refactor: lib subpath imports for kit v3

.oxlintrc.json

@@ -24,6 +24,17 @@
       "error",
       { "argsIgnorePattern": "^_", "varsIgnorePattern": "^_" }
     ],
-    "@typescript-eslint/no-explicit-any": "warn"
+    "@typescript-eslint/no-explicit-any": "warn",
+    "no-restricted-imports": [
+      "error",
+      {
+        "patterns": [
+          {
+            "regex": "^\\$lib(/|$)",
+            "message": "SvelteKit 3 removes $lib. Use #lib with an explicit extension (e.g. #lib/types/task.js)."
+          }
+        ]
+      }
+    ]
   }
 }

docs/guides/agent-rules/prisma-db.md

@@ -21,7 +21,7 @@ paths:
 
 ## Server-Only Code
 
-- Import the DB client (`$lib/server/database`) only in `src/lib/server/**` and in server-only services under `src/lib/services/**` and `src/features/**/services/**`
+- Import the DB client (`#lib/server/database.js`) only in `src/lib/server/**` and in server-only services under `src/lib/services/**` and `src/features/**/services/**`
 - Never import server-only code in client components
 
 ## Service Layer

docs/guides/agent-rules/server-cache.md

@@ -78,7 +78,7 @@ Services call `getCached*()` with a `fetchFn` that performs the DB query. The se
 
 ```typescript
 // In service file
-import { getCachedTasksMap } from '$lib/server/tasks/cache';
+import { getCachedTasksMap } from '#lib/server/tasks/cache.js';
 
 export async function getTasksByTaskId(): Promise<Map<string, Task>> {
   return getCachedTasksMap(async () => {
@@ -91,7 +91,7 @@ export async function getTasksByTaskId(): Promise<Map<string, Task>> {
 Mock cache in service tests to bypass caching:
 
 ```typescript
-vi.mock('$lib/server/tasks/cache', () => ({
+vi.mock('#lib/server/tasks/cache.js', () => ({
   getCachedTasksMap: (fetchFn: () => Promise<unknown>) => fetchFn(),
   invalidateTaskCaches: vi.fn(),
 }));

docs/guides/agent-rules/testing-e2e.md

@@ -10,7 +10,7 @@ paths:
 ## Setup
 
 - 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:
+- No path aliases or subpath imports (`$features` is resolved only by Vite; `#lib/*.js` resolves to `src/lib/*.js`, but the Playwright runner does not map it to the `.ts` source). Use type-only imports for types:
 
 ```typescript
 // Bad: runtime import fails in E2E

docs/guides/agent-rules/testing.md

@@ -70,7 +70,7 @@ test.each([TaskGrade.PENDING, TaskGrade.Q11, TaskGrade.Q10, TaskGrade.D6])(
 
 ### Service Layer (Prisma)
 
-Mock with `vi.mock('$lib/server/database', ...)`. Use helpers:
+Mock with `vi.mock('#lib/server/database.js', ...)`. Use helpers:
 
 ```typescript
 const mockFindUnique = (data) => db.task.findUnique.mockResolvedValue(data);
@@ -95,7 +95,7 @@ afterAll(() => disposeDomainCaches());
 beforeEach(() => invalidateDomainCaches());
 
 // Bypass caching in service tests:
-vi.mock('$lib/server/tasks/cache', () => ({
+vi.mock('#lib/server/tasks/cache.js', () => ({
   getCachedTasksMap: (fetchFn: () => Promise<unknown>) => fetchFn(),
   invalidateTaskCaches: vi.fn(),
 }));

docs/guides/architecture.md

@@ -75,7 +75,7 @@ feature 内は技術的な役割で分ける。必要なディレクトリだけ
 - `utils/`: 副作用のない関数。テストを隣接配置する。
 - `stores/`: Svelte Runes を使う `.svelte.ts`。
 
-`features/{feature}/server/` は `$lib/server/` と違い、SvelteKit が client import を自動では禁止しない。規約と推移的な server-only dependency により client から分離する。複数 feature で使うサーバコードは `src/lib/server/` へ移す。
+`features/{feature}/server/` は `src/lib/server/` と違い、SvelteKit が client import を自動では禁止しない。規約と推移的な server-only dependency により client から分離する。複数 feature で使うサーバコードは `src/lib/server/` へ移す。
 
 ### 3. src/lib
 
@@ -139,12 +139,15 @@ include: [
 ];
 ```
 
-### 6. path alias
+### 6. path alias と subpath imports
 
-`svelte.config.js` で `$lib` と `$features` を定義している。
+`src/lib` は `package.json#imports` の `#lib/*` で参照する。SvelteKit 3 で組み込みの `$lib` が削除されるため `$lib` は使わず、oxlint と ESLint の `no-restricted-imports` で禁止している。
+`#lib` には明示的な拡張子が必要で、TS モジュールは `.js`、コンポーネントは `.svelte`、runes モジュール（`.svelte.ts`）は `.svelte.js` と書く。`vi.mock` の specifier も同じ形にする。
+lint が検出するのは import・export 宣言（`import type`・`export … from` を含む）と `.ts` の動的 `import()` で、`vi.mock('$lib/...')` と `.svelte` 内の動的 `import()` は検出しない。import の specifier をまとめて変えたときは、`rg -n '\$lib' src e2e prisma` で残りが無いことも確かめる。
+`$features` は `svelte.config.js` の alias で定義している。
 
 ```typescript
-import { formatDate } from '$lib/utils/format';
+import { formatDate } from '#lib/utils/format.js';
 import WorkBookForm from '$features/workbooks/components/shared/WorkBookForm.svelte';
 import type { PageServerLoad } from './$types';
 ```

eslint.config.mjs

@@ -80,6 +80,19 @@ export default [
       'svelte/no-useless-mustaches': 'warn',
       'svelte/prefer-writable-derived': 'warn', // New in 3.6.0 - prefer $derived over $state+$effect
       'svelte/valid-prop-names-in-kit-pages': 'warn', // Allow props other than data/errors in pages
+      // Kit 2 still resolves $lib, so new imports would only break on Kit 3; oxlint covers JS/TS files
+      'no-restricted-imports': [
+        'error',
+        {
+          patterns: [
+            {
+              regex: '^\\$lib(/|$)',
+              message:
+                'SvelteKit 3 removes $lib. Use #lib with an explicit extension (e.g. #lib/types/task.js).',
+            },
+          ],
+        },
+      ],
       'no-unused-vars': 'off', // Use TypeScript version instead
       'no-undef': 'off', // TypeScript handles this
     },

package.json

@@ -70,6 +70,9 @@
     "zod": "4.6.7"
   },
   "type": "module",
+  "imports": {
+    "#lib/*": "./src/lib/*"
+  },
   "dependencies": {
     "@dnd-kit/helpers": "0.5.1",
     "@dnd-kit/svelte": "0.5.1",

src/features/account/components/delete/AccountDeletionForm.svelte

@@ -2,9 +2,9 @@
   import { Input, Button, Alert, Checkbox, Modal } from 'flowbite-svelte';
   import Info from '@lucide/svelte/icons/info';
 
-  import ContainerWrapper from '$lib/components/ContainerWrapper.svelte';
-  import FormWrapper from '$lib/components/FormWrapper.svelte';
-  import LabelWrapper from '$lib/components/LabelWrapper.svelte';
+  import ContainerWrapper from '#lib/components/ContainerWrapper.svelte';
+  import FormWrapper from '#lib/components/FormWrapper.svelte';
+  import LabelWrapper from '#lib/components/LabelWrapper.svelte';
   import WarningMessageOnDeletingAccount from './WarningMessageOnDeletingAccount.svelte';
 
   interface Props {

src/features/account/components/settings/AtCoderVerificationForm.svelte

@@ -3,10 +3,10 @@
   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';
+  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';
 
   interface Props {
     username: string;

src/features/account/services/atcoder_verification.test.ts

@@ -1,6 +1,6 @@
 import { describe, test, expect, vi, beforeEach, afterEach } from 'vitest';
 
-vi.mock('$lib/server/database', () => ({
+vi.mock('#lib/server/database.js', () => ({
   default: {
     user: {
       findUniqueOrThrow: vi.fn(),
@@ -13,13 +13,13 @@ vi.mock('$lib/server/database', () => ({
   },
 }));
 
-vi.mock('$lib/utils/hash', () => ({
+vi.mock('#lib/utils/hash.js', () => ({
   sha256: vi.fn().mockResolvedValue('mocked-hash'),
 }));
 
 import { Roles, type AtCoderAccount } from '@prisma/client';
 
-import prisma from '$lib/server/database';
+import prisma from '#lib/server/database.js';
 import { generate, validate, reset } from './atcoder_verification';
 
 // ---------------------------------------------------------------------------

src/features/account/services/atcoder_verification.ts

@@ -1,5 +1,5 @@
-import { default as db } from '$lib/server/database';
-import { sha256 } from '$lib/utils/hash';
+import { default as db } from '#lib/server/database.js';
+import { sha256 } from '#lib/utils/hash.js';
 
 const EXTERNAL_API_TIMEOUT_MS = 5000;
 

src/features/auth/server/session.test.ts

@@ -2,7 +2,7 @@ import { describe, test, expect, beforeEach, afterEach, vi } from 'vitest';
 
 import { Prisma, Roles } from '@prisma/client';
 
-vi.mock('$lib/server/database', () => ({
+vi.mock('#lib/server/database.js', () => ({
   default: {
     session: {
       create: vi.fn(),
@@ -13,7 +13,7 @@ vi.mock('$lib/server/database', () => ({
   },
 }));
 
-import db from '$lib/server/database';
+import db from '#lib/server/database.js';
 import { createSession, validateSession, invalidateSession, SESSION_COOKIE_NAME } from './session';
 
 const mockDb = db as unknown as {

src/features/auth/server/session.ts

@@ -1,7 +1,7 @@
 import { PrismaClientKnownRequestError } from '@prisma/client/runtime/library';
 import type { Roles } from '@prisma/client';
 
-import client from '$lib/server/database';
+import client from '#lib/server/database.js';
 import { generateRandomString } from './random';
 
 // lucia v2 defaults: active 24h, idle +14d

src/features/auth/services/admin_access.test.ts

@@ -19,12 +19,12 @@ vi.mock('@sveltejs/kit', () => {
   return { redirect: vi.fn(redirectImpl), error: vi.fn(errorImpl) };
 });
 
-vi.mock('$lib/services/users', () => ({
+vi.mock('#lib/services/users.js', () => ({
   getUser: vi.fn(),
 }));
 
-import * as userService from '$lib/services/users';
-import { Roles } from '$lib/types/user';
+import * as userService from '#lib/services/users.js';
+import { Roles } from '#lib/types/user.js';
 import { validateAdminAccess, validateAdminAccessForApi } from './admin_access';
 
 const createMockLocalsWithSession = (username = 'admin-user') =>

src/features/auth/services/admin_access.ts

@@ -1,15 +1,15 @@
 import { redirect, error } from '@sveltejs/kit';
 
-import * as userService from '$lib/services/users';
+import * as userService from '#lib/services/users.js';
 
-import { Roles } from '$lib/types/user';
+import { Roles } from '#lib/types/user.js';
 
-import { isAdmin } from '$lib/utils/authorship';
+import { isAdmin } from '#lib/utils/authorship.js';
 import {
   TEMPORARY_REDIRECT,
   UNAUTHORIZED,
   FORBIDDEN,
-} from '$lib/constants/http-response-status-codes';
+} from '#lib/constants/http-response-status-codes.js';
 
 import { buildLoginPath } from '../utils/login';
 

src/features/auth/services/credentials.test.ts

@@ -2,7 +2,7 @@ import { describe, test, expect, vi } from 'vitest';
 
 import { Prisma } from '@prisma/client';
 
-vi.mock('$lib/server/database', () => ({
+vi.mock('#lib/server/database.js', () => ({
   default: {
     $transaction: vi.fn(),
     user: {
@@ -20,7 +20,7 @@ vi.mock('../server/password', () => ({
   verifyPassword: vi.fn(),
 }));
 
-import db from '$lib/server/database';
+import db from '#lib/server/database.js';
 import { hashPassword, verifyPassword } from '../server/password';
 import { registerUser, authenticateUser } from './credentials';
 

src/features/auth/services/credentials.ts

@@ -1,6 +1,6 @@
 import { PrismaClientKnownRequestError } from '@prisma/client/runtime/library';
 
-import client from '$lib/server/database';
+import client from '#lib/server/database.js';
 import { hashPassword, verifyPassword } from '../server/password';
 import { generateRandomString } from '../server/random';
 

src/features/auth/services/session_guards.ts

@@ -1,6 +1,6 @@
 import { redirect } from '@sveltejs/kit';
 
-import { TEMPORARY_REDIRECT } from '$lib/constants/http-response-status-codes';
+import { TEMPORARY_REDIRECT } from '#lib/constants/http-response-status-codes.js';
 
 import { buildLoginPath } from '../utils/login';
 

src/features/auth/utils/login.ts

@@ -1,4 +1,4 @@
-import { LOGIN_PAGE } from '$lib/constants/navbar-links';
+import { LOGIN_PAGE } from '#lib/constants/navbar-links.js';
 
 /**
  * Builds the login path with an optional redirect parameter.

src/features/auth/utils/signup.ts

@@ -1,4 +1,4 @@
-import { SIGNUP_PAGE } from '$lib/constants/navbar-links';
+import { SIGNUP_PAGE } from '#lib/constants/navbar-links.js';
 
 /**
  * Builds the signup path with an optional redirect parameter.

src/features/tasks/components/contest-table/TaskTable.svelte

@@ -13,13 +13,13 @@
     TableHeadCell,
   } from 'flowbite-svelte';
 
-  import type { TaskResults, TaskResult } from '$lib/types/task';
+  import type { TaskResults, TaskResult } from '#lib/types/task.js';
   import type {
     ContestTableProvider,
     ContestTableDisplayConfig,
     ContestTableMetaData,
   } from '$features/tasks/types/contest-table/contest_table_provider';
-  import type { ContestTaskPairKey } from '$lib/types/contest_task_pair';
+  import type { ContestTaskPairKey } from '#lib/types/contest_task_pair.js';
   import type { VoteStatisticsMap } from '$features/votes/types/vote_result';
 
   import TaskTableBodyCell from './TaskTableBodyCell.svelte';
@@ -31,11 +31,11 @@
     type ContestTableProviderGroups,
   } from '$features/tasks/utils/contest-table/contest_table_provider';
 
-  import { useLocalStorage } from '$lib/stores/local_storage_helper.svelte';
+  import { useLocalStorage } from '#lib/stores/local_storage_helper.svelte.js';
 
-  import { getBackgroundColorFrom } from '$lib/services/submission_status';
-  import { areAllTasksAccepted } from '$lib/utils/task';
-  import { createContestTaskPairKey } from '$lib/utils/contest_task_pair';
+  import { getBackgroundColorFrom } from '#lib/services/submission_status.js';
+  import { areAllTasksAccepted } from '#lib/utils/task.js';
+  import { createContestTaskPairKey } from '#lib/utils/contest_task_pair.js';
   import { getBodyRowClasses } from './_utils/contest_table_layout';
 
   interface Props {

src/features/tasks/components/contest-table/TaskTableBodyCell.svelte

@@ -1,12 +1,12 @@
 <script lang="ts">
-  import type { TaskResult } from '$lib/types/task';
+  import type { TaskResult } from '#lib/types/task.js';
   import type { VoteStatisticsMap } from '$features/votes/types/vote_result';
 
   import VotableGrade from '@/features/votes/components/VotableGrade.svelte';
-  import ExternalLinkWrapper from '$lib/components/ExternalLinkWrapper.svelte';
-  import UpdatingDropdown from '$lib/components/SubmissionStatus/UpdatingDropdown.svelte';
+  import ExternalLinkWrapper from '#lib/components/ExternalLinkWrapper.svelte';
+  import UpdatingDropdown from '#lib/components/SubmissionStatus/UpdatingDropdown.svelte';
 
-  import { getTaskUrl, removeTaskIndexFromTitle } from '$lib/utils/task';
+  import { getTaskUrl, removeTaskIndexFromTitle } from '#lib/utils/task.js';
   import { formatAojTitle } from '$features/tasks/utils/contest-table/aoj_labels';
 
   interface Props {

src/features/tasks/fixtures/contest-table/contest_table_provider.ts

@@ -1,4 +1,4 @@
-import { TaskGrade, type TaskResult, type TaskResults } from '$lib/types/task';
+import { TaskGrade, type TaskResult, type TaskResults } from '#lib/types/task.js';
 
 // Default task result with minimal initialization.
 // Most fields are empty strings as they're not relevant for these tests.

src/features/tasks/stores/active_contest_type.svelte.ts

@@ -1,4 +1,4 @@
-import { useLocalStorage } from '$lib/stores/local_storage_helper.svelte';
+import { useLocalStorage } from '#lib/stores/local_storage_helper.svelte.js';
 import {
   type ContestTableProviderGroups,
   contestTableProviderGroups,

src/features/tasks/types/contest-table/contest_table_provider.ts

@@ -1,5 +1,5 @@
-import type { ContestType } from '$lib/contests/types/contest';
-import type { TaskResults, TaskResult } from '$lib/types/task';
+import type { ContestType } from '#lib/contests/types/contest.js';
+import type { TaskResults, TaskResult } from '#lib/types/task.js';
 
 /**
  * Provider interface for building and managing contest tables.

src/features/tasks/utils/contest-table/aalc_provider.test.ts

@@ -1,7 +1,7 @@
 import { describe, test, expect } from 'vitest';
 
-import { ContestType } from '$lib/contests/types/contest';
-import type { TaskResults } from '$lib/types/task';
+import { ContestType } from '#lib/contests/types/contest.js';
+import type { TaskResults } from '#lib/types/task.js';
 
 import { AALCProvider } from './aalc_provider';
 

src/features/tasks/utils/contest-table/aalc_provider.ts

@@ -2,9 +2,9 @@ import {
   type ContestTableMetaData,
   type ContestTableDisplayConfig,
 } from '$features/tasks/types/contest-table/contest_table_provider';
-import type { TaskResult } from '$lib/types/task';
+import type { TaskResult } from '#lib/types/task.js';
 
-import { classifyContest } from '$lib/contests';
+import { classifyContest } from '#lib/contests/index.js';
 
 import { ContestTableProviderBase } from './contest_table_provider_base';