refactor(server): drop type assertions in listenRouter via narrowed locals

Author: felixweinberger

packages/server/src/server/listenRouter.ts

@@ -85,7 +85,7 @@ function stampSubscriptionId(
  * marks `notifications` REQUIRED on the listen request).
  */
 export function parseListenFilter(message: JSONRPCRequest): SubscriptionFilter | undefined {
-    const raw = (message.params as { notifications?: unknown } | undefined)?.notifications;
+    const raw: unknown = message.params?.['notifications'];
     if (raw === undefined) return undefined;
     const parsed = SubscriptionFilterSchema.safeParse(raw);
     return parsed.success ? parsed.data : undefined;
@@ -193,7 +193,10 @@ export function createListenRouter(options: ListenRouterOptions): ListenRouter {
                 if (keepAliveMs > 0) {
                     keepAliveTimer = setInterval(() => writeFrame(': keepalive\n\n'), keepAliveMs);
                     // Do not hold the event loop open on idle subscriptions.
-                    (keepAliveTimer as { unref?: () => void }).unref?.();
+                    // Node's setInterval returns a Timeout with .unref(); browsers return a number.
+                    if (typeof keepAliveTimer === 'object' && 'unref' in keepAliveTimer && typeof keepAliveTimer.unref === 'function') {
+                        keepAliveTimer.unref();
+                    }
                 }
 
                 open.add(teardown);
@@ -331,7 +334,8 @@ export class StdioListenRouter {
         if (!CHANGE_NOTIFICATION_METHODS.has(message.method)) {
             return 'passthrough';
         }
-        const uri = typeof message.params?.['uri'] === 'string' ? (message.params['uri'] as string) : undefined;
+        const uriParam: unknown = message.params?.['uri'];
+        const uri = typeof uriParam === 'string' ? uriParam : undefined;
         const event = notificationToServerEvent(message.method, uri);
         const out: NotificationBody[] = [];
         for (const [subscriptionId, filter] of this._subs) {