diff --git a/tests/identity-db.test.ts b/tests/identity-db.test.ts
new file mode 100644
index 0000000..52a592e
--- /dev/null
+++ b/tests/identity-db.test.ts
@@ -0,0 +1,54 @@
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+
+import { IdentityDB } from '../src/core/identity-db';
+
+describe('IdentityDB topic and fact writes', () => {
+  let db: IdentityDB;
+
+  beforeEach(async () => {
+    db = await IdentityDB.connect({ client: 'sqlite', filename: ':memory:' });
+    await db.initialize();
+  });
+
+  afterEach(async () => {
+    await db.close();
+  });
+
+  it('deduplicates topics by normalized name during upsert', async () => {
+    const first = await db.upsertTopic({
+      name: 'TypeScript',
+      category: 'entity',
+      granularity: 'concrete',
+    });
+
+    const second = await db.upsertTopic({
+      name: '  typescript  ',
+      category: 'entity',
+      granularity: 'concrete',
+    });
+
+    expect(second.id).toBe(first.id);
+    expect(second.normalizedName).toBe('typescript');
+
+    const topics = await db.listTopics({ includeFacts: false });
+    expect(topics).toHaveLength(1);
+  });
+
+  it('adds one fact that links multiple topics', async () => {
+    const fact = await db.addFact({
+      statement: 'I have worked with TypeScript since 2025.',
+      topics: [
+        { name: 'I', category: 'entity', granularity: 'concrete', role: 'subject' },
+        { name: 'TypeScript', category: 'entity', granularity: 'concrete', role: 'object' },
+        { name: '2025', category: 'temporal', granularity: 'concrete', role: 'time' },
+      ],
+    });
+
+    expect(fact.statement).toBe('I have worked with TypeScript since 2025.');
+    expect(fact.topics.map((topic) => topic.name)).toEqual(['I', 'TypeScript', '2025']);
+
+    const typeScriptFacts = await db.getTopicFacts('TypeScript');
+    expect(typeScriptFacts).toHaveLength(1);
+    expect(typeScriptFacts[0]?.statement).toBe('I have worked with TypeScript since 2025.');
+  });
+});
diff --git a/tests/queries.test.ts b/tests/queries.test.ts
new file mode 100644
index 0000000..97a9d02
--- /dev/null
+++ b/tests/queries.test.ts
@@ -0,0 +1,84 @@
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+
+import { IdentityDB } from '../src/core/identity-db';
+
+async function seedMemoryGraph(db: IdentityDB): Promise<void> {
+  await db.addFact({
+    statement: 'I have worked with TypeScript since 2025.',
+    topics: [
+      { name: 'I', category: 'entity', granularity: 'concrete', role: 'subject' },
+      { name: 'TypeScript', category: 'entity', granularity: 'concrete', role: 'object' },
+      { name: '2025', category: 'temporal', granularity: 'concrete', role: 'time' },
+    ],
+  });
+
+  await db.addFact({
+    statement: 'TypeScript is a programming language.',
+    topics: [
+      { name: 'TypeScript', category: 'entity', granularity: 'concrete', role: 'subject' },
+      { name: 'programming language', category: 'concept', granularity: 'abstract', role: 'classification' },
+    ],
+  });
+}
+
+describe('IdentityDB queries', () => {
+  let db: IdentityDB;
+
+  beforeEach(async () => {
+    db = await IdentityDB.connect({ client: 'sqlite', filename: ':memory:' });
+    await db.initialize();
+    await seedMemoryGraph(db);
+  });
+
+  afterEach(async () => {
+    await db.close();
+  });
+
+  it('gets a topic with its facts', async () => {
+    const topic = await db.getTopicByName('TypeScript', { includeFacts: true });
+
+    expect(topic).not.toBeNull();
+    expect(topic?.name).toBe('TypeScript');
+    expect(topic?.facts).toHaveLength(2);
+    expect(topic?.facts.map((fact) => fact.statement)).toEqual([
+      'I have worked with TypeScript since 2025.',
+      'TypeScript is a programming language.',
+    ]);
+  });
+
+  it('gets only the facts linked to another topic', async () => {
+    const facts = await db.getTopicFactsLinkedTo('TypeScript', '2025');
+
+    expect(facts).toHaveLength(1);
+    expect(facts[0]?.statement).toBe('I have worked with TypeScript since 2025.');
+  });
+
+  it('lists topics without expanding facts', async () => {
+    const topics = await db.listTopics({ includeFacts: false });
+
+    expect(topics.map((topic) => topic.name)).toEqual([
+      '2025',
+      'I',
+      'programming language',
+      'TypeScript',
+    ]);
+    expect('facts' in topics[0]!).toBe(false);
+  });
+
+  it('finds connected topics with shared fact counts', async () => {
+    const connectedTopics = await db.findConnectedTopics('TypeScript');
+
+    expect(connectedTopics).toEqual([
+      expect.objectContaining({ name: '2025', sharedFactCount: 1 }),
+      expect.objectContaining({ name: 'I', sharedFactCount: 1 }),
+      expect.objectContaining({ name: 'programming language', sharedFactCount: 1 }),
+    ]);
+  });
+
+  it('finds facts that connect all requested topics', async () => {
+    const facts = await db.findFactsConnectingTopics(['I', 'TypeScript', '2025']);
+
+    expect(facts).toHaveLength(1);
+    expect(facts[0]?.statement).toBe('I have worked with TypeScript since 2025.');
+  });
+});