diff --git a/apps/api/test/helpers.ts b/apps/api/test/helpers.ts
index 2576b07..b570477 100644
--- a/apps/api/test/helpers.ts
+++ b/apps/api/test/helpers.ts
@@ -1,7 +1,7 @@
 import type { Hono } from 'hono';
 import { auth } from '../src/auth';
 import { db } from '../src/db/client';
-import { activities } from '../src/db/schema';
+import { account, activities, session, user, verification, workSessions } from '../src/db/schema';
 
 const PASSWORD = 'sterk-wachtwoord-123';
 const json = { 'content-type': 'application/json' };
@@ -44,6 +44,18 @@ export function bearer(token: string): Record<string, string> {
   return { authorization: `Bearer ${token}`, 'content-type': 'application/json' };
 }
 
+// Wipe all data rows (schema stays; migration already ran once in setup.ts).
+// Lets a domain suite start from an empty DB in beforeEach instead of inheriting
+// rows from earlier test files (removes the accumulate-and-scope fragility).
+export async function resetDb(): Promise<void> {
+  await db.delete(workSessions);
+  await db.delete(session);
+  await db.delete(account);
+  await db.delete(verification);
+  await db.delete(user);
+  await db.delete(activities);
+}
+
 // Insert an activity straight into the DB (test setup that should not depend on authz).
 export async function seedActivity(
   name: string,
diff --git a/apps/api/test/reset-db.test.ts b/apps/api/test/reset-db.test.ts
new file mode 100644
index 0000000..8112896
--- /dev/null
+++ b/apps/api/test/reset-db.test.ts
@@ -0,0 +1,21 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { db } from '../src/db/client';
+import { workSessions, user } from '../src/db/schema';
+import { resetDb, seedActivity, authToken } from './helpers';
+import { createApp } from '../src/app';
+
+describe('resetDb', () => {
+  beforeEach(resetDb);
+
+  it('clears domain and auth rows so counts start from zero', async () => {
+    const app = createApp();
+    await authToken(app, 'reset-a@example.com');
+    await seedActivity('Zagen');
+    expect((await db.select().from(user)).length).toBeGreaterThan(0);
+
+    await resetDb();
+
+    expect(await db.select().from(user)).toHaveLength(0);
+    expect(await db.select().from(workSessions)).toHaveLength(0);
+  });
+});
diff --git a/apps/api/test/sessions.test.ts b/apps/api/test/sessions.test.ts
index a005c27..86881b0 100644
--- a/apps/api/test/sessions.test.ts
+++ b/apps/api/test/sessions.test.ts
@@ -1,13 +1,15 @@
-import { describe, it, expect } from 'vitest';
+import { describe, it, expect, beforeEach } from 'vitest';
 import { createApp } from '../src/app';
 import { db } from '../src/db/client';
 import { workSessions } from '../src/db/schema';
 import { eq } from 'drizzle-orm';
-import { authToken, bearer, seedActivity } from './helpers';
+import { authToken, bearer, seedActivity, resetDb } from './helpers';
 
 const json = { 'content-type': 'application/json' };
 
 describe('session lifecycle', () => {
+  beforeEach(resetDb);
+
   it('401s start/stop/discard without a token', async () => {
     const app = createApp();
 
@@ -334,6 +336,8 @@ describe('session lifecycle', () => {
 });
 
 describe('session reads', () => {
+  beforeEach(resetDb);
+
   it('401s GET /api/sessions and /api/sessions/active without a token', async () => {
     const app = createApp();