diff --git a/src/test/tenant-isolation.spec.ts b/src/test/tenant-isolation.spec.ts
new file mode 100644
index 0000000..555a200
--- /dev/null
+++ b/src/test/tenant-isolation.spec.ts
@@ -0,0 +1,106 @@
+/**
+ * Tenant Isolation Integration Tests
+ *
+ * Verifies that data written under tenant-A is never readable from tenant-B session.
+ * Runs against real Drizzle/Postgres via DATABASE_URL env var.
+ * Skip if DATABASE_URL is not set (CI without DB).
+ */
+import { eq, and, isNull } from 'drizzle-orm';
+import { db } from '../db/client';
+import { goals, organizations, tasks } from '../db/schema';
+
+const HAS_DB = !!process.env.DATABASE_URL;
+
+const TENANT_A = '00000000-0000-0000-0000-000000000a01';
+const TENANT_B = '00000000-0000-0000-0000-000000000b02';
+const WS_A = '00000000-0000-0000-0000-000000000a03';
+const WS_B = '00000000-0000-0000-0000-000000000b04';
+const USER_A = '00000000-0000-0000-0000-000000000a05';
+const USER_B = '00000000-0000-0000-0000-000000000b05';
+
+(HAS_DB ? describe : describe.skip)('Tenant Isolation', () => {
+  let goalIdA: string;
+  let orgIdA: string;
+
+  afterAll(async () => {
+    // Cleanup test data
+    if (goalIdA) await db.delete(goals).where(eq(goals.id, goalIdA));
+    if (orgIdA) await db.delete(organizations).where(eq(organizations.id, orgIdA));
+  });
+
+  describe('Goals', () => {
+    it('tenant-A can create a goal', async () => {
+      // Arrange + Act
+      const [row] = await db
+        .insert(goals)
+        .values({
+          tenantId: TENANT_A,
+          ownerUserId: USER_A,
+          horizon: 'Q4 2026',
+          metric: 'MRR',
+          target: '100k',
+          milestones: [] as unknown[],
+        })
+        .returning();
+      goalIdA = row.id;
+
+      // Assert
+      expect(row.tenantId).toBe(TENANT_A);
+      expect(row.id).toBeTruthy();
+    });
+
+    it('tenant-B cannot see tenant-A goals', async () => {
+      // Act
+      const results = await db.query.goals.findMany({
+        where: and(eq(goals.tenantId, TENANT_B), isNull(goals.deletedAt)),
+      });
+
+      // Assert — no tenant-A goal leaks into tenant-B query
+      const leaked = results.filter((g) => g.tenantId === TENANT_A);
+      expect(leaked).toHaveLength(0);
+    });
+
+    it('tenant-A can see their own goal by id', async () => {
+      // Act
+      const row = await db.query.goals.findFirst({
+        where: and(eq(goals.id, goalIdA), eq(goals.tenantId, TENANT_A), isNull(goals.deletedAt)),
+      });
+
+      // Assert
+      expect(row).toBeDefined();
+      expect(row!.tenantId).toBe(TENANT_A);
+    });
+
+    it('tenant-B cannot fetch tenant-A goal by id', async () => {
+      // Act — tenant-B tries to access tenant-A goal with TENANT_B filter
+      const row = await db.query.goals.findFirst({
+        where: and(eq(goals.id, goalIdA), eq(goals.tenantId, TENANT_B)),
+      });
+
+      // Assert — should return undefined (not found)
+      expect(row).toBeUndefined();
+    });
+  });
+
+  describe('Organizations', () => {
+    it('tenant-A creates organization invisible to tenant-B', async () => {
+      // Arrange + Act
+      const [org] = await db
+        .insert(organizations)
+        .values({
+          tenantId: TENANT_A,
+          name: 'Tenant A Corp',
+          country: 'RO',
+        })
+        .returning();
+      orgIdA = org.id;
+
+      // tenant-B query
+      const tenantBOrgs = await db.query.organizations.findMany({
+        where: and(eq(organizations.tenantId, TENANT_B), isNull(organizations.deletedAt)),
+      });
+
+      expect(tenantBOrgs.find((o) => o.id === orgIdA)).toBeUndefined();
+    });
+  });
+});