diff --git a/src/lib/server/db.ts b/src/lib/server/db.ts
index c773506..67a7e10 100644
--- a/src/lib/server/db.ts
+++ b/src/lib/server/db.ts
@@ -36,6 +36,21 @@ export function getDb(): Database.Database {
   return db;
 }
 
+export function deleteOrganization(db: Database.Database, orgId: string): void {
+  const tx = db.transaction(() => {
+    // Instance events do not cascade, so remove them before their instances.
+    db.prepare(
+      'DELETE FROM instance_events WHERE instance_id IN (SELECT id FROM instances WHERE org_id = ?)',
+    ).run(orgId);
+    db.prepare('DELETE FROM instances WHERE org_id = ?').run(orgId);
+    db.prepare('DELETE FROM org_invitations WHERE org_id = ?').run(orgId);
+    db.prepare('DELETE FROM org_members WHERE org_id = ?').run(orgId);
+    db.prepare('DELETE FROM organizations WHERE id = ?').run(orgId);
+  });
+
+  tx();
+}
+
 // Fresh-install schema. Arc Launchpad creates its SQLite database on first
 // run; there is no upgrade path from older databases, so this is a single
 // flat set of CREATE TABLE statements rather than an incremental migration
diff --git a/src/lib/server/orgDeletion.test.ts b/src/lib/server/orgDeletion.test.ts
new file mode 100644
index 0000000..acd9cef
--- /dev/null
+++ b/src/lib/server/orgDeletion.test.ts
@@ -0,0 +1,36 @@
+import { describe, expect, it } from 'vitest';
+import { deleteOrganization, getDb } from './db';
+
+describe('organization deletion', () => {
+  it('deletes instances and their retained data before the organization', () => {
+    const db = getDb();
+    db.exec('DELETE FROM instance_events; DELETE FROM instances; DELETE FROM org_members; DELETE FROM organizations; DELETE FROM users;');
+    db.prepare('INSERT INTO users (id, email) VALUES (?, ?)').run('user-1', 'user@example.test');
+    db.prepare('INSERT INTO organizations (id, name, owner_user_id) VALUES (?, ?, ?)').run('org-1', 'Test org', 'user-1');
+    db.prepare('INSERT INTO org_members (org_id, user_id, role) VALUES (?, ?, ?)').run('org-1', 'user-1', 'owner');
+    db.prepare('INSERT INTO instances (id, org_id, resource_id, admin_token) VALUES (?, ?, ?, ?)').run(
+      'instance-1',
+      'org-1',
+      'resource-1',
+      'secret-token',
+    );
+    db.prepare('INSERT INTO instance_events (instance_id, event_type) VALUES (?, ?)').run('instance-1', 'connected');
+    db.prepare('INSERT INTO org_invitations (id, org_id, email, token, invited_by, expires_at) VALUES (?, ?, ?, ?, ?, ?)').run(
+      'invite-1',
+      'org-1',
+      'invitee@example.test',
+      'invite-token',
+      'user-1',
+      '2099-01-01T00:00:00.000Z',
+    );
+
+    deleteOrganization(db, 'org-1');
+
+    expect(db.prepare('SELECT 1 FROM organizations WHERE id = ?').get('org-1')).toBeUndefined();
+    expect(db.prepare('SELECT 1 FROM org_members WHERE org_id = ?').get('org-1')).toBeUndefined();
+    expect(db.prepare('SELECT 1 FROM org_invitations WHERE org_id = ?').get('org-1')).toBeUndefined();
+    expect(db.prepare('SELECT 1 FROM instances WHERE org_id = ?').get('org-1')).toBeUndefined();
+    expect(db.prepare('SELECT 1 FROM instance_events WHERE instance_id = ?').get('instance-1')).toBeUndefined();
+    expect(db.prepare('SELECT 1 FROM instances WHERE admin_token = ?').get('secret-token')).toBeUndefined();
+  });
+});
diff --git a/src/routes/api/v1/admin/orgs/[org_id]/+server.ts b/src/routes/api/v1/admin/orgs/[org_id]/+server.ts
index 57a3e9c..18059ca 100644
--- a/src/routes/api/v1/admin/orgs/[org_id]/+server.ts
+++ b/src/routes/api/v1/admin/orgs/[org_id]/+server.ts
@@ -1,6 +1,6 @@
 import { json } from '@sveltejs/kit';
 import type { RequestHandler } from './$types';
-import { getDb } from '$lib/server/db';
+import { deleteOrganization, getDb } from '$lib/server/db';
 import { logOperatorAction } from '$lib/server/audit';
 
 export const PATCH: RequestHandler = async ({ locals, params, request }) => {
@@ -40,13 +40,7 @@ export const DELETE: RequestHandler = async ({ locals, params }) => {
 
   // Removing an org drops its instance connections, members, and pending invites.
   // Connections are just stored URLs/tokens — nothing external to tear down.
-  const tx = db.transaction(() => {
-    db.prepare("UPDATE instances SET deleted_at = datetime('now'), status = 'deleted' WHERE org_id = ? AND deleted_at IS NULL").run(params.org_id);
-    db.prepare('DELETE FROM org_invitations WHERE org_id = ?').run(params.org_id);
-    db.prepare('DELETE FROM org_members WHERE org_id = ?').run(params.org_id);
-    db.prepare('DELETE FROM organizations WHERE id = ?').run(params.org_id);
-  });
-  tx();
+  deleteOrganization(db, params.org_id);
 
   logOperatorAction(locals.user.id, 'delete_org', 'org', params.org_id, { name: org.name });