fix: avoid GPN on root path Device. which returns the full parameter tree

Two complementary fixes:
- IdleState: skip root-level parent paths (Device., InternetGatewayDevice.)
  when building the GPN queue. Params like Device.RootDataModelVersion have
  Device. as parent but sending GPN on Device. with NextLevel=0 returns the
  entire TR-181 tree in one response (potentially several MB).
  These root-level params are classified via deeper subtree GPN or catalog.
- task_queue: use NextLevel=1 for root paths (1 segment) as a safety net,
  NextLevel=0 for deeper paths to get all leaves of that subtree.

app/services/cwmp/main_state_machine.ts

@@ -77,12 +77,19 @@ class IdleState extends DeviceState {
       return { nextState: new CriticalReadsState(), response: '' }
     }
 
-    // Extract unique parent paths from the UNCLASSIFIED params only
+    // Extract unique parent paths from the UNCLASSIFIED params only.
+    // Skip root-level paths (e.g. "Device." or "InternetGatewayDevice.") that would
+    // produce a huge GPN response — root-level params like Device.RootDataModelVersion
+    // will be discovered when deeper subtrees are explored or classified via catalog.
     const parentPaths = new Set<string>()
     for (const name of unclassified) {
       const lastDot = name.lastIndexOf('.')
-      if (lastDot > 0) {
-        parentPaths.add(name.substring(0, lastDot + 1))
+      if (lastDot <= 0) continue
+      const parentPath = name.substring(0, lastDot + 1)
+      // Only add paths with at least 2 segments (e.g. "Device.DeviceInfo." not "Device.")
+      const segments = parentPath.replace(/\.$/, '').split('.')
+      if (segments.length >= 2) {
+        parentPaths.add(parentPath)
       }
     }
 

app/services/cwmp/task_queue.ts

@@ -40,7 +40,12 @@ export enum TaskStatus {
 export class CWMPTaskQueue extends EventEmitter {
   static task_map: Record<string, (props: any) => string> = {
     get_parameter_names: (parameterPath: string) => {
-      return CWMPMessageBuilder.getParameterNames(undefined, parameterPath, false)
+      // Use NextLevel=1 for root paths (e.g. "Device." or "InternetGatewayDevice.")
+      // to avoid fetching the entire parameter tree in a single response.
+      // For deeper paths (e.g. "Device.DeviceInfo.") use NextLevel=0 to get all leaves.
+      const segments = parameterPath.replace(/\.$/, '').split('.')
+      const nextLevel = segments.length <= 1
+      return CWMPMessageBuilder.getParameterNames(undefined, parameterPath, nextLevel)
     },
     get_parameter_attributes: (parameterNames: string[]) => {
       return CWMPMessageBuilder.getParameterAttributes(undefined, parameterNames)