diff --git a/src/core/index.ts b/src/core/index.ts
new file mode 100644
index 0000000..b0da6f0
--- /dev/null
+++ b/src/core/index.ts
@@ -0,0 +1,111 @@
+import Database from 'better-sqlite3';
+import { mkdirSync } from 'fs';
+import { dirname } from 'path';
+import { getIndexPath } from './paths.js';
+
+export interface IndexEntry {
+  id: string;
+  type: string;
+  title: string;
+  content: string;
+  filePath: string;
+  createdAt: string;
+  updatedAt: string;
+  status?: string;
+  role?: string;
+  assignedTo?: string;
+  tags?: string;
+}
+
+export class Index {
+  private db: Database.Database;
+
+  constructor(cwd: string) {
+    const path = getIndexPath(cwd);
+    mkdirSync(dirname(path), { recursive: true });
+    this.db = new Database(path);
+    this.db.exec(`
+      CREATE TABLE IF NOT EXISTS entities (
+        id TEXT PRIMARY KEY,
+        type TEXT NOT NULL,
+        title TEXT NOT NULL,
+        content TEXT NOT NULL,
+        filePath TEXT NOT NULL,
+        createdAt TEXT NOT NULL,
+        updatedAt TEXT NOT NULL,
+        status TEXT,
+        role TEXT,
+        assignedTo TEXT,
+        tags TEXT
+      );
+      CREATE VIRTUAL TABLE IF NOT EXISTS search USING fts5(id, title, content);
+    `);
+  }
+
+  upsert(entry: IndexEntry): void {
+    const params = {
+      status: null,
+      role: null,
+      assignedTo: null,
+      tags: null,
+      ...entry,
+    };
+
+    const insert = this.db.prepare(`
+      INSERT INTO entities (id, type, title, content, filePath, createdAt, updatedAt, status, role, assignedTo, tags)
+      VALUES (@id, @type, @title, @content, @filePath, @createdAt, @updatedAt, @status, @role, @assignedTo, @tags)
+      ON CONFLICT(id) DO UPDATE SET
+        type=@type, title=@title, content=@content, filePath=@filePath,
+        createdAt=@createdAt, updatedAt=@updatedAt, status=@status, role=@role,
+        assignedTo=@assignedTo, tags=@tags
+    `);
+    insert.run(params);
+
+    const search = this.db.prepare(`
+      INSERT OR REPLACE INTO search (id, title, content) VALUES (@id, @title, @content)
+    `);
+    search.run(params);
+  }
+
+  search(query: string): Array<{ id: string; type: string; title: string }> {
+    const stmt = this.db.prepare(`
+      SELECT e.id, e.type, e.title
+      FROM search s
+      JOIN entities e ON s.id = e.id
+      WHERE search MATCH @query
+      ORDER BY rank
+    `);
+    return stmt.all({ query }) as Array<{ id: string; type: string; title: string }>;
+  }
+
+  list(type?: string, filters?: { status?: string; role?: string; assignedTo?: string }): IndexEntry[] {
+    let sql = 'SELECT * FROM entities WHERE 1=1';
+    const params: Record<string, string> = {};
+
+    if (type) {
+      sql += ' AND type = @type';
+      params.type = type;
+    }
+    if (filters?.status) {
+      sql += ' AND status = @status';
+      params.status = filters.status;
+    }
+    if (filters?.role) {
+      sql += ' AND role = @role';
+      params.role = filters.role;
+    }
+    if (filters?.assignedTo) {
+      sql += ' AND assignedTo = @assignedTo';
+      params.assignedTo = filters.assignedTo;
+    }
+
+    sql += ' ORDER BY createdAt DESC';
+
+    const stmt = this.db.prepare(sql);
+    return stmt.all(params) as IndexEntry[];
+  }
+
+  close(): void {
+    this.db.close();
+  }
+}
diff --git a/tests/index.test.ts b/tests/index.test.ts
new file mode 100644
index 0000000..5dda339
--- /dev/null
+++ b/tests/index.test.ts
@@ -0,0 +1,35 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { mkdtempSync, rmSync } from 'fs';
+import { tmpdir } from 'os';
+import { join } from 'path';
+import { Index } from '../src/core/index.js';
+
+describe('index', () => {
+  let cwd: string;
+
+  beforeEach(() => {
+    cwd = mkdtempSync(join(tmpdir(), 'agenthub-'));
+  });
+
+  afterEach(() => {
+    rmSync(cwd, { recursive: true, force: true });
+  });
+
+  it('indexes and searches a task', () => {
+    const index = new Index(cwd);
+    index.upsert({
+      id: 'TSK-0001',
+      type: 'task',
+      title: 'Implement DNS cache',
+      content: 'Add local DNS cache for performance',
+      filePath: join(cwd, '.agenthub', 'tasks', 'TSK-0001.md'),
+      createdAt: '2026-06-24T10:00:00Z',
+      updatedAt: '2026-06-24T10:00:00Z',
+    });
+
+    const results = index.search('DNS');
+    expect(results).toHaveLength(1);
+    expect(results[0].id).toBe('TSK-0001');
+    index.close();
+  });
+});