feat(hosts): generate unique 8-digit asset ID

Add a Generate button to the host create dialog that fetches a random
8-digit asset ID from the new GET /hosts/generate-asset-id endpoint.
The service retries against the unique index so the returned ID is
guaranteed unused. Edit mode hides the button.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/api/src/controllers/hosts.ts

@@ -29,6 +29,15 @@ export async function get(req: Request<{ id: string }>, res: Response, next: Nex
   }
 }
 
+export async function generateAssetId(_req: Request, res: Response, next: NextFunction) {
+  try {
+    const result = await prisma.$transaction((tx) => svc.generateAssetId(tx));
+    res.json(result);
+  } catch (err) {
+    next(err);
+  }
+}
+
 export async function create(req: Request, res: Response, next: NextFunction) {
   try {
     const input = req.validated!.body as CreateHostRequest;

apps/api/src/routes/hosts.ts

@@ -13,6 +13,7 @@ const router = Router();
 
 router.get('/', requireAuth, validate('query', HostListQuery), ctrl.list);
 router.post('/', requireAuth, requireRole('ADMIN'), validate('body', CreateHostRequest), ctrl.create);
+router.get('/generate-asset-id', requireAuth, requireRole('ADMIN'), ctrl.generateAssetId);
 router.get('/:id', requireAuth, ctrl.get);
 router.get('/:id/deployed-parts', requireAuth, ctrl.listDeployedParts);
 router.get('/:id/timeline', requireAuth, validate('query', HostTimelineQuery), ctrl.getTimeline);

apps/api/src/services/hosts.ts

@@ -41,6 +41,18 @@ export function get(tx: Tx, id: string) {
   return tx.host.findUnique({ where: { id } });
 }
 
+// Random 8-digit asset ID (zero-padded) that isn't already taken. With ~100M
+// possible values and only hundreds of hosts in practice, collisions are rare
+// — we still retry a few times to be safe, then bail instead of looping forever.
+export async function generateAssetId(tx: Tx): Promise<{ assetId: string }> {
+  for (let attempt = 0; attempt < 20; attempt++) {
+    const candidate = String(Math.floor(Math.random() * 100_000_000)).padStart(8, '0');
+    const existing = await tx.host.findUnique({ where: { assetId: candidate }, select: { id: true } });
+    if (!existing) return { assetId: candidate };
+  }
+  throw errors.conflict('Could not generate a unique asset ID');
+}
+
 export function listDeployedParts(tx: Tx, hostId: string) {
   return tx.part.findMany({
     where: { hostId, state: 'DEPLOYED' },