Keep snapshot polling independent of backup scans

Refs #1437

internal/monitoring/monitor.go

@@ -7536,17 +7536,7 @@ func (m *Monitor) pollPVEInstance(ctx context.Context, instanceName string, clie
 							parentCtx = context.Background()
 						}
 
-						backupCtx, cancel := context.WithTimeout(parentCtx, timeout)
-						defer cancel()
-
-						// Poll backup tasks
-						m.pollBackupTasks(backupCtx, inst, pveClient)
-
-						// Poll storage backups - pass nodes to avoid duplicate API calls
-						m.pollStorageBackupsWithNodes(backupCtx, inst, pveClient, nodes, nodeEffectiveStatus)
-
-						// Poll guest snapshots
-						m.pollGuestSnapshots(backupCtx, inst, pveClient)
+						m.pollPVEBackupsAndSnapshots(parentCtx, inst, pveClient, nodes, nodeEffectiveStatus, timeout)
 
 						duration := time.Since(startTime)
 						log.Info().
@@ -11084,6 +11074,34 @@ func (m *Monitor) calculateBackupOperationTimeout(instanceName string) time.Dura
 	return timeout
 }
 
+func (m *Monitor) pollPVEBackupsAndSnapshots(parentCtx context.Context, instanceName string, client PVEClientInterface, nodes []proxmox.Node, nodeEffectiveStatus map[string]string, timeout time.Duration) {
+	if parentCtx == nil {
+		parentCtx = context.Background()
+	}
+
+	backupCtx, cancel := context.WithTimeout(parentCtx, timeout)
+
+	// Poll backup tasks
+	m.pollBackupTasks(backupCtx, instanceName, client)
+
+	// Poll storage backups - pass nodes to avoid duplicate API calls
+	m.pollStorageBackupsWithNodes(backupCtx, instanceName, client, nodes, nodeEffectiveStatus)
+
+	backupErr := backupCtx.Err()
+	cancel()
+
+	if backupErr != nil && parentCtx.Err() == nil {
+		log.Warn().
+			Str("instance", instanceName).
+			Err(backupErr).
+			Msg("Backup storage polling budget was exhausted before guest snapshot polling; continuing snapshots with their own bounded poll budget")
+	}
+
+	// Snapshots are independent backup inventory. Let pollGuestSnapshots establish
+	// its own bounded budget so a slow storage scan cannot starve snapshot discovery.
+	m.pollGuestSnapshots(parentCtx, instanceName, client)
+}
+
 // pollGuestSnapshots polls snapshots for all VMs and containers
 func (m *Monitor) pollGuestSnapshots(ctx context.Context, instanceName string, client PVEClientInterface) {
 	log.Debug().Str("instance", instanceName).Msg("Polling guest snapshots")

internal/monitoring/monitor_snapshot_test.go

@@ -31,6 +31,42 @@ func (m *mockPVEClientSnapshots) GetVMMemAvailableFromAgent(ctx context.Context,
 	return 0, fmt.Errorf("not implemented")
 }
 
+type backupStorageTimeoutSnapshotClient struct {
+	mockPVEClientExtra
+	snapshots     []proxmox.Snapshot
+	snapshotCalls int
+	storageCalls  int
+}
+
+func (m *backupStorageTimeoutSnapshotClient) GetBackupTasks(ctx context.Context) ([]proxmox.Task, error) {
+	return nil, nil
+}
+
+func (m *backupStorageTimeoutSnapshotClient) GetStorage(ctx context.Context, node string) ([]proxmox.Storage, error) {
+	m.storageCalls++
+	if m.storageCalls > 1 {
+		return nil, nil
+	}
+
+	<-ctx.Done()
+	return nil, fmt.Errorf("storage scan exceeded backup inventory budget")
+}
+
+func (m *backupStorageTimeoutSnapshotClient) GetVMSnapshots(ctx context.Context, node string, vmid int) ([]proxmox.Snapshot, error) {
+	m.snapshotCalls++
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return m.snapshots, nil
+}
+
+func (m *backupStorageTimeoutSnapshotClient) GetContainerSnapshots(ctx context.Context, node string, vmid int) ([]proxmox.Snapshot, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return nil, nil
+}
+
 func TestMonitor_PollGuestSnapshots_Coverage(t *testing.T) {
 	m := &Monitor{
 		state: models.NewState(),
@@ -144,6 +180,48 @@ func TestMonitor_PollGuestSnapshots_PreservesPreviousOnPerVMError(t *testing.T)
 	}
 }
 
+func TestMonitor_PollPVEBackupsAndSnapshots_DoesNotStarveSnapshotsAfterStorageTimeout(t *testing.T) {
+	m := &Monitor{state: models.NewState()}
+
+	m.state.UpdateVMsForInstance("pve1", []models.VM{{
+		ID:       "qemu/100",
+		VMID:     100,
+		Node:     "node1",
+		Instance: "pve1",
+		Name:     "vm100",
+		Template: false,
+	}})
+
+	client := &backupStorageTimeoutSnapshotClient{
+		snapshots: []proxmox.Snapshot{{
+			Name:        "snap_after_storage_timeout",
+			SnapTime:    4000,
+			Description: "created while storage scan was slow",
+		}},
+	}
+
+	m.pollPVEBackupsAndSnapshots(
+		context.Background(),
+		"pve1",
+		client,
+		[]proxmox.Node{{Node: "node1", Status: "online"}},
+		map[string]string{"node1": "online"},
+		time.Millisecond,
+	)
+
+	if client.snapshotCalls == 0 {
+		t.Fatal("expected guest snapshot polling to run even after storage backup polling exhausted its budget")
+	}
+
+	got := m.state.GetSnapshot().PVEBackups.GuestSnapshots
+	if len(got) != 1 {
+		t.Fatalf("expected one guest snapshot after storage timeout, got %#v", got)
+	}
+	if got[0].Name != "snap_after_storage_timeout" {
+		t.Fatalf("expected fresh snapshot after storage timeout, got %#v", got[0])
+	}
+}
+
 func keys[K comparable, V any](m map[K]V) []K {
 	out := make([]K, 0, len(m))
 	for k := range m {