diff --git a/scripts/seed-demo.ts b/scripts/seed-demo.ts
index b4e5a6c..3f9fe49 100644
--- a/scripts/seed-demo.ts
+++ b/scripts/seed-demo.ts
@@ -8,91 +8,15 @@
  * 注意: 既存のDBファイルとuploadsディレクトリを削除してから再作成します
  *       (デモ用途のため、冪等に再実行できるようにリセット方式を採用)。
  *
- * 投入内容: 管理者1名 + 一般ユーザー5名、プロジェクト3件、各プロジェクトに
+ * 投入内容: 管理者1名 + 一般ユーザー約29名、プロジェクト約15件、各プロジェクトに
  * 掲示板/チャット/ToDo/メモ/ファイル/カレンダー/マイルストーン/ミーティング/
- * 通知/アクティビティログを網羅。
+ * 通知/アクティビティログを網羅(従来比 約5倍)。生成内容は固定シードで決定論的。
  */
 import fs from 'node:fs';
 import path from 'node:path';
-import bcrypt from 'bcrypt';
 import { SqliteDatabase } from '../lib/db/sqlite';
 import { Migrator } from '../lib/db/migrator';
-
-const BCRYPT_ROUNDS = 10;
-const now = () => new Date().toISOString();
-const daysFromNow = (d: number) => {
-  const dt = new Date();
-  dt.setDate(dt.getDate() + d);
-  return dt.toISOString();
-};
-const dayStr = (d: number) => daysFromNow(d).slice(0, 10);
-
-interface UserSeed {
-  name: string;
-  email: string;
-  password: string;
-  role: 'system_admin' | 'member';
-  status: 'active' | 'inactive';
-}
-
-const USERS: UserSeed[] = [
-  {
-    name: 'Admin User',
-    email: 'admin@example.com',
-    password: 'admin123',
-    role: 'system_admin',
-    status: 'active',
-  },
-  {
-    name: 'Alice Tanaka',
-    email: 'alice@example.com',
-    password: 'password',
-    role: 'member',
-    status: 'active',
-  },
-  {
-    name: 'Bob Sato',
-    email: 'bob@example.com',
-    password: 'password',
-    role: 'member',
-    status: 'active',
-  },
-  {
-    name: 'Carol Yamada',
-    email: 'carol@example.com',
-    password: 'password',
-    role: 'member',
-    status: 'active',
-  },
-  {
-    name: 'Dave Suzuki',
-    email: 'dave@example.com',
-    password: 'password',
-    role: 'member',
-    status: 'active',
-  },
-  {
-    name: 'Eve Mori (inactive)',
-    email: 'eve@example.com',
-    password: 'password',
-    role: 'member',
-    status: 'inactive',
-  },
-];
-
-// 1x1 透明PNG(ファイル共有デモ用)
-const PNG_BYTES = Buffer.from(
-  'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII=',
-  'base64'
-);
-
-function insert(
-  db: SqliteDatabase,
-  sql: string,
-  params: Record<string, unknown> = {}
-): number {
-  return Number(db.execute(sql, params).lastInsertRowid);
-}
+import { seedAll } from './seed/generators';
 
 function resetStorage(dbPath: string, uploadsDir: string): void {
   for (const p of [dbPath, `${dbPath}-wal`, `${dbPath}-shm`]) {
@@ -103,565 +27,6 @@ function resetStorage(dbPath: string, uploadsDir: string): void {
   fs.mkdirSync(uploadsDir, { recursive: true });
 }
 
-function seedUsers(db: SqliteDatabase): Map<string, number> {
-  const ids = new Map<string, number>();
-  for (const u of USERS) {
-    const id = insert(
-      db,
-      `INSERT INTO users (name, email, password_hash, avatar_url, role, status, created_at, updated_at)
-       VALUES (@name, @email, @passwordHash, NULL, @role, @status, @createdAt, @updatedAt)`,
-      {
-        name: u.name,
-        email: u.email,
-        passwordHash: bcrypt.hashSync(u.password, BCRYPT_ROUNDS),
-        role: u.role,
-        status: u.status,
-        createdAt: now(),
-        updatedAt: now(),
-      }
-    );
-    ids.set(u.email, id);
-  }
-  return ids;
-}
-
-interface ProjectSeed {
-  name: string;
-  description: string;
-  status: 'active' | 'on_hold' | 'completed' | 'archived';
-  owner: string; // email
-  members: { email: string; role: 'admin' | 'member' | 'guest' }[];
-}
-
-const PROJECTS: ProjectSeed[] = [
-  {
-    name: 'Website Redesign',
-    description: 'コーポレートサイトの全面リニューアルプロジェクト',
-    status: 'active',
-    owner: 'alice@example.com',
-    members: [
-      { email: 'bob@example.com', role: 'member' },
-      { email: 'carol@example.com', role: 'member' },
-    ],
-  },
-  {
-    name: 'Mobile App v2',
-    description: 'iOS/Androidアプリの次期メジャーバージョン開発',
-    status: 'active',
-    owner: 'bob@example.com',
-    members: [
-      { email: 'alice@example.com', role: 'member' },
-      { email: 'dave@example.com', role: 'member' },
-    ],
-  },
-  {
-    name: 'Marketing Campaign Q4',
-    description: '第4四半期マーケティングキャンペーンの企画・実行',
-    status: 'on_hold',
-    owner: 'carol@example.com',
-    members: [
-      { email: 'alice@example.com', role: 'member' },
-      { email: 'bob@example.com', role: 'member' },
-      { email: 'dave@example.com', role: 'guest' },
-    ],
-  },
-];
-
-function addMember(
-  db: SqliteDatabase,
-  projectId: number,
-  userId: number,
-  role: string
-): void {
-  insert(
-    db,
-    `INSERT INTO project_members (project_id, user_id, role, joined_at)
-     VALUES (@projectId, @userId, @role, @joinedAt)`,
-    { projectId, userId, role, joinedAt: now() }
-  );
-}
-
-function seedBoard(
-  db: SqliteDatabase,
-  projectId: number,
-  authorIds: number[]
-): void {
-  const threads = [
-    {
-      title: 'デザイン方針について',
-      body: '# デザイン方針\n\n- シンプルさを重視\n- モバイルファースト\n\nご意見ください。',
-      category: 'decision',
-      pinned: 1,
-      important: 1,
-    },
-    {
-      title: '週次進捗報告',
-      body: '今週の進捗を共有します。\n\n| タスク | 状態 |\n|---|---|\n| トップ画面 | 完了 |\n| About画面 | 進行中 |',
-      category: 'minutes',
-      pinned: 0,
-      important: 0,
-    },
-    {
-      title: 'FAQ: ログインできない',
-      body: 'ログインできない場合のトラブルシューティングです。',
-      category: 'trouble',
-      pinned: 0,
-      important: 0,
-    },
-  ];
-  for (const t of threads) {
-    const author = authorIds[0];
-    const threadId = insert(
-      db,
-      `INSERT INTO board_threads (project_id, title, body_md, author_id, category, is_pinned, is_important, created_at, updated_at, deleted_at)
-       VALUES (@projectId, @title, @bodyMd, @authorId, @category, @isPinned, @isImportant, @createdAt, @updatedAt, NULL)`,
-      {
-        projectId,
-        title: t.title,
-        bodyMd: t.body,
-        authorId: author,
-        category: t.category,
-        isPinned: t.pinned,
-        isImportant: t.important,
-        createdAt: now(),
-        updatedAt: now(),
-      }
-    );
-    // コメント
-    const commenter = authorIds[1] ?? author;
-    insert(
-      db,
-      `INSERT INTO board_comments (thread_id, author_id, body_md, created_at, updated_at, deleted_at)
-       VALUES (@threadId, @authorId, @bodyMd, @createdAt, @updatedAt, NULL)`,
-      {
-        threadId,
-        authorId: commenter,
-        bodyMd: '確認しました。ありがとうございます！',
-        createdAt: now(),
-        updatedAt: now(),
-      }
-    );
-  }
-}
-
-function seedChat(
-  db: SqliteDatabase,
-  projectId: number,
-  authorIds: number[]
-): void {
-  const messages = [
-    { author: 0, body: 'おはようございます！今日もよろしくお願いします。' },
-    {
-      author: 1,
-      body: 'おつですー。 @alice@example.com ちょっと確認したいことあります',
-    },
-    { author: 0, body: '何でしょう？' },
-    { author: 1, body: 'デザインのカラーパレット、これで確定で大丈夫ですか？' },
-    { author: 0, body: '問題ないです！進めましょう :)' },
-  ];
-  for (const m of messages) {
-    insert(
-      db,
-      `INSERT INTO chat_messages (project_id, author_id, body, created_at, updated_at, deleted_at)
-       VALUES (@projectId, @authorId, @body, @createdAt, @updatedAt, NULL)`,
-      {
-        projectId,
-        authorId: authorIds[m.author],
-        body: m.body,
-        createdAt: now(),
-        updatedAt: now(),
-      }
-    );
-  }
-}
-
-function seedTodos(
-  db: SqliteDatabase,
-  projectId: number,
-  memberIds: number[],
-  milestoneIds: number[]
-): void {
-  const columns = ['Backlog', 'To Do', 'In Progress', 'Review', 'Done'];
-  const colIds: number[] = [];
-  columns.forEach((name, idx) => {
-    colIds.push(
-      insert(
-        db,
-        `INSERT INTO todo_columns (project_id, name, order_index, created_at, updated_at)
-         VALUES (@projectId, @name, @orderIndex, @createdAt, @updatedAt)`,
-        { projectId, name, orderIndex: idx, createdAt: now(), updatedAt: now() }
-      )
-    );
-  });
-
-  const items = [
-    {
-      col: 0,
-      title: 'アイデア募集: ヘッダー案',
-      priority: 'low',
-      assignee: null,
-      due: null,
-      milestone: null,
-      completed: false,
-    },
-    {
-      col: 1,
-      title: 'トップ画面の実装',
-      priority: 'high',
-      assignee: 0,
-      due: dayStr(2),
-      milestone: 0,
-      completed: false,
-    },
-    {
-      col: 1,
-      title: 'About画面の実装',
-      priority: 'normal',
-      assignee: 1,
-      due: dayStr(5),
-      milestone: 0,
-      completed: false,
-    },
-    {
-      col: 2,
-      title: '問い合わせフォーム',
-      priority: 'normal',
-      assignee: 0,
-      due: dayStr(7),
-      milestone: 1,
-      completed: false,
-    },
-    {
-      col: 3,
-      title: 'デザインレビュー',
-      priority: 'high',
-      assignee: 1,
-      due: dayStr(1),
-      milestone: 1,
-      completed: false,
-    },
-    {
-      col: 4,
-      title: '要件定義',
-      priority: 'normal',
-      assignee: 0,
-      due: dayStr(-3),
-      milestone: 0,
-      completed: true,
-    },
-    {
-      col: 4,
-      title: 'ワイヤフレーム',
-      priority: 'normal',
-      assignee: 1,
-      due: dayStr(-1),
-      milestone: 0,
-      completed: true,
-    },
-  ];
-  items.forEach((it, idx) => {
-    const assigneeId = it.assignee === null ? null : memberIds[it.assignee];
-    const milestoneId =
-      it.milestone === null ? null : milestoneIds[it.milestone];
-    insert(
-      db,
-      `INSERT INTO todo_items (project_id, column_id, title, description, assignee_id, creator_id, priority, start_date, due_date, completed_at, order_index, milestone_id, created_at, updated_at, deleted_at)
-       VALUES (@projectId, @columnId, @title, @description, @assigneeId, @creatorId, @priority, NULL, @dueDate, @completedAt, @orderIndex, @milestoneId, @createdAt, @updatedAt, NULL)`,
-      {
-        projectId,
-        columnId: colIds[it.col],
-        title: it.title,
-        description: 'デモ用タスクです。',
-        assigneeId,
-        creatorId: memberIds[0],
-        priority: it.priority,
-        dueDate: it.due,
-        completedAt: it.completed ? now() : null,
-        orderIndex: idx,
-        milestoneId,
-        createdAt: now(),
-        updatedAt: now(),
-      }
-    );
-  });
-}
-
-function seedNotes(
-  db: SqliteDatabase,
-  projectId: number,
-  authorIds: number[]
-): void {
-  const notes = [
-    {
-      title: 'ミーティングメモ',
-      body: '# ミーティングメモ\n\n## 決定事項\n- カラーテーマ: 青\n- リリース: 来月\n\n## 宿題\n- [ ] デザイン作成\n- [ ] レビュー',
-      tags: 'meeting,notes',
-      pinned: 1,
-    },
-    {
-      title: '技術メモ',
-      body: '## 技術スタック\n\n- Next.js 15\n- SQLite\n- Tailwind CSS\n\n```ts\nconst x = 1;\n```',
-      tags: 'tech',
-      pinned: 0,
-    },
-    {
-      title: 'アイデア',
-      body: '面白い機能のアイデアをメモしておく場所。',
-      tags: null,
-      pinned: 0,
-    },
-  ];
-  for (const n of notes) {
-    insert(
-      db,
-      `INSERT INTO project_notes (project_id, title, body_md, tags, is_pinned, created_by_id, updated_by_id, created_at, updated_at, deleted_at)
-       VALUES (@projectId, @title, @bodyMd, @tags, @isPinned, @createdById, @updatedById, @createdAt, @updatedAt, NULL)`,
-      {
-        projectId,
-        title: n.title,
-        bodyMd: n.body,
-        tags: n.tags,
-        isPinned: n.pinned,
-        createdById: authorIds[0],
-        updatedById: authorIds[0],
-        createdAt: now(),
-        updatedAt: now(),
-      }
-    );
-  }
-}
-
-function seedFiles(
-  db: SqliteDatabase,
-  projectId: number,
-  uploaderId: number,
-  uploadsDir: string
-): void {
-  const dir = path.join(uploadsDir, String(projectId));
-  fs.mkdirSync(dir, { recursive: true });
-
-  // 画像ファイル
-  const imgName = `${crypto.randomUUID()}.png`;
-  const imgPath = path.join(dir, imgName);
-  fs.writeFileSync(imgPath, PNG_BYTES);
-  insert(
-    db,
-    `INSERT INTO file_assets (project_id, uploader_id, filename, original_name, mime_type, size, path, created_at, deleted_at)
-     VALUES (@projectId, @uploaderId, @filename, @originalName, @mimeType, @size, @path, @createdAt, NULL)`,
-    {
-      projectId,
-      uploaderId,
-      filename: imgName,
-      originalName: 'sample-diagram.png',
-      mimeType: 'image/png',
-      size: PNG_BYTES.length,
-      path: imgPath,
-      createdAt: now(),
-    }
-  );
-
-  // テキストファイル
-  const txtName = `${crypto.randomUUID()}.txt`;
-  const txtPath = path.join(dir, txtName);
-  const txtContent =
-    'これはデモ用テキストファイルです。\nシードスクリプトによって生成されました。';
-  fs.writeFileSync(txtPath, txtContent, 'utf-8');
-  insert(
-    db,
-    `INSERT INTO file_assets (project_id, uploader_id, filename, original_name, mime_type, size, path, created_at, deleted_at)
-     VALUES (@projectId, @uploaderId, @filename, @originalName, @mimeType, @size, @path, @createdAt, NULL)`,
-    {
-      projectId,
-      uploaderId,
-      filename: txtName,
-      originalName: 'spec-notes.txt',
-      mimeType: 'text/plain',
-      size: Buffer.byteLength(txtContent),
-      path: txtPath,
-      createdAt: now(),
-    }
-  );
-}
-
-function seedMilestones(db: SqliteDatabase, projectId: number): number[] {
-  const ms = [
-    { title: 'M1: デザイン完了', due: dayStr(7) },
-    { title: 'M2: 実装完了', due: dayStr(21) },
-  ];
-  const ids: number[] = [];
-  for (const m of ms) {
-    ids.push(
-      insert(
-        db,
-        `INSERT INTO milestones (project_id, title, description, due_date, status, created_at, updated_at, deleted_at)
-         VALUES (@projectId, @title, @description, @dueDate, 'open', @createdAt, @updatedAt, NULL)`,
-        {
-          projectId,
-          title: m.title,
-          description: 'マイルストーンです。',
-          dueDate: m.due,
-          createdAt: now(),
-          updatedAt: now(),
-        }
-      )
-    );
-  }
-  return ids;
-}
-
-function seedCalendar(
-  db: SqliteDatabase,
-  projectId: number,
-  creatorId: number
-): void {
-  const events = [
-    {
-      title: '定例ミーティング',
-      type: 'meeting',
-      start: daysFromNow(1),
-      end: daysFromNow(1),
-    },
-    {
-      title: 'デザインレビュー',
-      type: 'reminder',
-      start: daysFromNow(3),
-      end: null,
-    },
-    { title: 'リリース締切', type: 'deadline', start: dayStr(14), end: null },
-  ];
-  for (const e of events) {
-    insert(
-      db,
-      `INSERT INTO calendar_events (project_id, title, description, type, start_at, end_at, created_by_id, related_todo_id, related_milestone_id, related_meeting_id, created_at, updated_at, deleted_at)
-       VALUES (@projectId, @title, @description, @type, @startAt, @endAt, @createdById, NULL, NULL, NULL, @createdAt, @updatedAt, NULL)`,
-      {
-        projectId,
-        title: e.title,
-        description: 'カレンダーイベントです。',
-        type: e.type,
-        startAt: e.start,
-        endAt: e.end,
-        createdById: creatorId,
-        createdAt: now(),
-        updatedAt: now(),
-      }
-    );
-  }
-}
-
-function seedMeetings(
-  db: SqliteDatabase,
-  projectId: number,
-  creatorId: number,
-  memberIds: number[]
-): void {
-  const meetingId = insert(
-    db,
-    `INSERT INTO meetings (project_id, title, description, location, meeting_url, start_at, end_at, agenda_md, minutes_md, created_by_id, created_at, updated_at, deleted_at)
-     VALUES (@projectId, @title, @description, @location, @meetingUrl, @startAt, @endAt, @agendaMd, @minutesMd, @createdById, @createdAt, @updatedAt, NULL)`,
-    {
-      projectId,
-      title: '週次定例ミーティング',
-      description: '進捗確認と課題共有',
-      location: '会議室A / オンライン',
-      meetingUrl: 'https://meet.example.com/abc-defg-hij',
-      startAt: daysFromNow(2),
-      endAt: daysFromNow(2),
-      agendaMd: '# アジェンダ\n\n1. 進捗共有\n2. ブロッカー確認\n3. 次週の計画',
-      minutesMd: '# 議事録\n\n- トップ画面は完了\n- About画面は来週完了予定',
-      createdById: creatorId,
-      createdAt: now(),
-      updatedAt: now(),
-    }
-  );
-  for (const uid of memberIds) {
-    insert(
-      db,
-      `INSERT INTO meeting_members (meeting_id, user_id, status) VALUES (@meetingId, @userId, 'invited')`,
-      { meetingId, userId: uid }
-    );
-  }
-}
-
-function seedNotifications(
-  db: SqliteDatabase,
-  projectId: number,
-  memberIds: number[]
-): void {
-  const notifs = [
-    {
-      user: 0,
-      type: 'mention',
-      title: 'メンションされました',
-      body: 'チャットでメンションされました',
-    },
-    {
-      user: 1,
-      type: 'todo_assigned',
-      title: 'ToDoが割り当てられました',
-      body: 'トップ画面の実装',
-    },
-    {
-      user: 0,
-      type: 'meeting_invited',
-      title: 'ミーティングに招待されました',
-      body: '週次定例ミーティング',
-    },
-  ];
-  for (const n of notifs) {
-    insert(
-      db,
-      `INSERT INTO notifications (user_id, project_id, type, title, body, read_at, created_at)
-       VALUES (@userId, @projectId, @type, @title, @body, NULL, @createdAt)`,
-      {
-        userId: memberIds[n.user],
-        projectId,
-        type: n.type,
-        title: n.title,
-        body: n.body,
-        createdAt: now(),
-      }
-    );
-  }
-}
-
-function seedActivityLogs(
-  db: SqliteDatabase,
-  projectId: number,
-  actorIds: number[]
-): void {
-  const logs = [
-    { actor: 0, action: 'board_posted', targetType: 'thread', targetId: 1 },
-    { actor: 1, action: 'comment_added', targetType: 'comment', targetId: 1 },
-    { actor: 0, action: 'todo_created', targetType: 'todo', targetId: 1 },
-    { actor: 1, action: 'todo_completed', targetType: 'todo', targetId: 6 },
-    { actor: 0, action: 'file_uploaded', targetType: 'file', targetId: 1 },
-    { actor: 0, action: 'meeting_created', targetType: 'meeting', targetId: 1 },
-    { actor: 1, action: 'note_updated', targetType: 'note', targetId: 1 },
-    {
-      actor: 0,
-      action: 'milestone_updated',
-      targetType: 'milestone',
-      targetId: 1,
-    },
-  ];
-  for (const l of logs) {
-    insert(
-      db,
-      `INSERT INTO activity_logs (project_id, actor_id, action, target_type, target_id, metadata_json, created_at)
-       VALUES (@projectId, @actorId, @action, @targetType, @targetId, NULL, @createdAt)`,
-      {
-        projectId,
-        actorId: actorIds[l.actor],
-        action: l.action,
-        targetType: l.targetType,
-        targetId: l.targetId,
-        createdAt: now(),
-      }
-    );
-  }
-}
-
 function main(): void {
   const dbPath = process.env.SQLITE_PATH ?? './data/app.db';
   const uploadsDir = process.env.UPLOADS_PATH ?? './data/uploads';
@@ -675,54 +40,18 @@ function main(): void {
     path.join(process.cwd(), 'lib', 'db', 'migrations')
   ).migrate();
 
-  console.log('Seeding users...');
-  const userIds = seedUsers(db);
-
-  let projectCount = 0;
-  for (const p of PROJECTS) {
-    const ownerId = userIds.get(p.owner)!;
-    const projectId = insert(
-      db,
-      `INSERT INTO projects (name, description, status, owner_id, created_at, updated_at)
-       VALUES (@name, @description, @status, @ownerId, @createdAt, @updatedAt)`,
-      {
-        name: p.name,
-        description: p.description,
-        status: p.status,
-        ownerId,
-        createdAt: now(),
-        updatedAt: now(),
-      }
-    );
-    addMember(db, projectId, ownerId, 'admin');
-    const memberIds = [ownerId];
-    for (const m of p.members) {
-      const uid = userIds.get(m.email)!;
-      addMember(db, projectId, uid, m.role);
-      if (!memberIds.includes(uid)) memberIds.push(uid);
-    }
-
-    const milestoneIds = seedMilestones(db, projectId);
-    seedBoard(db, projectId, memberIds);
-    seedChat(db, projectId, memberIds);
-    seedTodos(db, projectId, memberIds, milestoneIds);
-    seedNotes(db, projectId, memberIds);
-    seedFiles(db, projectId, ownerId, uploadsDir);
-    seedCalendar(db, projectId, ownerId);
-    seedMeetings(db, projectId, ownerId, memberIds);
-    seedNotifications(db, projectId, memberIds);
-    seedActivityLogs(db, projectId, memberIds);
-    projectCount++;
-  }
+  console.log('Seeding demo data (~5x volume)...');
+  const { userCount, projectCount } = seedAll(db, uploadsDir);
 
   db.close();
 
   console.log('\n=== Seed complete ===');
-  console.log(`Users: ${USERS.length} | Projects: ${projectCount}`);
+  console.log(`Users: ${userCount} | Projects: ${projectCount}`);
   console.log('\nLogin credentials:');
   console.log('  Admin:    admin@example.com / admin123   (system_admin)');
   console.log('  Users:    alice / bob / carol / dave @example.com / password');
   console.log('  Inactive: eve@example.com / password     (ログイン不可)');
+  console.log('  Others:   <firstname>.<lastname>@example.com / password');
   console.log('\nStart the app with:  npm run dev   ->  http://localhost:3000');
 }
 
diff --git a/scripts/seed/content.ts b/scripts/seed/content.ts
new file mode 100644
index 0000000..8595f65
--- /dev/null
+++ b/scripts/seed/content.ts
@@ -0,0 +1,233 @@
+/**
+ * プロジェクト単位のコンテンツ生成器(掲示板/チャット/ToDo/メモ/ファイル)。
+ * いずれもFK順を担保し、挿入した実IDを呼び出し側へ返す。
+ */
+import fs from 'node:fs';
+import path from 'node:path';
+import type { SqliteDatabase } from '@/lib/db/sqlite';
+import { chance, pick, randInt, seededUuid, type Rng } from './rng';
+import {
+  BOARD_CATEGORIES,
+  BOARD_TITLES,
+  CHAT_PHRASES,
+  NOTE_TAGS,
+  NOTE_TITLES,
+  TODO_PRIORITIES,
+  TODO_TITLES,
+  markdownBody,
+  sentence,
+} from './pools';
+import { PNG_BYTES, dayStr, insert, now } from './helpers';
+
+export function seedBoard(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number,
+  memberIds: number[]
+): { threadIds: number[]; commentIds: number[] } {
+  const threadIds: number[] = [];
+  const commentIds: number[] = [];
+  const count = randInt(rng, 3, 5);
+  for (let i = 0; i < count; i++) {
+    const title = pick(rng, BOARD_TITLES);
+    const threadId = insert(
+      db,
+      `INSERT INTO board_threads (project_id, title, body_md, author_id, category, is_pinned, is_important, created_at, updated_at, deleted_at)
+       VALUES (@projectId, @title, @bodyMd, @authorId, @category, @isPinned, @isImportant, @createdAt, @updatedAt, NULL)`,
+      {
+        projectId,
+        title,
+        bodyMd: markdownBody(rng, title),
+        authorId: pick(rng, memberIds),
+        category: pick(rng, BOARD_CATEGORIES),
+        isPinned: chance(rng, 0.15) ? 1 : 0,
+        isImportant: chance(rng, 0.2) ? 1 : 0,
+        createdAt: now(),
+        updatedAt: now(),
+      }
+    );
+    threadIds.push(threadId);
+    const commentCount = randInt(rng, 0, 2);
+    for (let c = 0; c < commentCount; c++) {
+      const cid = insert(
+        db,
+        `INSERT INTO board_comments (thread_id, author_id, body_md, created_at, updated_at, deleted_at)
+         VALUES (@threadId, @authorId, @bodyMd, @createdAt, @updatedAt, NULL)`,
+        {
+          threadId,
+          authorId: pick(rng, memberIds),
+          bodyMd: pick(rng, CHAT_PHRASES),
+          createdAt: now(),
+          updatedAt: now(),
+        }
+      );
+      commentIds.push(cid);
+    }
+  }
+  return { threadIds, commentIds };
+}
+
+export function seedChat(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number,
+  memberIds: number[]
+): number[] {
+  const ids: number[] = [];
+  const count = randInt(rng, 5, 8);
+  for (let i = 0; i < count; i++) {
+    const id = insert(
+      db,
+      `INSERT INTO chat_messages (project_id, author_id, body, created_at, updated_at, deleted_at)
+       VALUES (@projectId, @authorId, @body, @createdAt, @updatedAt, NULL)`,
+      {
+        projectId,
+        authorId: pick(rng, memberIds),
+        body: pick(rng, CHAT_PHRASES),
+        createdAt: now(),
+        updatedAt: now(),
+      }
+    );
+    ids.push(id);
+  }
+  return ids;
+}
+
+export function seedTodos(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number,
+  memberIds: number[],
+  milestoneIds: number[]
+): number[] {
+  const columns = ['Backlog', 'To Do', 'In Progress', 'Review', 'Done'];
+  const colIds = columns.map((name, idx) =>
+    insert(
+      db,
+      `INSERT INTO todo_columns (project_id, name, order_index, created_at, updated_at)
+       VALUES (@projectId, @name, @orderIndex, @createdAt, @updatedAt)`,
+      { projectId, name, orderIndex: idx, createdAt: now(), updatedAt: now() }
+    )
+  );
+  const ids: number[] = [];
+  const count = randInt(rng, 7, 10);
+  for (let i = 0; i < count; i++) {
+    const colIdx = randInt(rng, 0, columns.length - 1);
+    const completed = colIdx === columns.length - 1;
+    const id = insert(
+      db,
+      `INSERT INTO todo_items (project_id, column_id, title, description, assignee_id, creator_id, priority, start_date, due_date, completed_at, order_index, milestone_id, created_at, updated_at, deleted_at)
+       VALUES (@projectId, @columnId, @title, @description, @assigneeId, @creatorId, @priority, NULL, @dueDate, @completedAt, @orderIndex, @milestoneId, @createdAt, @updatedAt, NULL)`,
+      {
+        projectId,
+        columnId: colIds[colIdx]!,
+        title: pick(rng, TODO_TITLES),
+        description: 'デモ用タスクです。',
+        assigneeId: chance(rng, 0.8) ? pick(rng, memberIds) : null,
+        creatorId: memberIds[0]!,
+        priority: pick(rng, TODO_PRIORITIES),
+        dueDate: chance(rng, 0.7) ? dayStr(randInt(rng, -10, 30)) : null,
+        completedAt: completed ? now() : null,
+        orderIndex: i,
+        milestoneId:
+          chance(rng, 0.6) && milestoneIds.length > 0
+            ? pick(rng, milestoneIds)
+            : null,
+        createdAt: now(),
+        updatedAt: now(),
+      }
+    );
+    ids.push(id);
+  }
+  return ids;
+}
+
+export function seedNotes(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number,
+  memberIds: number[]
+): number[] {
+  const ids: number[] = [];
+  const count = randInt(rng, 3, 5);
+  for (let i = 0; i < count; i++) {
+    const authorId = pick(rng, memberIds);
+    const title = pick(rng, NOTE_TITLES);
+    const id = insert(
+      db,
+      `INSERT INTO project_notes (project_id, title, body_md, tags, is_pinned, created_by_id, updated_by_id, created_at, updated_at, deleted_at)
+       VALUES (@projectId, @title, @bodyMd, @tags, @isPinned, @createdById, @updatedById, @createdAt, @updatedAt, NULL)`,
+      {
+        projectId,
+        title,
+        bodyMd: markdownBody(rng, title),
+        tags: pick(rng, NOTE_TAGS),
+        isPinned: chance(rng, 0.2) ? 1 : 0,
+        createdById: authorId,
+        updatedById: authorId,
+        createdAt: now(),
+        updatedAt: now(),
+      }
+    );
+    ids.push(id);
+  }
+  return ids;
+}
+
+export function seedFiles(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number,
+  uploaderId: number,
+  uploadsDir: string
+): number[] {
+  const dir = path.join(uploadsDir, String(projectId));
+  fs.mkdirSync(dir, { recursive: true });
+  const ids: number[] = [];
+  const count = randInt(rng, 2, 4);
+  for (let i = 0; i < count; i++) {
+    if (chance(rng, 0.5)) {
+      const filename = `${seededUuid(rng)}.png`;
+      const filePath = path.join(dir, filename);
+      fs.writeFileSync(filePath, PNG_BYTES);
+      const id = insert(
+        db,
+        `INSERT INTO file_assets (project_id, uploader_id, filename, original_name, mime_type, size, path, created_at, deleted_at)
+         VALUES (@projectId, @uploaderId, @filename, @originalName, @mimeType, @size, @path, @createdAt, NULL)`,
+        {
+          projectId,
+          uploaderId,
+          filename,
+          originalName: `diagram-${i + 1}.png`,
+          mimeType: 'image/png',
+          size: PNG_BYTES.length,
+          path: filePath,
+          createdAt: now(),
+        }
+      );
+      ids.push(id);
+    } else {
+      const filename = `${seededUuid(rng)}.txt`;
+      const filePath = path.join(dir, filename);
+      const content = `デモ用テキストファイル ${i + 1}。\n${sentence(rng)}`;
+      fs.writeFileSync(filePath, content, 'utf-8');
+      const id = insert(
+        db,
+        `INSERT INTO file_assets (project_id, uploader_id, filename, original_name, mime_type, size, path, created_at, deleted_at)
+         VALUES (@projectId, @uploaderId, @filename, @originalName, @mimeType, @size, @path, @createdAt, NULL)`,
+        {
+          projectId,
+          uploaderId,
+          filename,
+          originalName: `notes-${i + 1}.txt`,
+          mimeType: 'text/plain',
+          size: Buffer.byteLength(content),
+          path: filePath,
+          createdAt: now(),
+        }
+      );
+      ids.push(id);
+    }
+  }
+  return ids;
+}
diff --git a/scripts/seed/generators.ts b/scripts/seed/generators.ts
new file mode 100644
index 0000000..b9aa6ff
--- /dev/null
+++ b/scripts/seed/generators.ts
@@ -0,0 +1,203 @@
+/**
+ * シードデータ生成のオーケストレータ。
+ * ユーザーとプロジェクトを生成し、各プロジェクト単位の生成器(content.ts)をFK順に呼び出す。
+ * 生成内容は固定シード(mulberry32)で決定論的。
+ */
+import bcrypt from 'bcrypt';
+import type { SqliteDatabase } from '@/lib/db/sqlite';
+import { createRng, pick, pickN, randInt, chance, type Rng } from './rng';
+import {
+  FAMILY_NAMES,
+  GIVEN_NAMES,
+  PROJECT_DESCRIPTIONS,
+  PROJECT_NAMES,
+} from './pools';
+import {
+  CANONICAL_PROJECTS,
+  CANONICAL_USERS,
+  SEED,
+  TARGET_PROJECTS,
+  TARGET_USERS,
+  type UserSeed,
+  addMember,
+  bcryptSalt,
+  insert,
+  now,
+  type ProjectSpec,
+} from './helpers';
+import {
+  seedBoard,
+  seedChat,
+  seedFiles,
+  seedNotes,
+  seedTodos,
+} from './content';
+import { seedCalendar, seedMeetings, seedMilestones } from './schedule';
+import { seedActivityLogs, seedNotifications } from './logs';
+
+function buildUserSeeds(rng: Rng): UserSeed[] {
+  const seeds = [...CANONICAL_USERS];
+  const usedEmails = new Set(seeds.map((u) => u.email));
+  const usedNames = new Set(seeds.map((u) => u.name));
+  while (seeds.length < TARGET_USERS) {
+    const given = pick(rng, GIVEN_NAMES);
+    const family = pick(rng, FAMILY_NAMES);
+    const name = `${given} ${family}`;
+    if (usedNames.has(name)) continue;
+    let email = `${given.toLowerCase()}.${family.toLowerCase()}@example.com`;
+    let suffix = 1;
+    while (usedEmails.has(email)) {
+      email = `${given.toLowerCase()}.${family.toLowerCase()}${suffix}@example.com`;
+      suffix++;
+    }
+    usedEmails.add(email);
+    usedNames.add(name);
+    const status = chance(rng, 0.1) ? 'inactive' : 'active';
+    seeds.push({ name, email, password: 'password', role: 'member', status });
+  }
+  return seeds;
+}
+
+function seedUsers(
+  db: SqliteDatabase,
+  rng: Rng
+): { emailToId: Map<string, number>; activeMemberIds: number[] } {
+  const seeds = buildUserSeeds(rng);
+  const emailToId = new Map<string, number>();
+  const activeMemberIds: number[] = [];
+  for (const u of seeds) {
+    const id = insert(
+      db,
+      `INSERT INTO users (name, email, password_hash, avatar_url, role, status, created_at, updated_at)
+       VALUES (@name, @email, @passwordHash, NULL, @role, @status, @createdAt, @updatedAt)`,
+      {
+        name: u.name,
+        email: u.email,
+        passwordHash: bcrypt.hashSync(u.password, bcryptSalt(rng)),
+        role: u.role,
+        status: u.status,
+        createdAt: now(),
+        updatedAt: now(),
+      }
+    );
+    emailToId.set(u.email, id);
+    if (u.role === 'member' && u.status === 'active') activeMemberIds.push(id);
+  }
+  return { emailToId, activeMemberIds };
+}
+
+function buildProjectSpecs(rng: Rng): ProjectSpec[] {
+  const specs: ProjectSpec[] = CANONICAL_PROJECTS.map((p) => ({
+    name: p.name,
+    description: p.description,
+    status: p.status,
+    ownerEmail: p.ownerEmail,
+    memberEmails: p.memberEmails,
+  }));
+  const usedNames = new Set(specs.map((s) => s.name));
+  const names = pickN(rng, PROJECT_NAMES, PROJECT_NAMES.length).filter(
+    (n) => !usedNames.has(n)
+  );
+  const descs = pickN(rng, PROJECT_DESCRIPTIONS, PROJECT_DESCRIPTIONS.length);
+  let ni = 0;
+  let di = 0;
+  while (specs.length < TARGET_PROJECTS) {
+    const name = names[ni] ?? `Internal Project ${specs.length + 1}`;
+    ni++;
+    const description = descs[di % descs.length] ?? 'デモ用プロジェクトです。';
+    di++;
+    const r = rng();
+    const status: ProjectSpec['status'] =
+      r < 0.55
+        ? 'active'
+        : r < 0.75
+          ? 'on_hold'
+          : r < 0.9
+            ? 'completed'
+            : 'archived';
+    specs.push({
+      name,
+      description,
+      status,
+      ownerEmail: null,
+      memberEmails: [],
+    });
+  }
+  return specs;
+}
+
+export function seedAll(
+  db: SqliteDatabase,
+  uploadsDir: string
+): { userCount: number; projectCount: number } {
+  const rng = createRng(SEED);
+  const { emailToId, activeMemberIds } = seedUsers(db, rng);
+
+  const specs = buildProjectSpecs(rng);
+  for (const spec of specs) {
+    const ownerId = spec.ownerEmail
+      ? (emailToId.get(spec.ownerEmail) ?? activeMemberIds[0]!)
+      : pick(rng, activeMemberIds);
+    const projectId = insert(
+      db,
+      `INSERT INTO projects (name, description, status, owner_id, created_at, updated_at)
+       VALUES (@name, @description, @status, @ownerId, @createdAt, @updatedAt)`,
+      {
+        name: spec.name,
+        description: spec.description,
+        status: spec.status,
+        ownerId,
+        createdAt: now(),
+        updatedAt: now(),
+      }
+    );
+    addMember(db, projectId, ownerId, 'admin');
+    const memberIds = [ownerId];
+    const extras =
+      spec.memberEmails.length > 0
+        ? spec.memberEmails.map((m) => ({
+            id: emailToId.get(m.email)!,
+            role: m.role,
+          }))
+        : pickN(
+            rng,
+            activeMemberIds.filter((id) => id !== ownerId),
+            randInt(rng, 2, 4)
+          ).map((id) => ({ id, role: 'member' as const }));
+    for (const m of extras) {
+      if (!memberIds.includes(m.id)) {
+        addMember(db, projectId, m.id, m.role);
+        memberIds.push(m.id);
+      }
+    }
+
+    const milestoneIds = seedMilestones(db, rng, projectId);
+    const { threadIds, commentIds } = seedBoard(db, rng, projectId, memberIds);
+    seedChat(db, rng, projectId, memberIds);
+    const todoIds = seedTodos(db, rng, projectId, memberIds, milestoneIds);
+    const noteIds = seedNotes(db, rng, projectId, memberIds);
+    const fileIds = seedFiles(db, rng, projectId, ownerId, uploadsDir);
+    const meetingIds = seedMeetings(db, rng, projectId, ownerId, memberIds);
+    seedCalendar(
+      db,
+      rng,
+      projectId,
+      ownerId,
+      todoIds,
+      milestoneIds,
+      meetingIds
+    );
+    seedNotifications(db, rng, projectId, memberIds);
+    seedActivityLogs(db, rng, projectId, memberIds, {
+      threadIds,
+      commentIds,
+      todoIds,
+      fileIds,
+      meetingIds,
+      noteIds,
+      milestoneIds,
+    });
+  }
+
+  return { userCount: emailToId.size, projectCount: specs.length };
+}
diff --git a/scripts/seed/helpers.ts b/scripts/seed/helpers.ts
new file mode 100644
index 0000000..5781bef
--- /dev/null
+++ b/scripts/seed/helpers.ts
@@ -0,0 +1,170 @@
+/**
+ * シード生成器間で共有する定数・時刻ヘルパ・挿入ヘルパ・カノニカルデータ。
+ */
+import type { SqliteDatabase } from '@/lib/db/sqlite';
+import type { ProjectMemberRole } from '@/lib/types';
+import { type Rng } from './rng';
+
+export const BCRYPT_ROUNDS = 10;
+export const SEED = 0xc0ffee;
+export const TARGET_USERS = 30;
+export const TARGET_PROJECTS = 15;
+
+// 実行日(UTC 0時)を基準にすることで、同日内の再実行で同一データになる。
+const BASE_DATE = (() => {
+  const d = new Date();
+  d.setUTCHours(0, 0, 0, 0);
+  return d;
+})();
+const BASE_TIME = BASE_DATE.toISOString();
+export const now = (): string => BASE_TIME;
+export const daysFromNow = (d: number): string => {
+  const dt = new Date(BASE_DATE);
+  dt.setUTCDate(dt.getUTCDate() + d);
+  return dt.toISOString();
+};
+export const dayStr = (d: number): string => daysFromNow(d).slice(0, 10);
+
+export const PNG_BYTES = Buffer.from(
+  'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII=',
+  'base64'
+);
+
+const BCRYPT_SALT_ALPHABET =
+  './ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
+
+export function bcryptSalt(rng: Rng): string {
+  let salt = '';
+  for (let i = 0; i < 22; i++) {
+    salt +=
+      BCRYPT_SALT_ALPHABET[Math.floor(rng() * BCRYPT_SALT_ALPHABET.length)];
+  }
+  return `$2b$${BCRYPT_ROUNDS}$${salt}`;
+}
+
+export interface UserSeed {
+  name: string;
+  email: string;
+  password: string;
+  role: 'system_admin' | 'member';
+  status: 'active' | 'inactive';
+}
+
+export interface ProjectSpec {
+  name: string;
+  description: string;
+  status: 'active' | 'on_hold' | 'completed' | 'archived';
+  ownerEmail: string | null;
+  memberEmails: { email: string; role: 'admin' | 'member' | 'guest' }[];
+}
+
+export interface ActivityContext {
+  threadIds: number[];
+  commentIds: number[];
+  todoIds: number[];
+  fileIds: number[];
+  meetingIds: number[];
+  noteIds: number[];
+  milestoneIds: number[];
+}
+
+export const CANONICAL_USERS: UserSeed[] = [
+  {
+    name: 'Admin User',
+    email: 'admin@example.com',
+    password: 'admin123',
+    role: 'system_admin',
+    status: 'active',
+  },
+  {
+    name: 'Alice Tanaka',
+    email: 'alice@example.com',
+    password: 'password',
+    role: 'member',
+    status: 'active',
+  },
+  {
+    name: 'Bob Sato',
+    email: 'bob@example.com',
+    password: 'password',
+    role: 'member',
+    status: 'active',
+  },
+  {
+    name: 'Carol Yamada',
+    email: 'carol@example.com',
+    password: 'password',
+    role: 'member',
+    status: 'active',
+  },
+  {
+    name: 'Dave Suzuki',
+    email: 'dave@example.com',
+    password: 'password',
+    role: 'member',
+    status: 'active',
+  },
+  {
+    name: 'Eve Mori (inactive)',
+    email: 'eve@example.com',
+    password: 'password',
+    role: 'member',
+    status: 'inactive',
+  },
+];
+
+export const CANONICAL_PROJECTS: ProjectSpec[] = [
+  {
+    name: 'Website Redesign',
+    description: 'コーポレートサイトの全面リニューアルプロジェクト',
+    status: 'active',
+    ownerEmail: 'alice@example.com',
+    memberEmails: [
+      { email: 'bob@example.com', role: 'member' },
+      { email: 'carol@example.com', role: 'member' },
+    ],
+  },
+  {
+    name: 'Mobile App v2',
+    description: 'iOS/Androidアプリの次期メジャーバージョン開発',
+    status: 'active',
+    ownerEmail: 'bob@example.com',
+    memberEmails: [
+      { email: 'alice@example.com', role: 'member' },
+      { email: 'dave@example.com', role: 'member' },
+    ],
+  },
+  {
+    name: 'Marketing Campaign Q4',
+    description: '第4四半期マーケティングキャンペーンの企画・実行',
+    status: 'on_hold',
+    ownerEmail: 'carol@example.com',
+    memberEmails: [
+      { email: 'alice@example.com', role: 'member' },
+      { email: 'bob@example.com', role: 'member' },
+      { email: 'dave@example.com', role: 'guest' },
+    ],
+  },
+];
+
+export function insert(
+  db: SqliteDatabase,
+  sql: string,
+  params: Record<string, unknown> = {}
+): number {
+  return Number(db.execute(sql, params).lastInsertRowid);
+}
+
+export function addMember(
+  db: SqliteDatabase,
+  projectId: number,
+  userId: number,
+  role: ProjectMemberRole
+): void {
+  insert(
+    db,
+    `INSERT INTO project_members (project_id, user_id, role, joined_at)
+     VALUES (@projectId, @userId, @role, @joinedAt)`,
+    { projectId, userId, role, joinedAt: now() }
+  );
+}
diff --git a/scripts/seed/logs.ts b/scripts/seed/logs.ts
new file mode 100644
index 0000000..7f62b5f
--- /dev/null
+++ b/scripts/seed/logs.ts
@@ -0,0 +1,70 @@
+/**
+ * 通知とアクティビティログの生成器。アクティビティログは実IDを参照する。
+ */
+import type { SqliteDatabase } from '@/lib/db/sqlite';
+import { chance, pick, randInt, type Rng } from './rng';
+import { ACTIVITY_ACTIONS, NOTIF_TEMPLATES } from './pools';
+import { type ActivityContext, insert, now } from './helpers';
+
+export function seedNotifications(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number,
+  memberIds: number[]
+): void {
+  const count = randInt(rng, 3, 5);
+  for (let i = 0; i < count; i++) {
+    const t = pick(rng, NOTIF_TEMPLATES);
+    insert(
+      db,
+      `INSERT INTO notifications (user_id, project_id, type, title, body, read_at, created_at)
+       VALUES (@userId, @projectId, @type, @title, @body, @readAt, @createdAt)`,
+      {
+        userId: pick(rng, memberIds),
+        projectId,
+        type: t.type,
+        title: t.title,
+        body: t.body,
+        readAt: chance(rng, 0.3) ? now() : null,
+        createdAt: now(),
+      }
+    );
+  }
+}
+
+export function seedActivityLogs(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number,
+  memberIds: number[],
+  ctx: ActivityContext
+): void {
+  const targetsByType: Record<string, number[]> = {
+    thread: ctx.threadIds,
+    comment: ctx.commentIds,
+    todo: ctx.todoIds,
+    file: ctx.fileIds,
+    meeting: ctx.meetingIds,
+    note: ctx.noteIds,
+    milestone: ctx.milestoneIds,
+  };
+  const count = randInt(rng, 8, 12);
+  for (let i = 0; i < count; i++) {
+    const a = pick(rng, ACTIVITY_ACTIONS);
+    const pool = targetsByType[a.targetType] ?? [];
+    if (pool.length === 0) continue;
+    insert(
+      db,
+      `INSERT INTO activity_logs (project_id, actor_id, action, target_type, target_id, metadata_json, created_at)
+       VALUES (@projectId, @actorId, @action, @targetType, @targetId, NULL, @createdAt)`,
+      {
+        projectId,
+        actorId: pick(rng, memberIds),
+        action: a.action,
+        targetType: a.targetType,
+        targetId: pick(rng, pool),
+        createdAt: now(),
+      }
+    );
+  }
+}
diff --git a/scripts/seed/pools.ts b/scripts/seed/pools.ts
new file mode 100644
index 0000000..6e86b68
--- /dev/null
+++ b/scripts/seed/pools.ts
@@ -0,0 +1,374 @@
+/**
+ * シードデータ用のコンテンツプールとテキスト生成ヘルパ。
+ * lib/types/index.ts の列挙型に合わせた値のみを使用する。
+ */
+import type {
+  BoardCategory,
+  CalendarEventType,
+  NotificationType,
+  TodoPriority,
+} from '@/lib/types';
+import { type Rng, chance, pick, pickN, randInt } from './rng';
+
+export const GIVEN_NAMES = [
+  'Frank',
+  'Grace',
+  'Henry',
+  'Ivy',
+  'Jack',
+  'Karen',
+  'Leo',
+  'Mia',
+  'Noah',
+  'Olivia',
+  'Peter',
+  'Quinn',
+  'Rachel',
+  'Sam',
+  'Tina',
+  'Uma',
+  'Victor',
+  'Wendy',
+  'Xander',
+  'Yuki',
+  'Zoe',
+  'Amber',
+  'Brian',
+  'Chloe',
+  'Diego',
+  'Emma',
+  'Finn',
+  'Gina',
+  'Hiro',
+  'Iris',
+  'Jonas',
+  'Kira',
+];
+
+export const FAMILY_NAMES = [
+  'Yamamoto',
+  'Watanabe',
+  'Ito',
+  'Nakamura',
+  'Kobayashi',
+  'Saito',
+  'Takahashi',
+  'Kato',
+  'Yoshida',
+  'Sasaki',
+  'Matsumoto',
+  'Inoue',
+  'Kimura',
+  'Hayashi',
+  'Shimizu',
+  'Yamazaki',
+  'Mori',
+  'Abe',
+  'Ikeda',
+  'Hashimoto',
+  'Yamaguchi',
+  'Kondo',
+  'Ishikawa',
+  'Ogawa',
+];
+
+export const PROJECT_NAMES = [
+  'Website Redesign',
+  'Mobile App v2',
+  'Marketing Campaign Q4',
+  'Data Warehouse Migration',
+  'Security Audit 2026',
+  'HR Portal Revamp',
+  'Customer Support Bot',
+  'API Gateway Upgrade',
+  'Design System 2.0',
+  'Sales CRM Integration',
+  'Cloud Cost Optimization',
+  'Accessibility Audit',
+  'Onboarding Flow Redesign',
+  'Analytics Dashboard',
+  'DevOps Automation',
+  'Internal Wiki Migration',
+  'Payment Gateway v3',
+  'QA Automation Suite',
+];
+
+export const PROJECT_DESCRIPTIONS = [
+  'コーポレートサイトの全面リニューアルプロジェクト',
+  'iOS/Androidアプリの次期メジャーバージョン開発',
+  '第4四半期マーケティングキャンペーンの企画・実行',
+  'レガシーDWHからモダンデータプラットフォームへの移行',
+  '全社システムのセキュリティ監査と是正',
+  '人事ポータルのUX改善と再構築',
+  'カスタマーサポート向けチャットボットの開発',
+  'APIゲートウェイの刷新とレートリミット強化',
+  '組織横断デザインシステムの次世代化',
+  '営業CRMと社内DBの双方向連携',
+  'クラウド利用コストの可視化と削減',
+  '製品アクセシビリティの監査と改善',
+  '新規ユーザーオンボーディングフローの再設計',
+  '経営ダッシュボードの構築とBI連携',
+  'デプロイパイプラインの自動化とCI/CD強化',
+  '社内Wikiの新プラットフォームへの移行',
+  '決済ゲートウェイの次期バージョン開発',
+  '回帰テストの自動化とカバレッジ向上',
+];
+
+export const TODO_TITLES = [
+  '要件定義',
+  'ワイヤフレーム作成',
+  'デザインモックアップ',
+  'フロントエンド実装',
+  'バックエンドAPI実装',
+  'DBスキーマ設計',
+  'ユニットテスト追加',
+  'E2Eテスト作成',
+  'パフォーマンス計測',
+  'セキュリティレビュー',
+  'アクセシビリティ確認',
+  'ドキュメント整備',
+  'デプロイ手順策定',
+  'ロールバック確認',
+  '負荷テスト',
+  'ログ監視設定',
+  'エラーハンドリング整理',
+  'i18n対応',
+  'ダッシュボード実装',
+  '検索機能実装',
+  '認証フロー見直し',
+  'キャッシュ導入',
+  'マニュアル作成',
+  'レビュー対応',
+  'リファクタリング',
+  '依存ライブラリ更新',
+  '本番環境検証',
+  '顧客デモ準備',
+  'マイルストーン調整',
+  'バグトリアージ',
+  'データ移行スクリプト',
+  'バッチジョブ実装',
+  'Webhook連携',
+  'レポート出力',
+  '権限設定見直し',
+];
+
+export const TODO_PRIORITIES: readonly TodoPriority[] = [
+  'low',
+  'normal',
+  'high',
+];
+
+export const NOTE_TITLES = [
+  'ミーティングメモ',
+  '技術メモ',
+  'アイデア',
+  '議事録',
+  '振り返り',
+  '調査メモ',
+  '設計メモ',
+  'QAメモ',
+  'リリースノート案',
+  'トラブル対応記録',
+  'ブレスト',
+  '意思決定ログ',
+  'タスク洗い出し',
+  'インシデント報告',
+  '週報',
+];
+
+export const NOTE_TAGS = [
+  'meeting',
+  'tech',
+  'design',
+  'qa',
+  'release',
+  'idea',
+  'incident',
+  'weekly',
+  null,
+];
+
+export const CHAT_PHRASES = [
+  'おはようございます！',
+  'お疲れ様です。',
+  '進捗どうですか？',
+  '確認お願いします。',
+  'ちょっと相談があります。',
+  '了解しました。',
+  'ありがとうございます！',
+  '後で見ます。',
+  'LGTMです。',
+  'ブロッカー発生しました。',
+  '修正しました。レビューお願いします。',
+  'ミーティングの時間変更できますか？',
+  '資料を共有します。',
+  'いいですね！進めましょう。',
+  '懸念点をまとめました。',
+  'デプロイ完了しました。',
+  'テスト通りました。',
+  'バグを見つけました。',
+  '仕様を再確認しましょう。',
+  '承知しました。',
+];
+
+export const BOARD_TITLES = [
+  'デザイン方針について',
+  '週次進捗報告',
+  'FAQ: ログインできない',
+  'リリース計画の共有',
+  'アーキテクチャレビュー',
+  'スプリント振り返り',
+  '新メンバーへのお知らせ',
+  'トラブルシューティング',
+  '意思決定記録',
+  'テスト戦略',
+  'パフォーマンス改善案',
+  'セキュリティアップデート',
+  '顧客フィードバックまとめ',
+  'ドキュメント整理',
+  '次フェーズの構想',
+];
+
+export const BOARD_CATEGORIES: readonly BoardCategory[] = [
+  'notice',
+  'spec',
+  'minutes',
+  'question',
+  'decision',
+  'trouble',
+  'memo',
+];
+
+export const CALENDAR_TITLES = [
+  '定例ミーティング',
+  'デザインレビュー',
+  'リリース締切',
+  'スプリント計画',
+  '振り返り',
+  '1on1',
+  '全社朝会',
+  '顧客デモ',
+  '技術共有会',
+  '勉強会',
+  '保守ウィンドウ',
+  'デプロイ',
+  'テスト実施日',
+  'キックオフ',
+  '回顧展示',
+];
+
+export const CALENDAR_TYPES: readonly CalendarEventType[] = [
+  'meeting',
+  'deadline',
+  'milestone',
+  'todo',
+  'reminder',
+  'custom',
+];
+
+export const MEETING_TITLES = [
+  '週次定例ミーティング',
+  '設計レビュー会',
+  'スプリント計画会',
+  'リリース判定会',
+  '障害対応ブリーフィング',
+];
+
+export const NOTIF_TEMPLATES: {
+  type: NotificationType;
+  title: string;
+  body: string;
+}[] = [
+  {
+    type: 'mention',
+    title: 'メンションされました',
+    body: 'チャットでメンションされました',
+  },
+  {
+    type: 'todo_assigned',
+    title: 'ToDoが割り当てられました',
+    body: '新しいタスクが担当になりました',
+  },
+  {
+    type: 'todo_due_soon',
+    title: '期限が近づいています',
+    body: 'ToDoの期限が迫っています',
+  },
+  {
+    type: 'meeting_invited',
+    title: 'ミーティングに招待されました',
+    body: 'カレンダーを確認してください',
+  },
+  {
+    type: 'board_commented',
+    title: '掲示板に返信がありました',
+    body: 'あなたのスレッドにコメントがつきました',
+  },
+  {
+    type: 'project_added',
+    title: 'プロジェクトに追加されました',
+    body: '新しいプロジェクトのメンバーになりました',
+  },
+  {
+    type: 'file_shared',
+    title: 'ファイルが共有されました',
+    body: '新しいファイルがアップロードされました',
+  },
+  {
+    type: 'note_updated',
+    title: 'メモが更新されました',
+    body: '担当メモが更新されました',
+  },
+];
+
+export const ACTIVITY_ACTIONS: { action: string; targetType: string }[] = [
+  { action: 'board_posted', targetType: 'thread' },
+  { action: 'comment_added', targetType: 'comment' },
+  { action: 'todo_created', targetType: 'todo' },
+  { action: 'todo_updated', targetType: 'todo' },
+  { action: 'todo_completed', targetType: 'todo' },
+  { action: 'file_uploaded', targetType: 'file' },
+  { action: 'note_created', targetType: 'note' },
+  { action: 'note_updated', targetType: 'note' },
+  { action: 'meeting_created', targetType: 'meeting' },
+  { action: 'milestone_updated', targetType: 'milestone' },
+];
+
+const SENTENCES = [
+  '今週は計画通りに進捗した。',
+  'いくつかのブロッカーを解消した。',
+  '次フェーズのスコープを確定した。',
+  'レビューで指摘事項を整理した。',
+  'パフォーマンス測定を実施した。',
+  'ドキュメントを最新化した。',
+  'テストカバレッジを改善した。',
+  '依存ライブラリを更新した。',
+  '顧客からのフィードバックを反映した。',
+  'インフラ構成を見直した。',
+];
+
+const SECTIONS = ['概要', '背景', '決定事項', '宿題', '次のステップ'];
+
+export function sentence(rng: Rng): string {
+  return pick(rng, SENTENCES);
+}
+
+export function paragraph(rng: Rng, n: number): string {
+  return pickN(rng, SENTENCES, n).join(' ');
+}
+
+export function markdownBody(rng: Rng, heading: string): string {
+  const lines: string[] = [`# ${heading}`, ''];
+  const sectionCount = randInt(rng, 2, 4);
+  const sections = pickN(rng, SECTIONS, sectionCount);
+  for (const s of sections) {
+    lines.push(`## ${s}`, '');
+    lines.push(paragraph(rng, randInt(rng, 2, 3)));
+    if (chance(rng, 0.4)) {
+      lines.push('');
+      lines.push('- 項目A', '- 項目B', '- 項目C');
+    }
+    lines.push('');
+  }
+  return lines.join('\n');
+}
diff --git a/scripts/seed/rng.ts b/scripts/seed/rng.ts
new file mode 100644
index 0000000..34fe86d
--- /dev/null
+++ b/scripts/seed/rng.ts
@@ -0,0 +1,50 @@
+/**
+ * シードデータ生成用の決定論的乱数ユーティリティ。
+ * mulberry32 を用い、固定シードで再現可能なデータを生成する。
+ */
+
+export type Rng = () => number;
+
+export function createRng(seed: number): Rng {
+  let a = seed >>> 0;
+  return () => {
+    a |= 0;
+    a = (a + 0x6d2b79f5) | 0;
+    let t = Math.imul(a ^ (a >>> 15), 1 | a);
+    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
+    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
+  };
+}
+
+export function pick<T>(rng: Rng, arr: readonly T[]): T {
+  return arr[Math.floor(rng() * arr.length)]!;
+}
+
+export function pickN<T>(rng: Rng, arr: readonly T[], n: number): T[] {
+  return shuffle(rng, arr).slice(0, Math.min(n, arr.length));
+}
+
+export function randInt(rng: Rng, min: number, max: number): number {
+  return Math.floor(rng() * (max - min + 1)) + min;
+}
+
+export function shuffle<T>(rng: Rng, arr: readonly T[]): T[] {
+  const out = [...arr];
+  for (let i = out.length - 1; i > 0; i--) {
+    const j = Math.floor(rng() * (i + 1));
+    [out[i], out[j]] = [out[j]!, out[i]!];
+  }
+  return out;
+}
+
+export function chance(rng: Rng, p: number): boolean {
+  return rng() < p;
+}
+
+export function seededUuid(rng: Rng): string {
+  const hex = () =>
+    Math.floor(rng() * 0x10000)
+      .toString(16)
+      .padStart(4, '0');
+  return `${hex()}${hex()}-${hex()}-${hex()}-${hex()}-${hex()}${hex()}${hex()}`;
+}
diff --git a/scripts/seed/schedule.ts b/scripts/seed/schedule.ts
new file mode 100644
index 0000000..4c1c120
--- /dev/null
+++ b/scripts/seed/schedule.ts
@@ -0,0 +1,138 @@
+/**
+ * スケジュール系エンティティの生成器(マイルストーン/ミーティング/カレンダー)。
+ */
+import type { SqliteDatabase } from '@/lib/db/sqlite';
+import type { MeetingMemberStatus, MilestoneStatus } from '@/lib/types';
+import { chance, pick, pickN, randInt, seededUuid, type Rng } from './rng';
+import { CALENDAR_TITLES, CALENDAR_TYPES, MEETING_TITLES } from './pools';
+import { dayStr, daysFromNow, insert, now } from './helpers';
+
+const MILESTONE_STATUS_OPEN: MilestoneStatus = 'open';
+const MEETING_MEMBER_INVITED: MeetingMemberStatus = 'invited';
+
+export function seedMilestones(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number
+): number[] {
+  const ids: number[] = [];
+  const phases = ['計画', '設計', '実装', 'テスト', 'リリース', '振り返り'];
+  const count = randInt(rng, 2, 4);
+  for (let i = 0; i < count; i++) {
+    const id = insert(
+      db,
+      `INSERT INTO milestones (project_id, title, description, due_date, status, created_at, updated_at, deleted_at)
+       VALUES (@projectId, @title, @description, @dueDate, @status, @createdAt, @updatedAt, NULL)`,
+      {
+        projectId,
+        title: `M${i + 1}: ${phases[i % phases.length]}完了`,
+        description: 'マイルストーンです。',
+        dueDate: dayStr(randInt(rng, 3, 60)),
+        status: MILESTONE_STATUS_OPEN,
+        createdAt: now(),
+        updatedAt: now(),
+      }
+    );
+    ids.push(id);
+  }
+  return ids;
+}
+
+export function seedMeetings(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number,
+  creatorId: number,
+  memberIds: number[]
+): number[] {
+  const ids: number[] = [];
+  const count = randInt(rng, 1, 2);
+  for (let i = 0; i < count; i++) {
+    const offset = randInt(rng, -5, 30);
+    const id = insert(
+      db,
+      `INSERT INTO meetings (project_id, title, description, location, meeting_url, start_at, end_at, agenda_md, minutes_md, created_by_id, created_at, updated_at, deleted_at)
+       VALUES (@projectId, @title, @description, @location, @meetingUrl, @startAt, @endAt, @agendaMd, @minutesMd, @createdById, @createdAt, @updatedAt, NULL)`,
+      {
+        projectId,
+        title: pick(rng, MEETING_TITLES),
+        description: '進捗確認と課題共有',
+        location: pick(rng, [
+          '会議室A',
+          '会議室B',
+          'オンライン',
+          '会議室A / オンライン',
+        ]),
+        meetingUrl: chance(rng, 0.7)
+          ? `https://meet.example.com/${seededUuid(rng).slice(0, 8)}`
+          : null,
+        startAt: daysFromNow(offset),
+        endAt: daysFromNow(offset),
+        agendaMd:
+          '# アジェンダ\n\n1. 進捗共有\n2. ブロッカー確認\n3. 次週の計画',
+        minutesMd: chance(rng, 0.6)
+          ? '# 議事録\n\n- 進捗は順調\n- 課題を共有\n- 次週も継続'
+          : null,
+        createdById: creatorId,
+        createdAt: now(),
+        updatedAt: now(),
+      }
+    );
+    const attendeeCount = randInt(rng, 2, Math.max(2, memberIds.length));
+    for (const uid of pickN(rng, memberIds, attendeeCount)) {
+      insert(
+        db,
+        `INSERT INTO meeting_members (meeting_id, user_id, status)
+         VALUES (@meetingId, @userId, @status)`,
+        { meetingId: id, userId: uid, status: MEETING_MEMBER_INVITED }
+      );
+    }
+    ids.push(id);
+  }
+  return ids;
+}
+
+export function seedCalendar(
+  db: SqliteDatabase,
+  rng: Rng,
+  projectId: number,
+  creatorId: number,
+  todoIds: number[],
+  milestoneIds: number[],
+  meetingIds: number[]
+): number[] {
+  const ids: number[] = [];
+  const count = randInt(rng, 3, 5);
+  for (let i = 0; i < count; i++) {
+    const type = pick(rng, CALENDAR_TYPES);
+    const offset = randInt(rng, -7, 45);
+    const id = insert(
+      db,
+      `INSERT INTO calendar_events (project_id, title, description, type, start_at, end_at, created_by_id, related_todo_id, related_milestone_id, related_meeting_id, created_at, updated_at, deleted_at)
+       VALUES (@projectId, @title, @description, @type, @startAt, @endAt, @createdById, @relatedTodoId, @relatedMilestoneId, @relatedMeetingId, @createdAt, @updatedAt, NULL)`,
+      {
+        projectId,
+        title: pick(rng, CALENDAR_TITLES),
+        description: 'カレンダーイベントです。',
+        type,
+        startAt: type === 'deadline' ? dayStr(offset) : daysFromNow(offset),
+        endAt: chance(rng, 0.4) ? daysFromNow(offset) : null,
+        createdById: creatorId,
+        relatedTodoId:
+          chance(rng, 0.2) && todoIds.length > 0 ? pick(rng, todoIds) : null,
+        relatedMilestoneId:
+          chance(rng, 0.15) && milestoneIds.length > 0
+            ? pick(rng, milestoneIds)
+            : null,
+        relatedMeetingId:
+          chance(rng, 0.15) && meetingIds.length > 0
+            ? pick(rng, meetingIds)
+            : null,
+        createdAt: now(),
+        updatedAt: now(),
+      }
+    );
+    ids.push(id);
+  }
+  return ids;
+}