diff --git a/products/04-lightweight-idp/src/api/discovery.ts b/products/04-lightweight-idp/src/api/discovery.ts
index 4fde9be..444633a 100644
--- a/products/04-lightweight-idp/src/api/discovery.ts
+++ b/products/04-lightweight-idp/src/api/discovery.ts
@@ -72,7 +72,23 @@ export function registerDiscoveryRoutes(app: FastifyInstance) {
 
     await withTenant(tenantId, async (client) => {
       await client.query('UPDATE staged_updates SET status = $1 WHERE id = $2', [newStatus, id]);
-      // TODO: If applied, merge changes into services table
+      // If applied, merge staged changes into services table
+      if (action === 'apply') {
+        const staged = await client.query('SELECT * FROM staged_updates WHERE id = $1', [id]);
+        if (staged.rows[0]) {
+          const changes = staged.rows[0].changes;
+          await client.query(
+            `INSERT INTO services (tenant_id, name, type, owner, owner_source, tags, last_discovered_at)
+             VALUES ($1, $2, $3, $4, $5, $6, now())
+             ON CONFLICT (tenant_id, name) DO UPDATE SET
+               type = COALESCE(EXCLUDED.type, services.type),
+               owner = COALESCE(EXCLUDED.owner, services.owner),
+               tags = services.tags || EXCLUDED.tags,
+               last_discovered_at = now(), updated_at = now()`,
+            [tenantId, staged.rows[0].service_name, changes.type, changes.owner, changes.ownerSource ?? 'heuristic', JSON.stringify(changes.tags ?? {})],
+          );
+        }
+      }
     });
 
     return { status: newStatus };