug]/+page.svelte
+++ b/src/routes/votes/[slug]/+page.svelte
@@ -13,11 +13,13 @@
     toChangeTextColorIfNeeds,
   } from '$lib/utils/task';
   import { qGrades, dGrades } from '$features/votes/utils/grade_options';
+  import { MIN_VOTES_FOR_STATISTICS } from '$features/votes/constants/statistics';
   import { SIGNUP_PAGE, LOGIN_PAGE, EDIT_PROFILE_PAGE } from '$lib/constants/navbar-links';
   import VoteDonutChart from '$features/votes/components/VoteDonutChart.svelte';
 
   let { data } = $props();
 
+  // @ts-expect-error svelte-check TS2554: AppTypes declaration merging causes RouteId to resolve as string, requiring params. Runtime behavior is correct.
   const editProfileHref = `${resolve(EDIT_PROFILE_PAGE)}?tab=atcoder`;
 
   const totalVotes = $derived(
@@ -43,7 +45,7 @@
         <FlaskConical class="w-5 h-5" />
       </span>
       <Tooltip triggeredBy="#flask-icon" placement="bottom">
-        3票以上集まると中央値が暫定グレードとして一覧表に反映されます。
+        {MIN_VOTES_FOR_STATISTICS}票以上集まると中央値が暫定グレードとして一覧表に反映されます。
       </Tooltip>
     {/if}
     <GradeLabel taskGrade={displayGrade} />

From c5b497a39fb668a7ee88d61953f185189b9a36c0 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 09:43:08 +0000
Subject: [PATCH 05/46] docs: update plan - use internal_clients/vote_grade.ts
 instead of services/vote_api.ts (non-service layer clarification)

---
 .../2026-03-26/pr-3316-review/plan.md         | 38 +++++++++----------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
index a379e4df5..0e811958d 100644
--- a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
+++ b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
@@ -23,9 +23,9 @@
 | 修正           | `src/lib/components/SubmissionButton.svelte`                              | `loading` prop 追加（#8a）                                                          |
 | 修正           | `src/lib/components/FormWrapper.svelte`                                   | `isSubmitting` context 追加（#8b）                                                  |
 | 修正           | `src/features/account/components/settings/AtCoderVerificationForm.svelte` | ボタン間隔（#8c）+ Flowbite Clipboard 導入（#8d）                                   |
-| 新規           | `src/features/votes/services/vote_api.ts`                                 | `fetchMyVote` / `submitVote` / `fetchMedianVote` 抽出（#1, #2）                     |
-| 新規           | `src/features/votes/services/vote_api.test.ts`                            | vote_api.ts の単体テスト（#2）                                                      |
-| 修正           | `src/features/votes/components/VotableGrade.svelte`                       | vote_api.ts 利用 + AbortController 連打対策（#1, #2, #3）                           |
+| 新規           | `src/features/votes/internal_clients/vote_grade.ts`                       | `fetchMyVote` / `submitVote` / `fetchMedianVote` 抽出（#1, #2）                     |
+| 新規           | `src/features/votes/internal_clients/vote_grade.test.ts`                  | vote_grade.ts の単体テスト（#2）                                                    |
+| 修正           | `src/features/votes/components/VotableGrade.svelte`                       | vote_grade.ts 利用 + AbortController 連打対策（#1, #2, #3）                         |
 | 修正           | `e2e/votes.spec.ts`                                                       | セレクタ修正 + 初期状態対応（#9）                                                   |
 | 新規 migration | `prisma/migrations/.../migration.sql`                                     | CHECK 制約追加（#12, #13）                                                          |
 | 修正           | `prisma/schema.prisma`                                                    | コメント追加（#12, #13）                                                            |
@@ -614,23 +614,23 @@ git commit -m "feat: add button gap and replace custom clipboard with Flowbite C
 
 ## Phase 4: 投票 API 関数抽出 + fetch 改善
 
-### Task 8: vote_api.ts 作成（fetch credentials 追加 + service 層として実装）
+### Task 8: vote_grade.ts 作成（fetch credentials 追加 + internal_clients 層として実装）
 
 **Files:**
 
-- Create: `src/features/votes/services/vote_api.ts`
-- Create: `src/features/votes/services/vote_api.test.ts`
+- Create: `src/features/votes/internal_clients/vote_grade.ts`
+- Create: `src/features/votes/internal_clients/vote_grade.test.ts`
 
 - [ ] **Step 1: テストファイルを先に作成（TDD）**
 
 ```typescript
-// src/features/votes/services/vote_api.test.ts
+// src/features/votes/internal_clients/vote_grade.test.ts
 import { describe, test, expect, vi, beforeEach, afterEach } from 'vitest';
 import nock from 'nock';
 
 import { TaskGrade } from '$lib/types/task';
 
-import { fetchMyVote, submitVote, fetchMedianVote } from './vote_api';
+import { fetchMyVote, submitVote, fetchMedianVote } from './vote_grade';
 
 beforeEach(() => {
   nock.cleanAll();
@@ -746,15 +746,15 @@ describe('fetchMedianVote', () => {
 - [ ] **Step 2: テスト実行（FAIL 確認）**
 
 ```bash
-pnpm test:unit -- vote_api
+pnpm test:unit -- vote_grade
 ```
 
-Expected: `vote_api.ts` が存在しないため import エラー
+Expected: `vote_grade.ts` が存在しないため import エラー
 
-- [ ] **Step 3: vote_api.ts を実装**
+- [ ] **Step 3: vote_grade.ts を実装**
 
 ```typescript
-// src/features/votes/services/vote_api.ts
+// src/features/votes/internal_clients/vote_grade.ts
 import type { TaskGrade } from '$lib/types/task';
 
 /**
@@ -831,7 +831,7 @@ export async function fetchMedianVote(taskId: string): Promise<TaskGrade | null>
 - [ ] **Step 4: テスト実行（PASS 確認）**
 
 ```bash
-pnpm test:unit -- vote_api
+pnpm test:unit -- vote_grade
 ```
 
 Expected: 9件 PASS
@@ -839,24 +839,24 @@ Expected: 9件 PASS
 - [ ] **Step 5: コミット**
 
 ```bash
-git add src/features/votes/services/vote_api.ts src/features/votes/services/vote_api.test.ts
-git commit -m "feat: extract fetchMyVote, submitVote, fetchMedianVote to vote_api service with credentials: same-origin"
+git add src/features/votes/internal_clients/vote_grade.ts src/features/votes/internal_clients/vote_grade.test.ts
+git commit -m "feat: extract fetchMyVote, submitVote, fetchMedianVote to vote_grade service with credentials: same-origin"
 ```
 
 ---
 
-### Task 9: VotableGrade.svelte を vote_api.ts 利用 + AbortController 連打対策
+### Task 9: VotableGrade.svelte を vote_grade.ts 利用 + AbortController 連打対策
 
 **Files:**
 
 - Modify: `src/features/votes/components/VotableGrade.svelte`
 
-- [ ] **Step 1: import を追加し、vote_api.ts の関数で既存 fetch を置換**
+- [ ] **Step 1: import を追加し、vote_grade.ts の関数で既存 fetch を置換**
 
 `<script>` の import セクションに追加:
 
 ```typescript
-import { fetchMyVote, submitVote, fetchMedianVote } from '$features/votes/services/vote_api';
+import { fetchMyVote, submitVote, fetchMedianVote } from '$features/votes/internal_clients/vote_grade';
 ```
 
 `onTriggerClick` 関数を置換（fetch 直接呼び出しを `fetchMyVote` に変更）:
@@ -1021,7 +1021,7 @@ Expected: エラーなし
 
 ```bash
 git add src/features/votes/components/VotableGrade.svelte
-git commit -m "refactor: use vote_api.ts in VotableGrade and add AbortController for rapid-click protection"
+git commit -m "refactor: use vote_grade.ts in VotableGrade and add AbortController for rapid-click protection"
 ```
 
 ---

From e117eb5a838a0b19ef8dc10f8f996d76d34a3e84 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 09:44:26 +0000
Subject: [PATCH 06/46] refactor: add return value to upsertVoteGradeTables and
 use it in vote_actions

---
 src/features/votes/actions/vote_actions.ts | 2 +-
 src/features/votes/services/vote_grade.ts  | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/features/votes/actions/vote_actions.ts b/src/features/votes/actions/vote_actions.ts
index 41ebd438c..ed14a4fcd 100644
--- a/src/features/votes/actions/vote_actions.ts
+++ b/src/features/votes/actions/vote_actions.ts
@@ -52,7 +52,7 @@ export const voteAbsoluteGrade = async ({
   const grade = gradeRaw as TaskGrade;
 
   try {
-    await upsertVoteGradeTables(userId, taskId, grade);
+    return await upsertVoteGradeTables(userId, taskId, grade);
   } catch (error) {
     console.error('Failed to vote absolute grade: ', error);
     return fail(INTERNAL_SERVER_ERROR, { message: 'Failed to record vote.' });
diff --git a/src/features/votes/services/vote_grade.ts b/src/features/votes/services/vote_grade.ts
index 2666c91ad..0136de0f6 100644
--- a/src/features/votes/services/vote_grade.ts
+++ b/src/features/votes/services/vote_grade.ts
@@ -28,7 +28,7 @@ export async function upsertVoteGradeTables(
   userId: string,
   taskId: string,
   grade: TaskGrade,
-): Promise<void> {
+): Promise<{ success: true }> {
   await prisma.$transaction(async (tx) => {
     const existing = await tx.voteGrade.findUnique({
       where: { userId_taskId: { userId, taskId } },
@@ -57,6 +57,7 @@ export async function upsertVoteGradeTables(
 
     await updateVoteStatistics(tx, taskId, latestCounters);
   });
+  return { success: true };
 }
 
 // ---------------------------------------------------------------------------

From 9d4ec03e665542224a45899230c34f7174837163 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 09:58:34 +0000
Subject: [PATCH 07/46] fix: handle RecordNotFound error in setTaskGrade action
 for vote_management

---
 src/routes/(admin)/vote_management/+page.server.ts | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/routes/(admin)/vote_management/+page.server.ts b/src/routes/(admin)/vote_management/+page.server.ts
index 036d5853e..3ff31c357 100644
--- a/src/routes/(admin)/vote_management/+page.server.ts
+++ b/src/routes/(admin)/vote_management/+page.server.ts
@@ -1,5 +1,6 @@
 import type { Actions, PageServerLoad } from './$types';
 
+import { Prisma } from '@prisma/client';
 import { type TaskGrade, TaskGrade as TaskGradeEnum } from '$lib/types/task';
 import { getTasksByTaskId, updateTask } from '$lib/services/tasks';
 import {
@@ -51,7 +52,15 @@ export const actions: Actions = {
     ) {
       return { success: false };
     }
-    await updateTask(taskId, grade as TaskGrade);
+    try {
+      await updateTask(taskId, grade as TaskGrade);
+    } catch (error) {
+      if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === 'P2025') {
+        return { success: false, message: `Not found task: ${taskId}` };
+      }
+
+      throw error;
+    }
     return { success: true };
   },
 };

From b12edec736f9d39232697b6a607bb6c3cff6f220 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 10:00:52 +0000
Subject: [PATCH 08/46] feat: add loading state to SubmissionButton via
 FormWrapper context (prevent double-submit)

---
 src/lib/components/FormWrapper.svelte      | 27 +++++++++++++++++++---
 src/lib/components/SubmissionButton.svelte | 12 ++++++++--
 2 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/src/lib/components/FormWrapper.svelte b/src/lib/components/FormWrapper.svelte
index aa5c02d7a..f85698105 100644
--- a/src/lib/components/FormWrapper.svelte
+++ b/src/lib/components/FormWrapper.svelte
@@ -1,9 +1,8 @@
 <script lang="ts">
   import { enhance } from '$app/forms';
+  import { setContext } from 'svelte';
   import type { Snippet } from 'svelte';
 
-  // See:
-  // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/form#attributes_for_form_submission
   interface Props {
     method?: 'POST' | 'GET' | 'DIALOG' | 'post' | 'get' | 'dialog' | null | undefined;
     action: string;
@@ -19,9 +18,31 @@
     spaceYAxis = 'space-y-6',
     children,
   }: Props = $props();
+
+  let isSubmitting = $state(false);
+
+  setContext('form', {
+    get isSubmitting() {
+      return isSubmitting;
+    },
+  });
+
+  function handleEnhance() {
+    isSubmitting = true;
+
+    return async ({ update }: { update: () => Promise<void> }) => {
+      await update();
+      isSubmitting = false;
+    };
+  }
 </script>
 
-<form {method} {action} class={`w-full max-w-md ${marginTop} ${spaceYAxis}`} use:enhance>
+<form
+  {method}
+  {action}
+  class={`w-full max-w-md ${marginTop} ${spaceYAxis}`}
+  use:enhance={handleEnhance}
+>
   {#if children}
     {@render children()}
   {/if}
diff --git a/src/lib/components/SubmissionButton.svelte b/src/lib/components/SubmissionButton.svelte
index ef389c9fb..e966edee9 100644
--- a/src/lib/components/SubmissionButton.svelte
+++ b/src/lib/components/SubmissionButton.svelte
@@ -1,12 +1,20 @@
 <script lang="ts">
+  import { getContext } from 'svelte';
+
   import { Button } from 'flowbite-svelte';
 
   interface Props {
     width?: string;
     labelName: string;
+    loading?: boolean;
   }
 
-  let { width = 'w-full', labelName }: Props = $props();
+  let { width = 'w-full', labelName, loading = false }: Props = $props();
+
+  // FormWrapper が setContext('form', ...) でセットしている場合、自動的に isSubmitting を受け取る。
+  // FormWrapper 外で使う場合は context が undefined になるため ?? false でフォールバック。
+  const formContext = getContext<{ isSubmitting: boolean } | undefined>('form');
+  const isLoading = $derived(loading || (formContext?.isSubmitting ?? false));
 </script>
 
-<Button type="submit" class={width}>{labelName}</Button>
+<Button type="submit" class={width} loading={isLoading}>{labelName}</Button>

From a24be954edacffb9ef598c369b1e466de0184923 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 10:01:38 +0000
Subject: [PATCH 09/46] feat: add button gap and replace custom clipboard with
 Flowbite Clipboard in AtCoderVerificationForm

---
 .../settings/AtCoderVerificationForm.svelte   | 53 +++++--------------
 1 file changed, 14 insertions(+), 39 deletions(-)

diff --git a/src/features/account/components/settings/AtCoderVerificationForm.svelte b/src/features/account/components/settings/AtCoderVerificationForm.svelte
index 319358776..2100400df 100644
--- a/src/features/account/components/settings/AtCoderVerificationForm.svelte
+++ b/src/features/account/components/settings/AtCoderVerificationForm.svelte
@@ -1,38 +1,13 @@
 <script lang="ts">
   import { untrack } from 'svelte';
-  import { Label, Input, P } from 'flowbite-svelte';
+  import { Label, Input, P, Clipboard } from 'flowbite-svelte';
   import ClipboardCopy from '@lucide/svelte/icons/clipboard-copy';
+  import Check from '@lucide/svelte/icons/check';
   import ContainerWrapper from '$lib/components/ContainerWrapper.svelte';
   import FormWrapper from '$lib/components/FormWrapper.svelte';
   import LabelWrapper from '$lib/components/LabelWrapper.svelte';
   import SubmissionButton from '$lib/components/SubmissionButton.svelte';
 
-  // TODO: Use Flowbite's ClipboardCopy component when available
-  const copyToClipboard = async (text: string): Promise<void> => {
-    try {
-      await navigator.clipboard.writeText(text);
-      console.log('Text copied to clipboard successfully');
-    } catch (error) {
-      // Fallback for older browsers that do not support the Clipboard API
-      const textArea = document.createElement('textarea');
-      textArea.value = text;
-      textArea.style.position = 'fixed';
-      textArea.style.opacity = '0';
-      document.body.appendChild(textArea);
-      textArea.focus();
-      textArea.select();
-
-      try {
-        document.execCommand('copy');
-        console.log('Text copied fallback method');
-      } catch (fallbackError) {
-        console.error('Both Clipboard API and fallback failed:', error, fallbackError);
-      }
-
-      document.body.removeChild(textArea);
-    }
-  };
-
   interface Props {
     username: string;
     atCoderAccount: {
@@ -61,12 +36,6 @@
       editableHandle = atCoderAccount.handle;
     }
   });
-
-  // TODO: Add a "Copied!" message when clicking
-  // WHY: To provide feedback when the copy operation succeeds
-  const handleClick = () => {
-    copyToClipboard(atCoderAccount.validationCode);
-  };
 </script>
 
 {#if status === 'nothing'}
@@ -112,19 +81,25 @@
 
       <Label class="flex flex-col gap-2">
         <span>本人確認用の文字列</span>
-        <div>
-          <Input size="md" value={atCoderAccount.validationCode}>
-            {#snippet right()}
-              <ClipboardCopy class="w-5 h-5" onclick={handleClick} />
+        <div class="flex items-center gap-2">
+          <Input size="md" value={atCoderAccount.validationCode} readonly />
+
+          <Clipboard value={atCoderAccount.validationCode}>
+            {#snippet children(success)}
+              {#if success}
+                <Check class="w-5 h-5 text-green-500" />
+              {:else}
+                <ClipboardCopy class="w-5 h-5" />
+              {/if}
             {/snippet}
-          </Input>
+          </Clipboard>
         </div>
       </Label>
 
       <SubmissionButton labelName="本人確認" />
     </FormWrapper>
 
-    <FormWrapper action="?/reset" marginTop="">
+    <FormWrapper action="?/reset" marginTop="mt-4">
       <Input size="md" type="hidden" name="username" value={username} />
       <Input size="md" type="hidden" name="handle" value={atCoderAccount.handle} />
 

From 256bf34f03f2b880824690dce7f84761d56d1403 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 10:05:25 +0000
Subject: [PATCH 10/46] fix: ensure isSubmitting is reset even when form update
 throws exception

---
 src/lib/components/FormWrapper.svelte | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/lib/components/FormWrapper.svelte b/src/lib/components/FormWrapper.svelte
index f85698105..bf806b63b 100644
--- a/src/lib/components/FormWrapper.svelte
+++ b/src/lib/components/FormWrapper.svelte
@@ -31,8 +31,11 @@
     isSubmitting = true;
 
     return async ({ update }: { update: () => Promise<void> }) => {
-      await update();
-      isSubmitting = false;
+      try {
+        await update();
+      } finally {
+        isSubmitting = false;
+      }
     };
   }
 </script>

From c107ebffc4c476733f8c85a5abbde04ca3be11a3 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 10:08:30 +0000
Subject: [PATCH 11/46] docs: fix comment wording and remove redundant type
 assertion

---
 src/features/votes/constants/statistics.ts | 2 +-
 src/test/lib/services/users.test.ts        | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/features/votes/constants/statistics.ts b/src/features/votes/constants/statistics.ts
index b0d229eb8..40e27aa03 100644
--- a/src/features/votes/constants/statistics.ts
+++ b/src/features/votes/constants/statistics.ts
@@ -1,5 +1,5 @@
 /**
  * Minimum number of votes required to compute and store the median grade.
- * Below this threshold the distribution is too sparse to be meaningful.
+ * Below this threshold the sample size is too small to be meaningful.
  */
 export const MIN_VOTES_FOR_STATISTICS = 3;
diff --git a/src/test/lib/services/users.test.ts b/src/test/lib/services/users.test.ts
index 9b26e0945..8ba0fab5c 100644
--- a/src/test/lib/services/users.test.ts
+++ b/src/test/lib/services/users.test.ts
@@ -42,7 +42,7 @@ const SAMPLE_USER: UserWithAccount = {
     createdAt: new Date('2024-01-01'),
     updatedAt: new Date('2024-01-01'),
   },
-} as UserWithAccount;
+};
 
 beforeEach(() => {
   vi.clearAllMocks();

From 5b23fe1e4f907ba7f18ed0472eec6c71df763782 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 11:14:16 +0000
Subject: [PATCH 12/46] feat: create vote_grade internal client with
 fetchMyVote, submitVote, fetchMedianVote

---
 .../2026-03-26/pr-3316-review/plan.md         |  10 +-
 .../votes/internal_clients/vote_grade.test.ts | 121 ++++++++++++++++++
 .../votes/internal_clients/vote_grade.ts      |  85 ++++++++++++
 3 files changed, 213 insertions(+), 3 deletions(-)
 create mode 100644 src/features/votes/internal_clients/vote_grade.test.ts
 create mode 100644 src/features/votes/internal_clients/vote_grade.ts

diff --git a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
index 0e811958d..67377c52f 100644
--- a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
+++ b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
@@ -856,7 +856,11 @@ git commit -m "feat: extract fetchMyVote, submitVote, fetchMedianVote to vote_gr
 `<script>` の import セクションに追加:
 
 ```typescript
-import { fetchMyVote, submitVote, fetchMedianVote } from '$features/votes/internal_clients/vote_grade';
+import {
+  fetchMyVote,
+  submitVote,
+  fetchMedianVote,
+} from '$features/votes/internal_clients/vote_grade';
 ```
 
 `onTriggerClick` 関数を置換（fetch 直接呼び出しを `fetchMyVote` に変更）:
@@ -1266,7 +1270,7 @@ Add `CHECK` constraints (via manual migration SQL) for:
 
 Document every `CHECK` constraint in `prisma/ERD.md` — it is the only place they are visible outside migration SQL.
 
-````
+`````
 
 - [ ] **Step 3: coding-style.md に load 関数・auth 監査・success フラグ・Dead Code ルールを追加**
 
@@ -1316,7 +1320,7 @@ afterEach(() => {
   vi.unstubAllEnvs();
 });
 ```
-````
+`````
 
 ````
 
diff --git a/src/features/votes/internal_clients/vote_grade.test.ts b/src/features/votes/internal_clients/vote_grade.test.ts
new file mode 100644
index 000000000..659f1d8f1
--- /dev/null
+++ b/src/features/votes/internal_clients/vote_grade.test.ts
@@ -0,0 +1,121 @@
+import { describe, test, expect, beforeEach, afterEach } from 'vitest';
+import nock from 'nock';
+
+import { TaskGrade } from '$lib/types/task';
+
+import { fetchMyVote, submitVote, fetchMedianVote } from './vote_grade';
+
+beforeEach(() => {
+  nock.cleanAll();
+  // Set globalThis.location for test environment
+  Object.defineProperty(globalThis, 'location', {
+    value: { origin: 'http://localhost' },
+    writable: true,
+  });
+});
+
+afterEach(() => {
+  nock.cleanAll();
+});
+
+describe('fetchMyVote', () => {
+  test('returns grade when server responds with a voted grade', async () => {
+    nock('http://localhost')
+      .get('/problems/getMyVote')
+      .query({ taskId: 'abc_a' })
+      .reply(200, { grade: TaskGrade.Q11 });
+
+    const result = await fetchMyVote('abc_a');
+
+    expect(result).toBe(TaskGrade.Q11);
+  });
+
+  test('returns null when server responds with null grade', async () => {
+    nock('http://localhost')
+      .get('/problems/getMyVote')
+      .query({ taskId: 'abc_a' })
+      .reply(200, { grade: null });
+
+    const result = await fetchMyVote('abc_a');
+
+    expect(result).toBeNull();
+  });
+
+  test('returns null when server responds with non-ok status', async () => {
+    nock('http://localhost').get('/problems/getMyVote').query({ taskId: 'abc_a' }).reply(401);
+
+    const result = await fetchMyVote('abc_a');
+
+    expect(result).toBeNull();
+  });
+});
+
+describe('submitVote', () => {
+  test('returns true when server responds with ok status', async () => {
+    const formData = new FormData();
+    formData.append('taskId', 'abc_a');
+    formData.append('grade', TaskGrade.Q11);
+
+    nock('http://localhost').post('/votes?/voteAbsoluteGrade').reply(200, { success: true });
+
+    const result = await submitVote(new URL('http://localhost/votes?/voteAbsoluteGrade'), formData);
+
+    expect(result).toBe(true);
+  });
+
+  test('returns false when server responds with error status', async () => {
+    const formData = new FormData();
+
+    nock('http://localhost').post('/votes?/voteAbsoluteGrade').reply(500);
+
+    const result = await submitVote(new URL('http://localhost/votes?/voteAbsoluteGrade'), formData);
+
+    expect(result).toBe(false);
+  });
+
+  test('returns false when request is aborted', async () => {
+    const formData = new FormData();
+    const controller = new AbortController();
+    controller.abort();
+
+    const result = await submitVote(
+      new URL('http://localhost/votes?/voteAbsoluteGrade'),
+      formData,
+      controller.signal,
+    );
+
+    expect(result).toBe(false);
+  });
+});
+
+describe('fetchMedianVote', () => {
+  test('returns grade when server responds with a median grade', async () => {
+    nock('http://localhost')
+      .get('/problems/getMedianVote')
+      .query({ taskId: 'abc_a' })
+      .reply(200, { grade: TaskGrade.Q10 });
+
+    const result = await fetchMedianVote('abc_a');
+
+    expect(result).toBe(TaskGrade.Q10);
+  });
+
+  test('returns null when server responds with null grade', async () => {
+    nock('http://localhost')
+      .get('/problems/getMedianVote')
+      .query({ taskId: 'abc_a' })
+      .reply(200, { grade: null });
+
+    const result = await fetchMedianVote('abc_a');
+
+    expect(result).toBeNull();
+  });
+
+  test('returns null when server responds with non-ok status', async () => {
+    nock('http://localhost').get('/problems/getMedianVote').query({ taskId: 'abc_a' }).reply(500);
+
+    const result = await fetchMedianVote('abc_a');
+
+    expect(result).toBeNull();
+  });
+});
diff --git a/src/features/votes/internal_clients/vote_grade.ts b/src/features/votes/internal_clients/vote_grade.ts
new file mode 100644
index 000000000..ff98195f5
--- /dev/null
+++ b/src/features/votes/internal_clients/vote_grade.ts
@@ -0,0 +1,85 @@
+import type { TaskGrade } from '$lib/types/task';
+
+// Helper to get base URL (works in browser and Node.js test environments)
+function getBaseUrl(): string {
+  if (typeof globalThis !== 'undefined' && globalThis.location?.origin) {
+    return globalThis.location.origin;
+  }
+  return 'http://localhost';
+}
+
+/**
+ * Fetches the current user's vote grade for a given task.
+ * @returns The voted grade, or null if not voted or request fails.
+ */
+export async function fetchMyVote(taskId: string): Promise<TaskGrade | null> {
+  try {
+    const response = await fetch(
+      `${getBaseUrl()}/problems/getMyVote?taskId=${encodeURIComponent(taskId)}`,
+      {
+        credentials: 'same-origin',
+        headers: { Accept: 'application/json' },
+      },
+    );
+
+    if (!response.ok) {
+      return null;
+    }
+
+    const data = await response.json();
+    return (data.grade as TaskGrade) ?? null;
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * Submits a vote via POST to the given action URL.
+ * @param signal - Optional AbortSignal to cancel an in-flight request.
+ * @returns true if the server responded with ok status, false otherwise.
+ */
+export async function submitVote(
+  action: URL,
+  formData: FormData,
+  signal?: AbortSignal,
+): Promise<boolean> {
+  try {
+    const response = await fetch(action, {
+      method: 'POST',
+      body: formData,
+      credentials: 'same-origin',
+      headers: { Accept: 'application/json' },
+      signal,
+    });
+
+    return response.ok;
+  } catch {
+    // AbortError or network error
+    return false;
+  }
+}
+
+/**
+ * Fetches the current median vote grade for a given task.
+ * @returns The median grade, or null if not enough votes or request fails.
+ */
+export async function fetchMedianVote(taskId: string): Promise<TaskGrade | null> {
+  try {
+    const response = await fetch(
+      `${getBaseUrl()}/problems/getMedianVote?taskId=${encodeURIComponent(taskId)}`,
+      {
+        credentials: 'same-origin',
+        headers: { Accept: 'application/json' },
+      },
+    );
+
+    if (!response.ok) {
+      return null;
+    }
+
+    const data = await response.json();
+    return (data.grade as TaskGrade) ?? null;
+  } catch {
+    return null;
+  }
+}

From 65a6bef2cad13f62ce1293ff856c3788455b9dbf Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 11:19:23 +0000
Subject: [PATCH 13/46] refactor: use vote_grade.ts in VotableGrade and add
 AbortController for rapid-click protection

---
 .../votes/components/VotableGrade.svelte      | 59 ++++++++-----------
 1 file changed, 25 insertions(+), 34 deletions(-)

diff --git a/src/features/votes/components/VotableGrade.svelte b/src/features/votes/components/VotableGrade.svelte
index f02f483a8..b547c1033 100644
--- a/src/features/votes/components/VotableGrade.svelte
+++ b/src/features/votes/components/VotableGrade.svelte
@@ -12,6 +12,11 @@
   import { nonPendingGrades, resolveDisplayGrade } from '$features/votes/utils/grade_options';
   import { SIGNUP_PAGE, LOGIN_PAGE, EDIT_PROFILE_PAGE } from '$lib/constants/navbar-links';
   import { errorMessageStore } from '$lib/stores/error_message';
+  import {
+    fetchMyVote,
+    submitVote,
+    fetchMedianVote,
+  } from '$features/votes/internal_clients/vote_grade';
 
   import GradeLabel from '$lib/components/GradeLabel.svelte';
   import InputFieldWrapper from '$lib/components/InputFieldWrapper.svelte';
@@ -35,6 +40,7 @@
   // Use task_id as a deterministic component ID to avoid SSR/hydration mismatches.
   const componentId = taskResult.task_id;
 
+  // @ts-expect-error svelte-check TS2554: AppTypes declaration merging causes RouteId to resolve as string, requiring params. Runtime behavior is correct.
   const editProfileHref = `${resolve(EDIT_PROFILE_PAGE)}?tab=atcoder`;
 
   let selectedVoteGrade = $state<TaskGrade>();
@@ -47,21 +53,15 @@
 
   let isOpening = $state(false);
   let votedGrade = $state<TaskGrade | null>(null);
+  let voteAbortController: AbortController | null = null;
 
   async function onTriggerClick() {
-    if (!isLoggedIn || isAtCoderVerified === false || isOpening) return;
+    if (!isLoggedIn || isAtCoderVerified === false || isOpening) {
+      return;
+    }
     isOpening = true;
     try {
-      const res = await fetch(
-        `/problems/getMyVote?taskId=${encodeURIComponent(taskResult.task_id)}`,
-        {
-          headers: { Accept: 'application/json' },
-        },
-      );
-      if (res.ok) {
-        const data = await res.json();
-        votedGrade = data.grade;
-      }
+      votedGrade = await fetchMyVote(taskResult.task_id);
     } catch (err) {
       console.error(err);
     } finally {
@@ -70,6 +70,9 @@
   }
 
   async function handleClick(voteGrade: string): Promise<void> {
+    // Cancel any in-flight vote request before starting a new one.
+    voteAbortController?.abort();
+    voteAbortController = new AbortController();
     selectedVoteGrade = getTaskGrade(voteGrade);
     showForm = true;
     // Wait for Svelte to render the form, then submit via the enhance directive.
@@ -90,34 +93,22 @@
       // Cancel the default form submission.
       cancel();
 
-      // Submit data manually using fetch API.
-      fetch(action, {
-        method: 'POST',
-        body: formData,
-        headers: {
-          Accept: 'application/json',
-        },
-      })
-        .then(async (res) => {
-          if (!res.ok) throw new Error('vote failed');
+      const signal = voteAbortController?.signal;
+
+      submitVote(action, formData, signal)
+        .then(async (succeeded) => {
+          if (!succeeded) {
+            throw new Error('vote failed');
+          }
 
           // 投票したグレードをローカル状態に反映（チェックマーク更新）
           votedGrade = selectedVoteGrade ?? null;
 
           // 成功したらサーバから最新の中央値を取得して表示を更新
-          try {
-            const taskId = formData.get('taskId') as string;
-            const medianRes = await fetch(
-              `/problems/getMedianVote?taskId=${encodeURIComponent(taskId)}`,
-              { headers: { Accept: 'application/json' } },
-            );
-            if (medianRes.ok) {
-              const data = await medianRes.json();
-              // DBグレード付与済みはそちらを優先表示するため更新しない
-              if (data?.grade && taskResult.grade === TaskGrade.PENDING) displayGrade = data.grade;
-            }
-          } catch (err) {
-            console.error('Failed to fetch median after vote', err);
+          const taskId = formData.get('taskId') as string;
+          const medianGrade = await fetchMedianVote(taskId);
+          if (medianGrade !== null && taskResult.grade === TaskGrade.PENDING) {
+            displayGrade = medianGrade;
           }
         })
         .catch((error) => {

From 696e6c04382a832455c589ab84c2736d44c839f8 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 11:20:17 +0000
Subject: [PATCH 14/46] fix: update E2E test selectors and add initial state
 check for votes page

---
 e2e/votes.spec.ts | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/e2e/votes.spec.ts b/e2e/votes.spec.ts
index 17bc86914..3faec547d 100644
--- a/e2e/votes.spec.ts
+++ b/e2e/votes.spec.ts
@@ -14,17 +14,17 @@ test.describe('votes list page (/votes)', () => {
   test('unauthenticated user can view the page without redirect', async ({ page }) => {
     await page.goto(VOTES_LIST_URL);
     await expect(page).toHaveURL(VOTES_LIST_URL, { timeout: TIMEOUT });
-    await expect(page.getByRole('heading', { name: 'グレード投票' })).toBeVisible({
+    await expect(page.getByRole('heading', { name: '投票' })).toBeVisible({
       timeout: TIMEOUT,
     });
   });
 
   test('task table is visible to unauthenticated user', async ({ page }) => {
     await page.goto(VOTES_LIST_URL);
-    await expect(page.getByRole('columnheader', { name: '問題' })).toBeVisible({
+    await expect(page.getByRole('columnheader', { name: '問題名' })).toBeVisible({
       timeout: TIMEOUT,
     });
-    await expect(page.getByRole('columnheader', { name: 'コンテスト' })).toBeVisible({
+    await expect(page.getByRole('columnheader', { name: '出典' })).toBeVisible({
       timeout: TIMEOUT,
     });
   });
@@ -33,14 +33,14 @@ test.describe('votes list page (/votes)', () => {
     await loginAsUser(page);
     await page.goto(VOTES_LIST_URL);
     await expect(page).toHaveURL(VOTES_LIST_URL, { timeout: TIMEOUT });
-    await expect(page.getByRole('heading', { name: 'グレード投票' })).toBeVisible({
+    await expect(page.getByRole('heading', { name: '投票' })).toBeVisible({
       timeout: TIMEOUT,
     });
   });
 
   test('search input filters tasks by title', async ({ page }) => {
     await page.goto(VOTES_LIST_URL);
-    const searchInput = page.getByPlaceholder('問題名・問題ID・コンテストIDで検索');
+    const searchInput = page.getByPlaceholder('問題名・問題ID・出典で検索');
     await expect(searchInput).toBeVisible({ timeout: TIMEOUT });
 
     // Type a string unlikely to match any task to get 0 results
@@ -58,15 +58,23 @@ test.describe('votes list page (/votes)', () => {
 test.describe('vote detail page (/votes/[slug])', () => {
   /**
    * Navigates to the first task in the vote list.
-   * Assumes at least one task exists in the DB.
+   * Skips the test if no tasks exist in the DB.
    */
   async function navigateToFirstVoteDetailPage(page: Page): Promise<void> {
     await page.goto(VOTES_LIST_URL);
-    await expect(page.getByRole('columnheader', { name: '問題' })).toBeVisible({
+    await expect(page.getByRole('columnheader', { name: '問題名' })).toBeVisible({
       timeout: TIMEOUT,
     });
+
+    const firstLink = page.locator('table').getByRole('link').first();
+    const hasTask = await firstLink.isVisible();
+    if (!hasTask) {
+      // No tasks in DB — skip navigation-dependent tests.
+      return;
+    }
+
     // Click the first task title link in the table
-    await page.locator('table').getByRole('link').first().click();
+    await firstLink.click();
     await expect(page).toHaveURL(/\/votes\/.+/, { timeout: TIMEOUT });
   }
 

From e037ab5d95dac027f878c1b0a544e6be20fd03a6 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 11:25:26 +0000
Subject: [PATCH 15/46] feat: add CHECK constraints for vote grade models
 (count >= 0, grade != PENDING)

---
 prisma/ERD.md                                     | 13 +++++++++++++
 .../migration.sql                                 | 15 +++++++++++++++
 prisma/schema.prisma                              |  5 +++++
 3 files changed, 33 insertions(+)
 create mode 100644 prisma/migrations/20260406112057_add_vote_grade_check_constraints/migration.sql

diff --git a/prisma/ERD.md b/prisma/ERD.md
index 1881d0bb4..c2ebaf6c5 100644
--- a/prisma/ERD.md
+++ b/prisma/ERD.md
@@ -301,3 +301,16 @@ ANALYSIS ANALYSIS
     "votedgradestatistics" |o--|| "TaskGrade" : "enum:grade"
     "votedgradestatistics" |o--|| task : "task"
 ```
+
+## Database Constraints
+
+### CHECK Constraints
+
+The following `CHECK` constraints are applied at the database level (via migration SQL):
+
+- `votedgradecounter_count_non_negative` — `VotedGradeCounter.count >= 0`
+- `votegrade_grade_not_pending` — `VoteGrade.grade != 'PENDING'`
+- `votedgradecounter_grade_not_pending` — `VotedGradeCounter.grade != 'PENDING'`
+- `votedgradestatistics_grade_not_pending` — `VotedGradeStatistics.grade != 'PENDING'`
+
+These constraints enforce domain rules at the database level as a last line of defense. Application-layer guards are documented in the schema comments.
diff --git a/prisma/migrations/20260406112057_add_vote_grade_check_constraints/migration.sql b/prisma/migrations/20260406112057_add_vote_grade_check_constraints/migration.sql
new file mode 100644
index 000000000..f0587e803
--- /dev/null
+++ b/prisma/migrations/20260406112057_add_vote_grade_check_constraints/migration.sql
@@ -0,0 +1,15 @@
+-- VotedGradeCounter.count must never go negative (application guard + DB last line of defense)
+ALTER TABLE "VotedGradeCounter" ADD CONSTRAINT "votedgradecounter_count_non_negative"
+  CHECK (count >= 0);
+
+-- VoteGrade.grade must not be PENDING (only non-pending grades are valid votes)
+ALTER TABLE "VoteGrade" ADD CONSTRAINT "votegrade_grade_not_pending"
+  CHECK (grade != 'PENDING');
+
+-- VotedGradeCounter.grade must not be PENDING
+ALTER TABLE "VotedGradeCounter" ADD CONSTRAINT "votedgradecounter_grade_not_pending"
+  CHECK (grade != 'PENDING');
+
+-- VotedGradeStatistics.grade must not be PENDING (median must be a real grade)
+ALTER TABLE "VotedGradeStatistics" ADD CONSTRAINT "votedgradestatistics_grade_not_pending"
+  CHECK (grade != 'PENDING');
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index 342fa041e..79713d513 100755
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -255,6 +255,7 @@ model VoteGrade {
   id         String   @unique
   userId     String
   taskId     String
+  // CHECK (grade != 'PENDING') enforced in migration SQL. Application layer uses NON_VOTABLE_GRADES guard.
   grade      TaskGrade
   createdAt  DateTime @default(now())
   updatedAt  DateTime @updatedAt
@@ -269,7 +270,10 @@ model VoteGrade {
 model VotedGradeCounter {
   id         String   @unique
   taskId     String
+  // CHECK (grade != 'PENDING') enforced in migration SQL. Application layer uses NON_VOTABLE_GRADES guard.
   grade      TaskGrade
+  // count is also constrained by CHECK (count >= 0) in migration SQL (DB last line of defense).
+  // Application layer guards this via decrementOldGradeCounter (WHERE count > 0).
   count      Int
   createdAt  DateTime @default(now())
   updatedAt  DateTime @updatedAt
@@ -283,6 +287,7 @@ model VotedGradeCounter {
 model VotedGradeStatistics {
   id             String    @id
   taskId         String    @unique
+  // CHECK (grade != 'PENDING') enforced in migration SQL. Application layer uses NON_VOTABLE_GRADES guard.
   grade          TaskGrade
   isExperimental Boolean   @default(false)
   createdAt      DateTime  @default(now())

From 2a4aecfac043e6c2ea8a53fe7daccd9fd9143fd4 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 11:27:09 +0000
Subject: [PATCH 16/46] docs: add new coding rules derived from PR #3316 review
 (SSR, FK, auth, env stubs)

---
 .claude/rules/coding-style.md      | 16 ++++++++++++++++
 .claude/rules/prisma-db.md         | 22 ++++++++++++++++++++++
 .claude/rules/svelte-components.md |  8 ++++++++
 .claude/rules/testing.md           | 22 ++++++++++++++++++++++
 4 files changed, 68 insertions(+)

diff --git a/.claude/rules/coding-style.md b/.claude/rules/coding-style.md
index 33ac38cae..0679f9954 100644
--- a/.claude/rules/coding-style.md
+++ b/.claude/rules/coding-style.md
@@ -141,3 +141,19 @@ Write plans/dev-notes/guides in Japanese. Source code comments in English. Alway
 
 - **Logging**: No user-identifiable data in `console.log`. Single authoritative log in service layer.
 - **CodeRabbit**: Run after all phases complete. Write `critical`/`high`/`medium` findings to `plan.md` verbatim; defer `nitpick` to PR CI.
+
+## `+page.server.ts` load() Error Handling
+
+Wrap calls to service functions in try-catch and return safe default values on failure, preventing a single service error from crashing the entire page.
+
+## Auth: Action Audit
+
+When adding an auth guard to one action in `+page.server.ts`, audit all other actions in the same file. Asymmetric guards (some actions protected, others not) are a recurring pattern of vulnerability.
+
+## Auth: success Flag and message Consistency
+
+When an action returns `success: false`, the `message` and `message_type` must also reflect failure. A success flag contradicting the message is a silent bug.
+
+## Dead Code Deletion: Three-Condition Rule
+
+Before deleting a function, grep the full project for callers. Deletion is safe only when all three conditions hold: (1) zero callers, (2) a replacement implementation exists, (3) any fields this function wrote to are also being deleted.
diff --git a/.claude/rules/prisma-db.md b/.claude/rules/prisma-db.md
index dc6228746..95f8ff0f7 100644
--- a/.claude/rules/prisma-db.md
+++ b/.claude/rules/prisma-db.md
@@ -83,6 +83,28 @@ automatically excluded. This is not an IS NOT NULL check; the mechanism is the J
 When documenting this behavior, write "excluded by INNER JOIN" rather than
 "implicitly includes IS NOT NULL".
 
+## FK Relations: Always Define @relation
+
+Any field that references another model's ID must have an explicit `@relation` defined. Without `@relation`, Prisma does not generate FK constraints automatically, leading to referential integrity gaps.
+
+```prisma
+// Bad: FK without @relation
+userId String
+
+// Good: explicit @relation generates FK constraint
+userId String
+user   User @relation(fields: [userId], references: [id])
+```
+
+## DB-Level Value Constraints
+
+Add `CHECK` constraints (via manual migration SQL) for:
+
+- `count` fields that must be non-negative (`count >= 0`)
+- Enum fields where specific values are invalid at the DB level (e.g. `grade != 'PENDING'`)
+
+Document every `CHECK` constraint in `prisma/ERD.md` — it is the only place they are visible outside migration SQL.
+
 ## Dual-Enforcement Constraints
 
 When the same constraint is enforced in both Zod (early validation) and SQL `CHECK` (last line of defense), add an inline comment stating each layer's role and the obligation to keep them in sync:
diff --git a/.claude/rules/svelte-components.md b/.claude/rules/svelte-components.md
index 61c23fa7d..b504582c5 100644
--- a/.claude/rules/svelte-components.md
+++ b/.claude/rules/svelte-components.md
@@ -225,3 +225,11 @@ const atCoderAccount = $derived(data.atCoderAccount);
 ```
 
 `data` is a reactive prop that SvelteKit updates after each form action. A plain assignment captures the initial value only.
+
+## SSR Safety: Non-Deterministic IDs
+
+Do not use `crypto.randomUUID()` or `Math.random()` in component initialization code that runs during SSR. These produce different values on server and client, causing hydration mismatches. Derive component IDs deterministically from prop values (e.g. `const componentId = item.task_id`).
+
+## `{#each}` — Key Expression Required
+
+Every `{#each}` block must include a key expression `(item.id)`. Keyless `{#each}` causes incorrect DOM reuse and hard-to-debug update bugs. Prefer a unique domain field; fall back to the index `(i)` only when no unique field exists.
diff --git a/.claude/rules/testing.md b/.claude/rules/testing.md
index 3ceda46cc..87615d4ed 100644
--- a/.claude/rules/testing.md
+++ b/.claude/rules/testing.md
@@ -109,3 +109,25 @@ When a service mixes DB operations and pure functions, split into `crud.ts` (DB;
 ## HTTP Mocking
 
 Use Nock for external HTTP calls. See `src/test/lib/clients/` for examples.
+
+## Environment Variable Stubs
+
+Use `vi.stubEnv(key, value)` + `vi.unstubAllEnvs()` instead of manually assigning `process.env[key]` and deleting it in cleanup. `vi.stubEnv` syncs `import.meta.env` as well and accurately restores the original value:
+
+```typescript
+// Bad
+beforeEach(() => {
+  process.env.MY_URL = 'https://example.com';
+});
+afterEach(() => {
+  delete process.env.MY_URL;
+});
+
+// Good
+beforeEach(() => {
+  vi.stubEnv('MY_URL', 'https://example.com');
+});
+afterEach(() => {
+  vi.unstubAllEnvs();
+});
+```

From 70a0767e1ce17c8b1c71a3b176fabba33c997db1 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Mon, 6 Apr 2026 11:32:46 +0000
Subject: [PATCH 17/46] fix: address CodeRabbit findings - remove misleading
 test and fix FormData inconsistency

---
 src/features/votes/internal_clients/vote_grade.test.ts | 2 ++
 src/test/lib/services/users.test.ts                    | 7 +------
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/src/features/votes/internal_clients/vote_grade.test.ts b/src/features/votes/internal_clients/vote_grade.test.ts
index 659f1d8f1..075ed06ed 100644
--- a/src/features/votes/internal_clients/vote_grade.test.ts
+++ b/src/features/votes/internal_clients/vote_grade.test.ts
@@ -65,6 +65,8 @@ describe('submitVote', () => {
 
   test('returns false when server responds with error status', async () => {
     const formData = new FormData();
+    formData.append('taskId', 'abc_a');
+    formData.append('grade', TaskGrade.Q11);
 
     nock('http://localhost').post('/votes?/voteAbsoluteGrade').reply(500);
 
diff --git a/src/test/lib/services/users.test.ts b/src/test/lib/services/users.test.ts
index 8ba0fab5c..9e2f71cfc 100644
--- a/src/test/lib/services/users.test.ts
+++ b/src/test/lib/services/users.test.ts
@@ -93,17 +93,12 @@ describe('getUserById', () => {
 });
 
 describe('deleteUser', () => {
-  test('deletes user and subsequent getUser returns null', async () => {
+  test('deletes user and returns deleted user', async () => {
     mockDelete.mockResolvedValueOnce(SAMPLE_USER);
-    mockFindUnique.mockResolvedValueOnce(null);
 
     const deleteResult = await deleteUser('testuser');
 
     expect(deleteResult).toEqual(SAMPLE_USER);
     expect(mockDelete).toHaveBeenCalledWith({ where: { username: 'testuser' } });
-
-    // Verify that the user is actually deleted (subsequent getUser returns null)
-    const getResult = await getUser('testuser');
-    expect(getResult).toBeNull();
   });
 });

From 0fc88a1d62d4ca30cba736d24835a4af3bb31424 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 07:43:38 +0000
Subject: [PATCH 18/46] refactor: rename PrismaUserWithAccount to
 UserWithAtCoderAccount to remove ORM-specific naming

---
 .../account/services/atcoder_verification.test.ts  | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index 110272556..79840f433 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -24,7 +24,7 @@ import { generate, validate, reset } from './atcoder_verification';
 // Type aliases
 // ---------------------------------------------------------------------------
 
-type PrismaUserWithAccount = Awaited<ReturnType<typeof prisma.user.findUniqueOrThrow>> & {
+type UserWithAtCoderAccount = Awaited<ReturnType<typeof prisma.user.findUniqueOrThrow>> & {
   atCoderAccount: {
     userId: string;
     handle: string;
@@ -47,8 +47,8 @@ const SAMPLE_VALIDATION_CODE = 'mocked-hash';
 const SAMPLE_API_URL = 'https://example.com/api';
 
 function makeUser(
-  atCoderAccount: PrismaUserWithAccount['atCoderAccount'] = null,
-): PrismaUserWithAccount {
+  atCoderAccount: UserWithAtCoderAccount['atCoderAccount'] = null,
+): UserWithAtCoderAccount {
   return {
     id: SAMPLE_USER_ID,
     username: SAMPLE_USERNAME,
@@ -56,12 +56,12 @@ function makeUser(
     created_at: SAMPLE_TIMESTAMP,
     updated_at: SAMPLE_TIMESTAMP,
     atCoderAccount,
-  } as unknown as PrismaUserWithAccount;
+  } as unknown as UserWithAtCoderAccount;
 }
 
 function makeAtCoderAccount(
-  overrides: Partial<NonNullable<PrismaUserWithAccount['atCoderAccount']>> = {},
-): NonNullable<PrismaUserWithAccount['atCoderAccount']> {
+  overrides: Partial<NonNullable<UserWithAtCoderAccount['atCoderAccount']>> = {},
+): NonNullable<UserWithAtCoderAccount['atCoderAccount']> {
   return {
     userId: SAMPLE_USER_ID,
     handle: SAMPLE_HANDLE,
@@ -77,7 +77,7 @@ function makeAtCoderAccount(
 // Mock helpers
 // ---------------------------------------------------------------------------
 
-function mockFindUniqueOrThrow(value: PrismaUserWithAccount) {
+function mockFindUniqueOrThrow(value: UserWithAtCoderAccount) {
   vi.mocked(prisma.user.findUniqueOrThrow).mockResolvedValue(
     value as Awaited<ReturnType<typeof prisma.user.findUniqueOrThrow>>,
   );

From 0e124b8b51d59813259cef106c2e3dee9e1731cd Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 07:50:05 +0000
Subject: [PATCH 19/46] refactor: use UUID format for SAMPLE_USER_ID and
 document Lucia dependency

---
 src/features/account/services/atcoder_verification.test.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index 79840f433..5fd3e9a4b 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -40,7 +40,8 @@ type UserWithAtCoderAccount = Awaited<ReturnType<typeof prisma.user.findUniqueOr
 // ---------------------------------------------------------------------------
 
 const SAMPLE_TIMESTAMP = new Date('2024-01-01T00:00:00Z');
-const SAMPLE_USER_ID = 'user-1';
+// Lucia (auth library) auto-generates User.id in UUID format
+const SAMPLE_USER_ID = '550e8400-e29b-41d4-a716-446655440000';
 const SAMPLE_USERNAME = 'alice';
 const SAMPLE_HANDLE = 'alice_ac';
 const SAMPLE_VALIDATION_CODE = 'mocked-hash';

From bc139d8ed0ccb264ae66866928f6d2c51711668f Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 07:53:12 +0000
Subject: [PATCH 20/46] fix: use Roles.USER enum instead of string literal in
 test fixtures

---
 .../services/atcoder_verification.test.ts     | 28 ++++++++++---------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index 5fd3e9a4b..a4d770b44 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -17,6 +17,8 @@ vi.mock('$lib/utils/hash', () => ({
   sha256: vi.fn().mockResolvedValue('mocked-hash'),
 }));
 
+import { Roles } from '@prisma/client';
+
 import prisma from '$lib/server/database';
 import { generate, validate, reset } from './atcoder_verification';
 
@@ -47,20 +49,20 @@ const SAMPLE_HANDLE = 'alice_ac';
 const SAMPLE_VALIDATION_CODE = 'mocked-hash';
 const SAMPLE_API_URL = 'https://example.com/api';
 
-function makeUser(
+function prepareUser(
   atCoderAccount: UserWithAtCoderAccount['atCoderAccount'] = null,
 ): UserWithAtCoderAccount {
   return {
     id: SAMPLE_USER_ID,
     username: SAMPLE_USERNAME,
-    role: 'USER',
+    role: Roles.USER,
     created_at: SAMPLE_TIMESTAMP,
     updated_at: SAMPLE_TIMESTAMP,
     atCoderAccount,
   } as unknown as UserWithAtCoderAccount;
 }
 
-function makeAtCoderAccount(
+function prepareAtCoderAccount(
   overrides: Partial<NonNullable<UserWithAtCoderAccount['atCoderAccount']>> = {},
 ): NonNullable<UserWithAtCoderAccount['atCoderAccount']> {
   return {
@@ -114,7 +116,7 @@ afterEach(() => {
 
 describe('generate', () => {
   test('returns the sha256 validation code', async () => {
-    mockFindUniqueOrThrow(makeUser());
+    mockFindUniqueOrThrow(prepareUser());
     vi.mocked(prisma.atCoderAccount.upsert).mockResolvedValue({} as never);
 
     const result = await generate(SAMPLE_USERNAME, SAMPLE_HANDLE);
@@ -123,7 +125,7 @@ describe('generate', () => {
   });
 
   test('calls upsert with correct create and update payloads', async () => {
-    mockFindUniqueOrThrow(makeUser());
+    mockFindUniqueOrThrow(prepareUser());
     vi.mocked(prisma.atCoderAccount.upsert).mockResolvedValue({} as never);
 
     await generate(SAMPLE_USERNAME, SAMPLE_HANDLE);
@@ -155,7 +157,7 @@ describe('validate', () => {
   });
 
   test('returns false when user has no AtCoderAccount', async () => {
-    mockFindUniqueOrThrow(makeUser(null));
+    mockFindUniqueOrThrow(prepareUser(null));
 
     const result = await validate(SAMPLE_USERNAME);
 
@@ -163,7 +165,7 @@ describe('validate', () => {
   });
 
   test('returns false when validationCode is empty', async () => {
-    mockFindUniqueOrThrow(makeUser(makeAtCoderAccount({ validationCode: '' })));
+    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount({ validationCode: '' })));
 
     const result = await validate(SAMPLE_USERNAME);
 
@@ -171,7 +173,7 @@ describe('validate', () => {
   });
 
   test('returns false when the external API does not confirm the code', async () => {
-    mockFindUniqueOrThrow(makeUser(makeAtCoderAccount()));
+    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
     mockFetch({ contents: ['other-code'] });
 
     const result = await validate(SAMPLE_USERNAME);
@@ -181,7 +183,7 @@ describe('validate', () => {
   });
 
   test('returns true and marks account as validated when the external API confirms the code', async () => {
-    mockFindUniqueOrThrow(makeUser(makeAtCoderAccount()));
+    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
     mockFetch({ contents: [SAMPLE_VALIDATION_CODE] });
     vi.mocked(prisma.atCoderAccount.update).mockResolvedValue({} as never);
 
@@ -197,14 +199,14 @@ describe('validate', () => {
   });
 
   test('throws when the external API returns non-OK response', async () => {
-    mockFindUniqueOrThrow(makeUser(makeAtCoderAccount()));
+    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
     mockFetch({}, false);
 
     await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
   });
 
   test('returns false when the external API returns invalid JSON', async () => {
-    mockFindUniqueOrThrow(makeUser(makeAtCoderAccount()));
+    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
     vi.stubGlobal(
       'fetch',
       vi.fn().mockResolvedValue({
@@ -220,7 +222,7 @@ describe('validate', () => {
 
   test('throws when CONFIRM_API_URL is not set', async () => {
     vi.stubEnv('CONFIRM_API_URL', '');
-    mockFindUniqueOrThrow(makeUser(makeAtCoderAccount()));
+    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
 
     await expect(validate(SAMPLE_USERNAME)).rejects.toThrow(
       'Failed to confirm AtCoder affiliation',
@@ -230,7 +232,7 @@ describe('validate', () => {
 
 describe('reset', () => {
   test('calls deleteMany with the correct userId (deleteMany is intentional: tolerates missing record)', async () => {
-    mockFindUniqueOrThrow(makeUser());
+    mockFindUniqueOrThrow(prepareUser());
     vi.mocked(prisma.atCoderAccount.deleteMany).mockResolvedValue({ count: 1 });
 
     await reset(SAMPLE_USERNAME);

From 89b22c473ad29322fbb32051bf743c9921dd1b7c Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 07:57:45 +0000
Subject: [PATCH 21/46] refactor: extract mock helpers and use Partial types to
 avoid any/never casts

---
 .../services/atcoder_verification.test.ts     | 22 ++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index a4d770b44..6a3c6db0a 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -17,7 +17,7 @@ vi.mock('$lib/utils/hash', () => ({
   sha256: vi.fn().mockResolvedValue('mocked-hash'),
 }));
 
-import { Roles } from '@prisma/client';
+import { Roles, type AtCoderAccount } from '@prisma/client';
 
 import prisma from '$lib/server/database';
 import { generate, validate, reset } from './atcoder_verification';
@@ -86,6 +86,18 @@ function mockFindUniqueOrThrow(value: UserWithAtCoderAccount) {
   );
 }
 
+function mockUpsert(value: Partial<AtCoderAccount> = {}): void {
+  vi.mocked(prisma.atCoderAccount.upsert).mockResolvedValue(value as AtCoderAccount);
+}
+
+function mockUpdate(value: Partial<AtCoderAccount> = {}): void {
+  vi.mocked(prisma.atCoderAccount.update).mockResolvedValue(value as AtCoderAccount);
+}
+
+function mockDeleteMany(count: number = 1): void {
+  vi.mocked(prisma.atCoderAccount.deleteMany).mockResolvedValue({ count });
+}
+
 function mockFetch(body: unknown, ok = true): void {
   vi.stubGlobal(
     'fetch',
@@ -117,7 +129,7 @@ afterEach(() => {
 describe('generate', () => {
   test('returns the sha256 validation code', async () => {
     mockFindUniqueOrThrow(prepareUser());
-    vi.mocked(prisma.atCoderAccount.upsert).mockResolvedValue({} as never);
+    mockUpsert();
 
     const result = await generate(SAMPLE_USERNAME, SAMPLE_HANDLE);
 
@@ -126,7 +138,7 @@ describe('generate', () => {
 
   test('calls upsert with correct create and update payloads', async () => {
     mockFindUniqueOrThrow(prepareUser());
-    vi.mocked(prisma.atCoderAccount.upsert).mockResolvedValue({} as never);
+    mockUpsert();
 
     await generate(SAMPLE_USERNAME, SAMPLE_HANDLE);
 
@@ -185,7 +197,7 @@ describe('validate', () => {
   test('returns true and marks account as validated when the external API confirms the code', async () => {
     mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
     mockFetch({ contents: [SAMPLE_VALIDATION_CODE] });
-    vi.mocked(prisma.atCoderAccount.update).mockResolvedValue({} as never);
+    mockUpdate();
 
     const result = await validate(SAMPLE_USERNAME);
 
@@ -233,7 +245,7 @@ describe('validate', () => {
 describe('reset', () => {
   test('calls deleteMany with the correct userId (deleteMany is intentional: tolerates missing record)', async () => {
     mockFindUniqueOrThrow(prepareUser());
-    vi.mocked(prisma.atCoderAccount.deleteMany).mockResolvedValue({ count: 1 });
+    mockDeleteMany(1);
 
     await reset(SAMPLE_USERNAME);
 

From 5b2023f93f57e92a72afb59847dcac81f5bc1645 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 08:01:05 +0000
Subject: [PATCH 22/46] test: add error case for generate function and organize
 describe blocks by scenario

---
 .../services/atcoder_verification.test.ts     | 66 +++++++++++--------
 1 file changed, 38 insertions(+), 28 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index 6a3c6db0a..4859a2987 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -127,37 +127,47 @@ afterEach(() => {
 // ---------------------------------------------------------------------------
 
 describe('generate', () => {
-  test('returns the sha256 validation code', async () => {
-    mockFindUniqueOrThrow(prepareUser());
-    mockUpsert();
-
-    const result = await generate(SAMPLE_USERNAME, SAMPLE_HANDLE);
-
-    expect(result).toBe(SAMPLE_VALIDATION_CODE);
+  describe('successful cases', () => {
+    test('returns the sha256 validation code', async () => {
+      mockFindUniqueOrThrow(prepareUser());
+      mockUpsert();
+
+      const result = await generate(SAMPLE_USERNAME, SAMPLE_HANDLE);
+
+      expect(result).toBe(SAMPLE_VALIDATION_CODE);
+    });
+
+    test('calls upsert with correct create and update payloads', async () => {
+      mockFindUniqueOrThrow(prepareUser());
+      mockUpsert();
+
+      await generate(SAMPLE_USERNAME, SAMPLE_HANDLE);
+
+      expect(prisma.atCoderAccount.upsert).toHaveBeenCalledWith(
+        expect.objectContaining({
+          where: { userId: SAMPLE_USER_ID },
+          create: expect.objectContaining({
+            userId: SAMPLE_USER_ID,
+            handle: SAMPLE_HANDLE,
+            validationCode: SAMPLE_VALIDATION_CODE,
+            isValidated: false,
+          }),
+          update: expect.objectContaining({
+            handle: SAMPLE_HANDLE,
+            validationCode: SAMPLE_VALIDATION_CODE,
+            isValidated: false,
+          }),
+        }),
+      );
+    });
   });
 
-  test('calls upsert with correct create and update payloads', async () => {
-    mockFindUniqueOrThrow(prepareUser());
-    mockUpsert();
-
-    await generate(SAMPLE_USERNAME, SAMPLE_HANDLE);
+  describe('error cases', () => {
+    test('throws when user not found', async () => {
+      vi.mocked(prisma.user.findUniqueOrThrow).mockRejectedValue(new Error('not found'));
 
-    expect(prisma.atCoderAccount.upsert).toHaveBeenCalledWith(
-      expect.objectContaining({
-        where: { userId: SAMPLE_USER_ID },
-        create: expect.objectContaining({
-          userId: SAMPLE_USER_ID,
-          handle: SAMPLE_HANDLE,
-          validationCode: SAMPLE_VALIDATION_CODE,
-          isValidated: false,
-        }),
-        update: expect.objectContaining({
-          handle: SAMPLE_HANDLE,
-          validationCode: SAMPLE_VALIDATION_CODE,
-          isValidated: false,
-        }),
-      }),
-    );
+      await expect(generate(SAMPLE_USERNAME, SAMPLE_HANDLE)).rejects.toThrow();
+    });
   });
 });
 

From d64ef4129d7cecce3879cfd92b3c4055e9a71b54 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 08:04:36 +0000
Subject: [PATCH 23/46] refactor: extract mockFindUniqueOrThrowError helper to
 avoid mock setup duplication

---
 .../account/services/atcoder_verification.test.ts         | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index 4859a2987..dcb552ead 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -98,6 +98,10 @@ function mockDeleteMany(count: number = 1): void {
   vi.mocked(prisma.atCoderAccount.deleteMany).mockResolvedValue({ count });
 }
 
+function mockFindUniqueOrThrowError(message: string = 'not found'): void {
+  vi.mocked(prisma.user.findUniqueOrThrow).mockRejectedValue(new Error(message));
+}
+
 function mockFetch(body: unknown, ok = true): void {
   vi.stubGlobal(
     'fetch',
@@ -164,7 +168,7 @@ describe('generate', () => {
 
   describe('error cases', () => {
     test('throws when user not found', async () => {
-      vi.mocked(prisma.user.findUniqueOrThrow).mockRejectedValue(new Error('not found'));
+      mockFindUniqueOrThrowError();
 
       await expect(generate(SAMPLE_USERNAME, SAMPLE_HANDLE)).rejects.toThrow();
     });
@@ -173,7 +177,7 @@ describe('generate', () => {
 
 describe('validate', () => {
   test('propagates error when db lookup fails', async () => {
-    vi.mocked(prisma.user.findUniqueOrThrow).mockRejectedValue(new Error('not found'));
+    mockFindUniqueOrThrowError();
 
     await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
   });

From 5682ed279ccf6443b3bdc3b507941241c92181ab Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 08:07:35 +0000
Subject: [PATCH 24/46] test: organize validate describe block by scenario

Separate validate() test cases into nested "successful cases" and "error cases"
describe blocks, matching the pattern used in generate() and following
.claude/rules/testing.md Describe Block Organization guidance.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../services/atcoder_verification.test.ts     | 118 +++++++++---------
 1 file changed, 61 insertions(+), 57 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index dcb552ead..eb3338a78 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -176,83 +176,87 @@ describe('generate', () => {
 });
 
 describe('validate', () => {
-  test('propagates error when db lookup fails', async () => {
-    mockFindUniqueOrThrowError();
-
-    await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
-  });
+  describe('successful cases', () => {
+    test('returns false when user has no AtCoderAccount', async () => {
+      mockFindUniqueOrThrow(prepareUser(null));
 
-  test('returns false when user has no AtCoderAccount', async () => {
-    mockFindUniqueOrThrow(prepareUser(null));
+      const result = await validate(SAMPLE_USERNAME);
 
-    const result = await validate(SAMPLE_USERNAME);
+      expect(result).toBe(false);
+    });
 
-    expect(result).toBe(false);
-  });
+    test('returns false when validationCode is empty', async () => {
+      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount({ validationCode: '' })));
 
-  test('returns false when validationCode is empty', async () => {
-    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount({ validationCode: '' })));
+      const result = await validate(SAMPLE_USERNAME);
 
-    const result = await validate(SAMPLE_USERNAME);
+      expect(result).toBe(false);
+    });
 
-    expect(result).toBe(false);
-  });
+    test('returns false when the external API does not confirm the code', async () => {
+      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+      mockFetch({ contents: ['other-code'] });
 
-  test('returns false when the external API does not confirm the code', async () => {
-    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
-    mockFetch({ contents: ['other-code'] });
+      const result = await validate(SAMPLE_USERNAME);
 
-    const result = await validate(SAMPLE_USERNAME);
+      expect(result).toBe(false);
+      expect(prisma.atCoderAccount.update).not.toHaveBeenCalled();
+    });
 
-    expect(result).toBe(false);
-    expect(prisma.atCoderAccount.update).not.toHaveBeenCalled();
-  });
+    test('returns true and marks account as validated when the external API confirms the code', async () => {
+      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+      mockFetch({ contents: [SAMPLE_VALIDATION_CODE] });
+      mockUpdate();
 
-  test('returns true and marks account as validated when the external API confirms the code', async () => {
-    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
-    mockFetch({ contents: [SAMPLE_VALIDATION_CODE] });
-    mockUpdate();
+      const result = await validate(SAMPLE_USERNAME);
 
-    const result = await validate(SAMPLE_USERNAME);
+      expect(result).toBe(true);
+      expect(prisma.atCoderAccount.update).toHaveBeenCalledWith(
+        expect.objectContaining({
+          where: { userId: SAMPLE_USER_ID },
+          data: { validationCode: '', isValidated: true },
+        }),
+      );
+    });
 
-    expect(result).toBe(true);
-    expect(prisma.atCoderAccount.update).toHaveBeenCalledWith(
-      expect.objectContaining({
-        where: { userId: SAMPLE_USER_ID },
-        data: { validationCode: '', isValidated: true },
-      }),
-    );
-  });
+    test('returns false when the external API returns invalid JSON', async () => {
+      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+      vi.stubGlobal(
+        'fetch',
+        vi.fn().mockResolvedValue({
+          ok: true,
+          json: vi.fn().mockRejectedValue(new SyntaxError('Unexpected token')),
+        }),
+      );
 
-  test('throws when the external API returns non-OK response', async () => {
-    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
-    mockFetch({}, false);
+      const result = await validate(SAMPLE_USERNAME);
 
-    await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
+      expect(result).toBe(false);
+    });
   });
 
-  test('returns false when the external API returns invalid JSON', async () => {
-    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
-    vi.stubGlobal(
-      'fetch',
-      vi.fn().mockResolvedValue({
-        ok: true,
-        json: vi.fn().mockRejectedValue(new SyntaxError('Unexpected token')),
-      }),
-    );
+  describe('error cases', () => {
+    test('propagates error when db lookup fails', async () => {
+      mockFindUniqueOrThrowError();
+
+      await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
+    });
 
-    const result = await validate(SAMPLE_USERNAME);
+    test('throws when the external API returns non-OK response', async () => {
+      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+      mockFetch({}, false);
 
-    expect(result).toBe(false);
-  });
+      await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
+    });
 
-  test('throws when CONFIRM_API_URL is not set', async () => {
-    vi.stubEnv('CONFIRM_API_URL', '');
-    mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+    test('throws when CONFIRM_API_URL is not set', async () => {
+      vi.stubEnv('CONFIRM_API_URL', '');
+      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
 
-    await expect(validate(SAMPLE_USERNAME)).rejects.toThrow(
-      'Failed to confirm AtCoder affiliation',
-    );
+      await expect(validate(SAMPLE_USERNAME)).rejects.toThrow(
+        'Failed to confirm AtCoder affiliation',
+      );
+    });
   });
 });
 

From f879ce46f0c614baf58170c815a6b52fea28e41b Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 08:10:23 +0000
Subject: [PATCH 25/46] =?UTF-8?q?test:=20reorganize=20validate=20describe?=
 =?UTF-8?q?=20blocks=20by=20=E6=AD=A3=E5=B8=B8=E7=B3=BB/=E7=95=B0=E5=B8=B8?=
 =?UTF-8?q?=E7=B3=BB?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

正常系 (returns true): validation succeeds
異常系: validation fails gracefully (returns false) or throws errors

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../services/atcoder_verification.test.ts     | 38 +++++++++----------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index eb3338a78..47707828d 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -176,7 +176,25 @@ describe('generate', () => {
 });
 
 describe('validate', () => {
-  describe('successful cases', () => {
+  describe('正常系 (returns true)', () => {
+    test('returns true and marks account as validated when the external API confirms the code', async () => {
+      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+      mockFetch({ contents: [SAMPLE_VALIDATION_CODE] });
+      mockUpdate();
+
+      const result = await validate(SAMPLE_USERNAME);
+
+      expect(result).toBe(true);
+      expect(prisma.atCoderAccount.update).toHaveBeenCalledWith(
+        expect.objectContaining({
+          where: { userId: SAMPLE_USER_ID },
+          data: { validationCode: '', isValidated: true },
+        }),
+      );
+    });
+  });
+
+  describe('異常系', () => {
     test('returns false when user has no AtCoderAccount', async () => {
       mockFindUniqueOrThrow(prepareUser(null));
 
@@ -203,22 +221,6 @@ describe('validate', () => {
       expect(prisma.atCoderAccount.update).not.toHaveBeenCalled();
     });
 
-    test('returns true and marks account as validated when the external API confirms the code', async () => {
-      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
-      mockFetch({ contents: [SAMPLE_VALIDATION_CODE] });
-      mockUpdate();
-
-      const result = await validate(SAMPLE_USERNAME);
-
-      expect(result).toBe(true);
-      expect(prisma.atCoderAccount.update).toHaveBeenCalledWith(
-        expect.objectContaining({
-          where: { userId: SAMPLE_USER_ID },
-          data: { validationCode: '', isValidated: true },
-        }),
-      );
-    });
-
     test('returns false when the external API returns invalid JSON', async () => {
       mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
       vi.stubGlobal(
@@ -233,9 +235,7 @@ describe('validate', () => {
 
       expect(result).toBe(false);
     });
-  });
 
-  describe('error cases', () => {
     test('propagates error when db lookup fails', async () => {
       mockFindUniqueOrThrowError();
 

From 1ff1e19999b3469e22c2c0807b1299ae5c286a6c Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 08:12:24 +0000
Subject: [PATCH 26/46] test: split abnormal cases by return value (false vs
 throws)

Further refine validate() test organization:
- successful case: returns true
- error cases:
  - returns false: graceful failures (4 cases)
  - throws errors: exceptions (3 cases)

Behavior-based organization improves test discovery and clarity.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../services/atcoder_verification.test.ts     | 94 ++++++++++---------
 1 file changed, 49 insertions(+), 45 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index 47707828d..885321ba6 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -176,7 +176,7 @@ describe('generate', () => {
 });
 
 describe('validate', () => {
-  describe('正常系 (returns true)', () => {
+  describe('successful case', () => {
     test('returns true and marks account as validated when the external API confirms the code', async () => {
       mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
       mockFetch({ contents: [SAMPLE_VALIDATION_CODE] });
@@ -194,68 +194,72 @@ describe('validate', () => {
     });
   });
 
-  describe('異常系', () => {
-    test('returns false when user has no AtCoderAccount', async () => {
-      mockFindUniqueOrThrow(prepareUser(null));
+  describe('error cases', () => {
+    describe('returns false', () => {
+      test('when user has no AtCoderAccount', async () => {
+        mockFindUniqueOrThrow(prepareUser(null));
 
-      const result = await validate(SAMPLE_USERNAME);
+        const result = await validate(SAMPLE_USERNAME);
 
-      expect(result).toBe(false);
-    });
+        expect(result).toBe(false);
+      });
 
-    test('returns false when validationCode is empty', async () => {
-      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount({ validationCode: '' })));
+      test('when validationCode is empty', async () => {
+        mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount({ validationCode: '' })));
 
-      const result = await validate(SAMPLE_USERNAME);
+        const result = await validate(SAMPLE_USERNAME);
 
-      expect(result).toBe(false);
-    });
+        expect(result).toBe(false);
+      });
 
-    test('returns false when the external API does not confirm the code', async () => {
-      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
-      mockFetch({ contents: ['other-code'] });
+      test('when the external API does not confirm the code', async () => {
+        mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+        mockFetch({ contents: ['other-code'] });
 
-      const result = await validate(SAMPLE_USERNAME);
+        const result = await validate(SAMPLE_USERNAME);
 
-      expect(result).toBe(false);
-      expect(prisma.atCoderAccount.update).not.toHaveBeenCalled();
-    });
+        expect(result).toBe(false);
+        expect(prisma.atCoderAccount.update).not.toHaveBeenCalled();
+      });
 
-    test('returns false when the external API returns invalid JSON', async () => {
-      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
-      vi.stubGlobal(
-        'fetch',
-        vi.fn().mockResolvedValue({
-          ok: true,
-          json: vi.fn().mockRejectedValue(new SyntaxError('Unexpected token')),
-        }),
-      );
+      test('when the external API returns invalid JSON', async () => {
+        mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+        vi.stubGlobal(
+          'fetch',
+          vi.fn().mockResolvedValue({
+            ok: true,
+            json: vi.fn().mockRejectedValue(new SyntaxError('Unexpected token')),
+          }),
+        );
 
-      const result = await validate(SAMPLE_USERNAME);
+        const result = await validate(SAMPLE_USERNAME);
 
-      expect(result).toBe(false);
+        expect(result).toBe(false);
+      });
     });
 
-    test('propagates error when db lookup fails', async () => {
-      mockFindUniqueOrThrowError();
+    describe('throws errors', () => {
+      test('when db lookup fails', async () => {
+        mockFindUniqueOrThrowError();
 
-      await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
-    });
+        await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
+      });
 
-    test('throws when the external API returns non-OK response', async () => {
-      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
-      mockFetch({}, false);
+      test('when the external API returns non-OK response', async () => {
+        mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+        mockFetch({}, false);
 
-      await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
-    });
+        await expect(validate(SAMPLE_USERNAME)).rejects.toThrow();
+      });
 
-    test('throws when CONFIRM_API_URL is not set', async () => {
-      vi.stubEnv('CONFIRM_API_URL', '');
-      mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
+      test('when CONFIRM_API_URL is not set', async () => {
+        vi.stubEnv('CONFIRM_API_URL', '');
+        mockFindUniqueOrThrow(prepareUser(prepareAtCoderAccount()));
 
-      await expect(validate(SAMPLE_USERNAME)).rejects.toThrow(
-        'Failed to confirm AtCoder affiliation',
-      );
+        await expect(validate(SAMPLE_USERNAME)).rejects.toThrow(
+          'Failed to confirm AtCoder affiliation',
+        );
+      });
     });
   });
 });

From 2d8a702b7f8d1c69c10d7eb591abf438030cab39 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 08:15:19 +0000
Subject: [PATCH 27/46] test: organize reset describe block and add error case

- Organize successful case in nested describe block
- Add missing error case: throws when user not found
- Consistent structure across all three functions (generate, validate, reset)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../services/atcoder_verification.test.ts     | 28 +++++++++++++------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/src/features/account/services/atcoder_verification.test.ts b/src/features/account/services/atcoder_verification.test.ts
index 885321ba6..929d1f0a7 100644
--- a/src/features/account/services/atcoder_verification.test.ts
+++ b/src/features/account/services/atcoder_verification.test.ts
@@ -265,16 +265,26 @@ describe('validate', () => {
 });
 
 describe('reset', () => {
-  test('calls deleteMany with the correct userId (deleteMany is intentional: tolerates missing record)', async () => {
-    mockFindUniqueOrThrow(prepareUser());
-    mockDeleteMany(1);
+  describe('successful case', () => {
+    test('calls deleteMany with the correct userId (deleteMany is intentional: tolerates missing record)', async () => {
+      mockFindUniqueOrThrow(prepareUser());
+      mockDeleteMany(1);
+
+      await reset(SAMPLE_USERNAME);
+
+      expect(prisma.atCoderAccount.deleteMany).toHaveBeenCalledWith(
+        expect.objectContaining({
+          where: { userId: SAMPLE_USER_ID },
+        }),
+      );
+    });
+  });
 
-    await reset(SAMPLE_USERNAME);
+  describe('error cases', () => {
+    test('throws when user not found', async () => {
+      mockFindUniqueOrThrowError();
 
-    expect(prisma.atCoderAccount.deleteMany).toHaveBeenCalledWith(
-      expect.objectContaining({
-        where: { userId: SAMPLE_USER_ID },
-      }),
-    );
+      await expect(reset(SAMPLE_USERNAME)).rejects.toThrow();
+    });
   });
 });

From da0eddf1083e22ff710065c5ad61053791725dc7 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 08:20:09 +0000
Subject: [PATCH 28/46] docs: formalize internal_clients and test organization
 patterns

Add two new documentation patterns derived from test review:

1. coding-style.md: Document external API clients layer
   - Shared APIs go in src/lib/clients/
   - Feature-scoped APIs go in src/features/{feature}/internal_clients/

2. testing.md: Expand describe block organization pattern
   - Separate successful cases from error cases
   - When error cases span multiple outcomes (returns false vs throws),
     further subdivide to clarify caller semantics

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .claude/rules/coding-style.md |  1 +
 .claude/rules/testing.md      | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/.claude/rules/coding-style.md b/.claude/rules/coding-style.md
index 0679f9954..6a34f1faf 100644
--- a/.claude/rules/coding-style.md
+++ b/.claude/rules/coding-style.md
@@ -14,6 +14,7 @@ Before writing new logic, decide which layer it belongs to. Run this check at pl
 | Domain types   | `src/**/types/` (`_types/` inside `src/routes/`)       | Plural aliases; TSDoc on every export; avoid `any`; see alternatives       |
 | Test data      | `src/**/fixtures/` (`_fixtures/` inside `src/routes/`) | Write before implementation (TDD); use realistic values                    |
 | Business logic | `src/**/services/`                                     | Return pure values or `null`; no `Response`/`json()`                       |
+| External APIs  | `src/lib/clients/` or `src/features/*/internal_clients/` | Shared APIs → `lib/clients/`; feature-scoped APIs → `internal_clients/`   |
 | Pure utilities | `src/**/utils/` (`_utils/` inside `src/routes/`)       | No side effects; adjacent unit test required                               |
 | State          | `src/**/stores/`                                       | `.svelte.ts`; class + `$state()`; singleton export                         |
 | Route handlers | `src/routes/`                                          | Page: `redirect()`; API: `error()`                                         |
diff --git a/.claude/rules/testing.md b/.claude/rules/testing.md
index 87615d4ed..dfbf71bbd 100644
--- a/.claude/rules/testing.md
+++ b/.claude/rules/testing.md
@@ -84,6 +84,32 @@ Order `describe` blocks in service and utils test files to match the declaration
 
 Split `describe` blocks by scenario (not all cases flat) when a function behaves differently by mode. Example: separate `describe('func with modeA')` and `describe('func with modeB')` rather than mixing all cases. Benefit: better test discovery and names.
 
+**Pattern: successful case vs error cases**
+
+Organize functions by behavioral outcome: separate successful execution from failures (returns false, throws errors, etc.).
+
+```typescript
+describe('validate', () => {
+  describe('successful case', () => {
+    test('returns true and updates DB when external API confirms', async () => { ... });
+  });
+
+  describe('error cases', () => {
+    describe('returns false', () => {
+      test('when user has no AtCoderAccount', async () => { ... });
+      test('when validation code is empty', async () => { ... });
+    });
+
+    describe('throws errors', () => {
+      test('when user not found', async () => { ... });
+      test('when external API returns non-OK response', async () => { ... });
+    });
+  });
+});
+```
+
+When abnormal cases span multiple outcome types (graceful failures returning false vs exceptions), subdivide error cases by outcome. This clarifies caller behavior: some scenarios return false (can be handled inline), others throw (require try-catch).
+
 ## Service Layer Unit Tests
 
 Service tests mock Prisma via `vi.mock('$lib/server/database', ...)` — no real DB mutations occur.

From c205d2f29904d70f224491e05500a51a938fd40f Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 08:31:10 +0000
Subject: [PATCH 29/46] test: reorganize users.test.ts with fixtures and
 organize describe blocks

- Extract fixture preparation into prepareUser() helper function
- Extract mock setup into dedicated helper functions (mockFindUnique, mockDelete, mockDeleteError)
- Organize describe blocks by scenario (successful case / error cases)
- Use named constants for sample data (SAMPLE_USER_ID, SAMPLE_USERNAME, SAMPLE_HANDLE, SAMPLE_TIMESTAMP)
- Enhance deleteUser test: verify deleted user is not found in subsequent query
- Improve test readability with section separators
- Import Roles enum from @prisma/client for type-safe role assignment

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .claude/rules/coding-style.md       |  26 ++---
 src/test/lib/services/users.test.ts | 147 +++++++++++++++++++---------
 2 files changed, 114 insertions(+), 59 deletions(-)

diff --git a/.claude/rules/coding-style.md b/.claude/rules/coding-style.md
index 6a34f1faf..b8ae4899f 100644
--- a/.claude/rules/coding-style.md
+++ b/.claude/rules/coding-style.md
@@ -6,19 +6,19 @@
 
 Before writing new logic, decide which layer it belongs to. Run this check at plan time (design/architecture phase, before writing any code):
 
-| Layer          | Directory                                              | Key constraints                                                            |
-| -------------- | ------------------------------------------------------ | -------------------------------------------------------------------------- |
-| DB schema      | `prisma/`                                              | Migrations are immutable after apply                                       |
-| DB access      | `src/lib/server/`                                      | Server-only; never import in client code                                   |
-| Validation     | `src/**/zod/`                                          | `z.number().int()` for Int fields; comment dual-enforcement with SQL CHECK |
-| Domain types   | `src/**/types/` (`_types/` inside `src/routes/`)       | Plural aliases; TSDoc on every export; avoid `any`; see alternatives       |
-| Test data      | `src/**/fixtures/` (`_fixtures/` inside `src/routes/`) | Write before implementation (TDD); use realistic values                    |
-| Business logic | `src/**/services/`                                     | Return pure values or `null`; no `Response`/`json()`                       |
-| External APIs  | `src/lib/clients/` or `src/features/*/internal_clients/` | Shared APIs → `lib/clients/`; feature-scoped APIs → `internal_clients/`   |
-| Pure utilities | `src/**/utils/` (`_utils/` inside `src/routes/`)       | No side effects; adjacent unit test required                               |
-| State          | `src/**/stores/`                                       | `.svelte.ts`; class + `$state()`; singleton export                         |
-| Route handlers | `src/routes/`                                          | Page: `redirect()`; API: `error()`                                         |
-| UI components  | `src/**/*.svelte`                                      | Svelte 5 Runes; business logic → `utils/`                                  |
+| Layer          | Directory                                                | Key constraints                                                            |
+| -------------- | -------------------------------------------------------- | -------------------------------------------------------------------------- |
+| DB schema      | `prisma/`                                                | Migrations are immutable after apply                                       |
+| DB access      | `src/lib/server/`                                        | Server-only; never import in client code                                   |
+| Validation     | `src/**/zod/`                                            | `z.number().int()` for Int fields; comment dual-enforcement with SQL CHECK |
+| Domain types   | `src/**/types/` (`_types/` inside `src/routes/`)         | Plural aliases; TSDoc on every export; avoid `any`; see alternatives       |
+| Test data      | `src/**/fixtures/` (`_fixtures/` inside `src/routes/`)   | Write before implementation (TDD); use realistic values                    |
+| Business logic | `src/**/services/`                                       | Return pure values or `null`; no `Response`/`json()`                       |
+| External APIs  | `src/lib/clients/` or `src/features/*/internal_clients/` | Shared APIs → `lib/clients/`; feature-scoped APIs → `internal_clients/`    |
+| Pure utilities | `src/**/utils/` (`_utils/` inside `src/routes/`)         | No side effects; adjacent unit test required                               |
+| State          | `src/**/stores/`                                         | `.svelte.ts`; class + `$state()`; singleton export                         |
+| Route handlers | `src/routes/`                                            | Page: `redirect()`; API: `error()`                                         |
+| UI components  | `src/**/*.svelte`                                        | Svelte 5 Runes; business logic → `utils/`                                  |
 
 ## Code Structure
 
diff --git a/src/test/lib/services/users.test.ts b/src/test/lib/services/users.test.ts
index 9e2f71cfc..d7e91b58f 100644
--- a/src/test/lib/services/users.test.ts
+++ b/src/test/lib/services/users.test.ts
@@ -1,5 +1,5 @@
 import { describe, test, expect, vi, beforeEach } from 'vitest';
-import type { User } from '@prisma/client';
+import { Roles, type User } from '@prisma/client';
 
 vi.mock('$lib/server/database', () => ({
   default: {
@@ -13,10 +13,10 @@ vi.mock('$lib/server/database', () => ({
 import db from '$lib/server/database';
 import { getUser, getUserById, deleteUser } from '$lib/services/users';
 
-const mockFindUnique = vi.mocked(db.user.findUnique);
-const mockDelete = vi.mocked(db.user.delete);
+// ---------------------------------------------------------------------------
+// Type aliases
+// ---------------------------------------------------------------------------
 
-// Type-safe fixture (no `as any`)
 type UserWithAccount = User & {
   atCoderAccount: {
     userId: string;
@@ -28,77 +28,132 @@ type UserWithAccount = User & {
   };
 };
 
-const SAMPLE_USER: UserWithAccount = {
-  id: 'user-abc123',
-  username: 'testuser',
-  role: 'USER',
-  created_at: new Date('2024-01-01'),
-  updated_at: new Date('2024-01-01'),
-  atCoderAccount: {
-    userId: 'user-abc123',
-    handle: 'testuser_ac',
-    isValidated: true,
-    validationCode: 'code-xyz',
-    createdAt: new Date('2024-01-01'),
-    updatedAt: new Date('2024-01-01'),
-  },
-};
+// ---------------------------------------------------------------------------
+// Fixtures
+// ---------------------------------------------------------------------------
+
+const SAMPLE_TIMESTAMP = new Date('2024-01-01');
+const SAMPLE_USER_ID = 'user-abc123';
+const SAMPLE_USERNAME = 'testuser';
+const SAMPLE_HANDLE = 'testuser_ac';
+
+function prepareUser(overrides: Partial<UserWithAccount> = {}): UserWithAccount {
+  return {
+    id: SAMPLE_USER_ID,
+    username: SAMPLE_USERNAME,
+    role: Roles.USER,
+    created_at: SAMPLE_TIMESTAMP,
+    updated_at: SAMPLE_TIMESTAMP,
+    atCoderAccount: {
+      userId: SAMPLE_USER_ID,
+      handle: SAMPLE_HANDLE,
+      isValidated: true,
+      validationCode: 'code-xyz',
+      createdAt: SAMPLE_TIMESTAMP,
+      updatedAt: SAMPLE_TIMESTAMP,
+    },
+    ...overrides,
+  };
+}
+
+// ---------------------------------------------------------------------------
+// Mock helpers
+// ---------------------------------------------------------------------------
+
+function mockFindUnique(value: UserWithAccount | null): void {
+  vi.mocked(db.user.findUnique).mockResolvedValueOnce(value);
+}
+
+function mockDelete(value: UserWithAccount): void {
+  vi.mocked(db.user.delete).mockResolvedValueOnce(value);
+}
+
+function mockDeleteError(message: string = 'not found'): void {
+  vi.mocked(db.user.delete).mockRejectedValueOnce(new Error(message));
+}
+
+// ---------------------------------------------------------------------------
+// Setup
+// ---------------------------------------------------------------------------
 
 beforeEach(() => {
   vi.clearAllMocks();
 });
 
 describe('getUser', () => {
-  test('returns user with atCoderAccount when found', async () => {
-    mockFindUnique.mockResolvedValueOnce(SAMPLE_USER);
+  describe('successful case', () => {
+    test('returns user with atCoderAccount when found', async () => {
+      mockFindUnique(prepareUser());
 
-    const result = await getUser('testuser');
+      const result = await getUser(SAMPLE_USERNAME);
 
-    expect(result).toEqual(SAMPLE_USER);
-    expect(mockFindUnique).toHaveBeenCalledWith({
-      where: { username: 'testuser' },
-      include: { atCoderAccount: true },
+      expect(result).toEqual(prepareUser());
+      expect(vi.mocked(db.user.findUnique)).toHaveBeenCalledWith({
+        where: { username: SAMPLE_USERNAME },
+        include: { atCoderAccount: true },
+      });
     });
   });
 
-  test('returns null when user is not found', async () => {
-    mockFindUnique.mockResolvedValueOnce(null);
+  describe('error cases', () => {
+    test('returns null when user is not found', async () => {
+      mockFindUnique(null);
 
-    const result = await getUser('nonexistent');
+      const result = await getUser('nonexistent');
 
-    expect(result).toBeNull();
+      expect(result).toBeNull();
+    });
   });
 });
 
 describe('getUserById', () => {
-  test('returns user with atCoderAccount when found', async () => {
-    mockFindUnique.mockResolvedValueOnce(SAMPLE_USER);
+  describe('successful case', () => {
+    test('returns user with atCoderAccount when found', async () => {
+      mockFindUnique(prepareUser());
 
-    const result = await getUserById('user-abc123');
+      const result = await getUserById(SAMPLE_USER_ID);
 
-    expect(result).toEqual(SAMPLE_USER);
-    expect(mockFindUnique).toHaveBeenCalledWith({
-      where: { id: 'user-abc123' },
-      include: { atCoderAccount: true },
+      expect(result).toEqual(prepareUser());
+      expect(vi.mocked(db.user.findUnique)).toHaveBeenCalledWith({
+        where: { id: SAMPLE_USER_ID },
+        include: { atCoderAccount: true },
+      });
     });
   });
 
-  test('returns null when user is not found', async () => {
-    mockFindUnique.mockResolvedValueOnce(null);
+  describe('error cases', () => {
+    test('returns null when user is not found', async () => {
+      mockFindUnique(null);
 
-    const result = await getUserById('nonexistent-id');
+      const result = await getUserById('nonexistent-id');
 
-    expect(result).toBeNull();
+      expect(result).toBeNull();
+    });
   });
 });
 
 describe('deleteUser', () => {
-  test('deletes user and returns deleted user', async () => {
-    mockDelete.mockResolvedValueOnce(SAMPLE_USER);
+  describe('successful case', () => {
+    test('deletes user and returns deleted user; subsequent getUser returns null', async () => {
+      mockDelete(prepareUser());
+      mockFindUnique(null); // Subsequent getUser should not find the deleted user
+
+      const deleteResult = await deleteUser(SAMPLE_USERNAME);
+      const userAfterDelete = await getUser(SAMPLE_USERNAME);
+
+      expect(deleteResult).toEqual(prepareUser());
+      expect(userAfterDelete).toBeNull();
+      expect(vi.mocked(db.user.delete)).toHaveBeenCalledWith({
+        where: { username: SAMPLE_USERNAME },
+      });
+    });
+  });
 
-    const deleteResult = await deleteUser('testuser');
+  describe('error cases', () => {
+    test('throws when user not found', async () => {
+      mockDeleteError('User not found');
 
-    expect(deleteResult).toEqual(SAMPLE_USER);
-    expect(mockDelete).toHaveBeenCalledWith({ where: { username: 'testuser' } });
+      await expect(deleteUser(SAMPLE_USERNAME)).rejects.toThrow();
+    });
   });
 });

From 3355d24933048b2f537c53fff7a8161dff28c113 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 08:39:37 +0000
Subject: [PATCH 30/46] refactor: translate SubmissionButton comment to English

- Convert Japanese comment to English for consistency with codebase
- Clarify context behavior for FormWrapper integration

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 src/lib/components/SubmissionButton.svelte | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/lib/components/SubmissionButton.svelte b/src/lib/components/SubmissionButton.svelte
index e966edee9..d11b486e5 100644
--- a/src/lib/components/SubmissionButton.svelte
+++ b/src/lib/components/SubmissionButton.svelte
@@ -11,8 +11,7 @@
 
   let { width = 'w-full', labelName, loading = false }: Props = $props();
 
-  // FormWrapper が setContext('form', ...) でセットしている場合、自動的に isSubmitting を受け取る。
-  // FormWrapper 外で使う場合は context が undefined になるため ?? false でフォールバック。
+  // Get isSubmitting from FormWrapper's context, default to false if undefined.
   const formContext = getContext<{ isSubmitting: boolean } | undefined>('form');
   const isLoading = $derived(loading || (formContext?.isSubmitting ?? false));
 </script>

From ef1977c1f2c5072e90109bc9317d6ff1339f04e3 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 09:09:12 +0000
Subject: [PATCH 31/46] feat: add color prop to SubmissionButton and improve
 ButtonColor type extraction

- Add optional color prop to SubmissionButton (defaults to 'primary')
- Use 'alternative' color for Clipboard and reset button in AtCoderVerificationForm
- Refactor ButtonColor type to extract from ButtonProps instead of hardcoding
- Remove hardcoded type union and resolve FIXME with proper type extraction

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../settings/AtCoderVerificationForm.svelte   |  4 ++--
 src/lib/components/SubmissionButton.svelte    |  6 +++--
 src/lib/types/flowbite-svelte-wrapper.ts      | 22 ++++---------------
 3 files changed, 10 insertions(+), 22 deletions(-)

diff --git a/src/features/account/components/settings/AtCoderVerificationForm.svelte b/src/features/account/components/settings/AtCoderVerificationForm.svelte
index 2100400df..506cb4b28 100644
--- a/src/features/account/components/settings/AtCoderVerificationForm.svelte
+++ b/src/features/account/components/settings/AtCoderVerificationForm.svelte
@@ -84,7 +84,7 @@
         <div class="flex items-center gap-2">
           <Input size="md" value={atCoderAccount.validationCode} readonly />
 
-          <Clipboard value={atCoderAccount.validationCode}>
+          <Clipboard value={atCoderAccount.validationCode} color="alternative">
             {#snippet children(success)}
               {#if success}
                 <Check class="w-5 h-5 text-green-500" />
@@ -103,7 +103,7 @@
       <Input size="md" type="hidden" name="username" value={username} />
       <Input size="md" type="hidden" name="handle" value={atCoderAccount.handle} />
 
-      <SubmissionButton labelName="リセット" />
+      <SubmissionButton color="alternative" labelName="リセット" />
     </FormWrapper>
   </ContainerWrapper>
 {:else if status === 'validated'}
diff --git a/src/lib/components/SubmissionButton.svelte b/src/lib/components/SubmissionButton.svelte
index d11b486e5..e48d2d66c 100644
--- a/src/lib/components/SubmissionButton.svelte
+++ b/src/lib/components/SubmissionButton.svelte
@@ -2,18 +2,20 @@
   import { getContext } from 'svelte';
 
   import { Button } from 'flowbite-svelte';
+  import type { ButtonColor } from '$lib/types/flowbite-svelte-wrapper';
 
   interface Props {
     width?: string;
     labelName: string;
     loading?: boolean;
+    color?: ButtonColor;
   }
 
-  let { width = 'w-full', labelName, loading = false }: Props = $props();
+  let { width = 'w-full', labelName, loading = false, color = 'primary' }: Props = $props();
 
   // Get isSubmitting from FormWrapper's context, default to false if undefined.
   const formContext = getContext<{ isSubmitting: boolean } | undefined>('form');
   const isLoading = $derived(loading || (formContext?.isSubmitting ?? false));
 </script>
 
-<Button type="submit" class={width} loading={isLoading}>{labelName}</Button>
+<Button type="submit" {color} class={width} loading={isLoading}>{labelName}</Button>
diff --git a/src/lib/types/flowbite-svelte-wrapper.ts b/src/lib/types/flowbite-svelte-wrapper.ts
index c9ba06d21..a7f705e50 100644
--- a/src/lib/types/flowbite-svelte-wrapper.ts
+++ b/src/lib/types/flowbite-svelte-wrapper.ts
@@ -1,19 +1,5 @@
-// ドキュメントで公開されている型の一覧に載っておらず、ボタンコンポーネントの内部でのみ定義されている
-// FIXME: ButtonColorTypeをインポートすると、ts2322エラーが出る
-// HACK: 同じ属性を使っているのに、以下のようにハードコーディングするとなぜかエラーが出ない
+// Extract ButtonColor from ButtonProps (Flowbite Svelte exports ButtonProps)
+import type { ButtonProps } from 'flowbite-svelte';
 
-// See:
-// https://flowbite-svelte.com/docs/pages/typescript
-// https://github.com/themesberg/flowbite-svelte/blob/main/src/lib/buttons/Button.svelte
-// https://github.com/iamrishupatel/trello-clone/blob/16635c8bfcc46ffca1ab89c26752d745b2326b6f/src/lib/components/NewTask/NewTask.component.svelte
-export type ButtonColor =
-  | 'alternative'
-  | 'blue'
-  | 'dark'
-  | 'green'
-  | 'light'
-  | 'primary'
-  | 'purple'
-  | 'red'
-  | 'yellow'
-  | 'none';
+// Get the color type from ButtonProps
+export type ButtonColor = NonNullable<ButtonProps['color']>;

From 68ca9c09cc702accbfe2f8c96aa982e87e46a621 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 09:41:59 +0000
Subject: [PATCH 32/46] test: refactor vote_grade.test.ts with HTTP mock
 helpers and parametrized tests

- Add coding-style rule: use named HTTP status constants in test code for clarity
- Add testing rule: HTTP mock helper pattern (mockGetMyVote, mockGetMedianVote) for DRY
- Add testing rule: parametrized tests with test.each() for enum value coverage
- Organize vote_grade.test.ts with successful/error case describe blocks
- Extract BASE_URL and TASK_ID as module-level constants
- Replace hardcoded status codes (200, 401, 500) with named constants
- Use test.each() for TaskGrade boundary sampling (PENDING, Q11, Q10, Q1, D1, D6)
- Extract mock builders (mockGetMyVote, mockGetMedianVote) at describe scope
- Enhance submitVote test: parametrized error status codes (4xx/5xx)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .claude/rules/coding-style.md                 |  18 ++
 .claude/rules/testing.md                      |  77 +++++++
 .../votes/internal_clients/vote_grade.test.ts | 196 +++++++++++-------
 3 files changed, 216 insertions(+), 75 deletions(-)

diff --git a/.claude/rules/coding-style.md b/.claude/rules/coding-style.md
index b8ae4899f..6ce878afd 100644
--- a/.claude/rules/coding-style.md
+++ b/.claude/rules/coding-style.md
@@ -71,6 +71,24 @@ const response = await fetch(SUBMIT_URL, options);
 
 Place constants at the top of the file, or in a dedicated `constants/` module when shared across files.
 
+#### Test Code: Status Code Constants
+
+Applies equally to test code. HTTP status codes especially benefit from named constants for clarity of intent.
+
+```typescript
+import * as statusCodes from '$lib/constants/http-response-status-codes';
+
+// Bad: what does 200 mean here?
+nock('http://localhost').get('/user').reply(200, data);
+nock('http://localhost').get('/user').reply(500);
+
+// Good: intent is immediately clear
+nock('http://localhost').get('/user').reply(statusCodes.OK, data);
+nock('http://localhost').get('/user').reply(statusCodes.INTERNAL_SERVER_ERROR);
+```
+
+Test readers (reviewers, future maintainers) must quickly understand **what is being tested**. Named constants (`OK`, `UNAUTHORIZED`) communicate intent far better than numeric codes.
+
 ### Function Ordering
 
 Within a file, order declarations as follows:
diff --git a/.claude/rules/testing.md b/.claude/rules/testing.md
index dfbf71bbd..11ea913de 100644
--- a/.claude/rules/testing.md
+++ b/.claude/rules/testing.md
@@ -136,6 +136,83 @@ When a service mixes DB operations and pure functions, split into `crud.ts` (DB;
 
 Use Nock for external HTTP calls. See `src/test/lib/clients/` for examples.
 
+### HTTP Mock Helpers: DRY and Intent
+
+Extract repeated HTTP mock setup into helpers at describe scope. Benefits: DRY, readable test names, easier assertion updates.
+
+#### Naming convention
+
+- Mock builder: `mock<Endpoint>()` (e.g. `mockGetMyVote()`, `mockPostSubmit()`)
+- Data builder: `create<Entity>()` (e.g. `createFormData()`, `createRequestBody()`)
+
+#### Pattern: declare once, use many
+
+```typescript
+describe('fetchUser', () => {
+  const baseUrl = 'http://localhost';
+  const endpoint = '/api/user';
+
+  const mockGetUser = (statusCode: number, user?: User) => {
+    nock(baseUrl)
+      .get(endpoint)
+      .reply(statusCode, user ? { user } : undefined);
+  };
+
+  test('success', async () => {
+    mockGetUser(statusCodes.OK, { id: '1', name: 'Alice' });
+    expect(await fetchUser()).toEqual({ id: '1', name: 'Alice' });
+  });
+
+  test('not found', async () => {
+    mockGetUser(statusCodes.NOT_FOUND);
+    expect(await fetchUser()).toBeNull();
+  });
+});
+```
+
+**Benefit**: Reduces duplication, clarifies each test's focus, simplifies mock updates across multiple tests.
+
+## Parametrized Tests
+
+When a function accepts domain enum values, test across representative samples rather than a single value.
+
+#### Sampling strategy
+
+- **Boundaries**: first value (Q11), last value (D6), special states (PENDING)
+- **Mid-range**: one typical value (Q10)
+- **Exception**: separate `test()` for distinct behavioral branches (e.g. null return)
+
+#### Pattern: test.each() for variants
+
+```typescript
+// Bad: tests only one value
+test('returns grade', async () => {
+  mockGetVote(statusCodes.OK, TaskGrade.Q10);
+  expect(await fetchVote()).toBe(TaskGrade.Q10);
+});
+
+// Good: parametrized boundaries + typical value
+test.each([
+  TaskGrade.PENDING,
+  TaskGrade.Q11,
+  TaskGrade.Q10,
+  TaskGrade.Q1,
+  TaskGrade.D1,
+  TaskGrade.D6,
+])('returns grade %s when voted', async (grade) => {
+  mockGetVote(statusCodes.OK, grade);
+  expect(await fetchVote()).toBe(grade);
+});
+
+// Separate test for distinct behavior
+test('returns null when no vote', async () => {
+  mockGetVote(statusCodes.OK, null);
+  expect(await fetchVote()).toBeNull();
+});
+```
+
+**Benefit**: Catches enum-related bugs (misspellings, missing cases); prevents regressions when enum values change.
+
 ## Environment Variable Stubs
 
 Use `vi.stubEnv(key, value)` + `vi.unstubAllEnvs()` instead of manually assigning `process.env[key]` and deleting it in cleanup. `vi.stubEnv` syncs `import.meta.env` as well and accurately restores the original value:
diff --git a/src/features/votes/internal_clients/vote_grade.test.ts b/src/features/votes/internal_clients/vote_grade.test.ts
index 075ed06ed..80adfc956 100644
--- a/src/features/votes/internal_clients/vote_grade.test.ts
+++ b/src/features/votes/internal_clients/vote_grade.test.ts
@@ -5,11 +5,16 @@ import { TaskGrade } from '$lib/types/task';
 
 import { fetchMyVote, submitVote, fetchMedianVote } from './vote_grade';
 
+import * as statusCodes from '$lib/constants/http-response-status-codes';
+
+const BASE_URL = 'http://localhost';
+const TASK_ID = 'abc_a';
+
 beforeEach(() => {
   nock.cleanAll();
   // Set globalThis.location for test environment
   Object.defineProperty(globalThis, 'location', {
-    value: { origin: 'http://localhost' },
+    value: { origin: BASE_URL },
     writable: true,
   });
 });
@@ -19,105 +24,146 @@ afterEach(() => {
 });
 
 describe('fetchMyVote', () => {
-  test('returns grade when server responds with a voted grade', async () => {
-    nock('http://localhost')
-      .get('/problems/getMyVote')
-      .query({ taskId: 'abc_a' })
-      .reply(200, { grade: TaskGrade.Q11 });
-
-    const result = await fetchMyVote('abc_a');
-
-    expect(result).toBe(TaskGrade.Q11);
+  const endpoint = '/problems/getMyVote';
+
+  const mockGetMyVote = (statusCode: number, grade?: TaskGrade | null) => {
+    nock(BASE_URL)
+      .get(endpoint)
+      .query({ taskId: TASK_ID })
+      .reply(statusCode, grade !== undefined ? { grade } : undefined);
+  };
+
+  describe('successful case', () => {
+    test.each([
+      TaskGrade.PENDING,
+      TaskGrade.Q11,
+      TaskGrade.Q10,
+      TaskGrade.Q1,
+      TaskGrade.D1,
+      TaskGrade.D6,
+    ])('returns grade %s when voted', async (grade) => {
+      mockGetMyVote(statusCodes.OK, grade);
+
+      const result = await fetchMyVote(TASK_ID);
+
+      expect(result).toBe(grade);
+    });
+
+    test('returns null when no vote exists', async () => {
+      mockGetMyVote(statusCodes.OK, null);
+
+      const result = await fetchMyVote(TASK_ID);
+
+      expect(result).toBeNull();
+    });
   });
 
-  test('returns null when server responds with null grade', async () => {
-    nock('http://localhost')
-      .get('/problems/getMyVote')
-      .query({ taskId: 'abc_a' })
-      .reply(200, { grade: null });
+  describe('error cases', () => {
+    test('returns null when unauthorized', async () => {
+      mockGetMyVote(statusCodes.UNAUTHORIZED);
 
-    const result = await fetchMyVote('abc_a');
+      const result = await fetchMyVote(TASK_ID);
 
-    expect(result).toBeNull();
-  });
+      expect(result).toBeNull();
+    });
 
-  test('returns null when server responds with non-ok status', async () => {
-    nock('http://localhost').get('/problems/getMyVote').query({ taskId: 'abc_a' }).reply(401);
+    test('returns null when server error', async () => {
+      mockGetMyVote(statusCodes.INTERNAL_SERVER_ERROR);
 
-    const result = await fetchMyVote('abc_a');
+      const result = await fetchMyVote(TASK_ID);
 
-    expect(result).toBeNull();
+      expect(result).toBeNull();
+    });
   });
 });
 
 describe('submitVote', () => {
-  test('returns true when server responds with ok status', async () => {
-    const formData = new FormData();
-    formData.append('taskId', 'abc_a');
-    formData.append('grade', TaskGrade.Q11);
-
-    nock('http://localhost').post('/votes?/voteAbsoluteGrade').reply(200, { success: true });
-
-    const result = await submitVote(new URL('http://localhost/votes?/voteAbsoluteGrade'), formData);
-
-    expect(result).toBe(true);
+  const endpoint = '/votes?/voteAbsoluteGrade';
+  const actionUrl = new URL(`${BASE_URL}${endpoint}`);
+  const formData = (() => {
+    const data = new FormData();
+    data.append('taskId', TASK_ID);
+    data.append('grade', TaskGrade.Q11);
+    return data;
+  })();
+
+  describe('successful case', () => {
+    test('returns true when status code is 2xx', async () => {
+      nock(BASE_URL).post(endpoint).reply(statusCodes.OK, { success: true });
+
+      const result = await submitVote(actionUrl, formData);
+
+      expect(result).toBe(true);
+    });
   });
 
-  test('returns false when server responds with error status', async () => {
-    const formData = new FormData();
-    formData.append('taskId', 'abc_a');
-    formData.append('grade', TaskGrade.Q11);
+  describe('error cases', () => {
+    test.each([
+      statusCodes.BAD_REQUEST,
+      statusCodes.UNAUTHORIZED,
+      statusCodes.FORBIDDEN,
+      statusCodes.INTERNAL_SERVER_ERROR,
+    ])('returns false when status code is %s', async (statusCode) => {
+      nock(BASE_URL).post(endpoint).reply(statusCode);
 
-    nock('http://localhost').post('/votes?/voteAbsoluteGrade').reply(500);
+      const result = await submitVote(actionUrl, formData);
 
-    const result = await submitVote(new URL('http://localhost/votes?/voteAbsoluteGrade'), formData);
+      expect(result).toBe(false);
+    });
 
-    expect(result).toBe(false);
-  });
-
-  test('returns false when request is aborted', async () => {
-    const formData = new FormData();
-    const controller = new AbortController();
-    controller.abort();
+    test('returns false when request is aborted', async () => {
+      const controller = new AbortController();
+      controller.abort();
 
-    const result = await submitVote(
-      new URL('http://localhost/votes?/voteAbsoluteGrade'),
-      formData,
-      controller.signal,
-    );
+      const result = await submitVote(actionUrl, formData, controller.signal);
 
-    expect(result).toBe(false);
+      expect(result).toBe(false);
+    });
   });
 });
 
 describe('fetchMedianVote', () => {
-  test('returns grade when server responds with a median grade', async () => {
-    nock('http://localhost')
-      .get('/problems/getMedianVote')
-      .query({ taskId: 'abc_a' })
-      .reply(200, { grade: TaskGrade.Q10 });
-
-    const result = await fetchMedianVote('abc_a');
-
-    expect(result).toBe(TaskGrade.Q10);
-  });
-
-  test('returns null when server responds with null grade', async () => {
-    nock('http://localhost')
-      .get('/problems/getMedianVote')
-      .query({ taskId: 'abc_a' })
-      .reply(200, { grade: null });
-
-    const result = await fetchMedianVote('abc_a');
-
-    expect(result).toBeNull();
+  const endpoint = '/problems/getMedianVote';
+
+  const mockGetMedianVote = (statusCode: number, grade?: TaskGrade | null) => {
+    nock(BASE_URL)
+      .get(endpoint)
+      .query({ taskId: TASK_ID })
+      .reply(statusCode, grade !== undefined ? { grade } : undefined);
+  };
+
+  describe('successful case', () => {
+    test.each([
+      TaskGrade.PENDING,
+      TaskGrade.Q11,
+      TaskGrade.Q10,
+      TaskGrade.Q1,
+      TaskGrade.D1,
+      TaskGrade.D6,
+    ])('returns grade %s when fetched', async (grade) => {
+      mockGetMedianVote(statusCodes.OK, grade);
+
+      const result = await fetchMedianVote(TASK_ID);
+
+      expect(result).toBe(grade);
+    });
+
+    test('returns null when no median exists', async () => {
+      mockGetMedianVote(statusCodes.OK, null);
+
+      const result = await fetchMedianVote(TASK_ID);
+
+      expect(result).toBeNull();
+    });
   });
 
-  test('returns null when server responds with non-ok status', async () => {
-    nock('http://localhost').get('/problems/getMedianVote').query({ taskId: 'abc_a' }).reply(500);
+  describe('error cases', () => {
+    test('returns null when server error', async () => {
+      mockGetMedianVote(statusCodes.INTERNAL_SERVER_ERROR);
 
-    const result = await fetchMedianVote('abc_a');
+      const result = await fetchMedianVote(TASK_ID);
 
-    expect(result).toBeNull();
+      expect(result).toBeNull();
+    });
   });
 });

From 609addf1a94e53ef6f37db497ae0561bd7469327 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 12:39:31 +0000
Subject: [PATCH 33/46] refactor: move getBaseUrl helper after exported
 functions in vote_grade.ts

- Reorder to follow function ordering convention: exports first, internal helpers last
- No behavioral change

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../votes/internal_clients/vote_grade.ts         | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/features/votes/internal_clients/vote_grade.ts b/src/features/votes/internal_clients/vote_grade.ts
index ff98195f5..7508c20d1 100644
--- a/src/features/votes/internal_clients/vote_grade.ts
+++ b/src/features/votes/internal_clients/vote_grade.ts
@@ -1,13 +1,5 @@
 import type { TaskGrade } from '$lib/types/task';
 
-// Helper to get base URL (works in browser and Node.js test environments)
-function getBaseUrl(): string {
-  if (typeof globalThis !== 'undefined' && globalThis.location?.origin) {
-    return globalThis.location.origin;
-  }
-  return 'http://localhost';
-}
-
 /**
  * Fetches the current user's vote grade for a given task.
  * @returns The voted grade, or null if not voted or request fails.
@@ -83,3 +75,11 @@ export async function fetchMedianVote(taskId: string): Promise<TaskGrade | null>
     return null;
   }
 }
+
+// Helper to get base URL (works in browser and Node.js test environments)
+function getBaseUrl(): string {
+  if (typeof globalThis !== 'undefined' && globalThis.location?.origin) {
+    return globalThis.location.origin;
+  }
+  return 'http://localhost';
+}

From 556822e7138280880032fd83eeed527f6b198d2d Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 12:40:59 +0000
Subject: [PATCH 34/46] chore: fix order

---
 src/features/votes/components/VotableGrade.svelte | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/features/votes/components/VotableGrade.svelte b/src/features/votes/components/VotableGrade.svelte
index b547c1033..fd604178b 100644
--- a/src/features/votes/components/VotableGrade.svelte
+++ b/src/features/votes/components/VotableGrade.svelte
@@ -8,9 +8,6 @@
   import FlaskConical from '@lucide/svelte/icons/flask-conical';
 
   import { TaskGrade, getTaskGrade, type TaskResult } from '$lib/types/task';
-  import { getTaskGradeLabel } from '$lib/utils/task';
-  import { nonPendingGrades, resolveDisplayGrade } from '$features/votes/utils/grade_options';
-  import { SIGNUP_PAGE, LOGIN_PAGE, EDIT_PROFILE_PAGE } from '$lib/constants/navbar-links';
   import { errorMessageStore } from '$lib/stores/error_message';
   import {
     fetchMyVote,
@@ -18,6 +15,10 @@
     fetchMedianVote,
   } from '$features/votes/internal_clients/vote_grade';
 
+  import { getTaskGradeLabel } from '$lib/utils/task';
+  import { nonPendingGrades, resolveDisplayGrade } from '$features/votes/utils/grade_options';
+  import { SIGNUP_PAGE, LOGIN_PAGE, EDIT_PROFILE_PAGE } from '$lib/constants/navbar-links';
+
   import GradeLabel from '$lib/components/GradeLabel.svelte';
   import InputFieldWrapper from '$lib/components/InputFieldWrapper.svelte';
 

From 2a5cd6146daa11a1e69fa6ac9ef02caf3085ad66 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 12:54:28 +0000
Subject: [PATCH 35/46] docs: clean up completed plan.md for PR #3316 review

- Remove detailed implementation tasks (steps 1-5) as all rules have been added
- Retain verification section for reference

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../2026-03-26/pr-3316-review/plan.md         | 1231 +----------------
 1 file changed, 1 insertion(+), 1230 deletions(-)

diff --git a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
index 67377c52f..d563c1204 100644
--- a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
+++ b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
@@ -1,1032 +1,6 @@
 # PR #3316 マージ後修正 実装計画
 
-> **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:** `review.md` に記載されたマージ後修正タスク（#1〜#13、#優先度中テスト）を実施し、コード品質・テスト・UI/UX・DB整合性を改善する。
-
-**Architecture:** 低リスク（テスト・定数）→ 中リスク（UI・サービス）→ 高リスク（DB migration）の順で実施。`Pct → percentage` リネーム（#6）は現コードベースに `Pct` が存在しないため実施不要（既解決）。並行投票対策（#14）は優先度低・将来対応のためスコープ外。
-
-**Tech Stack:** SvelteKit 2 + Svelte 5 Runes, TypeScript, Prisma, Vitest, Playwright, Flowbite Svelte
-
----
-
-## 対象ファイル一覧
-
-| 操作           | ファイル                                                                  | 理由                                                                                |
-| -------------- | ------------------------------------------------------------------------- | ----------------------------------------------------------------------------------- |
-| 修正           | `src/features/account/services/atcoder_verification.test.ts`              | `vi.stubEnv` パターンへ移行（#11）                                                  |
-| 新規           | `src/test/lib/services/users.test.ts`                                     | `getUser` / `getUserById` / `deleteUser` のテスト追加（#10）                        |
-| 修正           | `src/features/votes/services/vote_grade.ts`                               | `MIN_VOTES_FOR_STATISTICS` を export + `upsertVoteGradeTables` 戻り値追加（#4, #5） |
-| 修正           | `src/features/votes/actions/vote_actions.ts`                              | `upsertVoteGradeTables` 戻り値を利用（#4）                                          |
-| 修正           | `src/routes/votes/[slug]/+page.svelte`                                    | `MIN_VOTES_FOR_STATISTICS` 参照に変更（#5）                                         |
-| 修正           | `src/routes/(admin)/vote_management/+page.server.ts`                      | `updateTask` に try/catch 追加（#7）                                                |
-| 修正           | `src/lib/components/SubmissionButton.svelte`                              | `loading` prop 追加（#8a）                                                          |
-| 修正           | `src/lib/components/FormWrapper.svelte`                                   | `isSubmitting` context 追加（#8b）                                                  |
-| 修正           | `src/features/account/components/settings/AtCoderVerificationForm.svelte` | ボタン間隔（#8c）+ Flowbite Clipboard 導入（#8d）                                   |
-| 新規           | `src/features/votes/internal_clients/vote_grade.ts`                       | `fetchMyVote` / `submitVote` / `fetchMedianVote` 抽出（#1, #2）                     |
-| 新規           | `src/features/votes/internal_clients/vote_grade.test.ts`                  | vote_grade.ts の単体テスト（#2）                                                    |
-| 修正           | `src/features/votes/components/VotableGrade.svelte`                       | vote_grade.ts 利用 + AbortController 連打対策（#1, #2, #3）                         |
-| 修正           | `e2e/votes.spec.ts`                                                       | セレクタ修正 + 初期状態対応（#9）                                                   |
-| 新規 migration | `prisma/migrations/.../migration.sql`                                     | CHECK 制約追加（#12, #13）                                                          |
-| 修正           | `prisma/schema.prisma`                                                    | コメント追加（#12, #13）                                                            |
-| 修正           | `prisma/ERD.md`                                                           | CHECK 制約ドキュメント（#12, #13）                                                  |
-| 修正           | `.claude/rules/svelte-components.md`                                      | SSR 安全性・`{#each}` キー式ルール追加                                              |
-| 修正           | `.claude/rules/prisma-db.md`                                              | FK @relation・DB 値域制約ルール追加                                                 |
-| 修正           | `.claude/rules/coding-style.md`                                           | load関数 try-catch・auth 監査・success フラグ・Dead Code ルール追加                 |
-| 修正           | `.claude/rules/testing.md`                                                | `vi.stubEnv` ルール追加                                                             |
-
----
-
-## Phase 1: テスト品質改善
-
-### Task 1: vi.stubEnv パターンへ移行（atcoder_verification.test.ts）
-
-**Files:**
-
-- Modify: `src/features/account/services/atcoder_verification.test.ts:1-60`
-
-- [ ] **Step 1: テスト実行（修正前の失敗確認は不要。現在パスしていることを確認）**
-
-```bash
-pnpm test:unit -- atcoder_verification
-```
-
-Expected: 全テスト PASS
-
-- [ ] **Step 2: `beforeEach` / `afterEach` の手動 `process.env` を `vi.stubEnv` に置換**
-
-ファイル冒頭の import に `afterAll` を追加し、以下のように変更する:
-
-```typescript
-// 変更前
-beforeEach(() => {
-  process.env.CONFIRM_API_URL = SAMPLE_API_URL;
-});
-
-afterEach(() => {
-  delete process.env.CONFIRM_API_URL;
-});
-
-// 変更後
-beforeEach(() => {
-  vi.stubEnv('CONFIRM_API_URL', SAMPLE_API_URL);
-});
-
-afterEach(() => {
-  vi.unstubAllEnvs();
-});
-```
-
-- [ ] **Step 3: テスト再実行**
-
-```bash
-pnpm test:unit -- atcoder_verification
-```
-
-Expected: 全テスト PASS（11件）
-
-- [ ] **Step 4: コミット**
-
-```bash
-git add src/features/account/services/atcoder_verification.test.ts
-git commit -m "test: migrate process.env manual stubs to vi.stubEnv in atcoder_verification tests"
-```
-
----
-
-### Task 2: users.ts 単体テスト追加
-
-**Files:**
-
-- Create: `src/test/lib/services/users.test.ts`
-
-- [ ] **Step 1: テストファイルを作成（実装なし・FAIL 確認用）**
-
-```typescript
-import { describe, test, expect, vi, beforeEach } from 'vitest';
-import type { User } from '@prisma/client';
-
-vi.mock('$lib/server/database', () => ({
-  default: {
-    user: {
-      findUnique: vi.fn(),
-      delete: vi.fn(),
-    },
-  },
-}));
-
-import db from '$lib/server/database';
-import { getUser, getUserById, deleteUser } from '$lib/services/users';
-
-const mockFindUnique = vi.mocked(db.user.findUnique);
-const mockDelete = vi.mocked(db.user.delete);
-
-// Type-safe fixture (no `as any`)
-type UserWithAccount = User & {
-  atCoderAccount: {
-    userId: string;
-    handle: string;
-    isValidated: boolean;
-    validationCode: string;
-    createdAt: Date;
-    updatedAt: Date;
-  };
-};
-
-const SAMPLE_USER: UserWithAccount = {
-  id: 'user-abc123',
-  username: 'testuser',
-  atCoderAccount: {
-    userId: 'user-abc123',
-    handle: 'testuser_ac',
-    isValidated: true,
-    validationCode: 'code-xyz',
-    createdAt: new Date('2024-01-01'),
-    updatedAt: new Date('2024-01-01'),
-  },
-} as UserWithAccount;
-
-beforeEach(() => {
-  vi.clearAllMocks();
-});
-
-describe('getUser', () => {
-  test('returns user with atCoderAccount when found', async () => {
-    mockFindUnique.mockResolvedValueOnce(SAMPLE_USER);
-
-    const result = await getUser('testuser');
-
-    expect(result).toEqual(SAMPLE_USER);
-    expect(mockFindUnique).toHaveBeenCalledWith({
-      where: { username: 'testuser' },
-      include: { atCoderAccount: true },
-    });
-  });
-
-  test('returns null when user is not found', async () => {
-    mockFindUnique.mockResolvedValueOnce(null);
-
-    const result = await getUser('nonexistent');
-
-    expect(result).toBeNull();
-  });
-});
-
-describe('getUserById', () => {
-  test('returns user with atCoderAccount when found', async () => {
-    mockFindUnique.mockResolvedValueOnce(SAMPLE_USER);
-
-    const result = await getUserById('user-abc123');
-
-    expect(result).toEqual(SAMPLE_USER);
-    expect(mockFindUnique).toHaveBeenCalledWith({
-      where: { id: 'user-abc123' },
-      include: { atCoderAccount: true },
-    });
-  });
-
-  test('returns null when user is not found', async () => {
-    mockFindUnique.mockResolvedValueOnce(null);
-
-    const result = await getUserById('nonexistent-id');
-
-    expect(result).toBeNull();
-  });
-});
-
-describe('deleteUser', () => {
-  test('deletes user and subsequent getUser returns null', async () => {
-    mockDelete.mockResolvedValueOnce(SAMPLE_USER);
-    mockFindUnique.mockResolvedValueOnce(null);
-
-    const deleteResult = await deleteUser('testuser');
-
-    expect(deleteResult).toEqual(SAMPLE_USER);
-    expect(mockDelete).toHaveBeenCalledWith({ where: { username: 'testuser' } });
-
-    // Verify that the user is actually deleted (subsequent getUser returns null)
-    const getResult = await getUser('testuser');
-    expect(getResult).toBeNull();
-  });
-});
-```
-
-- [ ] **Step 2: テスト実行（FAIL 確認）**
-
-```bash
-pnpm test:unit -- src/test/lib/services/users
-```
-
-Expected: テストファイルが存在しないためエラー（または関数が存在しないため FAIL）
-
-- [ ] **Step 3: テスト実行（PASS 確認）**
-
-実装は `src/lib/services/users.ts` に既存（変更不要）。
-
-```bash
-pnpm test:unit -- src/test/lib/services/users
-```
-
-Expected: 5件 PASS
-
-- [ ] **Step 4: コミット**
-
-```bash
-git add src/test/lib/services/users.test.ts
-git commit -m "test: add unit tests for getUser, getUserById, and deleteUser"
-```
-
----
-
-## Phase 2: サービス・ルート修正
-
-### Task 3: MIN_VOTES_FOR_STATISTICS を export し hardcode を除去
-
-**Files:**
-
-- Modify: `src/features/votes/services/vote_grade.ts:27`
-- Modify: `src/routes/votes/[slug]/+page.svelte:46`
-
-- [ ] **Step 1: vote_grade.ts の定数を export に変更**
-
-```typescript
-// 変更前（line 27）
-const MIN_VOTES_FOR_STATISTICS = 3;
-
-// 変更後
-export const MIN_VOTES_FOR_STATISTICS = 3;
-```
-
-- [ ] **Step 2: votes/[slug]/+page.svelte の hardcode を置換**
-
-import を追加し、Tooltip テキストを定数参照に変更:
-
-```typescript
-// script 内の import に追加
-import { MIN_VOTES_FOR_STATISTICS } from '$features/votes/services/vote_grade';
-```
-
-```svelte
-<!-- 変更前（line 46） -->
-3票以上集まると中央値が暫定グレードとして一覧表に反映されます。
-
-<!-- 変更後 -->
-{MIN_VOTES_FOR_STATISTICS}票以上集まると中央値が暫定グレードとして一覧表に反映されます。
-```
-
-- [ ] **Step 3: 型チェック**
-
-```bash
-pnpm check
-```
-
-Expected: エラーなし
-
-- [ ] **Step 4: コミット**
-
-```bash
-git add src/features/votes/services/vote_grade.ts src/routes/votes/[slug]/+page.svelte
-git commit -m "refactor: export MIN_VOTES_FOR_STATISTICS and remove hardcoded '3' in votes page"
-```
-
----
-
-### Task 4: upsertVoteGradeTables の戻り値を { success: true } に変更
-
-**Files:**
-
-- Modify: `src/features/votes/services/vote_grade.ts:30-34`
-- Modify: `src/features/votes/actions/vote_actions.ts:54-58`
-
-- [ ] **Step 1: vote_grade.ts の関数シグネチャと戻り値を変更**
-
-```typescript
-// 変更前
-export async function upsertVoteGradeTables(
-  userId: string,
-  taskId: string,
-  grade: TaskGrade,
-): Promise<void> {
-  await prisma.$transaction(async (tx) => {
-    // ...
-  });
-}
-
-// 変更後
-export async function upsertVoteGradeTables(
-  userId: string,
-  taskId: string,
-  grade: TaskGrade,
-): Promise<{ success: true }> {
-  await prisma.$transaction(async (tx) => {
-    // ... (内容変更なし)
-  });
-  return { success: true };
-}
-```
-
-- [ ] **Step 2: vote_actions.ts でサービスの戻り値を返すよう変更**
-
-```typescript
-// 変更前
-try {
-  await upsertVoteGradeTables(userId, taskId, grade);
-} catch (error) {
-  console.error('Failed to vote absolute grade: ', error);
-  return fail(INTERNAL_SERVER_ERROR, { message: 'Failed to record vote.' });
-}
-// (暗黙の undefined return → SvelteKit が success として扱う)
-
-// 変更後
-try {
-  return await upsertVoteGradeTables(userId, taskId, grade);
-} catch (error) {
-  console.error('Failed to vote absolute grade: ', error);
-  return fail(INTERNAL_SERVER_ERROR, { message: 'Failed to record vote.' });
-}
-```
-
-- [ ] **Step 3: 型チェック**
-
-```bash
-pnpm check
-```
-
-Expected: エラーなし
-
-- [ ] **Step 4: コミット**
-
-```bash
-git add src/features/votes/services/vote_grade.ts src/features/votes/actions/vote_actions.ts
-git commit -m "refactor: make upsertVoteGradeTables return { success: true } for explicit action response"
-```
-
----
-
-### Task 5: vote_management の updateTask に 404 エラー処理を追加
-
-**Files:**
-
-- Modify: `src/routes/(admin)/vote_management/+page.server.ts:54`
-
-- [ ] **Step 1: `updateTask` 呼び出しを try/catch で囲む**
-
-Prisma の `P2025`（RecordNotFound）を明示的に処理する。import を追加:
-
-```typescript
-import { Prisma } from '@prisma/client';
-```
-
-アクション内を変更:
-
-```typescript
-// 変更前（line 54-55）
-await updateTask(taskId, grade as TaskGrade);
-return { success: true };
-
-// 変更後
-try {
-  await updateTask(taskId, grade as TaskGrade);
-} catch (error) {
-  if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === 'P2025') {
-    return { success: false, message: `Not found task: ${taskId}` };
-  }
-
-  throw error;
-}
-return { success: true };
-```
-
-- [ ] **Step 2: 型チェック**
-
-```bash
-pnpm check
-```
-
-Expected: エラーなし
-
-- [ ] **Step 3: コミット**
-
-```bash
-git add src/routes/(admin)/vote_management/+page.server.ts
-git commit -m "fix: handle RecordNotFound error in setTaskGrade action for vote_management"
-```
-
----
-
-## Phase 3: UI コンポーネント改善
-
-### Task 6: SubmissionButton loading prop + FormWrapper isSubmitting context
-
-**Files:**
-
-- Modify: `src/lib/components/SubmissionButton.svelte`
-- Modify: `src/lib/components/FormWrapper.svelte`
-
-- [ ] **Step 1: SubmissionButton に loading prop を追加し getContext で自動取得**
-
-`SubmissionButton.svelte` の内容を差し替え:
-
-```svelte
-<script lang="ts">
-  import { getContext } from 'svelte';
-
-  import { Button } from 'flowbite-svelte';
-
-  interface Props {
-    width?: string;
-    labelName: string;
-    loading?: boolean;
-  }
-
-  let { width = 'w-full', labelName, loading = false }: Props = $props();
-
-  // FormWrapper が setContext('form', ...) でセットしている場合、自動的に isSubmitting を受け取る。
-  // FormWrapper 外で使う場合は context が undefined になるため ?? false でフォールバック。
-  const formContext = getContext<{ isSubmitting: boolean } | undefined>('form');
-  const isLoading = $derived(loading || (formContext?.isSubmitting ?? false));
-</script>
-
-<Button type="submit" class={width} loading={isLoading}>{labelName}</Button>
-```
-
-- [ ] **Step 2: FormWrapper に isSubmitting state と setContext を追加**
-
-`FormWrapper.svelte` の内容を差し替え:
-
-```svelte
-<script lang="ts">
-  import { enhance } from '$app/forms';
-  import { setContext } from 'svelte';
-  import type { Snippet } from 'svelte';
-
-  interface Props {
-    method?: 'POST' | 'GET' | 'DIALOG' | 'post' | 'get' | 'dialog' | null | undefined;
-    action: string;
-    marginTop?: string;
-    spaceYAxis?: string;
-    children?: Snippet;
-  }
-
-  let {
-    method = 'POST',
-    action,
-    marginTop = 'mt-6',
-    spaceYAxis = 'space-y-6',
-    children,
-  }: Props = $props();
-
-  let isSubmitting = $state(false);
-
-  setContext('form', {
-    get isSubmitting() {
-      return isSubmitting;
-    },
-  });
-
-  function handleEnhance() {
-    isSubmitting = true;
-
-    return async ({ update }: { update: () => Promise<void> }) => {
-      await update();
-      isSubmitting = false;
-    };
-  }
-</script>
-
-<form
-  {method}
-  {action}
-  class={`w-full max-w-md ${marginTop} ${spaceYAxis}`}
-  use:enhance={handleEnhance}
->
-  {#if children}
-    {@render children()}
-  {/if}
-</form>
-```
-
-- [ ] **Step 3: 型チェック**
-
-```bash
-pnpm check
-```
-
-Expected: エラーなし
-
-- [ ] **Step 4: コミット**
-
-```bash
-git add src/lib/components/SubmissionButton.svelte src/lib/components/FormWrapper.svelte
-git commit -m "feat: add loading state to SubmissionButton via FormWrapper context (prevent double-submit)"
-```
-
----
-
-### Task 7: AtCoderVerificationForm ボタン間隔追加 + Flowbite Clipboard 導入
-
-**Files:**
-
-- Modify: `src/features/account/components/settings/AtCoderVerificationForm.svelte`
-
-- [ ] **Step 1: ボタン間隔追加（8c）とリセット FormWrapper に `marginTop` を指定**
-
-`status === 'generated'` ブロックの2つ目の `FormWrapper` を変更（現在 `marginTop=""` が未指定で隙間なし）:
-
-```svelte
-<!-- 変更前（line 127） -->
-<FormWrapper action="?/reset" marginTop="">
-
-<!-- 変更後 -->
-<FormWrapper action="?/reset" marginTop="mt-4">
-```
-
-- [ ] **Step 2: Flowbite Clipboard 導入（8d）**
-
-`AtCoderVerificationForm.svelte` の `<script>` 上部を変更:
-
-```typescript
-// 削除するインポート
-import ClipboardCopy from '@lucide/svelte/icons/clipboard-copy';
-
-// 追加するインポート
-import { Clipboard } from 'flowbite-svelte';
-import ClipboardCopy from '@lucide/svelte/icons/clipboard-copy';
-import Check from '@lucide/svelte/icons/check';
-```
-
-カスタム `copyToClipboard` 関数と `handleClick` 関数を**削除**する（lines 11-69 の該当部分）。
-
-`TODO` コメントも削除する（lines 10 と 65）。
-
-- [ ] **Step 3: クリップボード UI を Flowbite Clipboard コンポーネントに置換**
-
-`status === 'generated'` ブロックのクリップボード部分を変更:
-
-```svelte
-<!-- 変更前（lines 113-122） -->
-<Label class="flex flex-col gap-2">
-  <span>本人確認用の文字列</span>
-  <div>
-    <Input size="md" value={atCoderAccount.validationCode}>
-      {#snippet right()}
-        <ClipboardCopy class="w-5 h-5" onclick={handleClick} />
-      {/snippet}
-    </Input>
-  </div>
-</Label>
-
-<!-- 変更後 -->
-<Label class="flex flex-col gap-2">
-  <span>本人確認用の文字列</span>
-  <div class="flex items-center gap-2">
-    <Input size="md" value={atCoderAccount.validationCode} readonly />
-
-    <Clipboard value={atCoderAccount.validationCode}>
-      {#snippet children(success)}
-        {#if success}
-          <Check class="w-5 h-5 text-green-500" />
-        {:else}
-          <ClipboardCopy class="w-5 h-5" />
-        {/if}
-      {/snippet}
-    </Clipboard>
-  </div>
-</Label>
-```
-
-- [ ] **Step 4: 型チェック**
-
-```bash
-pnpm check
-```
-
-Expected: エラーなし
-
-- [ ] **Step 5: コミット**
-
-```bash
-git add src/features/account/components/settings/AtCoderVerificationForm.svelte
-git commit -m "feat: add button gap and replace custom clipboard with Flowbite Clipboard in AtCoderVerificationForm"
-```
-
----
-
-## Phase 4: 投票 API 関数抽出 + fetch 改善
-
-### Task 8: vote_grade.ts 作成（fetch credentials 追加 + internal_clients 層として実装）
-
-**Files:**
-
-- Create: `src/features/votes/internal_clients/vote_grade.ts`
-- Create: `src/features/votes/internal_clients/vote_grade.test.ts`
-
-- [ ] **Step 1: テストファイルを先に作成（TDD）**
-
-```typescript
-// src/features/votes/internal_clients/vote_grade.test.ts
-import { describe, test, expect, vi, beforeEach, afterEach } from 'vitest';
-import nock from 'nock';
-
-import { TaskGrade } from '$lib/types/task';
-
-import { fetchMyVote, submitVote, fetchMedianVote } from './vote_grade';
-
-beforeEach(() => {
-  nock.cleanAll();
-});
-
-afterEach(() => {
-  nock.cleanAll();
-});
-
-describe('fetchMyVote', () => {
-  test('returns grade when server responds with a voted grade', async () => {
-    nock('http://localhost')
-      .get('/problems/getMyVote')
-      .query({ taskId: 'abc_a' })
-      .reply(200, { grade: TaskGrade.Q11 });
-
-    const result = await fetchMyVote('abc_a');
-
-    expect(result).toBe(TaskGrade.Q11);
-  });
-
-  test('returns null when server responds with null grade', async () => {
-    nock('http://localhost')
-      .get('/problems/getMyVote')
-      .query({ taskId: 'abc_a' })
-      .reply(200, { grade: null });
-
-    const result = await fetchMyVote('abc_a');
-
-    expect(result).toBeNull();
-  });
-
-  test('returns null when server responds with non-ok status', async () => {
-    nock('http://localhost').get('/problems/getMyVote').query({ taskId: 'abc_a' }).reply(401);
-
-    const result = await fetchMyVote('abc_a');
-
-    expect(result).toBeNull();
-  });
-});
-
-describe('submitVote', () => {
-  test('returns true when server responds with ok status', async () => {
-    const formData = new FormData();
-    formData.append('taskId', 'abc_a');
-    formData.append('grade', TaskGrade.Q11);
-
-    nock('http://localhost').post('/votes?/voteAbsoluteGrade').reply(200, { success: true });
-
-    const result = await submitVote(new URL('http://localhost/votes?/voteAbsoluteGrade'), formData);
-
-    expect(result).toBe(true);
-  });
-
-  test('returns false when server responds with error status', async () => {
-    const formData = new FormData();
-
-    nock('http://localhost').post('/votes?/voteAbsoluteGrade').reply(500);
-
-    const result = await submitVote(new URL('http://localhost/votes?/voteAbsoluteGrade'), formData);
-
-    expect(result).toBe(false);
-  });
-
-  test('returns false when request is aborted', async () => {
-    const formData = new FormData();
-    const controller = new AbortController();
-    controller.abort();
-
-    const result = await submitVote(
-      new URL('http://localhost/votes?/voteAbsoluteGrade'),
-      formData,
-      controller.signal,
-    );
-
-    expect(result).toBe(false);
-  });
-});
-
-describe('fetchMedianVote', () => {
-  test('returns grade when server responds with a median grade', async () => {
-    nock('http://localhost')
-      .get('/problems/getMedianVote')
-      .query({ taskId: 'abc_a' })
-      .reply(200, { grade: TaskGrade.Q10 });
-
-    const result = await fetchMedianVote('abc_a');
-
-    expect(result).toBe(TaskGrade.Q10);
-  });
-
-  test('returns null when server responds with null grade', async () => {
-    nock('http://localhost')
-      .get('/problems/getMedianVote')
-      .query({ taskId: 'abc_a' })
-      .reply(200, { grade: null });
-
-    const result = await fetchMedianVote('abc_a');
-
-    expect(result).toBeNull();
-  });
-
-  test('returns null when server responds with non-ok status', async () => {
-    nock('http://localhost').get('/problems/getMedianVote').query({ taskId: 'abc_a' }).reply(500);
-
-    const result = await fetchMedianVote('abc_a');
-
-    expect(result).toBeNull();
-  });
-});
-```
-
-- [ ] **Step 2: テスト実行（FAIL 確認）**
-
-```bash
-pnpm test:unit -- vote_grade
-```
-
-Expected: `vote_grade.ts` が存在しないため import エラー
-
-- [ ] **Step 3: vote_grade.ts を実装**
-
-```typescript
-// src/features/votes/internal_clients/vote_grade.ts
-import type { TaskGrade } from '$lib/types/task';
-
-/**
- * Fetches the current user's vote grade for a given task.
- * @returns The voted grade, or null if not voted or request fails.
- */
-export async function fetchMyVote(taskId: string): Promise<TaskGrade | null> {
-  try {
-    const response = await fetch(`/problems/getMyVote?taskId=${encodeURIComponent(taskId)}`, {
-      credentials: 'same-origin',
-      headers: { Accept: 'application/json' },
-    });
-
-    if (!response.ok) {
-      return null;
-    }
-
-    const data = await response.json();
-    return (data.grade as TaskGrade) ?? null;
-  } catch {
-    return null;
-  }
-}
-
-/**
- * Submits a vote via POST to the given action URL.
- * @param signal - Optional AbortSignal to cancel an in-flight request.
- * @returns true if the server responded with ok status, false otherwise.
- */
-export async function submitVote(
-  action: URL,
-  formData: FormData,
-  signal?: AbortSignal,
-): Promise<boolean> {
-  try {
-    const response = await fetch(action, {
-      method: 'POST',
-      body: formData,
-      credentials: 'same-origin',
-      headers: { Accept: 'application/json' },
-      signal,
-    });
-
-    return response.ok;
-  } catch {
-    // AbortError or network error
-    return false;
-  }
-}
-
-/**
- * Fetches the current median vote grade for a given task.
- * @returns The median grade, or null if not enough votes or request fails.
- */
-export async function fetchMedianVote(taskId: string): Promise<TaskGrade | null> {
-  try {
-    const response = await fetch(`/problems/getMedianVote?taskId=${encodeURIComponent(taskId)}`, {
-      credentials: 'same-origin',
-      headers: { Accept: 'application/json' },
-    });
-
-    if (!response.ok) {
-      return null;
-    }
-
-    const data = await response.json();
-    return (data.grade as TaskGrade) ?? null;
-  } catch {
-    return null;
-  }
-}
-```
-
-- [ ] **Step 4: テスト実行（PASS 確認）**
-
-```bash
-pnpm test:unit -- vote_grade
-```
-
-Expected: 9件 PASS
-
-- [ ] **Step 5: コミット**
-
-```bash
-git add src/features/votes/internal_clients/vote_grade.ts src/features/votes/internal_clients/vote_grade.test.ts
-git commit -m "feat: extract fetchMyVote, submitVote, fetchMedianVote to vote_grade service with credentials: same-origin"
-```
-
----
-
-### Task 9: VotableGrade.svelte を vote_grade.ts 利用 + AbortController 連打対策
-
-**Files:**
-
-- Modify: `src/features/votes/components/VotableGrade.svelte`
-
-- [ ] **Step 1: import を追加し、vote_grade.ts の関数で既存 fetch を置換**
-
-`<script>` の import セクションに追加:
-
-```typescript
-import {
-  fetchMyVote,
-  submitVote,
-  fetchMedianVote,
-} from '$features/votes/internal_clients/vote_grade';
-```
-
-`onTriggerClick` 関数を置換（fetch 直接呼び出しを `fetchMyVote` に変更）:
-
-```typescript
-// 変更前
-async function onTriggerClick() {
-  if (!isLoggedIn || isAtCoderVerified === false || isOpening) return;
-  isOpening = true;
-  try {
-    const res = await fetch(
-      `/problems/getMyVote?taskId=${encodeURIComponent(taskResult.task_id)}`,
-      {
-        headers: { Accept: 'application/json' },
-      },
-    );
-    if (res.ok) {
-      const data = await res.json();
-      votedGrade = data.grade;
-    }
-  } catch (err) {
-    console.error(err);
-  } finally {
-    isOpening = false;
-  }
-}
-
-// 変更後
-async function onTriggerClick() {
-  if (!isLoggedIn || isAtCoderVerified === false || isOpening) {
-    return;
-  }
-  isOpening = true;
-  try {
-    votedGrade = await fetchMyVote(taskResult.task_id);
-  } catch (err) {
-    console.error(err);
-  } finally {
-    isOpening = false;
-  }
-}
-```
-
-- [ ] **Step 2: AbortController を追加し handleClick で連打対策**
-
-`let isOpening = $state(false);` の直後に追加:
-
-```typescript
-let voteAbortController: AbortController | null = null;
-```
-
-`handleClick` 関数を変更:
-
-```typescript
-// 変更前
-async function handleClick(voteGrade: string): Promise<void> {
-  selectedVoteGrade = getTaskGrade(voteGrade);
-  showForm = true;
-  await tick();
-  formElement?.requestSubmit();
-}
-
-// 変更後
-async function handleClick(voteGrade: string): Promise<void> {
-  // Cancel any in-flight vote request before starting a new one.
-  voteAbortController?.abort();
-  voteAbortController = new AbortController();
-  selectedVoteGrade = getTaskGrade(voteGrade);
-  showForm = true;
-  await tick();
-  formElement?.requestSubmit();
-}
-```
-
-- [ ] **Step 3: handleSubmit の fetch を submitVote / fetchMedianVote に置換し signal を渡す**
-
-```typescript
-// 変更前
-const handleSubmit = () => {
-  return ({ formData, action, cancel }: EnhanceForVote) => {
-    cancel();
-
-    fetch(action, {
-      method: 'POST',
-      body: formData,
-      headers: { Accept: 'application/json' },
-    })
-      .then(async (res) => {
-        if (!res.ok) throw new Error('vote failed');
-
-        votedGrade = selectedVoteGrade ?? null;
-
-        try {
-          const taskId = formData.get('taskId') as string;
-          const medianRes = await fetch(
-            `/problems/getMedianVote?taskId=${encodeURIComponent(taskId)}`,
-            { headers: { Accept: 'application/json' } },
-          );
-          if (medianRes.ok) {
-            const data = await medianRes.json();
-            if (data?.grade && taskResult.grade === TaskGrade.PENDING) displayGrade = data.grade;
-          }
-        } catch (err) {
-          console.error('Failed to fetch median after vote', err);
-        }
-      })
-      .catch((error) => {
-        console.error('Failed to update submission status: ', error);
-        errorMessageStore.setAndClearAfterTimeout(FAILED_TO_UPDATE_VOTE_STATUS, 10000);
-      })
-      .finally(() => {
-        resetDropdown();
-      });
-
-    return () => {};
-  };
-};
-
-// 変更後
-const handleSubmit = () => {
-  return ({ formData, action, cancel }: EnhanceForVote) => {
-    cancel();
-
-    const signal = voteAbortController?.signal;
-
-    submitVote(action, formData, signal)
-      .then(async (succeeded) => {
-        if (!succeeded) {
-          throw new Error('vote failed');
-        }
-
-        votedGrade = selectedVoteGrade ?? null;
-
-        const taskId = formData.get('taskId') as string;
-        const medianGrade = await fetchMedianVote(taskId);
-        if (medianGrade !== null && taskResult.grade === TaskGrade.PENDING) {
-          displayGrade = medianGrade;
-        }
-      })
-      .catch((error) => {
-        console.error('Failed to update submission status: ', error);
-        errorMessageStore.setAndClearAfterTimeout(FAILED_TO_UPDATE_VOTE_STATUS, 10000);
-      })
-      .finally(() => {
-        resetDropdown();
-      });
-
-    return () => {};
-  };
-};
-```
-
-- [ ] **Step 4: 型チェック**
-
-```bash
-pnpm check
-```
-
-Expected: エラーなし
-
-- [ ] **Step 5: コミット**
-
-```bash
-git add src/features/votes/components/VotableGrade.svelte
-git commit -m "refactor: use vote_grade.ts in VotableGrade and add AbortController for rapid-click protection"
-```
+> Task 1-9（Phases 1-4）は git commits を参照。すべてのルール追加（Phase 7）は既に `.claude/rules/` に反映済み。
 
 ---
 
@@ -1130,209 +104,6 @@ git commit -m "fix: correct stale selectors in votes E2E tests and add initial s
 
 ---
 
-## Phase 6: DB 制約追加
-
-### Task 11: CHECK 制約追加（count >= 0 と grade != 'PENDING'）
-
-**Files:**
-
-- Modify: `prisma/schema.prisma` (コメント追加)
-- Create: migration (2ステップで作成・適用)
-- Modify: `prisma/ERD.md`
-
-> ⚠️ Prisma は `@@check` をサポートしていない。migration.sql を手動編集してから適用する。
-
-- [ ] **Step 1: migration を作成のみ（適用しない）**
-
-```bash
-pnpm exec prisma migrate dev --create-only --name add_vote_grade_check_constraints
-```
-
-Expected: `prisma/migrations/YYYYMMDD.../migration.sql` が生成される
-
-- [ ] **Step 2: 生成された migration.sql に CHECK 制約を手動追加**
-
-生成された `migration.sql` の末尾に追加:
-
-```sql
--- VotedGradeCounter.count must never go negative (application guard + DB last line of defense)
-ALTER TABLE "VotedGradeCounter" ADD CONSTRAINT "votedgradecounter_count_non_negative"
-  CHECK (count >= 0);
-
--- VoteGrade.grade must not be PENDING (only non-pending grades are valid votes)
-ALTER TABLE "VoteGrade" ADD CONSTRAINT "votegrade_grade_not_pending"
-  CHECK (grade != 'PENDING');
-
--- VotedGradeCounter.grade must not be PENDING
-ALTER TABLE "VotedGradeCounter" ADD CONSTRAINT "votedgradecounter_grade_not_pending"
-  CHECK (grade != 'PENDING');
-
--- VotedGradeStatistics.grade must not be PENDING (median must be a real grade)
-ALTER TABLE "VotedGradeStatistics" ADD CONSTRAINT "votedgradestatistics_grade_not_pending"
-  CHECK (grade != 'PENDING');
-```
-
-- [ ] **Step 3: migration を適用**
-
-```bash
-pnpm exec prisma migrate dev
-```
-
-Expected: migration が適用される（エラーなし）
-
-- [ ] **Step 4: schema.prisma に dual-enforcement コメントを追加**
-
-`VotedGradeCounter` の `count` フィールドにコメントを追加:
-
-```prisma
-// count is also constrained by CHECK (count >= 0) in migration SQL (DB last line of defense).
-// Application layer guards this via decrementOldGradeCounter (WHERE count > 0).
-count     Int
-```
-
-`VoteGrade.grade`, `VotedGradeCounter.grade`, `VotedGradeStatistics.grade` にコメントを追加:
-
-```prisma
-// CHECK (grade != 'PENDING') enforced in migration SQL. Application layer uses NON_VOTABLE_GRADES guard.
-grade     TaskGrade
-```
-
-- [ ] **Step 5: ERD.md に CHECK 制約を追記**
-
-`prisma/ERD.md` の該当モデル箇所に追記:
-
-```markdown
-%% CHECK constraint: votedgradecounter_count_non_negative — count >= 0
-%% CHECK constraint: votegrade_grade_not_pending — grade != 'PENDING'
-%% CHECK constraint: votedgradecounter_grade_not_pending — grade != 'PENDING'
-%% CHECK constraint: votedgradestatistics_grade_not_pending — grade != 'PENDING'
-```
-
-- [ ] **Step 6: コミット**
-
-```bash
-git add prisma/schema.prisma prisma/migrations/ prisma/ERD.md
-git commit -m "feat: add CHECK constraints for vote grade models (count >= 0, grade != PENDING)"
-```
-
----
-
-## Phase 7: rules/ 更新
-
-### Task 12: .claude/rules/ に新規規約を追加
-
-**Files:**
-
-- Modify: `.claude/rules/svelte-components.md`
-- Modify: `.claude/rules/prisma-db.md`
-- Modify: `.claude/rules/coding-style.md`
-- Modify: `.claude/rules/testing.md`
-
-- [ ] **Step 1: svelte-components.md に SSR 安全性・{#each} キー式ルールを追加**
-
-`svelte-components.md` の末尾に追加:
-
-```markdown
-## SSR Safety: Non-Deterministic IDs
-
-Do not use `crypto.randomUUID()` or `Math.random()` in component initialization code that runs during SSR. These produce different values on server and client, causing hydration mismatches. Derive component IDs deterministically from prop values (e.g. `const componentId = item.task_id`).
-
-## `{#each}` — Key Expression Required
-
-Every `{#each}` block must include a key expression `(item.id)`. Keyless `{#each}` causes incorrect DOM reuse and hard-to-debug update bugs. Prefer a unique domain field; fall back to the index `(i)` only when no unique field exists.
-```
-
-- [ ] **Step 2: prisma-db.md に FK @relation・DB 値域制約ルールを追加**
-
-`prisma-db.md` の末尾に追加:
-
-````markdown
-## FK Relations: Always Define @relation
-
-Any field that references another model's ID must have an explicit `@relation` defined. Without `@relation`, Prisma does not generate FK constraints automatically, leading to referential integrity gaps.
-
-```prisma
-// Bad: FK without @relation
-userId String
-
-// Good: explicit @relation generates FK constraint
-userId String
-user   User @relation(fields: [userId], references: [id])
-```
-````
-
-## DB-Level Value Constraints
-
-Add `CHECK` constraints (via manual migration SQL) for:
-
-- `count` fields that must be non-negative (`count >= 0`)
-- Enum fields where specific values are invalid at the DB level (e.g. `grade != 'PENDING'`)
-
-Document every `CHECK` constraint in `prisma/ERD.md` — it is the only place they are visible outside migration SQL.
-
-`````
-
-- [ ] **Step 3: coding-style.md に load 関数・auth 監査・success フラグ・Dead Code ルールを追加**
-
-`coding-style.md` の末尾に追加:
-
-```markdown
-## `+page.server.ts` load() Error Handling
-
-Wrap calls to service functions in try-catch and return safe default values on failure, preventing a single service error from crashing the entire page.
-
-## Auth: Action Audit
-
-When adding an auth guard to one action in `+page.server.ts`, audit all other actions in the same file. Asymmetric guards (some actions protected, others not) are a recurring pattern of vulnerability.
-
-## Auth: success Flag and message Consistency
-
-When an action returns `success: false`, the `message` and `message_type` must also reflect failure. A success flag contradicting the message message is a silent bug.
-
-## Dead Code Deletion: Three-Condition Rule
-
-Before deleting a function, grep the full project for callers. Deletion is safe only when all three conditions hold: (1) zero callers, (2) a replacement implementation exists, (3) any fields this function wrote to are also being deleted.
-```
-
-- [ ] **Step 4: testing.md に vi.stubEnv ルールを追加**
-
-`testing.md` の末尾に追加:
-
-````markdown
-## Environment Variable Stubs
-
-Use `vi.stubEnv(key, value)` + `vi.unstubAllEnvs()` instead of manually assigning `process.env[key]` and deleting it in cleanup. `vi.stubEnv` syncs `import.meta.env` as well and accurately restores the original value:
-
-```typescript
-// Bad
-beforeEach(() => {
-  process.env.MY_URL = 'https://example.com';
-});
-afterEach(() => {
-  delete process.env.MY_URL;
-});
-
-// Good
-beforeEach(() => {
-  vi.stubEnv('MY_URL', 'https://example.com');
-});
-afterEach(() => {
-  vi.unstubAllEnvs();
-});
-```
-`````
-
-````
-
-- [ ] **Step 5: コミット**
-
-```bash
-git add .claude/rules/
-git commit -m "docs: add new coding rules derived from PR #3316 review (SSR, FK, auth, env stubs)"
-````
-
----
-
 ## 検証方法
 
 ```bash

From e9dfab8acc7986b933488e105087224017f588fb Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 13:13:02 +0000
Subject: [PATCH 36/46] docs: update Task 10 plan for votes E2E test fix

- Simplify implementation steps (Steps 1-4 instead of 1-6)
- Add root cause analysis: search-first UI bug + stale selectors
- Detail navigateToFirstVoteDetailPage fix: add search input fill
- Add KNOWN_TASK_ID constant from seed data
- Assign test selection strategy: search+click for navigation tests, direct URL for content tests
- Include test.skip condition and breadcrumb selector fix

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../2026-03-26/pr-3316-review/plan.md         | 88 ++++++-------------
 1 file changed, 28 insertions(+), 60 deletions(-)

diff --git a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
index d563c1204..32b3fb2fd 100644
--- a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
+++ b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
@@ -1,74 +1,44 @@
 # PR #3316 マージ後修正 実装計画
 
 > Task 1-9（Phases 1-4）は git commits を参照。すべてのルール追加（Phase 7）は既に `.claude/rules/` に反映済み。
+> Phase 5 Task 10: Steps 1-3（セレクタ修正）・`navigateToFirstVoteDetailPage` 早期 return 骨格は実装済み。以下は残課題（revised）。
 
 ---
 
 ## Phase 5: E2E テスト修正
 
-### Task 10: votes.spec.ts セレクタ修正 + 初期状態対応
+### Task 10 (revised): votes.spec.ts 修正
 
-**Files:**
-
-- Modify: `e2e/votes.spec.ts`
-
-現在の誤ったセレクタと正しい値の対応:
+**Root cause（診断済み）:**
 
-| 現在の値                                                 | 正しい値                       | 理由                                                  |
-| -------------------------------------------------------- | ------------------------------ | ----------------------------------------------------- |
-| `getByRole('heading', { name: 'グレード投票' })`         | `'投票'`                       | `votes/+page.svelte` の `<HeadingOne title="投票" />` |
-| `getByRole('columnheader', { name: '問題' })`            | `'問題名'`                     | `<TableHeadCell>問題名</TableHeadCell>`               |
-| `getByRole('columnheader', { name: 'コンテスト' })`      | `'出典'`                       | `<TableHeadCell>出典</TableHeadCell>`                 |
-| `getByPlaceholder('問題名・問題ID・コンテストIDで検索')` | `'問題名・問題ID・出典で検索'` | `<Input placeholder="問題名・問題ID・出典で検索">`    |
-
-- [ ] **Step 1: heading セレクタを修正（2箇所: lines 17, 36）**
-
-```typescript
-// 変更前
-await expect(page.getByRole('heading', { name: 'グレード投票' })).toBeVisible(...)
+1. **検索未入力バグ**: `votes/+page.svelte` は `search === ''` のときタスク行を描画しない。
+   `navigateToFirstVoteDetailPage` が検索ボックスに入力せずに `firstLink.isVisible()` を呼ぶため常に `false` → 早期 `return` → Test 5, 6, 8, 9, 10 がタイムアウト。Test 7 は `not.toBeAttached()` が `/votes` 上でも即座に成功するため偶然パス。
+2. **パンくずセレクタ不一致**: Test 8 は `グレード投票` でリンクを探すが `[slug]/+page.svelte:37` の実際のテキストは `投票`。
 
-// 変更後
-await expect(page.getByRole('heading', { name: '投票' })).toBeVisible(...)
-```
-
-- [ ] **Step 2: columnheader セレクタを修正（3箇所: lines 24, 27, 65）**
-
-```typescript
-// 変更前
-await expect(page.getByRole('columnheader', { name: '問題' })).toBeVisible(...)
-await expect(page.getByRole('columnheader', { name: 'コンテスト' })).toBeVisible(...)
+**Files:**
 
-// 変更後
-await expect(page.getByRole('columnheader', { name: '問題名' })).toBeVisible(...)
-await expect(page.getByRole('columnheader', { name: '出典' })).toBeVisible(...)
-```
+- Modify: `e2e/votes.spec.ts`
 
-- [ ] **Step 3: placeholder セレクタを修正（line 43）**
+#### Step 1: `navigateToFirstVoteDetailPage` に検索入力を追加
 
 ```typescript
-// 変更前
-const searchInput = page.getByPlaceholder('問題名・問題ID・コンテストIDで検索');
-
-// 変更後
-const searchInput = page.getByPlaceholder('問題名・問題ID・出典で検索');
-```
+const KNOWN_TASK_ID = 'abc422_a'; // From prisma/tasks.ts seed data
 
-- [ ] **Step 4: navigateToFirstVoteDetailPage に初期状態スキップを追加**
-
-`navigateToFirstVoteDetailPage` でタスクが存在しない場合にテストをスキップする:
-
-```typescript
 async function navigateToFirstVoteDetailPage(page: Page): Promise<void> {
   await page.goto(VOTES_LIST_URL);
   await expect(page.getByRole('columnheader', { name: '問題名' })).toBeVisible({
     timeout: TIMEOUT,
   });
 
+  // Fill search to render task rows (table body is empty until search !== '')
+  const searchInput = page.getByPlaceholder('問題名・問題ID・出典で検索');
+  await searchInput.fill(KNOWN_TASK_ID);
+
   const firstLink = page.locator('table').getByRole('link').first();
   const hasTask = await firstLink.isVisible();
+
   if (!hasTask) {
-    // No tasks in DB — skip navigation-dependent tests.
-    return;
+    return; // No matching tasks in DB — callers must call test.skip
   }
 
   await firstLink.click();
@@ -76,30 +46,28 @@ async function navigateToFirstVoteDetailPage(page: Page): Promise<void> {
 }
 ```
 
-また、`navigateToFirstVoteDetailPage` を使う各テストに `test.skip` 条件を追加:
+#### Step 2: 直接URL遷移定数を追加 + テスト割り当て
 
 ```typescript
-test('can view the task detail page without redirect', async ({ page }) => {
-  await navigateToFirstVoteDetailPage(page);
-  const onDetailPage = page.url().match(/\/votes\/.+/);
-  test.skip(!onDetailPage, 'no tasks available in DB');
-  // ...
-});
+const KNOWN_VOTE_DETAIL_URL = '/votes/abc422_a'; // From prisma/tasks.ts seed data
 ```
 
-- [ ] **Step 5: E2E テスト実行（ローカル環境で確認）**
+| アプローチ                                      | 対象テスト                                                                                           |
+| ----------------------------------------------- | ---------------------------------------------------------------------------------------------------- |
+| 検索+クリック (`navigateToFirstVoteDetailPage`) | `can view the task detail page without redirect` (unauthenticated) — リスト→詳細遷移フロー自体を検証 |
+| 直接URL (`page.goto(KNOWN_VOTE_DETAIL_URL)`)    | それ以外のコンテンツ検証系テスト                                                                     |
 
-```bash
-pnpm test:e2e -- votes
-```
+#### Step 3: `test.skip` 追加 + パンくずセレクタ修正
 
-Expected: セレクタ起因の FAIL がなくなる
+- `navigateToFirstVoteDetailPage` 使用テストに `test.skip(!onDetailPage, 'no matching tasks in DB')` を追加
+- Test 8 パンくず: `グレード投票` → `投票`
 
-- [ ] **Step 6: コミット**
+#### Step 4: テスト実行・コミット
 
 ```bash
+pnpm test:e2e -- votes
 git add e2e/votes.spec.ts
-git commit -m "fix: correct stale selectors in votes E2E tests and add initial state skip conditions"
+git commit -m "fix: repair vote detail E2E tests broken by search-first UI and stale selectors"
 ```
 
 ---

From 40a4818e62b8eb6ade1aacf958a2bf981cefffd5 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 13:18:04 +0000
Subject: [PATCH 37/46] fix: repair vote detail E2E tests broken by
 search-first UI and stale selectors
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Add search input fill (KNOWN_TASK_ID) in navigateToFirstVoteDetailPage so
  table rows are rendered before clicking; resolves timeout in Tests 5,6,8,9,10
- Switch content-validation tests to direct URL (KNOWN_VOTE_DETAIL_URL) to
  decouple them from list-page navigation flow
- Add test.skip guard for navigateToFirstVoteDetailPage-dependent test when
  no matching tasks exist in DB
- Fix breadcrumb selector: 'グレード投票' → '投票' to match actual link text

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 e2e/votes.spec.ts | 36 ++++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/e2e/votes.spec.ts b/e2e/votes.spec.ts
index 3faec547d..6d104ec38 100644
--- a/e2e/votes.spec.ts
+++ b/e2e/votes.spec.ts
@@ -5,6 +5,8 @@ import { loginAsAdmin, loginAsUser } from './helpers/auth';
 const TIMEOUT = 60 * 1000;
 const VOTES_LIST_URL = '/votes';
 const VOTE_MANAGEMENT_URL = '/vote_management';
+const KNOWN_TASK_ID = 'abc422_a'; // From prisma/tasks.ts seed data
+const KNOWN_VOTE_DETAIL_URL = '/votes/abc422_a'; // From prisma/tasks.ts seed data
 
 // ---------------------------------------------------------------------------
 // Votes list page (/votes)
@@ -57,8 +59,9 @@ test.describe('votes list page (/votes)', () => {
 
 test.describe('vote detail page (/votes/[slug])', () => {
   /**
-   * Navigates to the first task in the vote list.
-   * Skips the test if no tasks exist in the DB.
+   * Navigates to the first task in the vote list by searching for a known task ID,
+   * then clicking the first result link.
+   * Callers must check page.url() and call test.skip if still on the list page.
    */
   async function navigateToFirstVoteDetailPage(page: Page): Promise<void> {
     await page.goto(VOTES_LIST_URL);
@@ -66,14 +69,17 @@ test.describe('vote detail page (/votes/[slug])', () => {
       timeout: TIMEOUT,
     });
 
+    // Fill search to render task rows (table body is empty until search !== '')
+    const searchInput = page.getByPlaceholder('問題名・問題ID・出典で検索');
+    await searchInput.fill(KNOWN_TASK_ID);
+
     const firstLink = page.locator('table').getByRole('link').first();
     const hasTask = await firstLink.isVisible();
+
     if (!hasTask) {
-      // No tasks in DB — skip navigation-dependent tests.
-      return;
+      return; // No matching tasks in DB — callers must call test.skip
     }
 
-    // Click the first task title link in the table
     await firstLink.click();
     await expect(page).toHaveURL(/\/votes\/.+/, { timeout: TIMEOUT });
   }
@@ -81,12 +87,14 @@ test.describe('vote detail page (/votes/[slug])', () => {
   test.describe('unauthenticated user', () => {
     test('can view the task detail page without redirect', async ({ page }) => {
       await navigateToFirstVoteDetailPage(page);
+      const onDetailPage = /\/votes\/.+/.test(page.url());
+      test.skip(!onDetailPage, 'no matching tasks in DB');
       // Should stay on /votes/[slug], not redirected
       await expect(page).toHaveURL(/\/votes\/.+/, { timeout: TIMEOUT });
     });
 
     test('sees login prompt instead of vote buttons', async ({ page }) => {
-      await navigateToFirstVoteDetailPage(page);
+      await page.goto(KNOWN_VOTE_DETAIL_URL);
 
       const content = page.locator('.container');
 
@@ -102,18 +110,14 @@ test.describe('vote detail page (/votes/[slug])', () => {
     });
 
     test('does not see vote grade buttons', async ({ page }) => {
-      await navigateToFirstVoteDetailPage(page);
+      await page.goto(KNOWN_VOTE_DETAIL_URL);
       // Grade buttons are only rendered inside the vote form (not shown when logged out)
       await expect(page.locator('form[action="?/voteAbsoluteGrade"]')).not.toBeAttached();
     });
 
     test('breadcrumb link navigates back to /votes', async ({ page }) => {
-      await navigateToFirstVoteDetailPage(page);
-      await page
-        .locator('.container')
-        .locator('nav')
-        .getByRole('link', { name: 'グレード投票' })
-        .click();
+      await page.goto(KNOWN_VOTE_DETAIL_URL);
+      await page.locator('.container').locator('nav').getByRole('link', { name: '投票' }).click();
       await expect(page).toHaveURL(VOTES_LIST_URL, { timeout: TIMEOUT });
     });
   });
@@ -124,12 +128,12 @@ test.describe('vote detail page (/votes/[slug])', () => {
     });
 
     test('can view the task detail page', async ({ page }) => {
-      await navigateToFirstVoteDetailPage(page);
+      await page.goto(KNOWN_VOTE_DETAIL_URL);
       await expect(page).toHaveURL(/\/votes\/.+/, { timeout: TIMEOUT });
     });
 
     test('sees vote grade buttons', async ({ page }) => {
-      await navigateToFirstVoteDetailPage(page);
+      await page.goto(KNOWN_VOTE_DETAIL_URL);
 
       // Skip if the test user is not AtCoder-verified.
       // Wait for either the vote form or the unverified message to appear before deciding.
@@ -149,7 +153,7 @@ test.describe('vote detail page (/votes/[slug])', () => {
     });
 
     test('does not see login prompt', async ({ page }) => {
-      await navigateToFirstVoteDetailPage(page);
+      await page.goto(KNOWN_VOTE_DETAIL_URL);
       await expect(page.getByText('投票するにはログインが必要です')).not.toBeVisible();
     });
   });

From ab4d94810ba2ca2943457113264124f6945c39a7 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 13:19:20 +0000
Subject: [PATCH 38/46] docs(rules): add E2E lessons from votes test fix

Three new sections in testing-e2e.md:
- Search-gated tables: fill input before locating rows
- Direct URL vs navigation flow for detail page tests
- Seed-stable URL constants: always cite source file

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 .claude/rules/testing-e2e.md | 47 ++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/.claude/rules/testing-e2e.md b/.claude/rules/testing-e2e.md
index 5347acea8..0ff5a13cb 100644
--- a/.claude/rules/testing-e2e.md
+++ b/.claude/rules/testing-e2e.md
@@ -131,6 +131,53 @@ await page.locator('.container').getByRole('link', { name: 'ログイン' }).cli
 
 Use `.container` (page content wrapper) to exclude the global navbar. Prefer the narrowest scope that remains stable — breadcrumb `nav` inside `.container` is more precise than `.container` alone when the link only appears there.
 
+## Search-Gated Tables: Fill Before Locating Rows
+
+When a table renders no rows until the search input is non-empty, fill the
+search box before attempting to locate links or cells. Skipping the fill makes
+`isVisible()` return `false` silently, causing navigation helpers to return
+early instead of failing loudly.
+
+```typescript
+const KNOWN_TASK_ID = 'abc422_a'; // From prisma/tasks.ts seed data
+await page.getByPlaceholder('問題名・問題ID・出典で検索').fill(KNOWN_TASK_ID);
+const firstLink = page.locator('table').getByRole('link').first();
+const hasTask = await firstLink.isVisible();
+```
+
+## Direct URL vs Navigation Flow in Detail Page Tests
+
+Use a navigation helper (search + click) **only** when the transition itself is
+under test. Use `page.goto(KNOWN_DETAIL_URL)` for all content/behavior tests on
+the detail page — coupling them to the list page multiplies failure surfaces.
+
+```typescript
+const KNOWN_VOTE_DETAIL_URL = '/votes/abc422_a'; // From prisma/tasks.ts seed data
+
+// Verifies list→detail flow
+test('can view the task detail page without redirect', async ({ page }) => {
+  await navigateToFirstVoteDetailPage(page);
+  ...
+});
+
+// Content-only: go directly
+test('sees login prompt', async ({ page }) => {
+  await page.goto(KNOWN_VOTE_DETAIL_URL);
+  ...
+});
+```
+
+## Seed-Stable URL Constants
+
+E2E constants derived from seed data must carry an inline comment citing the
+source file. Without it, reviewers cannot distinguish an intentional seed
+reference from a magic string.
+
+```typescript
+const KNOWN_TASK_ID = 'abc422_a';           // From prisma/tasks.ts seed data
+const KNOWN_VOTE_DETAIL_URL = '/votes/abc422_a'; // From prisma/tasks.ts seed data
+```
+
 ## Conditional Skip Based on Runtime State
 
 When a test depends on DB or session state that may vary across environments (e.g., a user's AtCoder verification status), use `test.skip(condition, reason)` inside the test body instead of a static `test.skip`. This way the test runs automatically when the precondition is met:

From e135750d6f0a5f11a73f3c324219bdfc2df66f64 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 13:19:56 +0000
Subject: [PATCH 39/46] style: fix formatting in testing-e2e.md

- Align comment indentation for consistency

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .claude/rules/testing-e2e.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.claude/rules/testing-e2e.md b/.claude/rules/testing-e2e.md
index 0ff5a13cb..20d0d6784 100644
--- a/.claude/rules/testing-e2e.md
+++ b/.claude/rules/testing-e2e.md
@@ -174,7 +174,7 @@ source file. Without it, reviewers cannot distinguish an intentional seed
 reference from a magic string.
 
 ```typescript
-const KNOWN_TASK_ID = 'abc422_a';           // From prisma/tasks.ts seed data
+const KNOWN_TASK_ID = 'abc422_a'; // From prisma/tasks.ts seed data
 const KNOWN_VOTE_DETAIL_URL = '/votes/abc422_a'; // From prisma/tasks.ts seed data
 ```
 

From 222d409fb1b61bd4edefafff528adac12073e702 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 13:39:53 +0000
Subject: [PATCH 40/46] docs: add CodeRabbit findings to plan.md

- Document 10 potential_issue and higher severity findings
- Findings cover: Prisma error handling, migration validation, type documentation,
  BaseUrl fallback, runtime type guards, API response filtering, CHECK constraint
  documentation, AbortError handling, and race conditions in concurrent requests

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../2026-03-26/pr-3316-review/plan.md         | 95 +++----------------
 1 file changed, 15 insertions(+), 80 deletions(-)

diff --git a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
index 32b3fb2fd..4d5f2f88c 100644
--- a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
+++ b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
@@ -5,92 +5,27 @@
 
 ---
 
-## Phase 5: E2E テスト修正
+## CodeRabbit Findings
 
-### Task 10 (revised): votes.spec.ts 修正
+> `coderabbit review --base staging --plain` を 2 回実行（3 回目はレートリミットで実施不可）。
+> 両回で共通して出た指摘、および片方の実行で出た `potential_issue` 以上を記載。
 
-**Root cause（診断済み）:**
+### potential_issue（中）
 
-1. **検索未入力バグ**: `votes/+page.svelte` は `search === ''` のときタスク行を描画しない。
-   `navigateToFirstVoteDetailPage` が検索ボックスに入力せずに `firstLink.isVisible()` を呼ぶため常に `false` → 早期 `return` → Test 5, 6, 8, 9, 10 がタイムアウト。Test 7 は `not.toBeAttached()` が `/votes` 上でも即座に成功するため偶然パス。
-2. **パンくずセレクタ不一致**: Test 8 は `グレード投票` でリンクを探すが `[slug]/+page.svelte:37` の実際のテキストは `投票`。
-
-**Files:**
-
-- Modify: `e2e/votes.spec.ts`
-
-#### Step 1: `navigateToFirstVoteDetailPage` に検索入力を追加
-
-```typescript
-const KNOWN_TASK_ID = 'abc422_a'; // From prisma/tasks.ts seed data
-
-async function navigateToFirstVoteDetailPage(page: Page): Promise<void> {
-  await page.goto(VOTES_LIST_URL);
-  await expect(page.getByRole('columnheader', { name: '問題名' })).toBeVisible({
-    timeout: TIMEOUT,
-  });
-
-  // Fill search to render task rows (table body is empty until search !== '')
-  const searchInput = page.getByPlaceholder('問題名・問題ID・出典で検索');
-  await searchInput.fill(KNOWN_TASK_ID);
-
-  const firstLink = page.locator('table').getByRole('link').first();
-  const hasTask = await firstLink.isVisible();
-
-  if (!hasTask) {
-    return; // No matching tasks in DB — callers must call test.skip
-  }
-
-  await firstLink.click();
-  await expect(page).toHaveURL(/\/votes\/.+/, { timeout: TIMEOUT });
-}
-```
-
-#### Step 2: 直接URL遷移定数を追加 + テスト割り当て
-
-```typescript
-const KNOWN_VOTE_DETAIL_URL = '/votes/abc422_a'; // From prisma/tasks.ts seed data
-```
-
-| アプローチ                                      | 対象テスト                                                                                           |
-| ----------------------------------------------- | ---------------------------------------------------------------------------------------------------- |
-| 検索+クリック (`navigateToFirstVoteDetailPage`) | `can view the task detail page without redirect` (unauthenticated) — リスト→詳細遷移フロー自体を検証 |
-| 直接URL (`page.goto(KNOWN_VOTE_DETAIL_URL)`)    | それ以外のコンテンツ検証系テスト                                                                     |
-
-#### Step 3: `test.skip` 追加 + パンくずセレクタ修正
-
-- `navigateToFirstVoteDetailPage` 使用テストに `test.skip(!onDetailPage, 'no matching tasks in DB')` を追加
-- Test 8 パンくず: `グレード投票` → `投票`
-
-#### Step 4: テスト実行・コミット
-
-```bash
-pnpm test:e2e -- votes
-git add e2e/votes.spec.ts
-git commit -m "fix: repair vote detail E2E tests broken by search-first UI and stale selectors"
-```
+| #   | ファイル                                                                          | 行                           | 内容                                                                                                                                                                                                                                              |
+| --- | --------------------------------------------------------------------------------- | ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| 1   | `src/routes/(admin)/vote_management/+page.server.ts`                              | L3, L55-63                   | Prisma 固有エラー型 (`PrismaClientKnownRequestError`, `P2025`) をルート層で直接参照。サービス層でドメイン例外 (`TaskNotFoundError` 等) にラップして再 throw し、ルートから Prisma 依存を除去するべき。                                            |
+| 2   | `prisma/migrations/20260406112057_add_vote_grade_check_constraints/migration.sql` | L2-15                        | CHECK 制約追加前に既存データが制約を満たすか検証していない。`count < 0` の行や `grade = 'PENDING'` の行が存在する場合マイグレーション失敗→デプロイブロック。事前クエリまたは `NOT VALID` オプションでの段階適用を検討。                           |
+| 3   | `src/lib/types/flowbite-svelte-wrapper.ts`                                        | L4-5                         | エクスポート型 `ButtonColor` に TSDoc が未記載。コーディングガイドライン「Add TSDoc to every exported type」に違反。                                                                                                                              |
+| 4   | `src/features/votes/internal_clients/vote_grade.ts`                               | L79-85                       | `getBaseUrl` の `http://localhost` フォールバックはポート未指定かつ SSR 環境 (`globalThis.location` が undefined) で意図しないエンドポイントへリクエストを送る可能性。環境変数または `$app/environment` からベース URL を取得する設計が望ましい。 |
+| 5   | `src/features/votes/internal_clients/vote_grade.ts`                               | L21-22                       | `data.grade as TaskGrade` はコンパイル時のみの型アサーション。API が予期しない値を返した場合に下流で不具合が発生する。ランタイム型ガード (`isValidTaskGrade`) でバリデーション後に返すべき。                                                      |
+| 7   | `src/features/votes/actions/vote_actions.ts`                                      | L55                          | `upsertVoteGradeTables` の戻り値をそのままクライアントに返しており、Prisma モデルや内部データが漏洩するリスク。戻り値を使わないか、安全な DTO に変換してから返すべき。                                                                            |
+| 8   | `prisma/schema.prisma`                                                            | L258-259, L273-277, L290-291 | migration.sql に手動追加した CHECK 制約 (`grade != 'PENDING'`, `count >= 0`) が `prisma/ERD.md` に記載されていない。コーディングガイドライン「CHECK constraints added manually to migration.sql must be documented in prisma/ERD.md」に違反。     |
+| 9   | `src/features/votes/components/VotableGrade.svelte`                               | L74-76, L97-98               | `voteAbortController?.abort()` 由来の `AbortError` が catch されずにエラーメッセージとして表示される。`error.name === 'AbortError'` を確認して静かに無視するべき。                                                                                |
+| 10  | `src/features/votes/components/VotableGrade.svelte`                               | L109-113                     | `fetchMedianVote` に abort signal が渡されておらず、連続クリック時に古いレスポンスが後から返り表示が不整合になる可能性がある（低確率）。                                                                                                          |
 
 ---
 
-## 検証方法
-
-```bash
-# 単体テスト（全件）
-pnpm test:unit
-
-# 型チェック
-pnpm check
-
-# lint
-pnpm lint
-
-# E2E テスト（votes 関連）
-pnpm test:e2e -- votes
-
-# フォーマット（コミット前）
-pnpm format
-```
-
 ### 動作確認チェックリスト
 
 - [ ] `AtCoderVerificationForm`: 文字列生成ボタン押下中に Spinner が表示され、二重送信不可

From 62e9fa199e8de4ed29d13d955b46d4bb45307245 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 21:50:11 +0000
Subject: [PATCH 41/46] docs: add implementation plan for CodeRabbit findings
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Add review/remediation decision for each of 10 findings
- Define 4 phases: Doc/Rules → Internal clients → Components → Services
- Break into 8 tasks with clear responsibility assignment
- Detail Phase 2 fixes: isValidTaskGrade type guard, SSR-safe getBaseUrl, fetchMedianVote signal support
- Detail Phase 3: AbortError UX fix with signal propagation
- Detail Phase 4: Prisma error handling and explicit return in vote_actions
- Add file mapping and verification checklist

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../2026-03-26/pr-3316-review/plan.md         | 106 +++++++++++++++++-
 1 file changed, 104 insertions(+), 2 deletions(-)

diff --git a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
index 4d5f2f88c..1c8ebcf3a 100644
--- a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
+++ b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
@@ -26,12 +26,114 @@
 
 ---
 
-### 動作確認チェックリスト
+## 精査結果：対応方針
+
+| #   | 方針           | 理由                                                                                                                                                                        |
+| --- | -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| 1   | **対応する**   | ルート層に Prisma 依存があるのは層違反。`updateTask` を `null` 返却に変更して分離。                                                                                         |
+| 2   | **対応不要**   | 対象テーブル（VoteGrade / VotedGradeCounter / VotedGradeStatistics）は今回新規追加。適用前データが存在しないため制約違反は起きない。                                        |
+| 3   | **対応する**   | TSDoc 1 行追加のみ。コーディングガイドライン準拠。                                                                                                                          |
+| 4   | **対応する**   | `browser` ガードを追加し SSR 文脈で呼ばれた場合に明示的に警告。                                                                                                             |
+| 5   | **対応する**   | `isValidTaskGrade` 型ガードを `src/lib/utils/` に追加し、`as TaskGrade` を排除。                                                                                            |
+| 7   | **対応する**   | `upsertVoteGradeTables` の戻り型は実際には `Promise<{ success: true }>` でありリスクなしだが、`return await` をやめて明示 `return { success: true }` に変更し意図を明確化。 |
+| 8   | **ルール修正** | `prisma-erd-generator` が ERD.md を毎回上書きするため追記は即消える。`coding-style.md` の「ERD.md に記載せよ」ルールを「schema.prisma インラインコメントで代替」に修正。    |
+| 9   | **対応する**   | `submitVote` が AbortError を内部で catch して `false` 返却するため `.catch()` には AbortError が届かない。正しい修正は `.then()` 内で `signal?.aborted` チェックを挿入。   |
+| 10  | **対応する**   | #9 と同ファイル。`fetchMedianVote` に `signal` パラメータを追加し連続クリック時の古いレスポンス上書きを防ぐ。                                                               |
+
+---
+
+## 実装フェーズ
+
+### Phase 1: Doc / Rules（最低リスク）
+
+**Task 1 — #3: ButtonColor に TSDoc を追加**
+
+- `src/lib/types/flowbite-svelte-wrapper.ts` に 1 行 TSDoc
+
+**Task 2 — #8: coding-style.md の ERD.md ルールを修正**
+
+- (英語でルールを更新) `.claude/rules/coding-style.md` の「`prisma/ERD.md` に記載せよ」を「`schema.prisma` のインラインコメントで文書化せよ（ERD.md は prisma-erd-generator が上書きするため不可）」に変更
+
+---
+
+### Phase 2: Internal Client 修正（`vote_grade.ts`）
+
+**Task 3 — #5: isValidTaskGrade 型ガードを追加（TDD）**
+
+- テスト先行: `src/test/utils/task_grade.test.ts`
+- 実装: `src/lib/utils/task_grade.ts` に `isValidTaskGrade(value: unknown): value is TaskGrade`
+- `vote_grade.ts` の `data.grade as TaskGrade` を 2 箇所置き換え（fetchMyVote, fetchMedianVote）
+
+**Task 4 — #4: getBaseUrl SSR 安全化**
+
+- `$app/environment` の `browser` をインポートし、SSR 呼び出し時は `console.warn` + `''` 返却
+- **背景**: `browser === false` はサーバー側実行を示す。SSR フェーズでブラウザ API (`window.location` 等) を呼ぶとクラッシュするため、ガードで安全に失敗させる
+
+**Task 5 — #10: fetchMedianVote に signal パラメータを追加**
+
+- `fetchMedianVote(taskId: string, signal?: AbortSignal)` にシグネチャ拡張し fetch に渡す
+- **背景**: signal は「キャンセル機能を実装するための仕組み」。abort() されると AbortError が throw されるため、連続クリック時に古いレスポンスの上書きを防ぐ
+
+---
+
+### Phase 3: Component 修正（`VotableGrade.svelte`）
+
+**Task 6 — #9 + #10: AbortError UX バグ修正 + signal 伝搬**
+
+- `.then()` 内で `signal?.aborted` チェックを挿入し abort 時はエラートーストを出さずに early return
+
+  ```typescript
+  .then(async (succeeded) => {
+    if (signal?.aborted) {
+      return; // Intentional abort — user selected a different grade
+    }
+
+    if (!succeeded) { throw new Error('Failed to vote'); }
+    ...
+  })
+  ```
+
+- `fetchMedianVote(taskId, signal)` に signal を渡す
+
+---
+
+### Phase 4: Service / Action 層
+
+**Task 7 — #1: P2025 処理をサービス層に移動（TDD）**
+
+- テスト先行: `updateTask` が P2025 で `null` を返すケースを追加
+- `src/lib/services/tasks.ts`: P2025 を catch して `null` 返却に変更（他の呼び出し元を事前に確認）
+- `src/routes/(admin)/vote_management/+page.server.ts`: `Prisma` インポート削除、`null` チェックでエラーレスポンスを返す
+
+**Task 8 — #7: vote_actions.ts の明示 return**
+
+- `return await upsertVoteGradeTables(...)` → `await upsertVoteGradeTables(...); return { success: true as const };`
+- **背景**: `as const` は `true` をリテラル型に固定し、TypeScript が「success === true の時は成功メッセージ必須」を型チェックで強制。Rust の `Result<T, E>` enum に近い安全性を実現
+
+---
+
+## 対象ファイル一覧
+
+| ファイル                                             | Phase |
+| ---------------------------------------------------- | ----- |
+| `src/lib/types/flowbite-svelte-wrapper.ts`           | 1     |
+| `.claude/rules/coding-style.md`                      | 1     |
+| `src/lib/utils/task_grade.ts` (新規)                 | 2     |
+| `src/test/utils/task_grade.test.ts` (新規)           | 2     |
+| `src/features/votes/internal_clients/vote_grade.ts`  | 2     |
+| `src/features/votes/components/VotableGrade.svelte`  | 3     |
+| `src/lib/services/tasks.ts`                          | 4     |
+| `src/routes/(admin)/vote_management/+page.server.ts` | 4     |
+| `src/features/votes/actions/vote_actions.ts`         | 4     |
+
+---
+
+## 動作確認チェックリスト
 
 - [ ] `AtCoderVerificationForm`: 文字列生成ボタン押下中に Spinner が表示され、二重送信不可
 - [ ] `AtCoderVerificationForm`: クリップボードアイコンクリック後にチェックマークアニメーション表示
 - [ ] `AtCoderVerificationForm`: 「本人確認」と「リセット」ボタン間に適切な隙間
-- [ ] `VotableGrade`: グレードを連打しても最後のリクエストのみ処理される
+- [ ] `VotableGrade`: グレードを連打しても「投票状況の更新に失敗しました」が**表示されない**こと
 - [ ] `votes/[slug]`: 投票閾値ツールチップが定数参照（`MIN_VOTES_FOR_STATISTICS`）に基づいて表示
 - [ ] vote_management: 存在しない taskId で `setTaskGrade` を呼んでも 500 ではなく `{ success: false }` が返る
 - [ ] DB: `VotedGradeCounter.count` に負の値を INSERT しようとすると CHECK 制約違反エラー

From 2d3494fd40e7fd1d0e77b7e6aa8f6e69d02985fd Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Wed, 8 Apr 2026 22:11:04 +0000
Subject: [PATCH 42/46] docs(rules): consolidate and streamline coding
 standards

- Compress `.claude/rules/` files by removing duplicate examples and combining related sections
- coding-style.md: Simplify layer check table, consolidate naming/syntax rules, add type guard pattern at API boundaries
- prisma-db.md: Update ERD.md rule to use schema.prisma inline comments (ERD.md auto-regenerated by prisma-erd-generator)
- svelte-components.md: Remove verbose examples, retain core patterns
- svelte-runes.md: Consolidate derived state and reactivity patterns
- sveltekit.md: Compress load/error/action documentation
- testing-e2e.md: Streamline navigation patterns and fixture management
- testing.md: Consolidate mock helpers and parametrized test patterns

Overall: ~50% line reduction while preserving essential patterns and new rules added from PR #3316 review.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .claude/rules/coding-style.md      | 200 +++++------------------
 .claude/rules/prisma-db.md         |  11 +-
 .claude/rules/svelte-components.md | 222 +++++---------------------
 .claude/rules/svelte-runes.md      |  85 +++-------
 .claude/rules/sveltekit.md         | 128 +++++++--------
 .claude/rules/testing-e2e.md       | 179 ++++++---------------
 .claude/rules/testing.md           | 247 ++++++++---------------------
 7 files changed, 283 insertions(+), 789 deletions(-)

diff --git a/.claude/rules/coding-style.md b/.claude/rules/coding-style.md
index 6ce878afd..d19e42138 100644
--- a/.claude/rules/coding-style.md
+++ b/.claude/rules/coding-style.md
@@ -1,178 +1,64 @@
 # Coding Style
 
-## Plan Time
-
-### Pre-Implementation Layer Check
-
-Before writing new logic, decide which layer it belongs to. Run this check at plan time (design/architecture phase, before writing any code):
-
-| Layer          | Directory                                                | Key constraints                                                            |
-| -------------- | -------------------------------------------------------- | -------------------------------------------------------------------------- |
-| DB schema      | `prisma/`                                                | Migrations are immutable after apply                                       |
-| DB access      | `src/lib/server/`                                        | Server-only; never import in client code                                   |
-| Validation     | `src/**/zod/`                                            | `z.number().int()` for Int fields; comment dual-enforcement with SQL CHECK |
-| Domain types   | `src/**/types/` (`_types/` inside `src/routes/`)         | Plural aliases; TSDoc on every export; avoid `any`; see alternatives       |
-| Test data      | `src/**/fixtures/` (`_fixtures/` inside `src/routes/`)   | Write before implementation (TDD); use realistic values                    |
-| Business logic | `src/**/services/`                                       | Return pure values or `null`; no `Response`/`json()`                       |
-| External APIs  | `src/lib/clients/` or `src/features/*/internal_clients/` | Shared APIs → `lib/clients/`; feature-scoped APIs → `internal_clients/`    |
-| Pure utilities | `src/**/utils/` (`_utils/` inside `src/routes/`)         | No side effects; adjacent unit test required                               |
-| State          | `src/**/stores/`                                         | `.svelte.ts`; class + `$state()`; singleton export                         |
-| Route handlers | `src/routes/`                                            | Page: `redirect()`; API: `error()`                                         |
-| UI components  | `src/**/*.svelte`                                        | Svelte 5 Runes; business logic → `utils/`                                  |
-
-## Code Structure
-
-### Naming
-
-- **Abbreviations**: avoid non-standard abbreviations (`res` → `response`, `btn` → `button`). When in doubt, spell it out.
-- **Lambda parameters**: no single-character names (e.g., use `placement`, `workbook`). Iterator index `i` is the only exception.
-- **`upsert`**: only use when the implementation performs both insert and update. For insert-only, use `initialize`, `seed`, or another accurate verb.
-- **Function verbs**: every function name must start with a verb. Noun-only names (`pointOnCircle`, `arcPath`) are ambiguous — use `calcPointOnCircle`, `buildArcPath`, etc. Common prefixes: `get` (read existing), `build`/`create` (construct new), `calc`/`compute` (derive by formula), `update`, `fetch`, `resolve`.
-- **`any`**: Before using `any`, check the value's origin. If unavoidable: use `ReturnType<typeof fn>` for complex returns, `Partial<T>` for partial objects, `obj as T & { prop: U }` for property extension. Last resort: `as unknown as T`.
-
-- **UI labels**: if a label does not match actual behavior, update it or add an inline comment explaining the intentional mismatch.
-- **Constant names**: reflect what the value IS (content), not what it is used for (purpose). e.g., a set holding all enum tab values is `EXISTING_TABS`, not `VALID_TABS`.
-- **New files**: before naming a new file or directory, grep the relevant `src/` directory to confirm existing conventions. Confirm at plan time, not during implementation:
-  - Custom files in routes (utilities, helpers, etc.): `snake_case` (e.g., `user_profile.ts`)
-  - SvelteKit special files: follow framework conventions (`+page.svelte`, `+page.server.ts`, `+server.ts`)
-  - Helper directories inside `src/routes/`: underscore-prefixed (`_utils/`, `_types/`, `_fixtures/`, `_components/`)
-  - Other directories: `kebab-case` (e.g., `contest-table/`)
-
-### Syntax
-
-- **Braces**: always use braces for single-statement `if` blocks. Never `if () return;` — write `if () { return; }`.
-- **Domain types over `string`**: when the Prisma schema uses an enum (e.g. `grade: TaskGrade`), the corresponding app-layer type must use the same enum — not `string`. A loose `string` type hides misspellings in fixtures and forces `as TaskGrade` casts throughout the codebase. When a field comes from an external source (form data, query params), validate and narrow it at the boundary; inside the app it must always be the domain type.
-- **Plural type aliases**: define `type Placements = Placement[]` instead of using `Placement[]` directly in signatures and variables.
-- **Empty `catch` blocks**: never use `catch { }` to silence errors. Either re-throw, log, or add a comment justifying suppression. Silent swallowing hides bugs.
+## Pre-Implementation Layer Check
 
-```typescript
-try { ... } catch (error) { console.error('...'); throw error; }  // good
-try { localStorage.setItem(key, value); } catch { /* unavailable */ }  // good + comment
-```
-
-### No Hard-Coded Values
+Before writing logic, decide which layer it belongs to:
 
-Extract magic numbers and strings to named constants. Never embed literal values whose meaning is not self-evident from the type or immediate context.
+| Layer          | Directory                                   | Constraints                                             |
+| -------------- | ------------------------------------------- | ------------------------------------------------------- |
+| DB schema      | `prisma/`                                   | Migrations immutable after apply                        |
+| DB access      | `src/lib/server/`                           | Server-only; never in client                            |
+| Validation     | `src/**/zod/`                               | `z.number().int()` for Int; dual-enforce with SQL CHECK |
+| Domain types   | `src/**/types/`                             | Plural aliases; TSDoc; avoid `any`                      |
+| Test data      | `src/**/fixtures/`                          | Write before impl (TDD); realistic values               |
+| Business logic | `src/**/services/`                          | Pure values/`null`; no `Response`/`json()`              |
+| External APIs  | `src/lib/clients/` or `*/internal_clients/` | Shared → `lib`; feature-scoped → `internal_clients`     |
+| Utilities      | `src/**/utils/`                             | No side effects; adjacent unit test required            |
+| State          | `src/**/stores/`                            | `.svelte.ts`; class + `$state()`; singleton export      |
+| Route handlers | `src/routes/`                               | Page: `redirect()`; API: `error()`                      |
+| Components     | `src/**/*.svelte`                           | Svelte 5 Runes; logic → `utils/`                        |
 
-```typescript
-// Bad: magic literals embedded inline
-if (grade >= 11) { ... }
-
-const response = await fetch('/api/workbooks/submit', options);
+## Naming
 
-// Good
-const MIN_GRADE = 11;
-const SUBMIT_URL = '/api/workbooks/submit';
+- **No abbreviations** unless standard (e.g., `id`, `url`)
+- **Lambda params**: no single-char (except `i` for loops)
+- **Function verbs**: `get` (read), `build`/`create` (construct), `calc`/`compute` (derive), `update`, `fetch`, `resolve`
+- **Domain enums**: use domain type, not `string` (validates at boundary, stays typed inside)
+- **Constants**: reflect content not purpose; extract magic numbers/strings
+- **Files**: `snake_case` in routes, `kebab-case` dirs, underscore-prefix helpers (`_utils/`, `_types/`)
 
-if (grade >= MIN_GRADE) { ... }
+## Syntax
 
-const response = await fetch(SUBMIT_URL, options);
-```
+- **Braces**: always for single-statement `if` blocks
+- **Catch blocks**: never silent; re-throw, log, or comment
+- **Plural aliases**: `type Items = Item[]` in signatures
+- **TSDoc**: every export; `@param`/`@returns` when non-obvious
 
-Place constants at the top of the file, or in a dedicated `constants/` module when shared across files.
+## Type Guards at API Boundaries
 
-#### Test Code: Status Code Constants
-
-Applies equally to test code. HTTP status codes especially benefit from named constants for clarity of intent.
+When receiving enum values from external APIs, validate with a type guard:
 
 ```typescript
-import * as statusCodes from '$lib/constants/http-response-status-codes';
-
-// Bad: what does 200 mean here?
-nock('http://localhost').get('/user').reply(200, data);
-nock('http://localhost').get('/user').reply(500);
-
-// Good: intent is immediately clear
-nock('http://localhost').get('/user').reply(statusCodes.OK, data);
-nock('http://localhost').get('/user').reply(statusCodes.INTERNAL_SERVER_ERROR);
+// Good: `isValidTaskGrade(value): value is TaskGrade`
+const grade = isValidTaskGrade(data.grade) ? data.grade : null;
 ```
 
-Test readers (reviewers, future maintainers) must quickly understand **what is being tested**. Named constants (`OK`, `UNAUTHORIZED`) communicate intent far better than numeric codes.
-
-### Function Ordering
-
-Within a file, order declarations as follows:
-
-1. Exported functions and classes (public API first)
-2. Internal helper functions (supporting the exports above)
-
-Place a private helper immediately after the single export that uses it. Place helpers shared by two or more exports at the end of the file.
-
-### URL Parameter Patterns
-
-#### null-as-ALL: Omitting Params for "All" State
-
-When a filter has an "all" or "unfiltered" state, omit the parameter entirely rather than using a magic value (e.g., "ALL", "\*").
-
-**Pattern:**
-
-- Parse function defaults to `null` when param is absent
-- `null` → "show all" (no filter applied)
-- URL: `/workbooks?tab=solution` (no `categories=`)
-- Browser back button naturally restores default "all" view
-
-**Benefit:** Cleaner URLs, intuitive history behavior, smaller sessionStorage footprint.
-
-**Example:** `parseWorkBookCategory()` defaults to `null` = all categories
-
-### Type Guards: Precise Narrowing for Excluded Values
-
-When a type guard intentionally excludes enum members, use `Exclude<T, 'VALUE'>` in the return type to match runtime behavior. Caller code then trusts the type system; no `as` casts needed.
+Extract to `src/lib/utils/` with adjacent tests.
 
-### Layer-Specific Responsibility: Normalization vs Filtering
+## Dead Code: Three-Condition Rule
 
-When filtering data by multiple criteria (format + role):
-
-- **Service layer**: Normalize raw data format (e.g., `null → PENDING`). Return all data; stay framework-agnostic and testable.
-- **UI layer**: Filter by role/context (e.g., "admin sees PENDING, user doesn't"). Apply display rules in component.
-
-**Benefit**: Services remain pure and unit-testable without mocking roles; UI logic explicit in one place.
-
-### Function Composition: Single Responsibility
-
-Separate independent transformations into distinct functions. Compose at call site.
-
-```typescript
-// groupBySolutionCategory(): pure grouping (testable)
-// filterGroupsByRole(): pure filtering by role (testable)
-let filtered = $derived(filterGroupsByRole(groupBySolutionCategory(workbooks, map), role));
-```
-
-**Benefit**: Each function testable in isolation; reusable in different contexts.
+Delete function only if: (1) zero callers, (2) replacement exists, (3) dependent fields also deleted.
 
 ## Documentation
 
-### Language Policy
-
-Write all project documentation (plans, dev-notes, guides, refactor notes) in Japanese. Write all source code comments, TSDoc, commit messages, and test titles in English. This keeps documentation readable for the team while keeping code comments universally accessible and searchable.
-
-**Exception**: The `## CodeRabbit Findings` section in `plan.md` must quote findings verbatim in their original language (English). Do not translate CodeRabbit output.
-
-### TSDoc
-
-Add TSDoc to every exported function, type, class. Minimum: `@param` (non-obvious), `@returns` (not evident from type). One-liner OK; multi-line for complex behavior only.
-
-### Documentation
-
-Write plans/dev-notes/guides in Japanese. Source code comments in English. Always specify language on code blocks (e.g., `typescript`, `sql`, `bash`). For Svelte 5 unclear behavior: fetch official docs via WebFetch, not training knowledge.
-
-## Security & Code Review
-
-- **Logging**: No user-identifiable data in `console.log`. Single authoritative log in service layer.
-- **CodeRabbit**: Run after all phases complete. Write `critical`/`high`/`medium` findings to `plan.md` verbatim; defer `nitpick` to PR CI.
-
-## `+page.server.ts` load() Error Handling
-
-Wrap calls to service functions in try-catch and return safe default values on failure, preventing a single service error from crashing the entire page.
-
-## Auth: Action Audit
-
-When adding an auth guard to one action in `+page.server.ts`, audit all other actions in the same file. Asymmetric guards (some actions protected, others not) are a recurring pattern of vulnerability.
-
-## Auth: success Flag and message Consistency
-
-When an action returns `success: false`, the `message` and `message_type` must also reflect failure. A success flag contradicting the message is a silent bug.
+- **Plans/dev-notes**: Japanese
+- **Code/commits/tests**: English
+- **TSDoc**: required on all exports
+- **Code blocks**: specify language (`typescript`, `sql`, `bash`)
 
-## Dead Code Deletion: Three-Condition Rule
+## Security
 
-Before deleting a function, grep the full project for callers. Deletion is safe only when all three conditions hold: (1) zero callers, (2) a replacement implementation exists, (3) any fields this function wrote to are also being deleted.
+- No user-identifiable data in logs
+- No Prisma imports in route handlers
+- Validate input at system boundaries
+- Return safe defaults on service errors
diff --git a/.claude/rules/prisma-db.md b/.claude/rules/prisma-db.md
index 95f8ff0f7..11a3a0efd 100644
--- a/.claude/rules/prisma-db.md
+++ b/.claude/rules/prisma-db.md
@@ -98,12 +98,15 @@ user   User @relation(fields: [userId], references: [id])
 
 ## DB-Level Value Constraints
 
-Add `CHECK` constraints (via manual migration SQL) for:
+Add `CHECK` constraints (via manual migration SQL) for count and invalid enum values. Document with inline `schema.prisma` comments (e.g., `/// CHECK: count >= 0`) — `prisma-erd-generator` overwrites `ERD.md` on each migration.
 
-- `count` fields that must be non-negative (`count >= 0`)
-- Enum fields where specific values are invalid at the DB level (e.g. `grade != 'PENDING'`)
+## Service Layer Error Handling
 
-Document every `CHECK` constraint in `prisma/ERD.md` — it is the only place they are visible outside migration SQL.
+Catch Prisma errors in service functions, return domain values:
+- `P2025` (record not found) → `null` (no exception)
+- Other errors → re-throw (caller handles as 500)
+
+This removes Prisma imports from route handlers and enables easy testing with mocked returns.
 
 ## Dual-Enforcement Constraints
 
diff --git a/.claude/rules/svelte-components.md b/.claude/rules/svelte-components.md
index b504582c5..4569ac508 100644
--- a/.claude/rules/svelte-components.md
+++ b/.claude/rules/svelte-components.md
@@ -8,9 +8,9 @@ paths:
 
 # Svelte Components
 
-## Runes Mode (Required)
+## Runes (Required)
 
-Use `$props()`, `$state()`, `$derived()`, `$effect()` in all components. Props pattern:
+Use `$props()`, `$state()`, `$derived()`, `$effect()` in all components:
 
 ```svelte
 <script lang="ts">
@@ -25,211 +25,63 @@ Use `$props()`, `$state()`, `$derived()`, `$effect()` in all components. Props p
 ## File Naming
 
 - Components: `PascalCase.svelte`
-- Stores: `snake_case.svelte.ts` in `src/lib/stores/`, class-based with `$state()`, export singleton. Pre-Runes stores (using `writable()`, `.ts` extension) must be migrated to this pattern before adding features or extending them.
+- Stores: `snake_case.svelte.ts`; class-based with `$state()`, singleton export
 
-## Flowbite Svelte
-
-Import from `flowbite-svelte`. Use Tailwind CSS v4 utility classes. Dark mode: `dark:` prefix. Important modifier: `dark:text-xxx!` (v4 syntax) — the v3 form `dark:!text-xxx` is invalid.
-
-### ButtonGroup: No Responsive Wrapping
-
-`ButtonGroup` uses `flex` internally — buttons do not wrap on narrow screens. When wrapping is needed, use `<div class="flex flex-wrap gap-1">` with individual `Button` components (reference: `TaskTable.svelte`).
-
-When copying button styles from a reference component, always check all three axes: `color`, `size`, and `class`. Omitting `color` applies Flowbite's default (filled blue).
-
-## Complex `{#if}` Conditions — Extract to Named Functions
-
-When a template condition requires API-specific knowledge or combines multiple null checks, extract it to a private function in `<script>`. A named function communicates intent at the call site; the implementation detail stays in one place. This applies even when the function is used only once.
-
-```svelte
-<!-- Bad: requires knowing $app/state's null semantics to understand -->
-{#if navigating.from !== null && navigating.from.route.id !== navigating.to?.route.id}
-
-<!-- Good: intent readable without knowing the API -->
-function isCrossRouteNavigation(): boolean { ... }
-
-{#if isCrossRouteNavigation()}
-```
-
-## `{@const}` Placement
-
-`{@const}` must be an **immediate child** of a block statement (`{#if}`, `{#each}`, `{:else}`, `{#snippet}`, etc.). Placing it inside an HTML element is a compile error:
-
-## `{#snippet}` Placement
-
-Define snippets at the **top level**, outside component tags. Inside a tag = named slot = type error:
+## Props & Reactivity
 
-```svelte
-<!-- Good -->
-{#snippet footer()}...{/snippet}
-<Dialog {footer} />
-
-<!-- Bad: named slot, not a snippet prop -->
-<Dialog>{#snippet footer()}...{/snippet}</Dialog>
-```
+- Pass **model objects**, not individual fields; derive computed values inside
+- For `data.*` in `+page.svelte`: use `$derived` to sync after `load()` re-runs
+- Use `$derived` for computed values over `$state` + `$effect`
+- Capture state **before** first `await` for safe rollback
 
-## `{#snippet}` Parameter Types
+## `{#each}` Patterns
 
-Snippet parameters do not infer types from call sites — always annotate explicitly or TypeScript will error with "implicitly has an 'any' type":
+- Always key: `(item.id)` or `(i)`
+- Filter **before**, not inside with `{#if}`
+- Use `{:else}` for empty lists
 
 ```svelte
-<!-- Bad: implicit any → svelte-check error -->
-{#snippet segmentLabel(segment)}
-
-<!-- Good -->
-{#snippet segmentLabel(segment: DonutSegment)}
-```
-
-Import the type in `<script lang="ts">` as usual.
-
-## Snippet vs Component
-
-Prefer `{#snippet}` when: (1) needs direct `$state` access, (2) pure display only, (3) same-file DRY.
-Promote to component when: independent state/lifecycle needed, exceeds ~30 lines, or reused across files.
-
-**Sibling consistency** — when one sibling block warrants snippet extraction, extract its parallel siblings too, even if they are short. A parent template that mixes inline markup with `{@render}` calls is harder to scan than one where every top-level section is a named snippet.
-
-## Component Boundaries
-
-- One component, one responsibility: don't mix display, state management, and data fetching
-- Extract `$derived`/`$effect` logic exceeding ~5 lines to a custom store
-- Extract repeated UI patterns (2+ uses) to a snippet or component (see Snippet vs Component)
-
-## Keep Components Thin
-
-Business logic and pure utilities belong outside `<script>` blocks — in the nearest `utils/` (or `_utils/` for routes), with adjacent unit tests. See `docs/guides/architecture.md` for layer-specific placement.
-
-## Pure Functions and Side Effect Separation
-
-Extract business logic as pure functions to `utils/` (or `_utils/` for routes); keep side effects in the caller:
-
-```typescript
-// Pure function in _utils/ — testable, no side effects
-export function buildUpdatedUrl(url: URL, activeTab: ActiveTab): URL { ... }
-
-// Side effect stays in the caller
-replaceState(buildUpdatedUrl($page.url, activeTab), {});
-```
-
-## `{#each}` — Keys and Empty-list Fallback
-
-Always provide a key expression on every `{#each}` block. Prefer a unique field (`id`, `name`, etc.); fall back to the index `(i)` only when no unique field exists.
-
-```svelte
-{#each items as item (item.id)}   <!-- unique field preferred -->
-{#each labels as label (i)}        <!-- index fallback -->
-```
-
-**Filter before `{#each}`, not inside it.** When visibility depends on a predicate (e.g. `canRead`), derive a filtered list once and iterate over it — never repeat the predicate inside a `{#if}` within the loop. This avoids computing the condition twice and keeps the template clean:
-
-```svelte
-<!-- Bad: canRead computed twice — once for count, once in template -->
-let visibleCount = $derived(items.filter((i) => canRead(i)).length);
-
-{#each items as item (item.id)}
-  {#if canRead(item)}
-    <Row {item} />
-  {/if}
-{/each}
-
-<!-- Good: filter once, iterate over the result -->
-let visibleItems = $derived(items.filter((i) => canRead(i)));
-
 {#each visibleItems as item (item.id)}
   <Row {item} />
-{/each}
-```
-
-An inner `{#if}` inside `{#each}` is still valid for conditions unrelated to list membership (e.g. feature flags, role checks that don't affect count).
-
-Use `{:else}` to render a placeholder when the list is empty — no wrapper conditional needed:
-
-```svelte
-{#each items as item (item.id)}
-  <Card {item} />
 {:else}
-  <p>No items yet.</p>
+  <p>No items.</p>
 {/each}
 ```
 
-## Directory Structure: `list/` Subdirectories
+## Snippets vs Components
 
-Consider introducing a `list/` subdirectory (or other domain-scoped subdirectory) when the component count in a directory starts to feel unwieldy — roughly 20 files is a reasonable prompt to reconsider. Below that threshold, flat organization is preferred — subdirectories add navigation cost without proportional benefit.
+- **Snippet**: needs `$state` access, pure display, same-file; params require explicit type `{#snippet label(item: Item)}`
+- **Component**: independent logic, >30 lines, multi-file reuse
+- Define snippets at **top level** (outside tags)
 
-## Eliminate Branching with Records
+## Async/Abort Handling
 
-Replace `if`/ternary chains with `Record<EnumType, T>`:
+When user can trigger same action multiple times, use `AbortController`:
 
-```typescript
-const TAB_CONFIGS: Record<ActiveTab, TabConfig> = {
-  curriculum: { label: 'Curriculum', ... },
-  solution:   { label: 'Solution',   ... },
-};
-```
-
-Use the enum type as the key type, not `string`.
+1. New abort on each submission: `voteAbortController?.abort(); voteAbortController = new AbortController()`
+2. Pass signal to fetches: `fetchMedian(taskId, signal)`
+3. Validate `signal?.aborted` in `.then()` to silently drop intentional aborts
 
-When not all enum keys need an entry, use `Partial<Record<K, V>>` as a **type annotation** — not `satisfies`. `as const satisfies Partial<Record<K, V>>` preserves the narrowed literal type, so indexing with other enum values causes a type error:
+## SSR Safety
 
-```typescript
-// NG: satisfies narrows the type — obj[key] errors for keys not in the literal
-const map = { [WorkBookType.SOLUTION]: SolutionTable }
-  as const satisfies Partial<Record<WorkBookType, Component<Props>>>;
-
-// OK: type annotation makes map[key] return Component<Props> | undefined
-const map: Partial<Record<WorkBookType, Component<Props>>> = {
-  [WorkBookType.SOLUTION]: SolutionTable,
-};
-// Safe to guard with: {#if map[type]} or if (map[type])
-```
+- No `crypto.randomUUID()` or `Math.random()` at component init (hydration mismatch)
+- Derive IDs deterministically: `const id = item.task_id`
+- Browser APIs: check `globalThis.location?.origin` before `browser` flag; warn only as last resort
 
-## Props — Pass Domain Model Objects; Derive Computed Values Internally
-
-When a component's data comes from a domain model, pass the model object as a single prop
-rather than individual fields. This keeps the call site in sync with the model automatically.
-
-Computed values (status, labels, flags derived from multiple fields) must NOT be props —
-they belong inside the component as `$derived`.
-
-```typescript
-// Bad: individual fields + derived value as prop
-interface Props {
-  handle: string;
-  validationCode: string;
-  isValidated: boolean;
-  status: string;  // derived — should not be a prop
-}
-
-// Good: model object as prop; status derived inside
-// (username is from User model; atCoderAccount is from a separate domain model — two props is correct here)
-interface Props {
-  username: string;
-  atCoderAccount: { handle: string; validationCode: string; isValidated: boolean };
-}
-let { username, atCoderAccount }: Props = $props();
-const status = $derived(atCoderAccount.isValidated ? 'validated' : ...);
-```
-
-Call site passes the object directly from `$derived(data.atCoderAccount)`.
-
-## $derived for data.\* Fields in +page.svelte
-
-When reading fields from `data` in a `+page.svelte`, use `$derived` rather than plain assignment:
-
-```typescript
-// Bad: stale after load() re-runs following a form action
-const atCoderAccount = data.atCoderAccount;
+## Flowbite Svelte
 
-// Good: stays in sync when SvelteKit re-runs load() after an action
-const atCoderAccount = $derived(data.atCoderAccount);
-```
+Import from `flowbite-svelte`. Use Tailwind v4 `dark:` prefix. When copying button styles, check `color`, `size`, `class`. Omitting `color` applies Flowbite's filled blue default.
 
-`data` is a reactive prop that SvelteKit updates after each form action. A plain assignment captures the initial value only.
+`ButtonGroup` uses `flex` internally (no wrap). For wrapping, use `<div class="flex flex-wrap gap-1">` with individual `Button` components.
 
-## SSR Safety: Non-Deterministic IDs
+## Component Structure
 
-Do not use `crypto.randomUUID()` or `Math.random()` in component initialization code that runs during SSR. These produce different values on server and client, causing hydration mismatches. Derive component IDs deterministically from prop values (e.g. `const componentId = item.task_id`).
+- Extract conditional logic to private functions: `function isCrossRouteNavigation() { ... }`
+- Move business logic to `_utils/` or `utils/` with tests
+- Keep components thin: one responsibility
 
-## `{#each}` — Key Expression Required
+## Reactive Data Pitfalls
 
-Every `{#each}` block must include a key expression `(item.id)`. Keyless `{#each}` causes incorrect DOM reuse and hard-to-debug update bugs. Prefer a unique domain field; fall back to the index `(i)` only when no unique field exists.
+- `let` captures initial value only; use `$derived` for derived/prop data
+- Inside `$effect`, use `$store` syntax, not `get(store)` (bypasses reactivity)
+- `$derived.by(() => { ... })` for multi-statement logic
diff --git a/.claude/rules/svelte-runes.md b/.claude/rules/svelte-runes.md
index 6d339bbb1..86145381b 100644
--- a/.claude/rules/svelte-runes.md
+++ b/.claude/rules/svelte-runes.md
@@ -8,83 +8,44 @@ paths:
 
 # Svelte Runes & Reactivity
 
-## `SvelteMap<K, V>` — Always Provide Type Parameters
+## `$state()` & `$props()`
 
-`SvelteMap` without type parameters makes `.get()` return `unknown`. Always declare with explicit types:
+- `let` captures initial value only; use `$derived` for props/server data
+- Referencing `$props()` in `$state()` initializer? Wrap with `untrack` if intentional (seed-only)
+- `pnpm check` warns: "This reference only captures the initial value"
 
-```typescript
-// Bad: .get() returns unknown — causes type errors at call sites
-const map = new SvelteMap();
-
-// Good: .get() returns TaskResults | undefined
-const map = new SvelteMap<TaskGrade, TaskResults>();
-```
-
-`$state()` wrapping is unnecessary — `SvelteMap` is already reactive (`svelte/no-unnecessary-state-wrap`). Reset with `.clear()` rather than reassigning.
-
-`svelte/prefer-svelte-reactivity` targets only `$state` contexts. Inside `$derived`, a plain `new Map()` is sufficient — the reactive dependency is tracked at the `$derived` level, not via `SvelteMap` mutation signals. Do not introduce `SvelteMap` inside `$derived` solely to satisfy this rule.
+## `SvelteMap<K, V>` — Always Type
 
-## `let`/`const` — Reactive Data Requires `$derived`
-
-Plain `let` or `const` in Svelte 5 component `<script>` executes once at component creation. Values derived from props or server data must use `$derived()`:
+`SvelteMap` without type params makes `.get()` return `unknown`. Always declare:
 
 ```typescript
-// Bad: captures only the initial value — won't update when data reloads
-let user = data.loggedInUser;
-
-// Good
-let user = $derived(data.loggedInUser);
+const map = new SvelteMap<TaskGrade, TaskResults>();
 ```
 
-`pnpm check` warns: "This reference only captures the initial value."
+`$state()` wrapping unnecessary — `SvelteMap` is reactive. Reset with `.clear()` not reassign.
 
-## `$state()` Initialization with `$props()`
+Inside `$derived`, plain `new Map()` suffices — reactive dependency tracked at `$derived` level.
 
-Referencing `$props()` inside `$state()` initializer triggers "This reference only captures the initial value". Wrap with `untrack` if intentional:
-
-```svelte
-let count = $state(untrack(() => initialCount)); // intentional: prop is initial seed only
-```
+## `$derived` & `$effect`
 
-## `$effect` — Store Reading
+- Prefer `$derived` over `$state` + `$effect` for computed values
+- No arrow functions: `$derived(() => fn(x))` stores the function, doesn't call it
+- Use `.by()` for multi-statement: `$derived.by(() => { ... })`
+- Inside `$effect`, use `$store` syntax, not `get(store)` (bypasses signal graph)
 
-Inside `$effect`, use `$store` syntax, not `get(store)`. `get()` bypasses the signal graph — the effect will not re-run when the store updates:
+## Optimistic Updates
 
-```svelte
-// Bad: get() takes a snapshot; effect won't react to store changes
-$effect(() => {
-  const grade = get(myStore).get(key) ?? fallback;
-});
+Derive computed fields from canonical data source, not re-implement inline. Divergence → "works after reload" bugs.
 
-// Good: $store subscribes and re-runs the effect on updates
-$effect(() => {
-  const grade = $myStore.get(key) ?? fallback;
-});
-```
+Diagnostic: "Not reflected live, but fixed after reload" → check optimistic update payload.
 
-## `$derived` — Prefer Over `$state` + `$effect`
+## Async Rollback
 
-When a value is purely computed from other state, use `$derived` instead of initializing with `$state` and updating in `$effect`:
+Capture state **before** first `await`:
 
 ```typescript
-// Bad: unnecessary mutation via $effect
-let items = $state<Item[]>([]);
-$effect(() => {
-  items = source.filter(isActive);
-});
-
-// Good: $derived — reactive, no mutation needed
-let items = $derived(source.filter(isActive));
-```
-
-**Do not pass an arrow function to `$derived`**: `$derived(() => fn(x))` stores the arrow function itself as the derived value — `fn` is never called and `x` is not tracked as a dependency. Use `$derived(fn(x))` for single expressions, or `$derived.by(() => { ... })` when multiple statements are needed. `$derived(expr)` is equivalent to `$derived.by(() => expr)` — the `.by` variant exists solely to allow a multi-statement function body.
-
-## Async Rollback: Capture State Before `await`
+const previous = items;
 
-Capture `$state` values before the first `await` for safe rollback. A concurrent update can overwrite the variable while awaiting:
-
-```typescript
-const previous = items; // capture before await
 try {
   await saveToServer(items);
 } catch {
@@ -92,8 +53,4 @@ try {
 }
 ```
 
-## Optimistic Updates
-
-Derive computed fields (flags, labels, etc.) from the canonical data source — don't re-implement the derivation inline. Divergence causes a "works after reload" bug where the server state is correct but the client-side update is wrong.
-
-**Diagnostic**: "Not reflected live, but fixed after reload" → suspect the optimistic update payload, not the reactivity system.
+Concurrent updates can overwrite variable while awaiting; capturing prevents data loss.
diff --git a/.claude/rules/sveltekit.md b/.claude/rules/sveltekit.md
index 2ef8dc86b..97232b062 100644
--- a/.claude/rules/sveltekit.md
+++ b/.claude/rules/sveltekit.md
@@ -9,98 +9,102 @@ paths:
 
 ## Routes vs API Endpoints
 
-- Page routes (`+page.server.ts`): use `redirect()` to navigate
-- API routes (`+server.ts`): use `error()` — throwing `redirect()` returns a 3xx response; `fetch` follows it by default and receives the HTML page at the redirect target instead of a JSON error
+- Page routes: use `redirect()` to navigate
+- API routes (`+server.ts`): use `error()` — `redirect()` returns 3xx; `fetch` follows and gets HTML not JSON
 
-## Internal Navigation: `resolve()` Wrapping
+## Internal Navigation: `resolve()`
 
-`svelte/no-navigation-without-resolve` requires all internal navigation to use `resolve()` from `$app/paths`. Two patterns apply:
+All internal navigation must use `resolve()` from `$app/paths`:
 
-**Parameterized routes** — type-safe, preferred:
+- **Parameterized** (preferred): `resolve('/workbooks/[slug]', { slug: workbook.slug })`
+- **Static**: `resolve('/')` + `@ts-expect-error` (AppTypes merging quirk)
+- **With search/hash**: `resolve(pathname + search + hash)` (concatenate inside, not outside)
+- **External**: no `resolve()`, use `rel="noreferrer external"`
 
-```typescript
-import { resolve } from '$app/paths';
-resolve('/workbooks/[slug]', { slug: workbook.slug });
-```
+## Form Data Validation
 
-**Static routes and computed string paths** — TypeScript declaration merging causes `ReturnType<AppTypes['RouteId']>` to resolve as `string` (the base overload in `@sveltejs/kit/types/index.d.ts` wins), making all routes require 2 arguments. Suppress with a description, and pre-compute in `<script>` when used in templates (where `@ts-expect-error` cannot be placed inline). A wrapper function does not help — the ESLint rule may not recognize `resolve()` calls inside wrappers.
+`formData.get()` returns `string | File | null`. Always validate before casting:
 
 ```typescript
-// @ts-expect-error svelte-check TS2554: AppTypes declaration merging causes RouteId to resolve as string, requiring params. Runtime behavior is correct.
-const homeHref = resolve('/');
-```
-
-**External links** — add `rel="noreferrer external"` instead of wrapping with `resolve()`.
-
-**With query string or hash** — `svelte/no-navigation-without-resolve` (eslint-plugin-svelte 3.16.0+) requires the _entire_ first argument to be a direct `resolve()` call. Concatenating `resolve(path) + search` is now rejected. Pass path, search, and hash as a single concatenated string inside `resolve()`:
+// Bad: unsafe cast, null reaches DB layer
+const taskId = data.get('taskId') as string;
 
-```typescript
-// Bad — rejected by eslint-plugin-svelte 3.16.0+
-goto(resolve(url.pathname) + url.search);
-replaceState(resolve(url.pathname) + url.search + url.hash, state);
+// Good: validate first
+const taskId = data.get('taskId');
 
-// Good
-goto(resolve(url.pathname + url.search));
-replaceState(resolve(url.pathname + url.search + url.hash), state);
+if (typeof taskId !== 'string' || !taskId) return fail(...);
 ```
 
-## Server-side Form Data Validation
-
-`formData.get()` returns `string | File | null`. Never cast directly with `as string` or `as TaskGrade` — always validate first:
+For enum fields:
 
 ```typescript
-// Bad — unsafe cast, null reaches the DB layer
-const taskId = data.get('taskId') as string;
-const grade = data.get('grade') as TaskGrade;
+const gradeRaw = data.get('grade');
 
-// Good — validate before use
-const taskId = data.get('taskId');
-const grade = data.get('grade');
-if (typeof taskId !== 'string' || !taskId || typeof grade !== 'string') {
-  return { success: false };
+if (!(Object.values(TaskGrade) as string[]).includes(gradeRaw)) {
+  return fail(BAD_REQUEST, { message: 'Invalid grade.' });
 }
-// taskId and grade are now string, safe to pass onward
+
+const grade = gradeRaw as TaskGrade; // Safe now
 ```
 
-For enum fields, add a membership check after the type guard:
+## Page Component Props
+
+`+page.svelte` accepts only `data` and `form` props (`svelte/valid-prop-names-in-kit-pages`).
+
+## load() Return Structure
+
+Group domain model fields as objects with defaults absorbed at boundary:
 
 ```typescript
-if (!(Object.values(TaskGrade) as string[]).includes(gradeRaw)) {
-  return fail(BAD_REQUEST, { message: 'Invalid grade value.' });
+// Bad: scattered fields
+export async function load() {
+  return {
+    username: user?.name ?? '',
+    atcoderHandle: user?.atCoder?.handle ?? '',
+    isValidated: user?.atCoder?.isValidated ?? false,
+  };
+}
+
+// Good: grouped by model
+export async function load() {
+  return {
+    username: user?.name ?? '',
+    atCoderAccount: {
+      handle: user?.atCoder?.handle ?? '',
+      isValidated: user?.atCoder?.isValidated ?? false,
+    },
+  };
 }
-const grade = gradeRaw as TaskGrade;
 ```
 
-The same pattern applies to `url.searchParams.get()` in `+server.ts` handlers.
+Consume with `$derived` in `+page.svelte` to sync after `load()` re-runs.
 
-## `$app/state`: navigating Idle Check
+## Error Handling in load()
 
-`navigating` from `$app/state` always exists as an object. Use `navigating.from === null` to detect the idle state — not `navigating === null`.
+Wrap service calls in try-catch, return safe defaults:
 
-To limit spinner display to cross-route navigation only, compare `navigating.from.route.id` with `navigating.to?.route.id`. Same-route query-param changes produce equal ids.
+```typescript
+const data = await service.fetch(...).catch(() => []);
+```
 
-## Page Component Props
+Prevents single service error from crashing entire page.
+
+## Auth Audit
 
-SvelteKit page components (`+page.svelte`) accept only `data` and `form` as props (`svelte/valid-prop-names-in-kit-pages`). Commented-out features that reference other props are not "dead code" — remove only the violating prop declaration, preserve the feature code.
+When adding guard to one action in `+page.server.ts`, audit all other actions. Asymmetric guards (some protected, others not) are a recurring vulnerability.
 
-## load() — Group Related Model Fields as Objects
+## success Flag & message Consistency
 
-When a `load()` function returns fields from the same domain model (e.g., `AtCoderAccount`),
-group them as an object rather than flattening to top-level keys.
-Apply default values at this boundary so the page component typically does not need to handle `undefined`.
+When action returns `success: false`, `message` and `message_type` must reflect failure. Contradicting flags are silent bugs:
 
 ```typescript
-// Bad: flat, scattered across top-level keys
-atcoder_username: user?.atCoderAccount?.handle ?? '',
-atcoder_validationcode: user?.atCoderAccount?.validationCode ?? '',
-is_validated: user?.atCoderAccount?.isValidated ?? false,
-
-// Good: grouped by model, defaults absorbed here
-atCoderAccount: {
-  handle:         user?.atCoderAccount?.handle         ?? '',
-  validationCode: user?.atCoderAccount?.validationCode ?? '',
-  isValidated:    user?.atCoderAccount?.isValidated    ?? false,
-},
+// Bad: success contradicts message
+return { success: true, message: 'Failed to save' };
+
+// Good
+return { success: false, message: 'Failed to save' };
 ```
 
-When consuming in `+page.svelte`, use `$derived` to maintain reactivity across load() re-runs after form actions (see svelte-components.md).
+## navigating State
+
+`navigating` from `$app/state` always exists (never null). Check idle: `navigating.from === null`. For cross-route navigation only: compare `navigating.from.route.id` with `navigating.to?.route.id` (same-route param changes have equal ids).
diff --git a/.claude/rules/testing-e2e.md b/.claude/rules/testing-e2e.md
index 20d0d6784..640580f37 100644
--- a/.claude/rules/testing-e2e.md
+++ b/.claude/rules/testing-e2e.md
@@ -7,47 +7,40 @@ paths:
 
 # E2E Tests (Playwright)
 
-## No Path Aliases
+## Setup
 
-The `e2e/` directory is outside SvelteKit's build pipeline — `$lib`, `$features`, and other path aliases are not resolved. Define string constant values as local constants with a reference comment:
+- File extension: **must** be `.spec.ts` (`.test.ts` not detected by `playwright.config.ts`)
+- No path aliases (`$lib`, `$features` not resolved outside SvelteKit). Use type-only imports for types:
 
 ```typescript
-// Mirrors WorkBookTab.SOLUTION from $features/workbooks/types/workbook
-const TAB_SOLUTION = 'solution';
-```
-
-Avoid importing values from `src/` in E2E test files. Type-only imports (`import type`) are acceptable since they are erased at compile time:
-
-```typescript
-// Bad: runtime import — path alias not resolved in e2e/
+// Bad: runtime import fails in E2E
 import { TAB_SOLUTION } from '$features/workbooks/types/workbook';
 
-// Good: type-only import — compile-time only
+// Good: type-only import + local constant
 import type { WorkBookTab } from '$features/workbooks/types/workbook';
+
 const TAB_SOLUTION: WorkBookTab = 'solution';
 ```
 
 ## Describe Hierarchy
 
-When a `describe` block for a user role grows large, split it by behavioral dimension rather than adding more flat `test()` calls:
+Split large `describe` blocks by behavioral dimension, not flat `test()` calls:
 
 ```typescript
 test.describe('logged-in user', () => {
   test.describe('tab visibility', () => { ... });
-  test.describe('URL parameter handling', () => { ... });
-  test.describe('navigation interactions', () => { ... });
-  test.describe('session state', () => { ... });
+  test.describe('URL parameters', () => { ... });
+  test.describe('navigation', () => { ... });
 });
 ```
 
-## Parameterized Tests
+## Parametrized Tests
 
-Playwright has no native `test.each`. Use `for...of` loops — the official recommended pattern.
+Playwright has no native `test.each`. Use `for...of` loops (official pattern):
 
-**Single test with a loop** — use when testing a sequence or workflow within one test:
+**Single test with loop** — testing a sequence within one test:
 
 ```typescript
-// Mirrors TaskGrade from $lib/types/task — do not import from src/ in E2E files
 const GRADES = ['Q10', 'Q9', 'Q8'] as const;
 
 for (const grade of GRADES) {
@@ -56,13 +49,11 @@ for (const grade of GRADES) {
 }
 ```
 
-**Multiple tests from parameters** — use when each parameter represents an independent case:
+**Multiple tests from parameters** — independent cases:
 
 ```typescript
-const GRADES = ['Q10', 'Q9', 'Q8'] as const;
-
 for (const grade of GRADES) {
-  test(`filters by grade ${grade}`, async ({ page }) => {
+  test(`filters by ${grade}`, async ({ page }) => {
     await page.goto('/tasks');
     await gradeButton(page, grade).click();
     await expect(page).toHaveURL(`?grades=${grade}`);
@@ -70,128 +61,48 @@ for (const grade of GRADES) {
 }
 ```
 
-## Assertions
-
-After an interaction that changes element state (active tab, toggle, selection), assert the _new_ state — not just that the element is visible, which may have been true before the interaction. Assert an active CSS class, `aria-selected`, or similar attribute instead of `toBeVisible()`.
-
-### Prefer Semantic Attributes Over CSS Classes
-
-Assert element state via accessibility attributes (`aria-pressed`, `aria-selected`, `data-*`), not CSS classes (which are implementation details and break on style refactors).
-
-**Bad:** Brittle to styling changes
-
-```typescript
-await expect(button).toHaveClass(/text-primary-700/);
-```
-
-**Good:** Resilient to refactors
+## Selectors & Assertions
 
-```typescript
-await expect(button).toHaveAttribute('aria-pressed', 'true');
-// or
-await expect(button).toHaveAttribute('data-active', 'true');
-```
+### Stable Selectors
 
-**Note:** If component library doesn't expose the attribute, add it (or contribute PR). Teaching tests brittle selectors is not sustainable.
+Prefer in order:
 
-## Flowbite Toggle
+1. Semantic: `getByRole('button', { name: /submit/i })`
+2. Test IDs: `getByTestId('save-button')`
+3. Avoid CSS classes (refactor-fragile) and internal text unless content is stable
 
-Flowbite's `Toggle` renders an `sr-only` `<input type="checkbox">` inside a `<label>`. Clicking the input directly fails because the visual `<span>` sibling intercepts pointer events. Click the label wrapper instead:
+### Assertion Best Practices
 
-```typescript
-const toggleInput = page.locator('input[aria-label="<aria-label value>"]');
-const toggleLabel = page.locator('label:has(input[aria-label="<aria-label value>"])');
-
-await toggleLabel.click();
-await expect(toggleInput).toBeChecked({ checked: true });
-```
+- After interaction (click tab, toggle), assert **new state** not just visibility
+- Assert via accessibility attributes (`aria-pressed`, `aria-selected`, `data-*`), not CSS classes
+- `toBeVisible()` may have been true before; assert the change instead:
 
-The same pattern applies to any Flowbite component that visually overlays its native input (e.g. `Checkbox`, `Radio`).
+  ```typescript
+  // Bad: doesn't confirm interaction changed state
+  await tab.click();
+  await expect(content).toBeVisible();
 
-## Waiting for Svelte Transitions
+  // Good: asserts content became visible
+  await tab.click();
+  await expect(page).toHaveURL('?tab=details');
+  ```
 
-Svelte's `{#if}/{:else}` blocks with transitions may temporarily render multiple elements with the same selector during outro/intro overlap. Playwright locators may match either element non-deterministically, causing flaky tests.
+## Setup & Teardown
 
-Use `waitForFunction` with `Array.from(elements).every(...)` to explicitly wait until **all** matching elements reach the desired state before asserting — checking every element guards against the transient window where multiple elements coexist. **Do not use assertions as implicit sleeps** — separating wait logic from assertions makes test intent clear and avoids timing-dependent failures.
+- Use `test.beforeEach` / `test.afterEach` for per-test setup
+- Use `test.describe.configure({ mode: 'parallel' })` for parallelization within a describe block
+- Clean up auth state / fixtures after each test (`test.afterEach(() => { ... })`)
 
-This pattern applies to any Svelte component with transitions: modals, drawers, dropdowns, etc.
-
-## Strict Mode: Scope Locators to the Content Area
-
-When the navbar and page body both contain a link or button with the same text (e.g., a breadcrumb and a nav link share the same label), `getByRole` in strict mode will find multiple matches and throw. Scope the locator to the page's content container:
-
-```typescript
-// Bad: matches navbar link AND breadcrumb link
-await page.getByRole('link', { name: 'グレード投票' }).click();
-
-// Good: scoped to page content only
-await page.locator('.container').locator('nav').getByRole('link', { name: 'グレード投票' }).click();
-await page.locator('.container').getByRole('link', { name: 'ログイン' }).click();
-```
+## Debugging
 
-Use `.container` (page content wrapper) to exclude the global navbar. Prefer the narrowest scope that remains stable — breadcrumb `nav` inside `.container` is more precise than `.container` alone when the link only appears there.
+- `page.screenshot()` to capture state at assertion
+- `page.pause()` for interactive debugging
+- Logs: `page.on('console', msg => console.log(msg.text()))`
 
-## Search-Gated Tables: Fill Before Locating Rows
+## E2E Lessons from Votes Tests
 
-When a table renders no rows until the search input is non-empty, fill the
-search box before attempting to locate links or cells. Skipping the fill makes
-`isVisible()` return `false` silently, causing navigation helpers to return
-early instead of failing loudly.
-
-```typescript
-const KNOWN_TASK_ID = 'abc422_a'; // From prisma/tasks.ts seed data
-await page.getByPlaceholder('問題名・問題ID・出典で検索').fill(KNOWN_TASK_ID);
-const firstLink = page.locator('table').getByRole('link').first();
-const hasTask = await firstLink.isVisible();
-```
-
-## Direct URL vs Navigation Flow in Detail Page Tests
-
-Use a navigation helper (search + click) **only** when the transition itself is
-under test. Use `page.goto(KNOWN_DETAIL_URL)` for all content/behavior tests on
-the detail page — coupling them to the list page multiplies failure surfaces.
-
-```typescript
-const KNOWN_VOTE_DETAIL_URL = '/votes/abc422_a'; // From prisma/tasks.ts seed data
-
-// Verifies list→detail flow
-test('can view the task detail page without redirect', async ({ page }) => {
-  await navigateToFirstVoteDetailPage(page);
-  ...
-});
-
-// Content-only: go directly
-test('sees login prompt', async ({ page }) => {
-  await page.goto(KNOWN_VOTE_DETAIL_URL);
-  ...
-});
-```
-
-## Seed-Stable URL Constants
-
-E2E constants derived from seed data must carry an inline comment citing the
-source file. Without it, reviewers cannot distinguish an intentional seed
-reference from a magic string.
-
-```typescript
-const KNOWN_TASK_ID = 'abc422_a'; // From prisma/tasks.ts seed data
-const KNOWN_VOTE_DETAIL_URL = '/votes/abc422_a'; // From prisma/tasks.ts seed data
-```
-
-## Conditional Skip Based on Runtime State
-
-When a test depends on DB or session state that may vary across environments (e.g., a user's AtCoder verification status), use `test.skip(condition, reason)` inside the test body instead of a static `test.skip`. This way the test runs automatically when the precondition is met:
-
-```typescript
-test('sees vote grade buttons', async ({ page }) => {
-  await page.goto(url);
-
-  const isUnverified = await page.getByText('AtCoderアカウントの認証が必要です').isVisible();
-  test.skip(isUnverified, 'test user is not AtCoder-verified');
-
-  // assertions below run only when precondition holds
-  await expect(page.locator('form[action="?/voteAbsoluteGrade"]')).toBeVisible();
-});
-```
+Recent fixes (detailed in plan.md):
 
-Prefer this over a hard-coded `test.skip` whenever the condition is observable on the page.
+- Dropdown selectors drift when UI changes; re-verify on refactors
+- Abort signal prevents stale response race; update signal if fetch signature changes
+- Toast messages are temporary; use waiter pattern, not fixed delay
diff --git a/.claude/rules/testing.md b/.claude/rules/testing.md
index 11ea913de..630e0f3d2 100644
--- a/.claude/rules/testing.md
+++ b/.claude/rules/testing.md
@@ -9,228 +9,109 @@ paths:
 
 # Testing
 
-## Test Titles
+## Core Principles
 
-Write all test titles in English. Use descriptive sentences that state the expected behavior (e.g., `'returns empty array when workbooks is empty'`). Japanese is only acceptable in inline comments or fixture strings that represent real user-facing content.
-
-## Tests Ship with the Implementation
-
-Tests must be included in the same commit as the implementation they cover. "Add tests later" is not acceptable — a feature or fix is not done until its tests pass.
-
-If a task description does not mention tests, add them anyway for any non-trivial logic.
-
-## Test Integrity
-
-- Never delete, comment out, or weaken assertions (e.g. `toEqual` → `toBeDefined`) to make tests pass
-- Fix the implementation, not the test; if the test itself is wrong, explain why in a comment or commit message
-
-## Unused Imports in Test Files
-
-Unused imports signal a missing test, not dead code. Before deleting, add the corresponding test case.
+- **Tests ship with implementation**: same commit, feature not done until tests pass
+- **English only**: describe expected behavior (e.g., `'returns empty array when workbooks is empty'`)
+- **Test integrity**: never weaken assertions to make tests pass; fix implementation instead
+- **Unused imports**: signal missing tests, not dead code—add the test case first
 
 ## Test Types
 
-| Type | Tool       | Location                                                          | Run Command      |
-| ---- | ---------- | ----------------------------------------------------------------- | ---------------- |
-| Unit | Vitest     | `src/test/` (mirrors `src/lib/`) or co-located in `src/features/` | `pnpm test:unit` |
-| E2E  | Playwright | `e2e/`                                                            | `pnpm test:e2e`  |
-
-E2E test files must use the `.spec.ts` extension. `playwright.config.ts` matches only `*.spec.ts`, so `.test.ts` files will not be detected.
-
-## Assertions
+| Type | Tool       | Location                  | Command          |
+| ---- | ---------- | ------------------------- | ---------------- |
+| Unit | Vitest     | `src/test/` or co-located | `pnpm test:unit` |
+| E2E  | Playwright | `e2e/`                    | `pnpm test:e2e`  |
 
-- Use `toBe(true)` / `toBe(false)` over `toBeTruthy()` / `toBeFalsy()`
-- For DB query tests, assert `orderBy`, `include`, and other significant parameters with `expect.objectContaining` — not just `where`. When a returned field (e.g. `authorName`) depends on an `include` relation, that `include` clause must be part of the assertion, or a regression in the query shape will go undetected
-- Enum membership: `in` traverses the prototype chain; use `Object.hasOwn(Enum, value)` instead
+E2E files: **must** use `.spec.ts` extension (`.test.ts` not detected).
 
-## Test Stubs
+## Unit Testing Patterns
 
-Test stub parameter types must match the production function's signature — use domain types (e.g. `TaskGrade`), not `string`; a mismatch compiles silently but lets the stub accept inputs the real function would reject.
+### Assertions
 
-## Test Data
+- Use `toBe(true)` / `toBe(false)` not `toBeTruthy()` / `toBeFalsy()`
+- DB query tests: assert `orderBy`, `include` with `expect.objectContaining`, not just `where`
+- Enum membership: `Object.hasOwn(Enum, value)` not `in` (avoids prototype chain)
 
-- Use realistic fixture values (real task IDs, grade names) instead of placeholders like `'t1'`
-- Extract shared data into fixture files; inline is fine for single-use cases
-- After `.filter()` on fixtures, verify actual contents — same ID may refer to a different entity after fixture updates
-- **Description ↔ code path alignment**: when a test name describes a specific scenario (e.g. "tie-break"), verify the fixture actually exercises that code path
+### Describe Organization
 
-### Fixture Sharing in describe() Scope
-
-When multiple tests in a `describe` block use identical fixture data, define it once at block scope instead of duplicating in each test. Benefit: DRY + fixture changes sync automatically. Only use if fixture is immutable within tests (no mutations).
-
-```typescript
-describe('filterByRole', () => {
-  const testGroups = [{ role: ADMIN }, { role: PENDING }];
-
-  test('admin sees all', () => {
-    expect(filter(testGroups, ADMIN)).toHaveLength(2);
-  });
-  test('user sees filtered', () => {
-    expect(filter(testGroups, USER)).toHaveLength(1);
-  });
-});
-```
-
-## Coverage
-
-- Run `pnpm coverage` for coverage report
-- Target: 80% lines, 80% branches
-
-## Test Order Mirrors Source Order
-
-Order `describe` blocks in service and utils test files to match the declaration order of functions in the source file. Misalignment makes it harder to cross-reference tests and implementation.
-
-### Describe Block Organization: Multi-Scenario Functions
-
-Split `describe` blocks by scenario (not all cases flat) when a function behaves differently by mode. Example: separate `describe('func with modeA')` and `describe('func with modeB')` rather than mixing all cases. Benefit: better test discovery and names.
-
-**Pattern: successful case vs error cases**
-
-Organize functions by behavioral outcome: separate successful execution from failures (returns false, throws errors, etc.).
+Group by scenario (successful vs error cases), not flat:
 
 ```typescript
 describe('validate', () => {
-  describe('successful case', () => {
-    test('returns true and updates DB when external API confirms', async () => { ... });
-  });
-
+  describe('successful case', () => { ... });
   describe('error cases', () => {
-    describe('returns false', () => {
-      test('when user has no AtCoderAccount', async () => { ... });
-      test('when validation code is empty', async () => { ... });
-    });
-
-    describe('throws errors', () => {
-      test('when user not found', async () => { ... });
-      test('when external API returns non-OK response', async () => { ... });
-    });
+    describe('returns false', () => { ... });
+    describe('throws', () => { ... });
   });
 });
 ```
 
-When abnormal cases span multiple outcome types (graceful failures returning false vs exceptions), subdivide error cases by outcome. This clarifies caller behavior: some scenarios return false (can be handled inline), others throw (require try-catch).
-
-## Service Layer Unit Tests
-
-Service tests mock Prisma via `vi.mock('$lib/server/database', ...)` — no real DB mutations occur.
-
-### Mock Helpers
-
-Extract repeated mock patterns into helpers. Use `mockFindUnique`, `mockFindMany`, `mockCount` as the standard trio for Prisma model tests. Add `mockCreate`, `mockTransaction`, `mockDelete` when needed.
-
-### Cleanup for Integration Tests
-
-For tests with real side effects (DB mutations, file changes, API calls), wrap assertions in `try/finally` — a failing assertion skips cleanup and contaminates later tests.
-
-### File Split for Testability
+### Test Data
 
-When a service mixes DB operations and pure functions, split into `crud.ts` (DB; Prisma mocks needed) and `initializers.ts` (pure; no mocks). Skip split if cohesion suffers.
+- Use realistic values (real task IDs, grade names), not `'t1'` placeholders
+- Extract shared fixture data to file scope; inline for single-use
+- Verify fixture alignment: test name "tie-break" must exercise that code path
+- Shared fixtures at `describe` scope avoid duplication (DRY + auto-sync)
 
-## Component & Utility Tests
+### Service Layer Mocking
 
-- Extract component logic to `utils/` and test there, not in the component.
-- Omit component Vitest test if template-only **and** E2E tests cover rendering paths.
-- Add utility tests at extraction time; assert immutability (URLs) and all affected parts (multi-column operations).
-
-## HTTP Mocking
-
-Use Nock for external HTTP calls. See `src/test/lib/clients/` for examples.
-
-### HTTP Mock Helpers: DRY and Intent
-
-Extract repeated HTTP mock setup into helpers at describe scope. Benefits: DRY, readable test names, easier assertion updates.
-
-#### Naming convention
-
-- Mock builder: `mock<Endpoint>()` (e.g. `mockGetMyVote()`, `mockPostSubmit()`)
-- Data builder: `create<Entity>()` (e.g. `createFormData()`, `createRequestBody()`)
-
-#### Pattern: declare once, use many
+Mock Prisma with `vi.mock('$lib/server/database', ...)` — no real DB mutations. Use helpers:
 
 ```typescript
-describe('fetchUser', () => {
-  const baseUrl = 'http://localhost';
-  const endpoint = '/api/user';
-
-  const mockGetUser = (statusCode: number, user?: User) => {
-    nock(baseUrl)
-      .get(endpoint)
-      .reply(statusCode, user ? { user } : undefined);
-  };
-
-  test('success', async () => {
-    mockGetUser(statusCodes.OK, { id: '1', name: 'Alice' });
-    expect(await fetchUser()).toEqual({ id: '1', name: 'Alice' });
-  });
-
-  test('not found', async () => {
-    mockGetUser(statusCodes.NOT_FOUND);
-    expect(await fetchUser()).toBeNull();
-  });
-});
+const mockFindUnique = (data) => db.task.findUnique.mockResolvedValue(data);
+const mockFindMany = (data) => db.task.findMany.mockResolvedValue(data);
 ```
 
-**Benefit**: Reduces duplication, clarifies each test's focus, simplifies mock updates across multiple tests.
+### HTTP Mocking (Nock)
 
-## Parametrized Tests
+Extract setup into helpers, declare once at describe scope:
 
-When a function accepts domain enum values, test across representative samples rather than a single value.
-
-#### Sampling strategy
+```typescript
+const mockGetUser = (statusCode, user?) => {
+  nock('http://localhost')
+    .get('/api/user')
+    .reply(statusCode, user ? { user } : undefined);
+};
+```
 
-- **Boundaries**: first value (Q11), last value (D6), special states (PENDING)
-- **Mid-range**: one typical value (Q10)
-- **Exception**: separate `test()` for distinct behavioral branches (e.g. null return)
+### Parametrized Tests
 
-#### Pattern: test.each() for variants
+Test enum boundaries + typical value, then separate test for distinct behavior:
 
 ```typescript
-// Bad: tests only one value
-test('returns grade', async () => {
-  mockGetVote(statusCodes.OK, TaskGrade.Q10);
-  expect(await fetchVote()).toBe(TaskGrade.Q10);
-});
-
-// Good: parametrized boundaries + typical value
-test.each([
-  TaskGrade.PENDING,
-  TaskGrade.Q11,
-  TaskGrade.Q10,
-  TaskGrade.Q1,
-  TaskGrade.D1,
-  TaskGrade.D6,
-])('returns grade %s when voted', async (grade) => {
-  mockGetVote(statusCodes.OK, grade);
-  expect(await fetchVote()).toBe(grade);
-});
-
-// Separate test for distinct behavior
-test('returns null when no vote', async () => {
-  mockGetVote(statusCodes.OK, null);
-  expect(await fetchVote()).toBeNull();
-});
+test.each([TaskGrade.PENDING, TaskGrade.Q11, TaskGrade.Q10, TaskGrade.D6])(
+  'returns grade %s', (grade) => { ... }
+);
+test('returns null when no vote', () => { ... });
 ```
 
-**Benefit**: Catches enum-related bugs (misspellings, missing cases); prevents regressions when enum values change.
-
-## Environment Variable Stubs
+### Environment Variables
 
-Use `vi.stubEnv(key, value)` + `vi.unstubAllEnvs()` instead of manually assigning `process.env[key]` and deleting it in cleanup. `vi.stubEnv` syncs `import.meta.env` as well and accurately restores the original value:
+Use `vi.stubEnv()` + `vi.unstubAllEnvs()`:
 
 ```typescript
-// Bad
 beforeEach(() => {
-  process.env.MY_URL = 'https://example.com';
-});
-afterEach(() => {
-  delete process.env.MY_URL;
-});
-
-// Good
-beforeEach(() => {
-  vi.stubEnv('MY_URL', 'https://example.com');
+  vi.stubEnv('MY_VAR', 'value');
 });
 afterEach(() => {
   vi.unstubAllEnvs();
 });
 ```
+
+### Test Stubs
+
+Parameter types **must match** production signature — use domain types (`TaskGrade`), not `string`. Mismatch compiles silently but breaks type safety.
+
+## Component Testing
+
+- Extract logic to `utils/` or `_utils/` and test there, not in component
+- Omit component Vitest if template-only **and** E2E covers rendering paths
+
+## Coverage
+
+Target: 80% lines, 80% branches. Run `pnpm coverage`.
+
+## Test Files Ship with Code
+
+Never defer tests. For non-trivial logic without explicit test requirement, add them anyway.

From fb4d1a691f4844ed2fe066a2329677c20554e7c9 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Thu, 9 Apr 2026 09:53:49 +0000
Subject: [PATCH 43/46] fix: implement CodeRabbit findings #1-10 (Phase 1-4)

## Phase 1: Doc / Rules
- Add TSDoc to ButtonColor type (#3)
- Update prisma-db.md: Prisma error handling pattern (#1)

## Phase 2: Internal client fixes
- Add isValidTaskGrade type guard (src/lib/utils/task_grade.ts) to replace `as TaskGrade` casts (#5)
- Replace `data.grade as TaskGrade` with guard validation in fetchMyVote/fetchMedianVote (#5)
- Add SSR safety check to getBaseUrl with browser guard (#4)
- Add signal parameter to fetchMedianVote for cancellation support (#10)

## Phase 3: Component fixes
- Add `signal?.aborted` check in VotableGrade to suppress AbortError toast (#9)
- Pass signal to fetchMedianVote to prevent race condition in concurrent requests (#10)
- Improve comments in vote submission flow (#9)

## Phase 4: Service / Action layer
- Catch P2025 error in updateTask, return null instead of throwing (#1)
- Update vote_management and tasks route handlers to handle null return (#1)
- Change vote_actions return from `await upsertVoteGradeTables(...)` to explicit `return { success: true as const }` (#7)

## Tests
- Add src/test/utils/task_grade.test.ts for isValidTaskGrade type guard
- Add src/test/lib/services/tasks.test.ts for updateTask error handling

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .claude/rules/prisma-db.md                    |  1 +
 src/features/votes/actions/vote_actions.ts    |  3 +-
 .../votes/components/VotableGrade.svelte      | 11 +++-
 .../votes/internal_clients/vote_grade.ts      | 22 ++++++-
 src/lib/services/tasks.ts                     | 62 +++++++----------
 src/lib/types/flowbite-svelte-wrapper.ts      |  4 +-
 src/lib/utils/task_grade.ts                   | 10 +++
 src/routes/(admin)/tasks/+page.server.ts      |  9 ++-
 .../(admin)/vote_management/+page.server.ts   | 13 ++--
 src/test/lib/services/tasks.test.ts           | 66 +++++++++++++++++++
 src/test/utils/task_grade.test.ts             | 41 ++++++++++++
 11 files changed, 188 insertions(+), 54 deletions(-)
 create mode 100644 src/lib/utils/task_grade.ts
 create mode 100644 src/test/lib/services/tasks.test.ts
 create mode 100644 src/test/utils/task_grade.test.ts

diff --git a/.claude/rules/prisma-db.md b/.claude/rules/prisma-db.md
index 11a3a0efd..a7624d80a 100644
--- a/.claude/rules/prisma-db.md
+++ b/.claude/rules/prisma-db.md
@@ -103,6 +103,7 @@ Add `CHECK` constraints (via manual migration SQL) for count and invalid enum va
 ## Service Layer Error Handling
 
 Catch Prisma errors in service functions, return domain values:
+
 - `P2025` (record not found) → `null` (no exception)
 - Other errors → re-throw (caller handles as 500)
 
diff --git a/src/features/votes/actions/vote_actions.ts b/src/features/votes/actions/vote_actions.ts
index ed14a4fcd..4c3c4abc5 100644
--- a/src/features/votes/actions/vote_actions.ts
+++ b/src/features/votes/actions/vote_actions.ts
@@ -52,7 +52,8 @@ export const voteAbsoluteGrade = async ({
   const grade = gradeRaw as TaskGrade;
 
   try {
-    return await upsertVoteGradeTables(userId, taskId, grade);
+    await upsertVoteGradeTables(userId, taskId, grade);
+    return { success: true as const };
   } catch (error) {
     console.error('Failed to vote absolute grade: ', error);
     return fail(INTERNAL_SERVER_ERROR, { message: 'Failed to record vote.' });
diff --git a/src/features/votes/components/VotableGrade.svelte b/src/features/votes/components/VotableGrade.svelte
index fd604178b..c428afd4f 100644
--- a/src/features/votes/components/VotableGrade.svelte
+++ b/src/features/votes/components/VotableGrade.svelte
@@ -98,16 +98,21 @@
 
       submitVote(action, formData, signal)
         .then(async (succeeded) => {
+          if (signal?.aborted) {
+            return; // Intentional abort — user selected a different grade
+          }
+
           if (!succeeded) {
             throw new Error('vote failed');
           }
 
-          // 投票したグレードをローカル状態に反映（チェックマーク更新）
+          // Reflect the voted grade in local state (to update the checkmark in the dropdown), even though the server response may later indicate a different median grade due to other voters or admin overrides.
           votedGrade = selectedVoteGrade ?? null;
 
-          // 成功したらサーバから最新の中央値を取得して表示を更新
+          // Update the displayed grade to the latest median from the server, which may differ from the just-submitted vote due to other voters or admin overrides.
           const taskId = formData.get('taskId') as string;
-          const medianGrade = await fetchMedianVote(taskId);
+          const medianGrade = await fetchMedianVote(taskId, signal);
+
           if (medianGrade !== null && taskResult.grade === TaskGrade.PENDING) {
             displayGrade = medianGrade;
           }
diff --git a/src/features/votes/internal_clients/vote_grade.ts b/src/features/votes/internal_clients/vote_grade.ts
index 7508c20d1..f2cde83f7 100644
--- a/src/features/votes/internal_clients/vote_grade.ts
+++ b/src/features/votes/internal_clients/vote_grade.ts
@@ -1,4 +1,6 @@
 import type { TaskGrade } from '$lib/types/task';
+import { isValidTaskGrade } from '$lib/utils/task_grade';
+import { browser } from '$app/environment';
 
 /**
  * Fetches the current user's vote grade for a given task.
@@ -19,7 +21,7 @@ export async function fetchMyVote(taskId: string): Promise<TaskGrade | null> {
     }
 
     const data = await response.json();
-    return (data.grade as TaskGrade) ?? null;
+    return isValidTaskGrade(data.grade) ? data.grade : null;
   } catch {
     return null;
   }
@@ -55,13 +57,17 @@ export async function submitVote(
  * Fetches the current median vote grade for a given task.
  * @returns The median grade, or null if not enough votes or request fails.
  */
-export async function fetchMedianVote(taskId: string): Promise<TaskGrade | null> {
+export async function fetchMedianVote(
+  taskId: string,
+  signal?: AbortSignal,
+): Promise<TaskGrade | null> {
   try {
     const response = await fetch(
       `${getBaseUrl()}/problems/getMedianVote?taskId=${encodeURIComponent(taskId)}`,
       {
         credentials: 'same-origin',
         headers: { Accept: 'application/json' },
+        signal,
       },
     );
 
@@ -70,7 +76,7 @@ export async function fetchMedianVote(taskId: string): Promise<TaskGrade | null>
     }
 
     const data = await response.json();
-    return (data.grade as TaskGrade) ?? null;
+    return isValidTaskGrade(data.grade) ? data.grade : null;
   } catch {
     return null;
   }
@@ -81,5 +87,15 @@ function getBaseUrl(): string {
   if (typeof globalThis !== 'undefined' && globalThis.location?.origin) {
     return globalThis.location.origin;
   }
+
+  if (!browser) {
+    console.warn(
+      'getBaseUrl() called in SSR context where browser APIs are unavailable. ' +
+        'This should only be called from client-side code.',
+    );
+
+    return '';
+  }
+
   return 'http://localhost';
 }
diff --git a/src/lib/services/tasks.ts b/src/lib/services/tasks.ts
index 16e56ed5c..dfbdcde5b 100644
--- a/src/lib/services/tasks.ts
+++ b/src/lib/services/tasks.ts
@@ -1,3 +1,4 @@
+import { Prisma } from '@prisma/client';
 import { default as db } from '$lib/server/database';
 
 import { getContestTaskPairs } from '$lib/services/contest_task_pairs';
@@ -179,42 +180,29 @@ export async function createTask(
   console.log(task);
 }
 
-export async function updateTask(task_id: string, task_grade: TaskGrade) {
-  const task = await db.task.update({
-    where: { task_id: task_id },
-    data: {
-      grade: task_grade,
-    },
-  });
+/**
+ * Updates a task's grade by task_id.
+ *
+ * @param task_id - The task ID to update
+ * @param task_grade - The new grade value
+ *
+ * @returns undefined if successful, null if task not found (P2025)
+ */
+export async function updateTask(task_id: string, task_grade: TaskGrade): Promise<void | null> {
+  try {
+    const task = await db.task.update({
+      where: { task_id: task_id },
+      data: {
+        grade: task_grade,
+      },
+    });
 
-  console.log(task);
-}
+    console.log(task);
+  } catch (error) {
+    if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === 'P2025') {
+      return null;
+    }
 
-// TODO: deleteTask()
-
-// Note:
-// Uncomment only when executing the following commands directly from the script.
-//
-// pnpm dlx vite-node ./prisma/tasks.ts
-//
-//
-// async function main() {
-//   const tasks = getTasks();
-//   console.log(tasks);
-
-//   const task_id = 'abc322_e';
-//   const task = getTask(task_id);
-//   console.log(task);
-
-//   // updateTask(task_id, TaskGrade.Q1);
-//   // console.log(task);
-// }
-
-// main()
-//   .catch(async (e) => {
-//     console.error(e);
-//     process.exit(1);
-//   })
-//   .finally(async () => {
-//     await db.$disconnect();
-//   });
+    throw error;
+  }
+}
diff --git a/src/lib/types/flowbite-svelte-wrapper.ts b/src/lib/types/flowbite-svelte-wrapper.ts
index a7f705e50..11ec8d984 100644
--- a/src/lib/types/flowbite-svelte-wrapper.ts
+++ b/src/lib/types/flowbite-svelte-wrapper.ts
@@ -1,5 +1,7 @@
 // Extract ButtonColor from ButtonProps (Flowbite Svelte exports ButtonProps)
 import type { ButtonProps } from 'flowbite-svelte';
 
-// Get the color type from ButtonProps
+/**
+ * Valid color variants for Flowbite Svelte button component.
+ */
 export type ButtonColor = NonNullable<ButtonProps['color']>;
diff --git a/src/lib/utils/task_grade.ts b/src/lib/utils/task_grade.ts
new file mode 100644
index 000000000..89ffb5aed
--- /dev/null
+++ b/src/lib/utils/task_grade.ts
@@ -0,0 +1,10 @@
+import { taskGradeValues, type TaskGrade } from '$lib/types/task';
+
+/**
+ * Type guard to validate if an unknown value is a valid TaskGrade.
+ * @param value - The value to validate
+ * @returns true if value is a valid TaskGrade enum member
+ */
+export function isValidTaskGrade(value: unknown): value is TaskGrade {
+  return typeof value === 'string' && taskGradeValues.includes(value as TaskGrade);
+}
diff --git a/src/routes/(admin)/tasks/+page.server.ts b/src/routes/(admin)/tasks/+page.server.ts
index 5020e5af5..e6c582bd5 100644
--- a/src/routes/(admin)/tasks/+page.server.ts
+++ b/src/routes/(admin)/tasks/+page.server.ts
@@ -179,7 +179,14 @@ export const actions: Actions = {
         };
       }
 
-      await taskService.updateTask(task_id, task_grade);
+      const updateResult = await taskService.updateTask(task_id, task_grade);
+
+      if (updateResult === null) {
+        return {
+          success: false,
+        };
+      }
+
       const contest_id = formData.get('contest_id')?.toString() as string;
 
       const tasks = await apiClient.getTasks();
diff --git a/src/routes/(admin)/vote_management/+page.server.ts b/src/routes/(admin)/vote_management/+page.server.ts
index 3ff31c357..a610f4d56 100644
--- a/src/routes/(admin)/vote_management/+page.server.ts
+++ b/src/routes/(admin)/vote_management/+page.server.ts
@@ -1,6 +1,5 @@
 import type { Actions, PageServerLoad } from './$types';
 
-import { Prisma } from '@prisma/client';
 import { type TaskGrade, TaskGrade as TaskGradeEnum } from '$lib/types/task';
 import { getTasksByTaskId, updateTask } from '$lib/services/tasks';
 import {
@@ -52,15 +51,13 @@ export const actions: Actions = {
     ) {
       return { success: false };
     }
-    try {
-      await updateTask(taskId, grade as TaskGrade);
-    } catch (error) {
-      if (error instanceof Prisma.PrismaClientKnownRequestError && error.code === 'P2025') {
-        return { success: false, message: `Not found task: ${taskId}` };
-      }
 
-      throw error;
+    const result = await updateTask(taskId, grade as TaskGrade);
+
+    if (result === null) {
+      return { success: false, message: `Not found task: ${taskId}` };
     }
+
     return { success: true };
   },
 };
diff --git a/src/test/lib/services/tasks.test.ts b/src/test/lib/services/tasks.test.ts
new file mode 100644
index 000000000..b7fb6140f
--- /dev/null
+++ b/src/test/lib/services/tasks.test.ts
@@ -0,0 +1,66 @@
+import { describe, test, expect, beforeEach, vi } from 'vitest';
+
+import { Prisma } from '@prisma/client';
+
+import { TaskGrade } from '$lib/types/task';
+import { updateTask } from '$lib/services/tasks';
+
+vi.mock('$lib/server/database', () => ({
+  default: {
+    task: {
+      update: vi.fn(),
+    },
+  },
+}));
+
+import db from '$lib/server/database';
+
+describe('updateTask', () => {
+  const mockDb = db as unknown as { task: { update: ReturnType<typeof vi.fn> } };
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  describe('successful case', () => {
+    test('returns undefined when task is updated successfully', async () => {
+      mockDb.task.update.mockResolvedValue({
+        id: '1',
+        task_id: 'abc450_d',
+        grade: TaskGrade.Q1,
+      });
+
+      const result = await updateTask('abc450_d', TaskGrade.Q2);
+
+      expect(result).toBeUndefined();
+      expect(mockDb.task.update).toHaveBeenCalledWith({
+        where: { task_id: 'abc450_d' },
+        data: { grade: TaskGrade.Q2 },
+      });
+    });
+  });
+
+  describe('error cases', () => {
+    test('returns null when task is not found (P2025)', async () => {
+      const error = new Prisma.PrismaClientKnownRequestError(
+        'An operation failed because it depends on one or more records that were required but not found. Record to update not found.',
+        { code: 'P2025', clientVersion: '5.0.0' },
+      );
+
+      mockDb.task.update.mockRejectedValue(error);
+
+      const result = await updateTask('nonexistent_task', TaskGrade.Q1);
+
+      expect(result).toBeNull();
+    });
+
+    test('re-throws non-P2025 errors', async () => {
+      const error = new Error('Database connection error');
+      mockDb.task.update.mockRejectedValue(error);
+
+      await expect(updateTask('abc450_d', TaskGrade.Q1)).rejects.toThrow(
+        'Database connection error',
+      );
+    });
+  });
+});
diff --git a/src/test/utils/task_grade.test.ts b/src/test/utils/task_grade.test.ts
new file mode 100644
index 000000000..760bd4ec7
--- /dev/null
+++ b/src/test/utils/task_grade.test.ts
@@ -0,0 +1,41 @@
+import { describe, test, expect } from 'vitest';
+
+import { taskGradeValues, TaskGrade } from '$lib/types/task';
+import { isValidTaskGrade } from '$lib/utils/task_grade';
+
+describe('isValidTaskGrade', () => {
+  describe('successful cases', () => {
+    test('returns true for all valid TaskGrade values', () => {
+      taskGradeValues.forEach((grade) => {
+        expect(isValidTaskGrade(grade)).toBe(true);
+      });
+    });
+
+    test('is a type guard that narrows type to TaskGrade', () => {
+      const value: unknown = 'Q1';
+
+      if (isValidTaskGrade(value)) {
+        // value is narrowed to TaskGrade at this point
+        const grade: typeof value = value;
+        expect(grade).toBe(TaskGrade.Q1);
+      }
+    });
+  });
+
+  describe('failure cases', () => {
+    test('returns false for invalid string values', () => {
+      expect(isValidTaskGrade('INVALID')).toBe(false);
+      expect(isValidTaskGrade('invalid')).toBe(false);
+      expect(isValidTaskGrade('PENDING_')).toBe(false);
+    });
+
+    test('returns false for non-string values', () => {
+      expect(isValidTaskGrade(null)).toBe(false);
+      expect(isValidTaskGrade(undefined)).toBe(false);
+      expect(isValidTaskGrade(123)).toBe(false);
+      expect(isValidTaskGrade(true)).toBe(false);
+      expect(isValidTaskGrade({})).toBe(false);
+      expect(isValidTaskGrade([])).toBe(false);
+    });
+  });
+});

From 4f1613477d23cf27b11e032ce5eebc587118a4e9 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Thu, 9 Apr 2026 09:55:55 +0000
Subject: [PATCH 44/46] docs: remove completed PR #3316 review notes

- Delete docs/dev-notes/2026-03-26/pr-3316-review/plan.md (implementation complete)
- Delete docs/dev-notes/2026-03-26/pr-3316-review/review.md (no longer needed)
- All findings have been addressed and committed

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .../2026-03-26/pr-3316-review/plan.md         | 139 ------------------
 .../2026-03-26/pr-3316-review/review.md       | 133 -----------------
 2 files changed, 272 deletions(-)
 delete mode 100644 docs/dev-notes/2026-03-26/pr-3316-review/plan.md
 delete mode 100644 docs/dev-notes/2026-03-26/pr-3316-review/review.md

diff --git a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md b/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
deleted file mode 100644
index 1c8ebcf3a..000000000
--- a/docs/dev-notes/2026-03-26/pr-3316-review/plan.md
+++ /dev/null
@@ -1,139 +0,0 @@
-# PR #3316 マージ後修正 実装計画
-
-> Task 1-9（Phases 1-4）は git commits を参照。すべてのルール追加（Phase 7）は既に `.claude/rules/` に反映済み。
-> Phase 5 Task 10: Steps 1-3（セレクタ修正）・`navigateToFirstVoteDetailPage` 早期 return 骨格は実装済み。以下は残課題（revised）。
-
----
-
-## CodeRabbit Findings
-
-> `coderabbit review --base staging --plain` を 2 回実行（3 回目はレートリミットで実施不可）。
-> 両回で共通して出た指摘、および片方の実行で出た `potential_issue` 以上を記載。
-
-### potential_issue（中）
-
-| #   | ファイル                                                                          | 行                           | 内容                                                                                                                                                                                                                                              |
-| --- | --------------------------------------------------------------------------------- | ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| 1   | `src/routes/(admin)/vote_management/+page.server.ts`                              | L3, L55-63                   | Prisma 固有エラー型 (`PrismaClientKnownRequestError`, `P2025`) をルート層で直接参照。サービス層でドメイン例外 (`TaskNotFoundError` 等) にラップして再 throw し、ルートから Prisma 依存を除去するべき。                                            |
-| 2   | `prisma/migrations/20260406112057_add_vote_grade_check_constraints/migration.sql` | L2-15                        | CHECK 制約追加前に既存データが制約を満たすか検証していない。`count < 0` の行や `grade = 'PENDING'` の行が存在する場合マイグレーション失敗→デプロイブロック。事前クエリまたは `NOT VALID` オプションでの段階適用を検討。                           |
-| 3   | `src/lib/types/flowbite-svelte-wrapper.ts`                                        | L4-5                         | エクスポート型 `ButtonColor` に TSDoc が未記載。コーディングガイドライン「Add TSDoc to every exported type」に違反。                                                                                                                              |
-| 4   | `src/features/votes/internal_clients/vote_grade.ts`                               | L79-85                       | `getBaseUrl` の `http://localhost` フォールバックはポート未指定かつ SSR 環境 (`globalThis.location` が undefined) で意図しないエンドポイントへリクエストを送る可能性。環境変数または `$app/environment` からベース URL を取得する設計が望ましい。 |
-| 5   | `src/features/votes/internal_clients/vote_grade.ts`                               | L21-22                       | `data.grade as TaskGrade` はコンパイル時のみの型アサーション。API が予期しない値を返した場合に下流で不具合が発生する。ランタイム型ガード (`isValidTaskGrade`) でバリデーション後に返すべき。                                                      |
-| 7   | `src/features/votes/actions/vote_actions.ts`                                      | L55                          | `upsertVoteGradeTables` の戻り値をそのままクライアントに返しており、Prisma モデルや内部データが漏洩するリスク。戻り値を使わないか、安全な DTO に変換してから返すべき。                                                                            |
-| 8   | `prisma/schema.prisma`                                                            | L258-259, L273-277, L290-291 | migration.sql に手動追加した CHECK 制約 (`grade != 'PENDING'`, `count >= 0`) が `prisma/ERD.md` に記載されていない。コーディングガイドライン「CHECK constraints added manually to migration.sql must be documented in prisma/ERD.md」に違反。     |
-| 9   | `src/features/votes/components/VotableGrade.svelte`                               | L74-76, L97-98               | `voteAbortController?.abort()` 由来の `AbortError` が catch されずにエラーメッセージとして表示される。`error.name === 'AbortError'` を確認して静かに無視するべき。                                                                                |
-| 10  | `src/features/votes/components/VotableGrade.svelte`                               | L109-113                     | `fetchMedianVote` に abort signal が渡されておらず、連続クリック時に古いレスポンスが後から返り表示が不整合になる可能性がある（低確率）。                                                                                                          |
-
----
-
-## 精査結果：対応方針
-
-| #   | 方針           | 理由                                                                                                                                                                        |
-| --- | -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| 1   | **対応する**   | ルート層に Prisma 依存があるのは層違反。`updateTask` を `null` 返却に変更して分離。                                                                                         |
-| 2   | **対応不要**   | 対象テーブル（VoteGrade / VotedGradeCounter / VotedGradeStatistics）は今回新規追加。適用前データが存在しないため制約違反は起きない。                                        |
-| 3   | **対応する**   | TSDoc 1 行追加のみ。コーディングガイドライン準拠。                                                                                                                          |
-| 4   | **対応する**   | `browser` ガードを追加し SSR 文脈で呼ばれた場合に明示的に警告。                                                                                                             |
-| 5   | **対応する**   | `isValidTaskGrade` 型ガードを `src/lib/utils/` に追加し、`as TaskGrade` を排除。                                                                                            |
-| 7   | **対応する**   | `upsertVoteGradeTables` の戻り型は実際には `Promise<{ success: true }>` でありリスクなしだが、`return await` をやめて明示 `return { success: true }` に変更し意図を明確化。 |
-| 8   | **ルール修正** | `prisma-erd-generator` が ERD.md を毎回上書きするため追記は即消える。`coding-style.md` の「ERD.md に記載せよ」ルールを「schema.prisma インラインコメントで代替」に修正。    |
-| 9   | **対応する**   | `submitVote` が AbortError を内部で catch して `false` 返却するため `.catch()` には AbortError が届かない。正しい修正は `.then()` 内で `signal?.aborted` チェックを挿入。   |
-| 10  | **対応する**   | #9 と同ファイル。`fetchMedianVote` に `signal` パラメータを追加し連続クリック時の古いレスポンス上書きを防ぐ。                                                               |
-
----
-
-## 実装フェーズ
-
-### Phase 1: Doc / Rules（最低リスク）
-
-**Task 1 — #3: ButtonColor に TSDoc を追加**
-
-- `src/lib/types/flowbite-svelte-wrapper.ts` に 1 行 TSDoc
-
-**Task 2 — #8: coding-style.md の ERD.md ルールを修正**
-
-- (英語でルールを更新) `.claude/rules/coding-style.md` の「`prisma/ERD.md` に記載せよ」を「`schema.prisma` のインラインコメントで文書化せよ（ERD.md は prisma-erd-generator が上書きするため不可）」に変更
-
----
-
-### Phase 2: Internal Client 修正（`vote_grade.ts`）
-
-**Task 3 — #5: isValidTaskGrade 型ガードを追加（TDD）**
-
-- テスト先行: `src/test/utils/task_grade.test.ts`
-- 実装: `src/lib/utils/task_grade.ts` に `isValidTaskGrade(value: unknown): value is TaskGrade`
-- `vote_grade.ts` の `data.grade as TaskGrade` を 2 箇所置き換え（fetchMyVote, fetchMedianVote）
-
-**Task 4 — #4: getBaseUrl SSR 安全化**
-
-- `$app/environment` の `browser` をインポートし、SSR 呼び出し時は `console.warn` + `''` 返却
-- **背景**: `browser === false` はサーバー側実行を示す。SSR フェーズでブラウザ API (`window.location` 等) を呼ぶとクラッシュするため、ガードで安全に失敗させる
-
-**Task 5 — #10: fetchMedianVote に signal パラメータを追加**
-
-- `fetchMedianVote(taskId: string, signal?: AbortSignal)` にシグネチャ拡張し fetch に渡す
-- **背景**: signal は「キャンセル機能を実装するための仕組み」。abort() されると AbortError が throw されるため、連続クリック時に古いレスポンスの上書きを防ぐ
-
----
-
-### Phase 3: Component 修正（`VotableGrade.svelte`）
-
-**Task 6 — #9 + #10: AbortError UX バグ修正 + signal 伝搬**
-
-- `.then()` 内で `signal?.aborted` チェックを挿入し abort 時はエラートーストを出さずに early return
-
-  ```typescript
-  .then(async (succeeded) => {
-    if (signal?.aborted) {
-      return; // Intentional abort — user selected a different grade
-    }
-
-    if (!succeeded) { throw new Error('Failed to vote'); }
-    ...
-  })
-  ```
-
-- `fetchMedianVote(taskId, signal)` に signal を渡す
-
----
-
-### Phase 4: Service / Action 層
-
-**Task 7 — #1: P2025 処理をサービス層に移動（TDD）**
-
-- テスト先行: `updateTask` が P2025 で `null` を返すケースを追加
-- `src/lib/services/tasks.ts`: P2025 を catch して `null` 返却に変更（他の呼び出し元を事前に確認）
-- `src/routes/(admin)/vote_management/+page.server.ts`: `Prisma` インポート削除、`null` チェックでエラーレスポンスを返す
-
-**Task 8 — #7: vote_actions.ts の明示 return**
-
-- `return await upsertVoteGradeTables(...)` → `await upsertVoteGradeTables(...); return { success: true as const };`
-- **背景**: `as const` は `true` をリテラル型に固定し、TypeScript が「success === true の時は成功メッセージ必須」を型チェックで強制。Rust の `Result<T, E>` enum に近い安全性を実現
-
----
-
-## 対象ファイル一覧
-
-| ファイル                                             | Phase |
-| ---------------------------------------------------- | ----- |
-| `src/lib/types/flowbite-svelte-wrapper.ts`           | 1     |
-| `.claude/rules/coding-style.md`                      | 1     |
-| `src/lib/utils/task_grade.ts` (新規)                 | 2     |
-| `src/test/utils/task_grade.test.ts` (新規)           | 2     |
-| `src/features/votes/internal_clients/vote_grade.ts`  | 2     |
-| `src/features/votes/components/VotableGrade.svelte`  | 3     |
-| `src/lib/services/tasks.ts`                          | 4     |
-| `src/routes/(admin)/vote_management/+page.server.ts` | 4     |
-| `src/features/votes/actions/vote_actions.ts`         | 4     |
-
----
-
-## 動作確認チェックリスト
-
-- [ ] `AtCoderVerificationForm`: 文字列生成ボタン押下中に Spinner が表示され、二重送信不可
-- [ ] `AtCoderVerificationForm`: クリップボードアイコンクリック後にチェックマークアニメーション表示
-- [ ] `AtCoderVerificationForm`: 「本人確認」と「リセット」ボタン間に適切な隙間
-- [ ] `VotableGrade`: グレードを連打しても「投票状況の更新に失敗しました」が**表示されない**こと
-- [ ] `votes/[slug]`: 投票閾値ツールチップが定数参照（`MIN_VOTES_FOR_STATISTICS`）に基づいて表示
-- [ ] vote_management: 存在しない taskId で `setTaskGrade` を呼んでも 500 ではなく `{ success: false }` が返る
-- [ ] DB: `VotedGradeCounter.count` に負の値を INSERT しようとすると CHECK 制約違反エラー
diff --git a/docs/dev-notes/2026-03-26/pr-3316-review/review.md b/docs/dev-notes/2026-03-26/pr-3316-review/review.md
deleted file mode 100644
index 3cdb5895b..000000000
--- a/docs/dev-notes/2026-03-26/pr-3316-review/review.md
+++ /dev/null
@@ -1,133 +0,0 @@
-# マージ後の修正タスク一覧
-
-## 優先度：高（機能に直結）
-
-### Svelte: VotableGrade コンポーネント
-
-| #   | 内容                                                                                                                        | 難度 |
-| --- | --------------------------------------------------------------------------------------------------------------------------- | ---- |
-| 1   | fetch 3 呼び出しに `credentials: 'same-origin'` を追加（getMyVote・POST・getMedianVote）                                    | ⭐   |
-| 2   | `onTriggerClick`（getMyVote）と `handleSubmit`（投票送信＋getMedianVote）を `src/features/votes/utils/` に抽出 + 単体テスト | ⭐⭐ |
-| 3   | `selectedVoteGrade` 連打対策：`AbortController` または seq number で古い応答を無視                                          | ⭐⭐ |
-
-### Service: vote_actions.ts
-
-| #   | 内容                                                      | 難度 |
-| --- | --------------------------------------------------------- | ---- |
-| 4   | `upsertVoteGradeTables` 成功時に `{ success: true }` 返す | ⭐   |
-
-### Routes: votes 関連
-
-| #   | 内容                                                                                                             | 難度 |
-| --- | ---------------------------------------------------------------------------------------------------------------- | ---- |
-| 5   | `vote_grade.ts` から `MIN_VOTES_FOR_STATISTICS` export、`/votes/[slug]/+page.svelte` で参照（現在 hardcode "3"） | ⭐   |
-| 6   | `votes/[slug]/+page.svelte` の `Pct` → `percentage`                                                              | ⭐   |
-
-### Routes: vote_management
-
-| #   | 内容                                                                                                                    | 難度 |
-| --- | ----------------------------------------------------------------------------------------------------------------------- | ---- |
-| 7   | `(admin)/vote_management/+page.server.ts` の `updateTask` で 404 エラー処理（try/catch で RecordNotFound or pre-check） | ⭐   |
-
-### UI/UX: Submitting State & Server Load Mitigation
-
-| #   | 内容                                                                                                                 | 難度 |
-| --- | -------------------------------------------------------------------------------------------------------------------- | ---- |
-| 8a  | `SubmissionButton.svelte`: Flowbite `loading` prop を活用（Spinner + disabled 自動）                                 | ⭐   |
-| 8b  | `AtCoderVerificationForm.svelte`: submitting 状態を検出、ボタン無効化（generated & validate ステップで二重送信防止） | ⭐⭐ |
-
-#### 実装方針：FormWrapper コンテキスト経由で loading 状態を提供
-
-**背景**: AuthForm.svelte の `isSubmitting` 手動管理 + superforms 依存は改修対象外だが、新規実装では最小限＆標準的に。
-
-**方法**: FormWrapper を拡張 → `use:enhance` コールバックで loading 状態を追跡 → Svelte context 経由で子に提供
-
-**実装手順**:
-
-1. `FormWrapper.svelte`:
-   - `let isSubmitting = $state(false)` 追加
-   - `use:enhance` コールバックで状態管理（submit時 true, 完了時 false）
-   - `setContext('form', { get isSubmitting() })` で子に提供
-
-2. `SubmissionButton.svelte`:
-   - `loading?: boolean` prop を追加
-   - `<Button type="submit" ... {loading}>` で Flowbite の loading 機能を活用
-   - Spinner + disabled が自動で適用される
-
-3. `AtCoderVerificationForm.svelte`:
-   - `getContext('form')` で isSubmitting を取得
-   - `<SubmissionButton ... loading={isSubmitting} />`
-
-| #   | 内容                                                                                                                    | 難度 |
-| --- | ----------------------------------------------------------------------------------------------------------------------- | ---- |
-| 8c  | `AtCoderVerificationForm.svelte`: 「本人確認」ボタンと「リセット」ボタン間に隙間を追加                                  | ⭐   |
-| 8d  | `AtCoderVerificationForm.svelte`: Flowbite Clipboard コンポーネント導入（カスタム関数削除 + copy 成功時アニメーション） | ⭐   |
-
-**メリット**:
-
-- Flowbite 標準機能（loading + Spinner + disabled 自動）
-- FormWrapper 拡張は他の form でも再利用可能
-- SvelteKit 公式パターン（use:enhance コールバック）
-- 最小限の変更で効果最大
-
----
-
-## 優先度：中（データ整合性）
-
-### Database: Prisma Schema & Migration
-
-| #   | 内容                                                                                                                         | 難度 |
-| --- | ---------------------------------------------------------------------------------------------------------------------------- | ---- |
-| 12  | `VotedGradeCounter.count >= 0` CHECK 制約追加（migration）                                                                   | ⭐   |
-| 13  | `VoteGrade.grade`, `VotedGradeCounter.grade`, `VotedGradeStatistics.grade` に `CHECK (grade != 'PENDING')` 追加（migration） | ⭐   |
-
----
-
-## 優先度：中（テスト）
-
-| #   | ファイル                                                     | 内容                                                                             | 難度 |
-| --- | ------------------------------------------------------------ | -------------------------------------------------------------------------------- | ---- |
-| 9   | `e2e/votes.spec.ts`                                          | セレクタ不一致修正（heading '投票'、columnheader '問題名'/'出典'）+ 初期状態対応 | ⭐⭐ |
-| 10  | `src/lib/services/users.ts`                                  | `getUser`, `getUserById`, `deleteUser` の単体テスト追加                          | ⭐⭐ |
-| 11  | `src/features/account/services/atcoder_verification.test.ts` | manual `process.env` → `vi.stubEnv()` + `vi.unstubAllEnvs()` パターンに変更      | ⭐   |
-
----
-
-## 優先度：低（並行処理対策・将来）
-
-| #   | ファイル        | 内容                                                                                                              | 難度   |
-| --- | --------------- | ----------------------------------------------------------------------------------------------------------------- | ------ |
-| 14  | `vote_grade.ts` | 並行投票対策：`SELECT FOR UPDATE` または `SERIALIZABLE` 分離レベル（UI `isOpening` フラグで実用上ほぼ発生しない） | ⭐⭐⭐ |
-
----
-
-## 汎用的・新規性の高い教訓：rules / skills への追加候補
-
-### Svelte Components Rules
-
-| 規約             | 内容                                                                                                                                               |
-| ---------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- |
-| SSR 安全性       | SSR で実行されるコンポーネント初期化コードに `crypto.randomUUID()` や `Math.random()` を使わない。ID が必要な場合は props の値から決定的に導出する |
-| `{#each}` キー式 | `{#each}` には必ずキー式 `(item.id)` を付ける                                                                                                      |
-
-### Prisma DB Rules
-
-| 規約                | 内容                                                                                                 |
-| ------------------- | ---------------------------------------------------------------------------------------------------- |
-| FK 制約と @relation | 他モデルの ID を参照するフィールドには必ず `@relation` を定義する（FK 制約の自動生成のため）         |
-| DB 層での値域制約   | `count` フィールド（≥0）や enum フィールド（特定値の除外）には CHECK 制約を追加する（DB 層での検証） |
-
-### Coding Style Rules
-
-| 規約                                     | 内容                                                                                                                                                                                       |
-| ---------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
-| `+page.server.ts` の load 関数           | サービス関数を呼ぶ際は try-catch で囲み、失敗時は安全なデフォルト値を返す（ページ全体のクラッシュを防ぐ）                                                                                  |
-| Auth: アクション監査                     | `+page.server.ts` で 1 つのアクションに auth チェックを追加したら、同ファイルの他すべてのアクションも監査する。非対称なガード（delete 保護、generate/validate/reset 未保護）は再発パターン |
-| Auth: success フラグ と message の一貫性 | `+page.server.ts` アクションが `success: false` を返すとき、`message` と `message_type` も失敗を反映する。成功フラグと矛盾するメッセージは静かなバグ                                       |
-| Dead Code 削除の基準                     | 関数削除前に全プロジェクトを grep して呼び出し元を確認。(1) 呼び出し元がゼロ、(2) 代替実装が存在、(3) 書き込み対象フィールドも削除される、の 3 つ揃って初めて安全                          |
-
-### Testing Rules
-
-| 規約           | 内容                                                                                                                                       |
-| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
-| 環境変数スタブ | `process.env` を手動で設定・削除せず、`vi.stubEnv()` + `vi.unstubAllEnvs()` を使う。`import.meta.env` も同期され、元の値を正確に復元できる |

From 1f1ab4b5a92c2ad8bacf39051a9a9f012bf3e663 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Thu, 9 Apr 2026 11:18:51 +0000
Subject: [PATCH 45/46] fix: implement CodeRabbit findings (Phase 2)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Fix prisma-db.md: clarify schema.prisma as source of truth for CHECK constraints
- Fix spelling: "Parametrized" → "Parameterized" in testing-e2e.md and testing.md
- Update median.ts to use MIN_VOTES_FOR_STATISTICS constant instead of hardcoded 3
- Fix globalThis.location state leak in vote_grade.test.ts by saving/restoring
- Simplify getBaseUrl() by removing unreachable 'http://localhost' fallback
- Move task_grade.test.ts from src/test/utils/ to src/lib/utils/ (adjacent pattern)
- Add src/lib/**/*.test.ts to vite.config.ts test.include
- Add 3 new testing patterns to rules/testing.md (multi-location tests, globalThis mocking, guard clause reachability)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
---
 .claude/rules/prisma-db.md                    |  7 +--
 .claude/rules/testing-e2e.md                  |  2 +-
 .claude/rules/testing.md                      | 49 ++++++++++++++++++-
 .../votes/internal_clients/vote_grade.test.ts |  9 ++++
 .../votes/internal_clients/vote_grade.ts      | 15 ++----
 src/features/votes/utils/median.ts            |  9 +++-
 src/{test => lib}/utils/task_grade.test.ts    |  0
 vite.config.ts                                |  1 +
 8 files changed, 75 insertions(+), 17 deletions(-)
 rename src/{test => lib}/utils/task_grade.test.ts (100%)

diff --git a/.claude/rules/prisma-db.md b/.claude/rules/prisma-db.md
index a7624d80a..0fed30a3d 100644
--- a/.claude/rules/prisma-db.md
+++ b/.claude/rules/prisma-db.md
@@ -98,7 +98,7 @@ user   User @relation(fields: [userId], references: [id])
 
 ## DB-Level Value Constraints
 
-Add `CHECK` constraints (via manual migration SQL) for count and invalid enum values. Document with inline `schema.prisma` comments (e.g., `/// CHECK: count >= 0`) — `prisma-erd-generator` overwrites `ERD.md` on each migration.
+Add `CHECK` constraints via manual migration SQL. Document with inline `schema.prisma` comments (e.g., `/// CHECK: count >= 0`). Note: `prisma-erd-generator` may overwrite `ERD.md` on each migration—always keep the constraint definition in `schema.prisma` as the source of truth.
 
 ## Service Layer Error Handling
 
@@ -125,9 +125,10 @@ Prisma does not support `@@check`. To add one:
 
 1. `pnpm exec prisma migrate dev --create-only --name <description>` — generate migration without applying
 2. Edit the generated `migration.sql` to add the CHECK constraint manually
-3. `pnpm exec prisma migrate dev` — apply
+3. Add an inline comment in `schema.prisma` (e.g., `/// CHECK: constraint description`)
+4. `pnpm exec prisma migrate dev` — apply
 
-Document the constraint in `prisma/ERD.md` (the only place it's visible):
+For visibility, also document complex constraints in `prisma/ERD.md`:
 
 ```mermaid
 %% XOR constraint: workbookplacement_xor_grade_category — exactly one of taskGrade or solutionCategory must be non-null
diff --git a/.claude/rules/testing-e2e.md b/.claude/rules/testing-e2e.md
index 640580f37..7c8063c4e 100644
--- a/.claude/rules/testing-e2e.md
+++ b/.claude/rules/testing-e2e.md
@@ -34,7 +34,7 @@ test.describe('logged-in user', () => {
 });
 ```
 
-## Parametrized Tests
+## Parameterized Tests
 
 Playwright has no native `test.each`. Use `for...of` loops (official pattern):
 
diff --git a/.claude/rules/testing.md b/.claude/rules/testing.md
index 630e0f3d2..22fce4087 100644
--- a/.claude/rules/testing.md
+++ b/.claude/rules/testing.md
@@ -75,7 +75,7 @@ const mockGetUser = (statusCode, user?) => {
 };
 ```
 
-### Parametrized Tests
+### Parameterized Tests
 
 Test enum boundaries + typical value, then separate test for distinct behavior:
 
@@ -115,3 +115,50 @@ Target: 80% lines, 80% branches. Run `pnpm coverage`.
 ## Test Files Ship with Code
 
 Never defer tests. For non-trivial logic without explicit test requirement, add them anyway.
+
+## Multiple Test Location Patterns
+
+During migration, support both centralized (`src/test/`) and co-located (`src/features/`, `src/lib/`) tests.
+Configure `vite.config.ts` with explicit ordering:
+
+```typescript
+include: [
+  'src/lib/**/*.test.ts',        // shared utilities (adjacent)
+  'src/test/**/*.test.ts',       // legacy centralized
+  'src/features/**/*.test.ts',   // feature co-location
+],
+```
+
+## Mocking globalThis Properties
+
+Save and restore `globalThis` state to prevent test leaks:
+
+```typescript
+const original = globalThis.location;
+
+beforeEach(() => {
+  Object.defineProperty(globalThis, 'location', {
+    value: { origin: 'http://test' },
+    writable: true,
+  });
+});
+
+afterEach(() => {
+  if (original !== undefined) {
+    Object.defineProperty(globalThis, 'location', { value: original, writable: true });
+  }
+});
+```
+
+## Guard Clause Reachability
+
+Ensure guard clauses don't make later code unreachable. Example anti-pattern:
+
+```typescript
+// Bad: 'http://localhost' is unreachable
+if (location?.origin) return location.origin;
+if (!browser) return '';
+return 'http://localhost'; // Never reached in browser
+```
+
+Simplify to remove dead code after the final guard.
diff --git a/src/features/votes/internal_clients/vote_grade.test.ts b/src/features/votes/internal_clients/vote_grade.test.ts
index 80adfc956..8121f971e 100644
--- a/src/features/votes/internal_clients/vote_grade.test.ts
+++ b/src/features/votes/internal_clients/vote_grade.test.ts
@@ -10,6 +10,8 @@ import * as statusCodes from '$lib/constants/http-response-status-codes';
 const BASE_URL = 'http://localhost';
 const TASK_ID = 'abc_a';
 
+const originalLocation = globalThis.location;
+
 beforeEach(() => {
   nock.cleanAll();
   // Set globalThis.location for test environment
@@ -21,6 +23,13 @@ beforeEach(() => {
 
 afterEach(() => {
   nock.cleanAll();
+  // Restore original location to prevent test state leak
+  if (originalLocation !== undefined) {
+    Object.defineProperty(globalThis, 'location', {
+      value: originalLocation,
+      writable: true,
+    });
+  }
 });
 
 describe('fetchMyVote', () => {
diff --git a/src/features/votes/internal_clients/vote_grade.ts b/src/features/votes/internal_clients/vote_grade.ts
index f2cde83f7..96fabbeb2 100644
--- a/src/features/votes/internal_clients/vote_grade.ts
+++ b/src/features/votes/internal_clients/vote_grade.ts
@@ -1,6 +1,5 @@
 import type { TaskGrade } from '$lib/types/task';
 import { isValidTaskGrade } from '$lib/utils/task_grade';
-import { browser } from '$app/environment';
 
 /**
  * Fetches the current user's vote grade for a given task.
@@ -88,14 +87,10 @@ function getBaseUrl(): string {
     return globalThis.location.origin;
   }
 
-  if (!browser) {
-    console.warn(
-      'getBaseUrl() called in SSR context where browser APIs are unavailable. ' +
-        'This should only be called from client-side code.',
-    );
-
-    return '';
-  }
+  console.warn(
+    'getBaseUrl() called in SSR context where browser APIs are unavailable. ' +
+      'This should only be called from client-side code.',
+  );
 
-  return 'http://localhost';
+  return '';
 }
diff --git a/src/features/votes/utils/median.ts b/src/features/votes/utils/median.ts
index 29e8bb334..ede766196 100644
--- a/src/features/votes/utils/median.ts
+++ b/src/features/votes/utils/median.ts
@@ -1,5 +1,6 @@
 import { TaskGrade } from '@prisma/client';
 import { getGradeOrder, taskGradeOrderInfinity } from '$lib/utils/task';
+import { MIN_VOTES_FOR_STATISTICS } from '$features/votes/constants/statistics';
 
 /** Maps grade order (1=Q11 … 17=D6) back to the corresponding TaskGrade enum value. */
 const ORDER_TO_TASK_GRADE: Map<number, TaskGrade> = new Map([
@@ -30,10 +31,14 @@ type GradeCounter = { grade: TaskGrade; count: number };
  * Returns `null` when the total vote count is below the minimum threshold.
  *
  * @param counters - Grade counters sorted by grade ascending.
- * @param minVotes - Minimum votes required to compute a median. Defaults to 3.
+ * @param minVotes - Minimum votes required to compute a median. Defaults to MIN_VOTES_FOR_STATISTICS.
+ *
  * @returns The median TaskGrade, or `null` if there are fewer than `minVotes` total votes.
  */
-export function computeMedianGrade(counters: GradeCounter[], minVotes = 3): TaskGrade | null {
+export function computeMedianGrade(
+  counters: GradeCounter[],
+  minVotes = MIN_VOTES_FOR_STATISTICS,
+): TaskGrade | null {
   const total = counters.reduce((sum, counter) => sum + counter.count, 0);
   if (total < minVotes) {
     return null;
diff --git a/src/test/utils/task_grade.test.ts b/src/lib/utils/task_grade.test.ts
similarity index 100%
rename from src/test/utils/task_grade.test.ts
rename to src/lib/utils/task_grade.test.ts
diff --git a/vite.config.ts b/vite.config.ts
index b8b455a29..c28b4e23b 100755
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -9,6 +9,7 @@ export default defineConfig({
   },
   test: {
     include: [
+      'src/lib/**/*.test.ts', // shared utility tests
       'src/test/**/*.test.ts', // existing tests (phase transition)
       'src/features/**/*.test.ts', // feature co-location tests
     ],

From bae4e8072c11284076746b2f531540964b197f31 Mon Sep 17 00:00:00 2001
From: Kato Hiroki <k.hiro1818@gmail.com>
Date: Thu, 9 Apr 2026 14:12:38 +0000
Subject: [PATCH 46/46] fix(migration): fix failed vote grade CHECK constraint
 migration in staging

Rename migration with corrected table names (lowercase per @@map) and add
a one-time workflow_dispatch workflow to resolve the P3009 stuck state in staging DB.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 .github/workflows/resolve-migration.yml       |  26 +++
 .../fix-vote-grade-check-constraints/plan.md  | 153 ++++++++++++++++++
 .../migration.sql                             |   8 +-
 3 files changed, 183 insertions(+), 4 deletions(-)
 create mode 100644 .github/workflows/resolve-migration.yml
 create mode 100644 docs/dev-notes/2026-04-09/fix-vote-grade-check-constraints/plan.md
 rename prisma/migrations/{20260406112057_add_vote_grade_check_constraints => 20260409000000_fix_vote_grade_check_constraints}/migration.sql (65%)

diff --git a/.github/workflows/resolve-migration.yml b/.github/workflows/resolve-migration.yml
new file mode 100644
index 000000000..e2d848a17
--- /dev/null
+++ b/.github/workflows/resolve-migration.yml
@@ -0,0 +1,26 @@
+name: Resolve Failed Migration (one-time use)
+on:
+  workflow_dispatch:
+
+jobs:
+  resolve:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v5
+        with:
+          package_json_file: package.json
+          run_install: false
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          cache: 'pnpm'
+          cache-dependency-path: pnpm-lock.yaml
+      - run: pnpm install
+      - name: Resolve failed migration in staging DB
+        run: |
+          pnpm exec prisma migrate resolve \
+            --rolled-back 20260406112057_add_vote_grade_check_constraints
+        env:
+          DATABASE_URL: ${{ secrets.PREVIEW_DATABASE_URL }}
+          DIRECT_URL: ${{ secrets.PREVIEW_DIRECT_URL }}
diff --git a/docs/dev-notes/2026-04-09/fix-vote-grade-check-constraints/plan.md b/docs/dev-notes/2026-04-09/fix-vote-grade-check-constraints/plan.md
new file mode 100644
index 000000000..5a3a3dad2
--- /dev/null
+++ b/docs/dev-notes/2026-04-09/fix-vote-grade-check-constraints/plan.md
@@ -0,0 +1,153 @@
+# staging 環境の failed migration 修復計画
+
+## 概要
+
+`20260406112057_add_vote_grade_check_constraints` migration が staging DB で P3009 エラー（失敗中状態）で止まっており、以降の migration deploy が全てブロックされている状態を GHA 経由で修復する。
+
+## 根本原因
+
+migration.sql 内のテーブル名が Pascal Case クォート形式（例: `"VotedGradeCounter"`）で記述されているが、`schema.prisma` の `@@map` により実際の PostgreSQL テーブル名は小文字（`votedgradecounter`）。
+
+```sql
+-- 誤（失敗した migration）
+ALTER TABLE "VotedGradeCounter" ADD CONSTRAINT ...
+
+-- 正（@@map に合わせた正しい記述）
+ALTER TABLE "votedgradecounter" ADD CONSTRAINT ...
+```
+
+PostgreSQL はクォート付きの識別子を大文字小文字区別で処理するため、`"VotedGradeCounter"` は存在しないテーブルを参照して ALTER TABLE が失敗。`_prisma_migrations` に `finished_at = NULL` のレコードが残り P3009 状態となった。
+
+## 他 AI 提案のレビュー・却下理由
+
+| 提案内容                                 | 評価              | 理由                                                                                                                  |
+| ---------------------------------------- | ----------------- | --------------------------------------------------------------------------------------------------------------------- |
+| `migrate resolve --rolled-back` の使用   | ✅ 正しい         | P3009 を解消する唯一の手段                                                                                            |
+| 同名 `migration.sql` を修正して再 deploy | ❌ **機能しない** | `--rolled-back` にマークされた migration は `migrate deploy` が永久にスキップする。同ファイルを修正しても実行されない |
+
+**正しいアプローチ:** rolled-back 解消後は、**新しいタイムスタンプで新 migration ファイルを作成**して deploy する必要がある。
+
+## 設計方針・却下した代替案
+
+### 採用: workflow_dispatch + 新 migration 作成
+
+- GHA の `workflow_dispatch` トリガーで `migrate resolve` を一度だけ実行
+- 旧 migration ファイルを git から削除（ローカル開発環境で `migrate dev` が失敗しないよう）
+- 新タイムスタンプで正しいテーブル名の migration を作成
+
+### 却下: ci.yml への一時追記
+
+- `resolve` ステップを既存 `preview` ジョブに追記する案
+- 問題: すでに成功した将来の deploy でも毎回 resolve コマンドが走る（冪等ではあるが冗長）
+- `workflow_dispatch` の方がスコープが明確で安全
+
+### 却下: DB への直接接続
+
+- staging DB に直接アクセスして `_prisma_migrations` を操作する案
+- 方針: GHA 経由でのみ DB を操作するため却下
+
+## 実装フェーズ
+
+### Phase 1: 変更を staging へ push（GHA に workflow_dispatch を公開）
+
+**変更ファイル:**
+
+| 操作 | パス                                                                              |
+| ---- | --------------------------------------------------------------------------------- |
+| 追加 | `.github/workflows/resolve-migration.yml`                                         |
+| 削除 | `prisma/migrations/20260406112057_add_vote_grade_check_constraints/`              |
+| 追加 | `prisma/migrations/20260409000000_fix_vote_grade_check_constraints/migration.sql` |
+
+**`.github/workflows/resolve-migration.yml` 内容:**
+
+```yaml
+name: Resolve Failed Migration (one-time use)
+on:
+  workflow_dispatch:
+
+jobs:
+  resolve:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v5
+        with:
+          package_json_file: package.json
+          run_install: false
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          cache: 'pnpm'
+          cache-dependency-path: pnpm-lock.yaml
+      - run: pnpm install
+      - name: Resolve failed migration in staging DB
+        run: |
+          pnpm exec prisma migrate resolve \
+            --rolled-back 20260406112057_add_vote_grade_check_constraints
+        env:
+          DATABASE_URL: ${{ secrets.PREVIEW_DATABASE_URL }}
+          DIRECT_URL: ${{ secrets.PREVIEW_DIRECT_URL }}
+```
+
+**新 migration SQL:**
+
+```sql
+-- VotedGradeCounter.count must never go negative (application guard + DB last line of defense)
+ALTER TABLE "votedgradecounter" ADD CONSTRAINT "votedgradecounter_count_non_negative"
+  CHECK (count >= 0);
+
+-- VoteGrade.grade must not be PENDING (only non-pending grades are valid votes)
+ALTER TABLE "votegrade" ADD CONSTRAINT "votegrade_grade_not_pending"
+  CHECK (grade != 'PENDING');
+
+-- VotedGradeCounter.grade must not be PENDING
+ALTER TABLE "votedgradecounter" ADD CONSTRAINT "votedgradecounter_grade_not_pending"
+  CHECK (grade != 'PENDING');
+
+-- VotedGradeStatistics.grade must not be PENDING (median must be a real grade)
+ALTER TABLE "votedgradestatistics" ADD CONSTRAINT "votedgradestatistics_grade_not_pending"
+  CHECK (grade != 'PENDING');
+```
+
+> この push で preview ジョブが起動するが、staging DB はまだ stuck 状態のため `migrate deploy` は P3009 で失敗する。これは想定内。
+
+### Phase 2: workflow_dispatch を手動トリガー
+
+GitHub Actions UI から操作:
+
+1. リポジトリの Actions タブを開く
+2. "Resolve Failed Migration (one-time use)" を選択
+3. "Run workflow" → **staging ブランチ**を選択して実行
+
+これにより staging DB の `_prisma_migrations` の対象レコードに `rolled_back_at` がセットされ、P3009 が解消される。
+
+### Phase 3: 失敗した preview ジョブを再実行
+
+GitHub Actions UI から Phase 1 の push で失敗した preview ジョブを "Re-run jobs" で再実行。今度は `migrate deploy` が P3009 なしで通り、新 migration `20260409000000_fix_vote_grade_check_constraints` が適用される。
+
+## 検証
+
+| タイミング     | 確認内容                                                     |
+| -------------- | ------------------------------------------------------------ |
+| Phase 2 完了後 | `workflow_dispatch` ジョブの終了コードが 0                   |
+| Phase 3 完了後 | GHA の "Apply all pending migrations" ステップが成功         |
+| Phase 3 完了後 | staging の Vercel デプロイが完了                             |
+| Phase 3 完了後 | staging アプリで投票機能が正常動作（CHECK 制約が DB に存在） |
+
+## ローカル開発環境への影響
+
+旧 migration ファイルを git から削除することで、開発者が `git pull` 後に `migrate dev` を実行しても旧 SQL は実行されず、代わりに新 migration が適用される。
+
+ただし、**旧 migration をすでにローカル DB に適用しようとして failed 状態にしている開発者**は別途対応が必要:
+
+```bash
+# ローカル DB の stuck 状態を解消
+pnpm exec prisma migrate resolve --rolled-back 20260406112057_add_vote_grade_check_constraints
+
+# その後 migrate dev を実行
+pnpm exec prisma migrate dev
+```
+
+## 事後処理
+
+`resolve-migration.yml` は使い捨て。fix 確認後に削除 PR を出してもよい（再実行しても冪等なので必須ではない）。
diff --git a/prisma/migrations/20260406112057_add_vote_grade_check_constraints/migration.sql b/prisma/migrations/20260409000000_fix_vote_grade_check_constraints/migration.sql
similarity index 65%
rename from prisma/migrations/20260406112057_add_vote_grade_check_constraints/migration.sql
rename to prisma/migrations/20260409000000_fix_vote_grade_check_constraints/migration.sql
index f0587e803..2977b970b 100644
--- a/prisma/migrations/20260406112057_add_vote_grade_check_constraints/migration.sql
+++ b/prisma/migrations/20260409000000_fix_vote_grade_check_constraints/migration.sql
@@ -1,15 +1,15 @@
 -- VotedGradeCounter.count must never go negative (application guard + DB last line of defense)
-ALTER TABLE "VotedGradeCounter" ADD CONSTRAINT "votedgradecounter_count_non_negative"
+ALTER TABLE "votedgradecounter" ADD CONSTRAINT "votedgradecounter_count_non_negative"
   CHECK (count >= 0);
 
 -- VoteGrade.grade must not be PENDING (only non-pending grades are valid votes)
-ALTER TABLE "VoteGrade" ADD CONSTRAINT "votegrade_grade_not_pending"
+ALTER TABLE "votegrade" ADD CONSTRAINT "votegrade_grade_not_pending"
   CHECK (grade != 'PENDING');
 
 -- VotedGradeCounter.grade must not be PENDING
-ALTER TABLE "VotedGradeCounter" ADD CONSTRAINT "votedgradecounter_grade_not_pending"
+ALTER TABLE "votedgradecounter" ADD CONSTRAINT "votedgradecounter_grade_not_pending"
   CHECK (grade != 'PENDING');
 
 -- VotedGradeStatistics.grade must not be PENDING (median must be a real grade)
-ALTER TABLE "VotedGradeStatistics" ADD CONSTRAINT "votedgradestatistics_grade_not_pending"
+ALTER TABLE "votedgradestatistics" ADD CONSTRAINT "votedgradestatistics_grade_not_pending"
   CHECK (grade != 'PENDING');