AtCoder-NoviSteps · KATO-Hiro · May 10, 2026 · May 10, 2026 · May 10, 2026 · May 10, 2026
diff --git a/.claude/skills/add-contest-table-provider/SKILL.md b/.claude/skills/add-contest-table-provider/SKILL.md
@@ -0,0 +1,13 @@
+---
+name: add-contest-table-provider
+description: Add a new ContestType and ContestTableProvider across 5 layers using TDD. Covers all 3 patterns. Asks targeted questions to gather pattern-specific requirements before touching code.
+argument-hint: '<ContestType> <contest_id>'
+---
+
+Add a new contest table provider for: $ARGUMENTS
+
+> When in doubt at any step, use AskUserQuestion before proceeding.
+
+0. **Seed check** — grep `prisma/tasks.ts` for the contest_id(s); report count + task_ids; if absent or incomplete, ask the user to add missing rows (reference: `https://kenkoooo.com/atcoder/resources/problems.json`)
+1. **Gather requirements** — infer the implementation pattern; confirm per [instructions.md §Requirements](instructions.md)
+2. **Implement** — follow [instructions.md](instructions.md) for the confirmed pattern across 5 layers (TDD)
diff --git a/.claude/skills/add-contest-table-provider/instructions.md b/.claude/skills/add-contest-table-provider/instructions.md
@@ -0,0 +1,123 @@
+# Add Contest Table Provider — Implementation Checklist
+
+Reference: `docs/guides/how-to-add-contest-table-provider.md`
+
+---
+
+## Requirements gathering
+
+Step 0 (seed check) is already done. Confirm the following before touching code:
+
+**All patterns:**
+
+- Which pattern? (State your inference from the data, ask to confirm)
+  - Pattern 1: numeric range filter (e.g. ABC 001–041)
+  - Pattern 2: single fixed contest_id (e.g. NDPC, TDPC, FPS_24)
+  - Pattern 3: multiple contest_ids unified in one table (e.g. ABS, ABC-Like)
+- Nearest neighbor ContestType for insertion order in `contestTypePriorities`?
+- New group or merge into existing? If new: group name / `buttonLabel` / `ariaLabel`?
+
+**Pattern 1 additional:**
+
+- Numeric range: start and end (open-ended if no upper bound)?
+- Shared problems with another contest (e.g. ARC–ABC overlap)? Which contest_ids appear in both?
+- Round label format (e.g. `ABC 042`)?
+
+**Pattern 3 additional:**
+
+- Show the full contest_id list found in `prisma/tasks.ts` — any missing or to exclude?
+- Does `prisma/contest_task_pairs.ts` need updating (shared task_ids across contests)?
+- task_table_index format: numeric (`001–`) or alphabetic (`A–`)?
+- Section splits needed? If yes: split key and section names?
+
+---
+
+## Layer 1 — Prisma schema
+
+- [ ] Add `XXX // Full Contest Name` to `prisma/schema.prisma` ContestType enum (after nearest neighbor)
+- [ ] `pnpm exec prisma generate` — non-interactive env; `migrate dev` requires interactive shell
+- [ ] `pnpm check` — expect a type error in `src/lib/types/contest.ts` (confirms client regenerated)
+
+## Layer 2 — TypeScript ContestType constant
+
+- [ ] Add `XXX: 'XXX', // Full Contest Name` to `ContestType` in `src/lib/types/contest.ts` (same position as schema)
+- [ ] `pnpm check` — error should be gone
+
+## Layer 3 — Contest utilities (TDD)
+
+### Write tests first
+
+- [ ] Add export to `src/test/lib/utils/test_cases/contest_type.ts` (after nearest neighbor)
+- [ ] Add export to `src/test/lib/utils/test_cases/contest_name_labels.ts` (after nearest neighbor)
+- [ ] Add three `describe('when contest_id is xxx')` blocks to `src/test/lib/utils/contest.test.ts`:
+  - under `classify contest`
+  - under `get contest priority`
+  - under `get contest name label`
+- [ ] `pnpm test:unit src/test/lib/utils/contest.test.ts` — **expect RED**
+
+### Implement
+
+- [ ] Add `classifyContest` branch after nearest neighbor's branch in `src/lib/utils/contest.ts`
+- [ ] Insert `[ContestType.XXX, N]` into `contestTypePriorities` after nearest neighbor
+  - All entries after the insertion point shift by +1
+  - **Update the JSDoc numeric ranges** — do NOT rename or split the existing four categories
+    (Educational / Contests for genius / Special contests / External platforms)
+  - **Search `src/test/lib/utils/task.test.ts` for hardcoded priority-diff expected values**
+    and decrement by 1 for every ContestType that shifted
+- [ ] Add `getContestNameLabel` branch after nearest neighbor's branch
+- [ ] `pnpm test:unit src/test/lib/utils/contest.test.ts` — **expect GREEN**
+
+---
+
+## Layer 4 — Provider class (TDD)
+
+### Pattern 2: single source
+
+- [ ] Add entry to `describe.each` array in `dp_providers.test.ts` (or the appropriate `*_providers.test.ts`)
+- [ ] Add import of new Provider class
+- [ ] `pnpm test:unit <providers.test.ts>` — **expect RED**
+- [ ] Implement Provider class in the appropriate `*_providers.ts` after nearest neighbor
+- [ ] `pnpm test:unit <providers.test.ts>` — **expect GREEN**
+
+### Pattern 1: range filter
+
+- [ ] Add test cases covering range boundaries and at least one mid-range value
+- [ ] If shared problems exist: add a test case with mixed contest_ids to confirm exclusion
+- [ ] `pnpm test:unit <providers.test.ts>` — **expect RED**
+- [ ] Implement Provider using `parseContestRound()` range check
+- [ ] `pnpm test:unit <providers.test.ts>` — **expect GREEN**
+
+### Pattern 3: composite
+
+- [ ] Confirm whether `prisma/contest_task_pairs.ts` needs new entries before writing tests
+- [ ] Add test cases for each constituent contest_id, plus a mixed-source test
+- [ ] If section splits: add one test per section
+- [ ] `pnpm test:unit <providers.test.ts>` — **expect RED**
+- [ ] Implement Provider (filter by `classifyContest` equality; add section subclasses if needed)
+- [ ] `pnpm test:unit <providers.test.ts>` — **expect GREEN**
+
+---
+
+## Layer 5 — Group registration (TDD)
+
+- [ ] Update `contest_table_provider_groups.test.ts`:
+  - New group name string, `buttonLabel`, `ariaLabel`
+  - `getSize()` incremented to reflect the new provider count
+  - Add `getProvider(ContestType.XXX)` assertion
+  - Add import of new Provider class
+- [ ] `pnpm test:unit contest_table_provider_groups.test.ts` — **expect RED**
+- [ ] Update `contest_table_provider_groups.ts`:
+  - Add import of new Provider class
+  - Update group name string, `buttonLabel`, `ariaLabel`
+  - Add `new XXXProvider(ContestType.XXX)` to `addProviders()`
+- [ ] `pnpm test:unit src/features/tasks/utils/contest-table/` — **expect GREEN**
+
+---
+
+## Final verification
+
+- [ ] `pnpm test:unit`
+- [ ] `pnpm check`
+- [ ] `pnpm lint`
+
+Commit Layer 1–3 and Layer 4–5 as separate commits.
diff --git a/docs/guides/claude-code.md b/docs/guides/claude-code.md
@@ -65,12 +65,13 @@ paths:
 
 **本プロジェクトの skills（`.claude/skills/` および superpowers plugin）:**
 
-| スキル           | 用途                                                                                                                               |
-| ---------------- | ---------------------------------------------------------------------------------------------------------------------------------- |
-| `/writing-plans` | 新機能・追加実装の詳細計画を生成（2-5分単位のタスク分解）。superpowers plugin 提供                                                 |
-| `/refactor-plan` | Issue 番号またはパスを渡してリファクタリング計画を出力（実装はしない）                                                             |
-| `/session-close` | セッション終了時のルーティン：テスト確認 → plan.md 更新 → rules 候補提示 → 肥大化チェック → 繰り返し指示検出                       |
-| `/dep-upgrade`   | ライブラリのメジャーバージョンアップ分析：破壊的変更の整理・本プロジェクトへの影響・新機能提案 → plan.md 生成 → アップグレード実行 |
+| スキル                        | 用途                                                                                                                                                            |
+| ----------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `/writing-plans`              | 新機能・追加実装の詳細計画を生成（2-5分単位のタスク分解）。superpowers plugin 提供                                                                              |
+| `/add-contest-table-provider` | 新しい ContestType と ContestTableProvider を TDD で 5 層実装（Prisma → 型 → ユーティリティ → Provider → グループ登録）。3 パターン対応。実装前に要件を確認する |
+| `/refactor-plan`              | Issue 番号またはパスを渡してリファクタリング計画を出力（実装はしない）                                                                                          |
+| `/session-close`              | セッション終了時のルーティン：テスト確認 → plan.md 更新 → rules 候補提示 → 肥大化チェック → 繰り返し指示検出                                                    |
+| `/dep-upgrade`                | ライブラリのメジャーバージョンアップ分析：破壊的変更の整理・本プロジェクトへの影響・新機能提案 → plan.md 生成 → アップグレード実行                              |
 
 **`/dep-upgrade` の使い方:**
 

diff --git a/docs/guides/how-to-add-contest-table-provider.md b/docs/guides/how-to-add-contest-table-provider.md
@@ -265,12 +265,14 @@ class TessokuBookSectionProvider extends TessokuBookProvider {
 | -------------- | ------------- | ---------- | ------------ |
 | EDPC           | `'dp'`        | 26問       | A～Z         |
 | TDPC           | `'tdpc'`      | 26問       | A～Z         |
+| NDPC           | `'ndpc'`      | 20問       | A～T         |
 | FPS_24         | `'fps-24'`    | 24問       | A～X         |
 | ACL_PRACTICE   | `'practice2'` | 12問       | A～L         |
 | ACL_BEGINNER\* | `'abl'`       | 6問        | A～F         |
 | ACL_CONTEST1\* | `'acl1'`      | 6問        | A～F         |
 
 \*注: ACL_PRACTICE、ACL_BEGINNER、ACL_CONTEST1 は `Acl` グループの下で 3 つのコンテストが統一管理されています。
+\*\*注: EDPC・TDPC・NDPC・FPS 24 は `dps` グループ下で 4 つのコンテストが統一管理されています。
 
 ### 複合ソース型
 
@@ -317,7 +319,7 @@ describe('MyNewProvider', () => {
   test('filters tasks correctly', () => {
     const provider = new MyNewProvider(ContestType.MY_NEW);
     const filtered = provider.filter(taskResultsForMyNew);
-    expect(filtered.every((t) => t.contest_id === 'my-contest')).toBe(true);
+    expect(filtered.every((task) => task.contest_id === 'my-contest')).toBe(true);
   });
 
   test('returns correct metadata', () => {
@@ -426,7 +428,7 @@ export const taskResultsForNewProvider: TaskResults = [
 
 ---
 
-## よくあるミス Top 4
+## よくあるミス Top 5
 
 ### 1. **getDisplayConfig() での属性漏れ**
 
@@ -502,6 +504,31 @@ describe('CustomProvider with unique config', () => {
 
 ---
 
+### 5. **contestTypePriorities の JSDoc カテゴリ名を変更してしまう**
+
+**問題**: 新しい ContestType を挿入して数値範囲が変わったとき、既存の4カテゴリ名
+（`Educational` / `Contests for genius` / `Special contests` / `External platforms`）を
+意図せず改名・分割・合体してしまい、歴史的経緯や分類上の意味が失われる。
+
+**解決策**: **カテゴリ名は絶対に変更しない**。変えてよいのは括弧内の数値範囲だけ。
+
+```typescript
+// Before: [ContestType.TDPC, 5] ... [ContestType.PAST, 6]
+// After inserting NDPC at 6:
+//   [ContestType.NDPC, 6], [ContestType.PAST, 7], ...
+
+// ✅ 数値範囲だけ更新
+// Educational contests (0–11, 17)
+// Contests for genius (12–16)
+// Special contests (18–20)
+// External platforms (21–23)
+
+// ❌ カテゴリを改名・分割・合体しない
+// Educational / DP contests (0–6)   ← NG
+```
+
+---
+
 ## 実装完了後
 
 ### ドキュメント更新チェックリスト
@@ -532,6 +559,7 @@ describe('CustomProvider with unique config', () => {
 - [#2797](https://github.com/AtCoder-NoviSteps/AtCoderNoviSteps/issues/2797) - FPS24Provider
 - [#2920](https://github.com/AtCoder-NoviSteps/AtCoderNoviSteps/issues/2920)、[#3120](https://github.com/AtCoder-NoviSteps/AtCoderNoviSteps/issues/3120) - ACLPracticeProvider、ACLBeginnerProvider、ACLProvider
 - [#3152](https://github.com/AtCoder-NoviSteps/AtCoderNoviSteps/issues/3152) - JOISemiFinalRoundProvider（本選 → セミファイナルステージ への対応）
+- NDPC実装 - NDPCProvider（パターン2: 単一ソース型、prisma/tasks.ts に 20 問存在）
 
 ### 実装ファイル
 
@@ -541,4 +569,4 @@ describe('CustomProvider with unique config', () => {
 
 ---
 
-**最終更新**: 2026-02-22
+**最終更新**: 2026-05-10
diff --git a/prisma/migrations/20260510075743_fix_atcoder_account_updated_at_default/migration.sql b/prisma/migrations/20260510075743_fix_atcoder_account_updated_at_default/migration.sql
@@ -0,0 +1,4 @@
+-- @updatedAt is managed by Prisma ORM, not the DB layer. The original
+-- split_atcoder_account migration incorrectly added DEFAULT CURRENT_TIMESTAMP
+-- to updatedAt. This migration aligns the migration history with the actual DB state.
+ALTER TABLE "atcoder_account" ALTER COLUMN "updatedAt" DROP DEFAULT;
diff --git a/prisma/migrations/20260510080034_add_ndpc_to_contest_type/migration.sql b/prisma/migrations/20260510080034_add_ndpc_to_contest_type/migration.sql
@@ -0,0 +1,2 @@
+-- AlterEnum
+ALTER TYPE "ContestType" ADD VALUE 'NDPC';
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
@@ -305,6 +305,7 @@ enum ContestType {
   PAST // Practical Algorithm Skill Test (アルゴリズム実技検定)
   EDPC // Educational DP Contest / DP まとめコンテスト
   TDPC // Typical DP Contest
+  NDPC // Next DP Contest
   JOI // Japanese Olympiad in Informatics
   TYPICAL90 // 競プロ典型 90 問
   TESSOKU_BOOK // 競技プログラミングの鉄則

diff --git a/prisma/tasks.ts b/prisma/tasks.ts
@@ -6346,6 +6346,146 @@ export const tasks = [
     title: 'A. コンテスト',
     grade: 'Q2',
   },
+  {
+    id: 'ndpc2026_t',
+    contest_id: 'ndpc',
+    problem_index: 'T',
+    name: 'Independent Set',
+    title: 'T. Independent Set',
+  },
+  {
+    id: 'ndpc2026_s',
+    contest_id: 'ndpc',
+    problem_index: 'S',
+    name: 'Two doors',
+    title: 'S. Two doors',
+  },
+  {
+    id: 'ndpc2026_r',
+    contest_id: 'ndpc',
+    problem_index: 'R',
+    name: 'Triples',
+    title: 'R. Triples',
+  },
+  {
+    id: 'ndpc2026_q',
+    contest_id: 'ndpc',
+    problem_index: 'Q',
+    name: 'Union of Intervals',
+    title: 'Q. Union of Intervals',
+  },
+  {
+    id: 'ndpc2026_p',
+    contest_id: 'ndpc',
+    problem_index: 'P',
+    name: 'LIS',
+    title: 'P. LIS',
+  },
+  {
+    id: 'ndpc2026_o',
+    contest_id: 'ndpc',
+    problem_index: 'O',
+    name: 'Game',
+    title: 'O. Game',
+  },
+  {
+    id: 'ndpc2026_n',
+    contest_id: 'ndpc',
+    problem_index: 'N',
+    name: 'Knapsack',
+    title: 'N. Knapsack',
+  },
+  {
+    id: 'ndpc2026_m',
+    contest_id: 'ndpc',
+    problem_index: 'M',
+    name: 'Numeral',
+    title: 'M. Numeral',
+  },
+  {
+    id: 'ndpc2026_l',
+    contest_id: 'ndpc',
+    problem_index: 'L',
+    name: 'LCM',
+    title: 'L. LCM',
+  },
+  {
+    id: 'ndpc2026_k',
+    contest_id: 'ndpc',
+    problem_index: 'K',
+    name: 'Addition and Subtraction',
+    title: 'K. Addition and Subtraction',
+  },
+  {
+    id: 'ndpc2026_j',
+    contest_id: 'ndpc',
+    problem_index: 'J',
+    name: 'Number and Total',
+    title: 'J. Number and Total',
+  },
+  {
+    id: 'ndpc2026_i',
+    contest_id: 'ndpc',
+    problem_index: 'I',
+    name: 'Update Positions',
+    title: 'I. Update Positions',
+  },
+  {
+    id: 'ndpc2026_h',
+    contest_id: 'ndpc',
+    problem_index: 'H',
+    name: 'Coin',
+    title: 'H. Coin',
+  },
+  {
+    id: 'ndpc2026_g',
+    contest_id: 'ndpc',
+    problem_index: 'G',
+    name: 'Mouth',
+    title: 'G. Mouth',
+  },
+  {
+    id: 'ndpc2026_f',
+    contest_id: 'ndpc',
+    problem_index: 'F',
+    name: 'Set',
+    title: 'F. Set',
+  },
+  {
+    id: 'ndpc2026_e',
+    contest_id: 'ndpc',
+    problem_index: 'E',
+    name: 'Summer Vacation',
+    title: 'E. Summer Vacation',
+  },
+  {
+    id: 'ndpc2026_d',
+    contest_id: 'ndpc',
+    problem_index: 'D',
+    name: 'Banknote',
+    title: 'D. Banknote',
+  },
+  {
+    id: 'ndpc2026_c',
+    contest_id: 'ndpc',
+    problem_index: 'C',
+    name: 'String',
+    title: 'C. String',
+  },
+  {
+    id: 'ndpc2026_b',
+    contest_id: 'ndpc',
+    problem_index: 'B',
+    name: 'DAG',
+    title: 'B. DAG',
+  },
+  {
+    id: 'ndpc2026_a',
+    contest_id: 'ndpc',
+    problem_index: 'A',
+    name: 'Polyomino',
+    title: 'A. Polyomino',
+  },
   {
     id: 'math_and_algorithm_bn',
     contest_id: 'math-and-algorithm',
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		-- AlterEnum
		ALTER TYPE "ContestType" ADD VALUE 'NDPC';