diff --git a/AGENTS.md b/AGENTS.md
index 16f2d7ae0..04649a06d 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -82,6 +82,8 @@ Run project tools with `pnpm exec`, never `pnpm dlx`: `dlx` downloads the latest
 
 Lefthook runs oxfmt, oxlint for JS/TS, and ESLint for Svelte before commit.
 
+`check` and `lint` fail on warnings: fix them or disable with a reason. oxlint skips `.svelte`, so set lint rules in ESLint too.
+
 Formatting belongs to oxfmt alone. Do not add ESLint or oxlint rules whose `meta.type` is `layout` (e.g. `svelte/indent`), because they would conflict with the formatter.
 
 ## Verification and Cross-review Before a PR
diff --git a/docs/guides/agent-rules/accessibility.md b/docs/guides/agent-rules/accessibility.md
index bf39e8ea0..2a949ad45 100644
--- a/docs/guides/agent-rules/accessibility.md
+++ b/docs/guides/agent-rules/accessibility.md
@@ -33,6 +33,8 @@ When `{#if}` reveals a modal, dialog, or focus-trap region, move focus programma
 
 Icon-only `<Button>` variants require an explicit `aria-label`; Flowbite Svelte does not generate one automatically. Omitting `color` only applies the `'primary'` default style — it has no effect on `aria-label`.
 
+`Tooltip`/`Popover` already make their trigger focusable; no `tabindex` or `<button>` needed.
+
 ## Form Labels
 
 Every `<input>`, `<select>`, and `<textarea>` must have an associated `<label>` (via `for`/`id`) or `aria-label`. Placeholder text does not substitute for a label.
diff --git a/docs/guides/agent-rules/coding-style.md b/docs/guides/agent-rules/coding-style.md
index d86a76a14..b869ec781 100644
--- a/docs/guides/agent-rules/coding-style.md
+++ b/docs/guides/agent-rules/coding-style.md
@@ -70,6 +70,7 @@ Before removing an import, grep the entire file for all usages — removing one
 When removing a dependency or renaming a symbol, sweep the **whole repo**, not just `src`:
 
 - `grep --include='*.{ts,svelte,md}'` does NOT brace-expand — it silently matches nothing. Use `rg -ni 'name' -g '*.ts' -g '*.svelte' -g '*.md'` instead.
+- `rg` alternation is `a|b`, not `a\|b`.
 - Include root files (CONTRIBUTING.md, README), `e2e/`, and config (`vite.config.ts`) — not only `src prisma .claude`.
 
 ## Documentation
diff --git a/docs/guides/agent-rules/svelte-runes.md b/docs/guides/agent-rules/svelte-runes.md
index bfea707a0..3dac3f3d2 100644
--- a/docs/guides/agent-rules/svelte-runes.md
+++ b/docs/guides/agent-rules/svelte-runes.md
@@ -12,6 +12,8 @@ paths:
 
 - `let` captures initial value only; use `$derived` for props/server data
 - Referencing `$props()` in `$state()` initializer? Wrap with `untrack` if intentional (seed-only)
+- Superforms: `superForm(untrack(() => data.form))`, never `$derived`
+- Pass reactive library options as getters: `get id() { return id; }`
 - `pnpm check` warns: "This reference only captures the initial value"
 
 ## `SvelteMap<K, V>` — Always Type
diff --git a/e2e/votes.spec.ts b/e2e/votes.spec.ts
index f416b2b6b..85972880d 100644
--- a/e2e/votes.spec.ts
+++ b/e2e/votes.spec.ts
@@ -7,6 +7,7 @@ const VOTES_LIST_URL = '/votes';
 const TASKS_GRADE_URL = '/tasks/grade';
 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
+const PROVISIONAL_TASK_ID = 'zone2021_f'; // PENDING task with a median in prisma/seed.ts
 
 // ---------------------------------------------------------------------------
 // Votes list page (/votes)
@@ -51,6 +52,24 @@ test.describe('votes list page (/votes)', () => {
       timeout: TIMEOUT,
     });
   });
+
+  test('provisional grade icon opens its tooltip on keyboard focus', async ({ page }) => {
+    await page.goto(VOTES_LIST_URL);
+    const searchInput = page.getByPlaceholder('問題名・問題ID・出典で検索');
+    await expect(searchInput).toBeVisible({ timeout: TIMEOUT });
+    await searchInput.fill(PROVISIONAL_TASK_ID);
+
+    const icon = page.getByRole('img', { name: '暫定グレード' });
+    const tooltip = page.getByRole('tooltip');
+    await expect(icon).toBeVisible({ timeout: TIMEOUT });
+    await expect(tooltip).toBeHidden();
+
+    // The markup has no tabindex; flowbite-svelte's Tooltip adds it to the trigger at runtime.
+    await expect(icon).toHaveAttribute('tabindex', '0');
+    await icon.focus();
+    await expect(icon).toBeFocused();
+    await expect(tooltip).toContainText('暫定グレード');
+  });
 });
 
 // ---------------------------------------------------------------------------
diff --git a/e2e/workbook_create.spec.ts b/e2e/workbook_create.spec.ts
new file mode 100644
index 000000000..9de0fb79c
--- /dev/null
+++ b/e2e/workbook_create.spec.ts
@@ -0,0 +1,21 @@
+import { test, expect } from '@playwright/test';
+
+import { loginAsAdmin } from './helpers/auth';
+
+const TIMEOUT = 60 * 1000;
+const WORKBOOK_CREATE_URL = '/workbooks/create';
+const ADMIN_USER_ID = '1'; // From prisma/users.ts seed data
+
+test.describe('workbook create form (admin)', () => {
+  test('pre-fills the admin as author of an official curriculum workbook', async ({ page }) => {
+    await loginAsAdmin(page);
+    await page.goto(WORKBOOK_CREATE_URL);
+
+    // Hidden inputs have no label, so select them by name.
+    await expect(page.locator('input[name="userId"]')).toHaveValue(ADMIN_USER_ID, {
+      timeout: TIMEOUT,
+    });
+    await expect(page.locator('input[name="isOfficial"]')).toHaveValue('true');
+    await expect(page.getByLabel('問題集の種類')).toHaveValue('CURRICULUM');
+  });
+});
diff --git a/lefthook.yml b/lefthook.yml
index a1a61ee44..038c0beb6 100644
--- a/lefthook.yml
+++ b/lefthook.yml
@@ -9,11 +9,11 @@ pre-commit:
       glob: '**/*.{js,jsx,ts,tsx,md,svelte}'
 
     - name: oxlint
-      run: pnpm exec oxlint {staged_files}
+      run: pnpm exec oxlint --deny-warnings {staged_files}
       glob: '**/*.{js,jsx,ts,tsx}'
 
     - name: eslint
-      run: pnpm exec eslint {staged_files}
+      run: pnpm exec eslint --max-warnings 0 --no-warn-ignored {staged_files}
       glob: '**/*.svelte'
 
     - name: plan-lambda-check
diff --git a/package.json b/package.json
index 31d6a5e75..840c3071f 100644
--- a/package.json
+++ b/package.json
@@ -11,9 +11,9 @@
     "build": "prisma generate && vite build",
     "preview": "vite preview",
     "test": "npm run test:e2e && npm run test:unit",
-    "check": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json",
+    "check": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json --fail-on-warnings",
     "check:watch": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json --watch",
-    "lint": "oxfmt --check && oxlint . && eslint .",
+    "lint": "oxfmt --check && oxlint --deny-warnings . && eslint --max-warnings 0 .",
     "format": "oxfmt",
     "test:e2e": "playwright test",
     "test:unit": "vitest",
diff --git a/prisma/seed.ts b/prisma/seed.ts
index 6e45ebea5..db50bfa1d 100755
--- a/prisma/seed.ts
+++ b/prisma/seed.ts
@@ -680,10 +680,12 @@ async function addAnswer(
   });
 }
 
-// Demo data: tasks with VotedGradeStatistics so the ±0 badge is visible in the UI.
-// grade matches the task's official grade → diff=0 → ±0 badge displayed.
+// Demo data: tasks with VotedGradeStatistics so vote-based UI is visible.
+// APG4bPython_co: grade matches the official grade → diff=0 → ±0 badge displayed.
+// zone2021_f: PENDING task with a median → provisional grade icon displayed (used by E2E).
 const VOTE_STATS_DEMO_DATA = [
   { id: 'demo-vote-stat-apg4b-co', taskId: 'APG4bPython_co', grade: 'Q8' },
+  { id: 'demo-vote-stat-zone2021-f', taskId: 'zone2021_f', grade: 'D3' },
 ] as const;
 
 async function addVoteStatisticsDemoData() {
diff --git a/src/features/votes/components/VotableGrade.svelte b/src/features/votes/components/VotableGrade.svelte
index d721ae804..ed08a00bf 100644
--- a/src/features/votes/components/VotableGrade.svelte
+++ b/src/features/votes/components/VotableGrade.svelte
@@ -56,11 +56,12 @@
   // 表示用のグレード（投票後に画面リロードなしで差し替えるためのローカル状態）
   // PENDING かつ estimatedGrade（集計済み中央値）があればそれを優先表示。
   // DBグレード付与済みの場合はそちらを優先。
-  const initialGrade = resolveDisplayGrade(taskResult.grade, estimatedGrade);
-  let displayGrade = $state<TaskGrade | string>(initialGrade);
+  let displayGrade = $state<TaskGrade | string>(
+    untrack(() => resolveDisplayGrade(taskResult.grade, estimatedGrade)),
+  );
 
   // Use task_id as a deterministic component ID to avoid SSR/hydration mismatches.
-  const componentId = taskResult.task_id;
+  const componentId = $derived(taskResult.task_id);
 
   const editProfileHref = `${resolve(EDIT_PROFILE_PAGE)}?tab=atcoder`;
 
diff --git a/src/features/workbooks/components/shared/WorkBookForm.svelte b/src/features/workbooks/components/shared/WorkBookForm.svelte
index e0639a2d8..1553d14a0 100644
--- a/src/features/workbooks/components/shared/WorkBookForm.svelte
+++ b/src/features/workbooks/components/shared/WorkBookForm.svelte
@@ -1,4 +1,6 @@
 <script lang="ts">
+  import { untrack } from 'svelte';
+
   import { Breadcrumb, BreadcrumbItem } from 'flowbite-svelte';
 
   import HeadingOne from '#lib/components/HeadingOne.svelte';
@@ -38,7 +40,7 @@
     submitButtonLabel = '',
   }: Props = $props();
 
-  const { form, message, errors, enhance } = superFormObject;
+  const { form, message, errors, enhance } = untrack(() => superFormObject);
 
   let workBookTasksForTable: WorkBookTasksCreate | WorkBookTasksEdit = $derived(
     $form.workBookTasks
diff --git a/src/lib/components/AuthForm.svelte b/src/lib/components/AuthForm.svelte
index 977f5c363..8dcd69014 100644
--- a/src/lib/components/AuthForm.svelte
+++ b/src/lib/components/AuthForm.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { tick } from 'svelte';
+  import { tick, untrack } from 'svelte';
   import { goto } from '$app/navigation';
   import { resolve } from '$app/paths';
 
@@ -40,7 +40,7 @@
     alternativePageLink,
   }: Props = $props();
 
-  const { form, message, errors, submitting, enhance } = formProperties;
+  const { form, message, errors, submitting, enhance } = untrack(() => formProperties);
 
   const homeHref = resolve(HOME_PAGE);
   const forgotPasswordHref = resolve(FORGOT_PASSWORD_PAGE);
diff --git a/src/lib/components/InputFieldWrapper.svelte b/src/lib/components/InputFieldWrapper.svelte
index b45058253..9b5b7049d 100644
--- a/src/lib/components/InputFieldWrapper.svelte
+++ b/src/lib/components/InputFieldWrapper.svelte
@@ -26,7 +26,7 @@
     message = '',
   }: Props = $props();
 
-  let isReadOnly = !isEditable;
+  let isReadOnly = $derived(!isEditable);
 </script>
 
 <Label class="flex flex-col gap-2">
diff --git a/src/routes/(admin)/account_transfer/+page.svelte b/src/routes/(admin)/account_transfer/+page.svelte
index ff52a06ca..fb5b9f66a 100644
--- a/src/routes/(admin)/account_transfer/+page.svelte
+++ b/src/routes/(admin)/account_transfer/+page.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { onMount, onDestroy } from 'svelte';
+  import { onMount, onDestroy, untrack } from 'svelte';
   import { run } from 'svelte/legacy';
 
   import { superForm } from 'sveltekit-superforms';
@@ -28,7 +28,7 @@
 
   let { data }: Props = $props();
 
-  const { form, errors, message, submitting, enhance } = superForm(data.form);
+  const { form, errors, message, submitting, enhance } = superForm(untrack(() => data.form));
 
   let accountTransferMessages: FloatingMessages = $state([]);
 
diff --git a/src/routes/(admin)/tags/+page.svelte b/src/routes/(admin)/tags/+page.svelte
index e22807c60..f99fcc7d3 100644
--- a/src/routes/(admin)/tags/+page.svelte
+++ b/src/routes/(admin)/tags/+page.svelte
@@ -3,7 +3,7 @@
   import TagListForEdit from '#lib/components/TagListForEdit.svelte';
 
   let { data } = $props();
-  let tags = data.tags;
+  let tags = $derived(data.tags);
 </script>
 
 <div class="container mx-auto w-5/6">
diff --git a/src/routes/(admin)/tags/[tag_id]/+page.svelte b/src/routes/(admin)/tags/[tag_id]/+page.svelte
index ddf77522c..baaf4a1a4 100644
--- a/src/routes/(admin)/tags/[tag_id]/+page.svelte
+++ b/src/routes/(admin)/tags/[tag_id]/+page.svelte
@@ -3,8 +3,8 @@
 
   let { data } = $props();
 
-  let tag = data.tag;
-  let tasks = data.tasks;
+  let tag = $derived(data.tag);
+  let tasks = $derived(data.tasks);
 </script>
 
 <div class="container mx-auto w-3/4">
diff --git a/src/routes/(admin)/tasks/[task_id]/+page.svelte b/src/routes/(admin)/tasks/[task_id]/+page.svelte
index fd269c19e..15bdb2c30 100644
--- a/src/routes/(admin)/tasks/[task_id]/+page.svelte
+++ b/src/routes/(admin)/tasks/[task_id]/+page.svelte
@@ -5,8 +5,8 @@
 
   let { data } = $props();
 
-  let task = data.task;
-  let tags = data.tags;
+  let task = $derived(data.task);
+  let tags = $derived(data.tags);
 </script>
 
 <div class="container mx-auto w-5/6 md:w-1/2">
diff --git a/src/routes/(admin)/workbooks/order/_components/KanbanColumn.svelte b/src/routes/(admin)/workbooks/order/_components/KanbanColumn.svelte
index 4d642cf55..f9ff73ddb 100644
--- a/src/routes/(admin)/workbooks/order/_components/KanbanColumn.svelte
+++ b/src/routes/(admin)/workbooks/order/_components/KanbanColumn.svelte
@@ -18,9 +18,13 @@
     get id() {
       return columnId;
     },
-    type: group,
+    get type() {
+      return group;
+    },
     collisionPriority: 1, // CollisionPriority.Low
-    accept: group,
+    get accept() {
+      return group;
+    },
   });
 
   function attachDroppable(node: HTMLElement): { destroy: () => void } {
diff --git a/src/routes/problems/[slug]/+page.svelte b/src/routes/problems/[slug]/+page.svelte
index 7e6cc0578..5fc16ed98 100644
--- a/src/routes/problems/[slug]/+page.svelte
+++ b/src/routes/problems/[slug]/+page.svelte
@@ -12,8 +12,8 @@
 
   let { data } = $props();
 
-  let taskResult = data.taskResult;
-  let buttons = data.buttons;
+  let taskResult = $derived(data.taskResult);
+  let buttons = $derived(data.buttons);
 </script>
 
 <!-- TODO: 回答状況は、一覧表のリストやテーブルから更新する -->
diff --git a/src/routes/users/[username]/+page.svelte b/src/routes/users/[username]/+page.svelte
index f6524b6ac..bfda211b7 100644
--- a/src/routes/users/[username]/+page.svelte
+++ b/src/routes/users/[username]/+page.svelte
@@ -8,10 +8,10 @@
 
   let { data } = $props();
 
-  let username = data.username;
-  let atcoder_username = data.atcoder_username;
-  let isLoggedIn = data.isLoggedIn;
-  let taskResults = data.taskResults;
+  let username = $derived(data.username);
+  let atcoder_username = $derived(data.atcoder_username);
+  let isLoggedIn = $derived(data.isLoggedIn);
+  let taskResults = $derived(data.taskResults);
 
   const problemsHref = resolve(PROBLEMS_PAGE);
 </script>
diff --git a/src/routes/votes/+page.svelte b/src/routes/votes/+page.svelte
index a78acea3f..be97efcbc 100644
--- a/src/routes/votes/+page.svelte
+++ b/src/routes/votes/+page.svelte
@@ -69,7 +69,6 @@
                     <span
                       id="flask-{task.task_id}"
                       class="cursor-help text-gray-500 dark:text-gray-400"
-                      tabindex="0"
                       role="img"
                       aria-label="暫定グレード"
                     >
diff --git a/src/routes/workbooks/[slug]/+page.svelte b/src/routes/workbooks/[slug]/+page.svelte
index dd6b36fd4..213d06d86 100644
--- a/src/routes/workbooks/[slug]/+page.svelte
+++ b/src/routes/workbooks/[slug]/+page.svelte
@@ -28,12 +28,12 @@
 
   let { data } = $props();
 
-  let workBook = data.workBook;
+  let workBook = $derived(data.workBook);
   let workBookTasks: WorkBookTaskBase[] = $state([]);
   let taskResults: Map<string, TaskResult> = $derived(data.taskResults);
   let voteStatisticsMap = $derived(data.voteStatisticsMap);
 
-  let isLoggedIn = data.isLoggedIn;
+  let isLoggedIn = $derived(data.isLoggedIn);
   let isAtCoderVerified = $derived(data.isAtCoderVerified);
 
   // TODO: 関数をutilへ移動させる
diff --git a/src/routes/workbooks/create/+page.svelte b/src/routes/workbooks/create/+page.svelte
index 78aaa6e2e..ce473ac1a 100644
--- a/src/routes/workbooks/create/+page.svelte
+++ b/src/routes/workbooks/create/+page.svelte
@@ -1,4 +1,5 @@
 <script lang="ts">
+  import { untrack } from 'svelte';
   import { superForm } from 'sveltekit-superforms/client';
 
   import type { Task } from '#lib/types/task.js';
@@ -8,22 +9,23 @@
 
   let { data } = $props();
 
+  // superForm owns the form state after init, so seed it once from the load data.
   // See:
   // https://superforms.rocks/concepts/nested-data
-  const initialData = {
+  const initialData = untrack(() => ({
     ...data.form,
     workBookTasks: [] as WorkBookTasksBase,
-  };
+  }));
   const superFormObject = superForm(initialData, {
     dataType: 'json',
   });
   const { form } = superFormObject;
 
-  $form.authorId = data.author.id;
-  $form.isOfficial = data.isAdmin;
+  $form.authorId = untrack(() => data.author.id);
+  $form.isOfficial = untrack(() => data.isAdmin);
   $form.workBookType = $form.isOfficial ? WorkBookType.CURRICULUM : WorkBookType.CREATED_BY_USER;
 
-  const tasksMapByIds: Map<string, Task> = data.tasksMapByIds;
+  const tasksMapByIds: Map<string, Task> = $derived(data.tasksMapByIds);
 </script>
 
 <WorkBookForm
diff --git a/src/routes/workbooks/edit/[slug]/+page.svelte b/src/routes/workbooks/edit/[slug]/+page.svelte
index 1d9891191..097e26c6f 100644
--- a/src/routes/workbooks/edit/[slug]/+page.svelte
+++ b/src/routes/workbooks/edit/[slug]/+page.svelte
@@ -1,4 +1,5 @@
 <script lang="ts">
+  import { untrack } from 'svelte';
   import { superForm } from 'sveltekit-superforms/client';
 
   import ErrorMessageAndReturnButton from '#lib/components/Messages/ErrorMessageAndReturnButton.svelte';
@@ -13,20 +14,21 @@
   let { data } = $props();
   let canView = $derived(data.status === FORBIDDEN ? false : true);
 
-  let workBook = data.workBook;
+  let workBook = $derived(data.workBook);
 
+  // superForm owns the form state after init, so seed it once from the load data.
   // See:
   // https://superforms.rocks/concepts/nested-data
-  const initialData = {
+  const initialData = untrack(() => ({
     ...data.form,
     workBookTasks: workBook.workBookTasks as WorkBookTasksBase,
-  };
+  }));
   const superFormObject = superForm(initialData, {
     dataType: 'json',
   });
 
   // Create data of workbook for edit based on database.
-  const tasksMapByIds: Map<string, Task> = data.tasksMapByIds;
+  const tasksMapByIds: Map<string, Task> = $derived(data.tasksMapByIds);
 </script>
 
 {#if canView}