diff --git a/tests/unit/services/cwmp/two_session_scenario.spec.ts b/tests/unit/services/cwmp/two_session_scenario.spec.ts
index 37dcf66..555463f 100644
--- a/tests/unit/services/cwmp/two_session_scenario.spec.ts
+++ b/tests/unit/services/cwmp/two_session_scenario.spec.ts
@@ -265,3 +265,136 @@ describe('Two-session scenario: same device, first contact then reconnect', () =
     console.log(`   Skipped: GPN test, inventory, SPV, ProvisioningCode`)
   })
 })
+
+import DeviceModel from '../../../../app/models/device.js'
+
+describe('GPN unsupported → catalog classification + persistence', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  it('GPN fault triggers catalog reclassification and persists to DB', async () => {
+    // Simulate a Livebox 4 (tr-181) device with Inform params
+    const device = new Device(new DeviceId('Sagemcom', 'F8B7FF', 'Livebox 4', 'LB4-TEST-001'))
+    device.setDataModel('tr-181')
+    const informParams = [
+      { Name: 'Device.DeviceInfo.HardwareVersion', Value: { _: 'v3.0' } },
+      { Name: 'Device.DeviceInfo.SoftwareVersion', Value: { _: 'SR50-5.0.0' } },
+      { Name: 'Device.ManagementServer.ConnectionRequestURL', Value: { _: 'http://cpe:7547/' } },
+      { Name: 'Device.ManagementServer.PeriodicInformInterval', Value: { _: '60' } },
+    ]
+    device.updateFromValues(informParams)
+    device.setTmpParamValues(informParams)
+    // gpnStatus = 'unknown' → will attempt GPN
+
+    const taskQueue = new CWMPTaskQueue()
+    const sm = new MainStateMachine(device, 'session-gpn-fail', taskQueue)
+
+    // Step 1: start → sends GPN for Device.DeviceInfo. (first unclassified path)
+    const step1 = await sm.start()
+    expect(step1).toContain('GetParameterNames')
+    expect(sm.getCurrentStateName()).toBe('discovering-parameters')
+
+    // Step 2: GPN Fault → mark unsupported + catalog classify + persist
+    const step2 = await sm.handleResponse(false, {
+      FaultCode: 9003,
+      FaultString: 'Method not supported',
+    })
+
+    // Verify: reclassifyDeviceFromCatalog was called
+    expect(vi.mocked(reclassifyDeviceFromCatalog)).toHaveBeenCalledWith(device)
+
+    // Verify: DeviceModel.createOrUpdate was called to persist the classification
+    expect(vi.mocked(DeviceModel.createOrUpdate)).toHaveBeenCalledWith(
+      expect.objectContaining({
+        gpnStatus: 'unsupported',
+        gpnCircuitBreaker: expect.objectContaining({ failureCount: 1 }),
+      })
+    )
+
+    // Verify: device is marked as unsupported
+    expect(device.gpnStatus).toBe('unsupported')
+    expect(device.gpnCircuitBreaker.failureCount).toBe(1)
+
+    // Verify: transitioned to critical-reads (sends GPV)
+    expect(step2).toContain('GetParameterValues')
+    expect(sm.getCurrentStateName()).toBe('critical-reads')
+  })
+
+  it('subsequent session with same params skips GPN (all classified)', async () => {
+    // Simulate device loaded from DB after first session (already classified)
+    const device = new Device(new DeviceId('Sagemcom', 'F8B7FF', 'Livebox 4', 'LB4-TEST-001'))
+    device.setDataModel('tr-181')
+    device.setGpnStatus('unsupported')
+
+    // After catalog classification, PeriodicInformInterval is a parameter (writable)
+    device.setParameter(new DeviceParameter(
+      'Device.ManagementServer.PeriodicInformInterval', '300', ParameterType.UNSIGNED_INT
+    ))
+    // Read-only params are properties
+    device.setProperty(new DeviceProperty('Device.DeviceInfo.HardwareVersion', 'v3.0', ParameterType.STRING))
+    device.setProperty(new DeviceProperty('Device.DeviceInfo.SoftwareVersion', 'SR50-5.0.0', ParameterType.STRING))
+    device.setProperty(new DeviceProperty('Device.ManagementServer.ConnectionRequestURL', 'http://cpe:7547/', ParameterType.STRING))
+
+    // Inform arrives with same params (all already classified)
+    const informParams = [
+      { Name: 'Device.DeviceInfo.HardwareVersion', Value: { _: 'v3.0' } },
+      { Name: 'Device.DeviceInfo.SoftwareVersion', Value: { _: 'SR50-5.0.0' } },
+      { Name: 'Device.ManagementServer.ConnectionRequestURL', Value: { _: 'http://cpe:7547/' } },
+      { Name: 'Device.ManagementServer.PeriodicInformInterval', Value: { _: '300' } },
+    ]
+    device.updateFromValues(informParams)
+    device.setTmpParamValues(informParams)
+
+    const taskQueue = new CWMPTaskQueue()
+    const sm = new MainStateMachine(device, 'session-2', taskQueue)
+
+    // Start → all params classified → skip GPN → directly to critical-reads (GPV)
+    const step1 = await sm.start()
+    expect(step1).toContain('GetParameterValues')
+    expect(step1).not.toContain('GetParameterNames')
+    expect(sm.getCurrentStateName()).toBe('critical-reads')
+
+    // reclassifyDeviceFromCatalog should NOT have been called
+    expect(vi.mocked(reclassifyDeviceFromCatalog)).not.toHaveBeenCalled()
+  })
+
+  it('session with NEW param in Inform (not yet in properties) triggers catalog classification', async () => {
+    // Device already classified from previous session
+    const device = new Device(new DeviceId('Sagemcom', 'F8B7FF', 'Livebox 4', 'LB4-TEST-001'))
+    device.setDataModel('tr-181')
+    device.setGpnStatus('unsupported')
+    device.setGpnCircuitBreaker({ failureCount: 1, lastFailureDate: new Date(), state: 'closed', cooldownUntil: null })
+
+    // Existing classified params
+    device.setParameter(new DeviceParameter('Device.ManagementServer.PeriodicInformInterval', '300', ParameterType.UNSIGNED_INT))
+    device.setProperty(new DeviceProperty('Device.DeviceInfo.HardwareVersion', 'v3.0', ParameterType.STRING))
+    device.setProperty(new DeviceProperty('Device.ManagementServer.ConnectionRequestURL', 'http://cpe:7547/', ParameterType.STRING))
+
+    // New Inform arrives with a NEW param that is NOT in _parameters/_properties
+    // (simulating a param that wasn't in the previous Inform and wasn't stored by updateFromValues)
+    const informParams = [
+      { Name: 'Device.DeviceInfo.HardwareVersion', Value: { _: 'v3.0' } },
+      { Name: 'Device.ManagementServer.ConnectionRequestURL', Value: { _: 'http://cpe:7547/' } },
+      { Name: 'Device.ManagementServer.PeriodicInformInterval', Value: { _: '300' } },
+      { Name: 'Device.WANDevice.1.ExternalIPAddress', Value: { _: '192.168.1.1' } }, // NEW - not in device yet
+    ]
+    // Only set tmpParamValues WITHOUT updateFromValues for the new param
+    device.setTmpParamValues(informParams)
+
+    const taskQueue = new CWMPTaskQueue()
+    const sm = new MainStateMachine(device, 'session-new-param', taskQueue)
+
+    // Start → detects 1 unclassified param (WANDevice not in _parameters/_properties)
+    // GPN unsupported → catalog classify
+    const step1 = await sm.start()
+
+    // Should have called catalog to classify the new param
+    expect(vi.mocked(reclassifyDeviceFromCatalog)).toHaveBeenCalledWith(device)
+
+    // Should go to critical-reads (GPV)
+    expect(step1).toContain('GetParameterValues')
+    expect(sm.getCurrentStateName()).toBe('critical-reads')
+  })
+})
+