diff --git a/lib/db/migrations/001_core.sql b/lib/db/migrations/001_core.sql
new file mode 100644
index 0000000..3a75247
--- /dev/null
+++ b/lib/db/migrations/001_core.sql
@@ -0,0 +1,45 @@
+CREATE TABLE spaces (
+  id          uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  slug        text NOT NULL UNIQUE,
+  name        text NOT NULL,
+  description text,
+  theme       text,
+  created_at  timestamptz NOT NULL DEFAULT now(),
+  updated_at  timestamptz NOT NULL DEFAULT now()
+);
+
+CREATE TABLE projects (
+  id           uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  space_id     uuid NOT NULL REFERENCES spaces(id) ON DELETE CASCADE,
+  slug         text NOT NULL,
+  name         text NOT NULL,
+  description  text,
+  status       text NOT NULL DEFAULT 'active'
+               CHECK (status IN ('idea','active','paused','done','abandoned')),
+  started_at   timestamptz,
+  completed_at timestamptz,
+  created_at   timestamptz NOT NULL DEFAULT now(),
+  updated_at   timestamptz NOT NULL DEFAULT now(),
+  UNIQUE (space_id, slug)
+);
+
+CREATE TABLE tasks (
+  id           uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  space_id     uuid NOT NULL REFERENCES spaces(id) ON DELETE CASCADE,
+  project_id   uuid REFERENCES projects(id) ON DELETE SET NULL,
+  title        text NOT NULL,
+  body         text,
+  status       text NOT NULL DEFAULT 'todo'
+               CHECK (status IN ('todo','doing','blocked','done')),
+  priority     int,
+  due_at       timestamptz,
+  position     int,
+  completed_at timestamptz,
+  created_at   timestamptz NOT NULL DEFAULT now(),
+  updated_at   timestamptz NOT NULL DEFAULT now()
+);
+
+CREATE INDEX idx_projects_space ON projects(space_id);
+CREATE INDEX idx_tasks_space ON tasks(space_id);
+CREATE INDEX idx_tasks_project ON tasks(project_id);
+CREATE INDEX idx_tasks_status ON tasks(status) WHERE status <> 'done';
diff --git a/tests/db/migration_001.test.js b/tests/db/migration_001.test.js
new file mode 100644
index 0000000..976cf16
--- /dev/null
+++ b/tests/db/migration_001.test.js
@@ -0,0 +1,36 @@
+import { describe, it, expect, beforeAll } from 'vitest';
+import { resetDb, withClient } from '../helpers/db.js';
+import { migrateUp } from '../../lib/db/migrate.js';
+
+describe('migration 001 — core', () => {
+  beforeAll(async () => { await resetDb(); await migrateUp(); });
+
+  it('creates spaces, projects, tasks tables', async () => {
+    await withClient(async (c) => {
+      for (const t of ['spaces', 'projects', 'tasks']) {
+        const { rows } = await c.query(
+          `SELECT to_regclass('public.' || $1) AS t;`, [t]
+        );
+        expect(rows[0].t).toBe(t);
+      }
+    });
+  });
+
+  it('enforces UNIQUE(space_id, slug) on projects', async () => {
+    await withClient(async (c) => {
+      const { rows: [s] } = await c.query(
+        `INSERT INTO spaces(slug, name) VALUES('test', 'Test') RETURNING id;`
+      );
+      await c.query(
+        `INSERT INTO projects(space_id, slug, name) VALUES($1, 'a', 'A');`,
+        [s.id]
+      );
+      await expect(
+        c.query(
+          `INSERT INTO projects(space_id, slug, name) VALUES($1, 'a', 'B');`,
+          [s.id]
+        )
+      ).rejects.toThrow(/duplicate key/i);
+    });
+  });
+});