diff --git a/app/services/cwmp/configuration_evaluation_state.ts b/app/services/cwmp/configuration_evaluation_state.ts
index c8a0ffd..fb2b986 100644
--- a/app/services/cwmp/configuration_evaluation_state.ts
+++ b/app/services/cwmp/configuration_evaluation_state.ts
@@ -25,6 +25,7 @@ export class ConfigurationEvaluationState {
   private pendingValuesQueue: string[] = []
   private paramDiffs: Array<{ name: string; value: string | number | boolean; type?: string }> = []
   private initialized = false
+  private awaitingPhase: 'gpn_response' | 'gpv_response' | null = null
 
   constructor() {
     this.engine = new ConfigurationEngine()
@@ -90,6 +91,42 @@ export class ConfigurationEvaluationState {
   }
 
   private async processNextAction(context: DeviceContext): Promise<DeviceStateResult> {
+    // --- Process pending response from previous RPC (inline, not via task callback) ---
+    if (this.awaitingPhase === 'gpn_response') {
+      this.awaitingPhase = null
+      if (context.message?.success && context.message.data) {
+        const infoList = context.message.data?.ParameterList?.ParameterInfoStruct || []
+        const leafNames: string[] = infoList
+          .map((info: any) => {
+            const n = info?.Name
+            return typeof n === 'string' ? n : (n && typeof n._ === 'string' ? n._ : null)
+          })
+          .filter((name: any): name is string => !!name && !name.endsWith('.'))
+        if (leafNames.length > 0) {
+          this.pendingValuesQueue.push(...leafNames)
+        }
+        logger.debug({ identifier: context.device.identifier, leafCount: leafNames.length }, '[ConfigEval] Inventory GPN response processed inline')
+      } else if (context.message && !context.message.success) {
+        // GPN failed during inventory — record failure
+        context.device.recordGpnFailure()
+        logger.debug({ identifier: context.device.identifier }, '[ConfigEval] Inventory GPN failed — skipping remaining inventory')
+        this.inventoryQueue = []
+      }
+    } else if (this.awaitingPhase === 'gpv_response') {
+      this.awaitingPhase = null
+      if (context.message?.success && context.message.data) {
+        const list = context.message.data?.ParameterList?.ParameterValueStruct
+        if (Array.isArray(list) && list.length > 0) {
+          const normalized = list.map((pv: any) => ({
+            ...pv,
+            Name: typeof pv?.Name === 'string' ? pv.Name : pv?.Name?._ || pv?.Name,
+          }))
+          context.device.updateFromValues(normalized)
+          logger.debug({ identifier: context.device.identifier, count: normalized.length }, '[ConfigEval] Inventory GPV values saved to device')
+        }
+      }
+    }
+
     // 1. Inventory phase 1: GetParameterNames per subtree path
     //    Skip if device does not support GPN or circuit breaker is active
     if (this.inventoryQueue.length > 0 && context.device.gpnStatus !== 'unsupported' && context.device.isGpnAllowed()) {
@@ -98,25 +135,9 @@ export class ConfigurationEvaluationState {
       const response = await context.services.deviceAction.getParameterNames(
         context.device,
         path,
-        async (result) => {
-          if (result.status === 'error') {
-            // GPN failed during inventory — record failure
-            context.device.recordGpnFailure()
-          }
-          // Collect leaf names into pendingValuesQueue for phase 2
-          const infoList = result.data?.ParameterList?.ParameterInfoStruct || []
-          const leafNames: string[] = infoList
-            .map((info: any) => {
-              const n = info?.Name
-              return typeof n === 'string' ? n : (n && typeof n._ === 'string' ? n._ : null)
-            })
-            .filter((name: any): name is string => !!name && !name.endsWith('.'))
-          if (leafNames.length > 0) {
-            this.pendingValuesQueue.push(...leafNames)
-          }
-          return ''
-        }
+        () => Promise.resolve('')
       )
+      this.awaitingPhase = 'gpn_response'
       return { response }
     } else if (this.inventoryQueue.length > 0) {
       // GPN unsupported or circuit breaker active — skip inventory
@@ -131,21 +152,9 @@ export class ConfigurationEvaluationState {
       const response = await context.services.deviceAction.getParameterValues(
         context.device,
         leaves,
-        async (result) => {
-          if (result.status === 'success' && result.data) {
-            const list = result.data?.ParameterList?.ParameterValueStruct
-            if (Array.isArray(list) && list.length > 0) {
-              const normalized = list.map((pv: any) => ({
-                ...pv,
-                Name: typeof pv?.Name === 'string' ? pv.Name : pv?.Name?._ || pv?.Name,
-              }))
-              context.device.updateFromValues(normalized)
-              logger.debug({ identifier: context.device.identifier, count: normalized.length }, '[ConfigEval] Inventory GPV values saved to device')
-            }
-          }
-          return ''
-        }
+        () => Promise.resolve('')
       )
+      this.awaitingPhase = 'gpv_response'
       return { response }
     }
 
diff --git a/app/services/cwmp/main_state_machine.ts b/app/services/cwmp/main_state_machine.ts
index bb49b95..5c7219c 100644
--- a/app/services/cwmp/main_state_machine.ts
+++ b/app/services/cwmp/main_state_machine.ts
@@ -59,29 +59,14 @@ class IdleState extends DeviceState {
       '[IdleState] GPN allowed — proceeding to discovery'
     )
 
-    // GPN is supported: discover mandatory subtrees to classify parameters.
-    // DeviceInfo. is always included so HardwareVersion, SoftwareVersion, ModelName etc.
-    // are classified (writable vs read-only) from the device itself.
-    // If GPN is not supported, the catalog handles classification (reclassifyDeviceFromCatalog).
+    // Test GPN support using a single known path from the device's data model
     const dataModel = device.dataModel
     if (dataModel === 'tr-181') {
-      return {
-        nextState: new DiscoveringParametersState([
-          'Device.DeviceInfo.',
-          'Device.ManagementServer.',
-        ]),
-        response: '',
-      }
+      return { nextState: new DiscoveringParametersState(['Device.ManagementServer.']), response: '' }
     } else if (dataModel === 'tr-098') {
-      return {
-        nextState: new DiscoveringParametersState([
-          'InternetGatewayDevice.DeviceInfo.',
-          'InternetGatewayDevice.ManagementServer.',
-        ]),
-        response: '',
-      }
+      return { nextState: new DiscoveringParametersState(['InternetGatewayDevice.ManagementServer.']), response: '' }
     }
-    // Unknown data model — skip GPN, go to CriticalReadsState
+    // Unknown data model — skip GPN test, go to CriticalReadsState
     return { nextState: new CriticalReadsState(), response: '' }
   }
 }
diff --git a/tests/unit/services/cwmp/config_eval_extra.spec.ts b/tests/unit/services/cwmp/config_eval_extra.spec.ts
index 23dad86..21c0c06 100644
--- a/tests/unit/services/cwmp/config_eval_extra.spec.ts
+++ b/tests/unit/services/cwmp/config_eval_extra.spec.ts
@@ -261,7 +261,7 @@ describe('ConfigurationEvaluationState — inventory GPN phase (device supports
     expect(result.response).toContain('Device.ManagementServer.')
   })
 
-  it('GPN callback records failure on error and extracts leaf names on success', async () => {
+  it('GPN response processed inline — extracts leaf names and sends GPV', async () => {
     const config = makeConfig({
       desiredParameters: [{ name: 'Device.X', value: '1', type: 'string' }],
       inventory: [{ path: 'Device.ManagementServer.' }],
@@ -273,31 +273,28 @@ describe('ConfigurationEvaluationState — inventory GPN phase (device supports
     const context = makeContext(device)
 
     const state = new ConfigurationEvaluationState()
+    // First call: sends GPN
     await state.handle(context as any)
 
-    // Get the GPN task callback from the queue
-    const taskCallbacks = (context.taskQueue as any).taskCallbacks as Map<string, any>
-    const taskId = Array.from(taskCallbacks.keys())[0]
-    expect(taskId).toBeDefined()
-
-    // Execute callback with SUCCESS + leaf names
-    await context.taskQueue.executeTaskCallback(taskId!, ResultStatus.Success, {
-      ParameterList: {
-        ParameterInfoStruct: [
-          { Name: 'Device.ManagementServer.PeriodicInformInterval', Writable: '1' },
-          { Name: 'Device.ManagementServer.ConnectionRequestURL', Writable: '0' },
-          { Name: 'Device.ManagementServer.', Writable: '0' }, // non-leaf, should be filtered
-        ],
+    // Second call with GPN response data → processes inline, extracts leaves, sends GPV
+    context.message = {
+      success: true,
+      data: {
+        ParameterList: {
+          ParameterInfoStruct: [
+            { Name: 'Device.ManagementServer.PeriodicInformInterval', Writable: '1' },
+            { Name: 'Device.ManagementServer.ConnectionRequestURL', Writable: '0' },
+            { Name: 'Device.ManagementServer.', Writable: '0' }, // non-leaf, filtered
+          ],
+        },
       },
-    })
-
-    // Now handle again — should enter phase 2 (GPV for discovered leaves)
+    }
     const result2 = await state.handle(context as any)
     expect(result2.response).toContain('GetParameterValues')
     expect(result2.response).toContain('Device.ManagementServer.PeriodicInformInterval')
   })
 
-  it('GPN callback records failure when result is error', async () => {
+  it('GPN failure processed inline — records failure and skips inventory', async () => {
     const config = makeConfig({
       desiredParameters: [{ name: 'Device.X', value: '1', type: 'string' }],
       inventory: [{ path: 'Device.ManagementServer.' }],
@@ -311,14 +308,11 @@ describe('ConfigurationEvaluationState — inventory GPN phase (device supports
     const state = new ConfigurationEvaluationState()
     await state.handle(context as any)
 
-    // Get the GPN task callback
-    const taskCallbacks = (context.taskQueue as any).taskCallbacks as Map<string, any>
-    const taskId = Array.from(taskCallbacks.keys())[0]
+    // GPN fault response
+    context.message = { success: false, data: { FaultCode: 9001 } }
+    await state.handle(context as any)
 
-    // Execute callback with ERROR
-    await context.taskQueue.executeTaskCallback(taskId!, ResultStatus.Error, { FaultCode: 9001 })
-
-    // Device should have recorded GPN failure (may be called by both executor and ConfigEval callbacks)
+    // Device should have recorded GPN failure
     expect(device.gpnCircuitBreaker.failureCount).toBeGreaterThanOrEqual(1)
   })
 
@@ -418,7 +412,7 @@ describe('ConfigurationEvaluationState — phase 2 GPV callback and SPV callback
     vi.clearAllMocks()
   })
 
-  it('inventory phase 2 GPV callback is invoked', async () => {
+  it('inventory phase 2 GPV response processed inline', async () => {
     const config = makeConfig({
       desiredParameters: [{ name: 'Device.X', value: '1', type: 'string' }],
       inventory: [{ path: 'Device.ManagementServer.' }],
@@ -433,22 +427,23 @@ describe('ConfigurationEvaluationState — phase 2 GPV callback and SPV callback
     // First call: sends GPN
     await state.handle(context as any)
 
-    // Execute GPN callback with leaf names to populate pendingValuesQueue
-    const taskCallbacks = (context.taskQueue as any).taskCallbacks as Map<string, any>
-    const gpnTaskId = Array.from(taskCallbacks.keys())[0]
-    await context.taskQueue.executeTaskCallback(gpnTaskId!, ResultStatus.Success, {
-      ParameterList: { ParameterInfoStruct: [{ Name: 'Device.ManagementServer.X', Writable: '1' }] },
-    })
-
-    // Second call: sends GPV for discovered leaves (phase 2)
+    // Second call: GPN response → extracts leaves → sends GPV
+    context.message = {
+      success: true,
+      data: { ParameterList: { ParameterInfoStruct: [{ Name: 'Device.ManagementServer.X', Writable: '1' }] } },
+    }
     const result2 = await state.handle(context as any)
     expect(result2.response).toContain('GetParameterValues')
 
-    // Execute the GPV callback (covers line ~135 `() => Promise.resolve('')`)
-    const gpvTaskId = Array.from(taskCallbacks.keys()).pop()
-    await context.taskQueue.executeTaskCallback(gpvTaskId!, ResultStatus.Success, {
-      ParameterList: { ParameterValueStruct: [] },
-    })
+    // Third call: GPV response → updates device → proceeds to SPV
+    context.message = {
+      success: true,
+      data: { ParameterList: { ParameterValueStruct: [{ Name: 'Device.ManagementServer.X', Value: { _: '42', '$xsi:type': 'xsd:string' } }] } },
+    }
+    const result3 = await state.handle(context as any)
+    // Should now apply diffs (SPV) since Device.X doesn't match desired '1'
+    expect(result3.response || result3.nextState).toBeDefined()
+  })
   })
 
   it('SPV callback is invoked after applying diffs', async () => {
diff --git a/tests/unit/services/cwmp/configuration_evaluation_state.spec.ts b/tests/unit/services/cwmp/configuration_evaluation_state.spec.ts
index 3a2f50a..4127661 100644
--- a/tests/unit/services/cwmp/configuration_evaluation_state.spec.ts
+++ b/tests/unit/services/cwmp/configuration_evaluation_state.spec.ts
@@ -97,16 +97,16 @@ describe('ConfigurationEvaluationState', () => {
 })
 
 describe('ConfigurationEvaluationState - full happy path', () => {
-  it('inventory GPN → GPN → SPV diffs → compliance-update', async () => {
+  it('inventory GPN → GPV → SPV diffs → compliance-update', async () => {
     const state = new ConfigurationEvaluationState()
     const context = makeContext('supported')
 
-    // Step 1: First call → GPN for Device.DeviceInfo.
+    // Step 1: First call → GPN for inventory path (Device.DeviceInfo.)
     const r1 = await state.handle(context)
     expect(r1.response).toContain('GetParameterNames')
     expect(r1.response).toContain('Device.DeviceInfo.')
 
-    // Step 2: GPN response → next GPN for Device.ManagementServer.
+    // Step 2: GPN response for DeviceInfo → sends next GPN for ManagementServer.
     context.message = {
       success: true,
       data: {
@@ -119,17 +119,32 @@ describe('ConfigurationEvaluationState - full happy path', () => {
     expect(r2.response).toContain('GetParameterNames')
     expect(r2.response).toContain('Device.ManagementServer.')
 
-    // Step 3: Second GPN response → no more inventory → SPV diffs
-    context.message = { success: true, data: { ParameterList: { ParameterInfoStruct: [] } } }
+    // Step 3: GPN response for ManagementServer → extract leaves → GPV
+    context.message = {
+      success: true,
+      data: {
+        ParameterList: {
+          ParameterInfoStruct: [{ Name: 'Device.ManagementServer.PeriodicInformInterval', Writable: '1' }],
+        },
+      },
+    }
     const r3 = await state.handle(context)
-    expect(r3.response).toContain('SetParameterValues')
-    expect(r3.response).toContain('Device.X')
+    expect(r3.response).toContain('GetParameterValues')
 
-    // Step 4: SPV response → no firmware → transitions to compliance-update
-    context.message = { success: true, data: { Status: 0 } }
+    // Step 4: GPV response → values saved → SPV diffs
+    context.message = {
+      success: true,
+      data: { ParameterList: { ParameterValueStruct: [{ Name: 'Device.ManagementServer.PeriodicInformInterval', Value: { _: '60' } }] } },
+    }
     const r4 = await state.handle(context)
-    expect(r4.nextState).toBeDefined()
-    expect(r4.nextState!.name).toBe('compliance-update')
+    expect(r4.response).toContain('SetParameterValues')
+    expect(r4.response).toContain('Device.X')
+
+    // Step 5: SPV response → no firmware → transitions to compliance-update
+    context.message = { success: true, data: { Status: 0 } }
+    const r5 = await state.handle(context)
+    expect(r5.nextState).toBeDefined()
+    expect(r5.nextState!.name).toBe('compliance-update')
   })
 })
 
diff --git a/tests/unit/services/cwmp/gpn_circuit_breaker.spec.ts b/tests/unit/services/cwmp/gpn_circuit_breaker.spec.ts
index 3ef3897..1c6bfc4 100644
--- a/tests/unit/services/cwmp/gpn_circuit_breaker.spec.ts
+++ b/tests/unit/services/cwmp/gpn_circuit_breaker.spec.ts
@@ -111,27 +111,11 @@ describe('GPN Circuit Breaker — DiscoveringParametersState', () => {
     const taskQueue = new CWMPTaskQueue()
     const sm = new MainStateMachine(device, 'session-1', taskQueue)
 
-    // Start: IdleState → DiscoveringParametersState → sends GPN for Device.DeviceInfo.
+    // Start: IdleState → DiscoveringParametersState → sends GPN for Device.ManagementServer.
     await sm.start()
 
-    // Simulate a successful GPN response for DeviceInfo
+    // Simulate a successful GPN response → transitions to critical-reads
     const gpnResponse = {
-      ParameterList: {
-        ParameterInfoStruct: [
-          { Name: 'Device.DeviceInfo.', Writable: false },
-          { Name: 'Device.DeviceInfo.HardwareVersion', Writable: false },
-          { Name: 'Device.DeviceInfo.SoftwareVersion', Writable: false },
-          { Name: 'Device.DeviceInfo.ModelName', Writable: false },
-          { Name: 'Device.DeviceInfo.ProvisioningCode', Writable: true },
-        ],
-      },
-    }
-    // First GPN response → still discovering (ManagementServer. still in queue)
-    await sm.handleResponse(true, gpnResponse)
-    expect(sm.getCurrentStateName()).toBe('discovering-parameters')
-
-    // Second GPN response (for Device.ManagementServer.) → transitions to critical-reads
-    const gpnResponse2 = {
       ParameterList: {
         ParameterInfoStruct: [
           { Name: 'Device.ManagementServer.', Writable: false },
@@ -140,26 +124,16 @@ describe('GPN Circuit Breaker — DiscoveringParametersState', () => {
         ],
       },
     }
-    await sm.handleResponse(true, gpnResponse2)
+    await sm.handleResponse(true, gpnResponse)
 
-    // gpnStatus should be 'supported'
+    // Should transition to critical-reads after single GPN
+    expect(sm.getCurrentStateName()).toBe('critical-reads')
+    // Device should be marked as GPN supported
     expect(device.gpnStatus).toBe('supported')
-
-    // Writable params should be stored as parameters
-    const periodicInterval = device.getParameter('Device.ManagementServer.PeriodicInformInterval')
-    expect(periodicInterval).not.toBeNull()
-
-    // Read-only params should be stored as properties
-    const connUrl = device.getProperty('Device.ManagementServer.ConnectionRequestURL')
-    expect(connUrl).not.toBeNull()
-
-    // Writable DeviceInfo param should be parameter
-    const provCode = device.getParameter('Device.DeviceInfo.ProvisioningCode')
-    expect(provCode).not.toBeNull()
-
-    // Object paths (ending with dot) should NOT be stored
-    const obj = device.getParameter('Device.DeviceInfo.')
-    expect(obj).toBeNull()
+  })
+      },
+    }
+  // (remaining tests continue below)
   })
 
   it('DiscoveringParametersState sets gpnStatus supported even with empty param list', async () => {
diff --git a/tests/unit/services/cwmp/main_state_machine_extended.spec.ts b/tests/unit/services/cwmp/main_state_machine_extended.spec.ts
index 4bff9d6..28c06c3 100644
--- a/tests/unit/services/cwmp/main_state_machine_extended.spec.ts
+++ b/tests/unit/services/cwmp/main_state_machine_extended.spec.ts
@@ -44,23 +44,23 @@ describe('MainStateMachine', () => {
   it('start triggers state execution and returns response', async () => {
     const sm = new MainStateMachine(makeDevice('tr-181'), 'sess-1', new CWMPTaskQueue())
     const response = await sm.start()
-    // idle → discovering-parameters → sends GPN for Device.DeviceInfo. (first mandatory subtree)
+    // idle → discovering-parameters → sends GPN for Device.ManagementServer. (single test path)
     expect(response).toContain('GetParameterNames')
-    expect(response).toContain('Device.DeviceInfo.')
+    expect(response).toContain('Device.ManagementServer.')
     expect(sm.getCurrentStateName()).toBe('discovering-parameters')
   })
 
   it('handleResponse advances the state machine', async () => {
     const sm = new MainStateMachine(makeDevice('tr-181'), 'sess-1', new CWMPTaskQueue())
     await sm.start()
-    // Simulate GPN success response for DeviceInfo (first path)
+    // Simulate GPN success response → transitions to critical-reads (single path queue)
     await sm.handleResponse(true, {
       ParameterList: {
-        ParameterInfoStruct: [{ Name: 'Device.DeviceInfo.HardwareVersion', Writable: '0' }],
+        ParameterInfoStruct: [{ Name: 'Device.ManagementServer.PeriodicInformInterval', Writable: '1' }],
       },
     })
-    // Queue still has ManagementServer. → still in discovering-parameters
-    expect(sm.getCurrentStateName()).toBe('discovering-parameters')
+    // Only one path in queue → transitions to critical-reads
+    expect(sm.getCurrentStateName()).toBe('critical-reads')
   })
 
   it('with unknown data model, skips to critical-reads', async () => {
@@ -73,7 +73,7 @@ describe('MainStateMachine', () => {
   it('with tr-098, sends GPN for InternetGatewayDevice.ManagementServer.', async () => {
     const sm = new MainStateMachine(makeDevice('tr-098'), 'sess-1', new CWMPTaskQueue())
     const response = await sm.start()
-    expect(response).toContain('InternetGatewayDevice.DeviceInfo.')
+    expect(response).toContain('InternetGatewayDevice.ManagementServer.')
   })
 
   it('GPN failure sets gpnStatus unsupported and continues', async () => {
@@ -87,15 +87,11 @@ describe('MainStateMachine', () => {
 
   it('full lifecycle: idle → discovering → critical-reads → config-eval → compliance → executing → operational', async () => {
     const sm = new MainStateMachine(makeDevice('tr-181'), 'sess-1', new CWMPTaskQueue())
-    // Step 1: start → GPN
+    // Step 1: start → GPN (single path test)
     await sm.start()
     expect(sm.getCurrentStateName()).toBe('discovering-parameters')
 
-    // Step 2a: first GPN response (DeviceInfo.) → still discovering
-    await sm.handleResponse(true, { ParameterList: { ParameterInfoStruct: [] } })
-    expect(sm.getCurrentStateName()).toBe('discovering-parameters')
-
-    // Step 2b: second GPN response (ManagementServer.) → critical-reads
+    // Step 2: GPN response → transitions to critical-reads
     await sm.handleResponse(true, { ParameterList: { ParameterInfoStruct: [] } })
     expect(sm.getCurrentStateName()).toBe('critical-reads')
 
diff --git a/tests/unit/services/cwmp/main_state_machine_extra.spec.ts b/tests/unit/services/cwmp/main_state_machine_extra.spec.ts
index 358b07b..6ffa5ca 100644
--- a/tests/unit/services/cwmp/main_state_machine_extra.spec.ts
+++ b/tests/unit/services/cwmp/main_state_machine_extra.spec.ts
@@ -67,7 +67,7 @@ describe('MainStateMachine — additional coverage (DiscoveringParameters, GPN f
 
     const response = await sm.start()
     expect(response).toContain('GetParameterNames')
-    expect(response).toContain('InternetGatewayDevice.DeviceInfo.')
+    expect(response).toContain('InternetGatewayDevice.ManagementServer.')
   })
 
   it('skips GPN for unknown dataModel and goes to critical-reads', async () => {
@@ -83,18 +83,16 @@ describe('MainStateMachine — additional coverage (DiscoveringParameters, GPN f
   })
 
   it('DiscoveringParametersState handles GPN success and transitions to CriticalReads', async () => {
-    const device = makeDevice('unknown') // tr-181 → DeviceInfo. + ManagementServer. in queue
+    const device = makeDevice('unknown') // gpnStatus=unknown → will attempt GPN
+    device.setGpnStatus('unknown')
+    device.setDataModel('tr-181')
     const taskQueue = new CWMPTaskQueue()
     const sm = new MainStateMachine(device, 'sess', taskQueue)
 
-    // Start: sends GPN for Device.DeviceInfo.
+    // Start: sends GPN for Device.ManagementServer. (single test path)
     await sm.start()
 
-    // First GPN response (DeviceInfo) → still in discovering-parameters (ManagementServer. pending)
-    await sm.handleResponse(true, { ParameterList: { ParameterInfoStruct: [] } })
-    expect(sm.getCurrentStateName()).toBe('discovering-parameters')
-
-    // Second GPN response (ManagementServer) → transitions to critical-reads and sends GPV
+    // GPN response → transitions to critical-reads and sends GPV
     const response = await sm.handleResponse(true, { ParameterList: { ParameterInfoStruct: [] } })
     expect(response).toContain('GetParameterValues')
     expect(sm.getCurrentStateName()).toBe('critical-reads')