feat(monitor): auto-prune expired maintenance windows

Background goroutine runs every 15 minutes, deletes maintenance windows
that expired beyond the retention period (default 7 days). Configurable
via UPTOP_MAINT_RETENTION env var (Go duration format).

Closes #72

cmd/uptop/main.go

@@ -379,6 +379,11 @@ func runServe(args []string) {
 	if aggStrategy != "" {
 		eng.SetAggStrategy(monitor.AggregationStrategy(aggStrategy))
 	}
+	if v := os.Getenv("UPTOP_MAINT_RETENTION"); v != "" {
+		if d, err := time.ParseDuration(v); err == nil && d > 0 {
+			eng.SetMaintRetention(d)
+		}
+	}
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()

internal/cluster/cluster_test.go

@@ -65,14 +65,15 @@ func (m *mockStore) GetActiveMaintenanceWindows() ([]models.MaintenanceWindow, e
 func (m *mockStore) GetAllMaintenanceWindows(int) ([]models.MaintenanceWindow, error) {
 	return nil, nil
 }
-func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error    { return nil }
+func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error         { return nil }
-func (m *mockStore) EndMaintenanceWindow(int) error                         { return nil }
+func (m *mockStore) EndMaintenanceWindow(int) error                              { return nil }
-func (m *mockStore) DeleteMaintenanceWindow(int) error                      { return nil }
+func (m *mockStore) DeleteMaintenanceWindow(int) error                           { return nil }
-func (m *mockStore) IsMonitorInMaintenance(int) (bool, error)               { return false, nil }
+func (m *mockStore) PruneExpiredMaintenanceWindows(time.Duration) (int64, error) { return 0, nil }
-func (m *mockStore) GetPreference(string) (string, error)                   { return "", nil }
+func (m *mockStore) IsMonitorInMaintenance(int) (bool, error)                    { return false, nil }
-func (m *mockStore) SetPreference(string, string) error                     { return nil }
+func (m *mockStore) GetPreference(string) (string, error)                        { return "", nil }
-func (m *mockStore) SaveStateChange(int, string, string, string) error      { return nil }
+func (m *mockStore) SetPreference(string, string) error                          { return nil }
-func (m *mockStore) GetStateChanges(int, int) ([]models.StateChange, error) { return nil, nil }
+func (m *mockStore) SaveStateChange(int, string, string, string) error           { return nil }
+func (m *mockStore) GetStateChanges(int, int) ([]models.StateChange, error)      { return nil, nil }
 func (m *mockStore) GetStateChangesSince(int, time.Time) ([]models.StateChange, error) {
 	return nil, nil
 }

internal/metrics/prometheus_test.go

@@ -63,14 +63,15 @@ func (m *mockStore) GetActiveMaintenanceWindows() ([]models.MaintenanceWindow, e
 func (m *mockStore) GetAllMaintenanceWindows(int) ([]models.MaintenanceWindow, error) {
 	return nil, nil
 }
-func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error    { return nil }
+func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error         { return nil }
-func (m *mockStore) EndMaintenanceWindow(int) error                         { return nil }
+func (m *mockStore) EndMaintenanceWindow(int) error                              { return nil }
-func (m *mockStore) DeleteMaintenanceWindow(int) error                      { return nil }
+func (m *mockStore) DeleteMaintenanceWindow(int) error                           { return nil }
-func (m *mockStore) IsMonitorInMaintenance(int) (bool, error)               { return false, nil }
+func (m *mockStore) PruneExpiredMaintenanceWindows(time.Duration) (int64, error) { return 0, nil }
-func (m *mockStore) GetPreference(string) (string, error)                   { return "", nil }
+func (m *mockStore) IsMonitorInMaintenance(int) (bool, error)                    { return false, nil }
-func (m *mockStore) SetPreference(string, string) error                     { return nil }
+func (m *mockStore) GetPreference(string) (string, error)                        { return "", nil }
-func (m *mockStore) SaveStateChange(int, string, string, string) error      { return nil }
+func (m *mockStore) SetPreference(string, string) error                          { return nil }
-func (m *mockStore) GetStateChanges(int, int) ([]models.StateChange, error) { return nil, nil }
+func (m *mockStore) SaveStateChange(int, string, string, string) error           { return nil }
+func (m *mockStore) GetStateChanges(int, int) ([]models.StateChange, error)      { return nil, nil }
 func (m *mockStore) GetStateChangesSince(int, time.Time) ([]models.StateChange, error) {
 	return nil, nil
 }

internal/monitor/monitor.go

@@ -17,10 +17,12 @@ import (
 )
 
 const (
-	maxLogEntries    = 100
+	maxLogEntries         = 100
-	pollInterval     = 5 * time.Second
+	pollInterval          = 5 * time.Second
-	minCheckInterval = 5
+	minCheckInterval      = 5
-	minPushGrace     = 60 * time.Second
+	minPushGrace          = 60 * time.Second
+	maintPruneInterval    = 15 * time.Minute
+	defaultMaintRetention = 7 * 24 * time.Hour
 )
 
 type AlertHealth struct {
@@ -59,6 +61,7 @@ type Engine struct {
 	db                  store.Store
 	insecureSkipVerify  bool
 	allowPrivateTargets bool
+	maintRetention      time.Duration
 	strictClient        *http.Client
 	insecureClient      *http.Client
 }
@@ -83,6 +86,7 @@ func newEngine(s store.Store, allowPrivateTargets bool) *Engine {
 		aggStrategy:         AggAnyDown,
 		isActive:            true,
 		allowPrivateTargets: allowPrivateTargets,
+		maintRetention:      defaultMaintRetention,
 		db:                  s,
 		strictClient: &http.Client{
 			Transport: &http.Transport{
@@ -103,6 +107,10 @@ func (e *Engine) SetInsecureSkipVerify(skip bool) {
 	e.insecureSkipVerify = skip
 }
 
+func (e *Engine) SetMaintRetention(d time.Duration) {
+	e.maintRetention = d
+}
+
 var ansiRe = regexp.MustCompile(`\x1b\[[0-9;]*[a-zA-Z]`)
 
 func sanitizeLog(s string) string {
@@ -337,6 +345,35 @@ func (e *Engine) Start(ctx context.Context) {
 			}
 		}
 	}()
+
+	go e.maintenancePruner(ctx)
+}
+
+func (e *Engine) maintenancePruner(ctx context.Context) {
+	ticker := time.NewTicker(maintPruneInterval)
+	defer ticker.Stop()
+
+	e.pruneMaintenanceWindows()
+
+	for {
+		select {
+		case <-ticker.C:
+			e.pruneMaintenanceWindows()
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+func (e *Engine) pruneMaintenanceWindows() {
+	pruned, err := e.db.PruneExpiredMaintenanceWindows(e.maintRetention)
+	if err != nil {
+		e.AddLog(fmt.Sprintf("Maintenance prune error: %v", err))
+		return
+	}
+	if pruned > 0 {
+		e.AddLog(fmt.Sprintf("Pruned %d expired maintenance window(s)", pruned))
+	}
 }
 
 func (e *Engine) UpdateSiteConfig(site models.Site) {

internal/monitor/monitor_test.go

@@ -73,13 +73,14 @@ func (m *mockStore) GetActiveMaintenanceWindows() ([]models.MaintenanceWindow, e
 func (m *mockStore) GetAllMaintenanceWindows(int) ([]models.MaintenanceWindow, error) {
 	return nil, nil
 }
-func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error    { return nil }
+func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error         { return nil }
-func (m *mockStore) EndMaintenanceWindow(int) error                         { return nil }
+func (m *mockStore) EndMaintenanceWindow(int) error                              { return nil }
-func (m *mockStore) DeleteMaintenanceWindow(int) error                      { return nil }
+func (m *mockStore) DeleteMaintenanceWindow(int) error                           { return nil }
-func (m *mockStore) GetPreference(string) (string, error)                   { return "", nil }
+func (m *mockStore) PruneExpiredMaintenanceWindows(time.Duration) (int64, error) { return 0, nil }
-func (m *mockStore) SetPreference(string, string) error                     { return nil }
+func (m *mockStore) GetPreference(string) (string, error)                        { return "", nil }
-func (m *mockStore) SaveStateChange(int, string, string, string) error      { return nil }
+func (m *mockStore) SetPreference(string, string) error                          { return nil }
-func (m *mockStore) GetStateChanges(int, int) ([]models.StateChange, error) { return nil, nil }
+func (m *mockStore) SaveStateChange(int, string, string, string) error           { return nil }
+func (m *mockStore) GetStateChanges(int, int) ([]models.StateChange, error)      { return nil, nil }
 func (m *mockStore) GetStateChangesSince(int, time.Time) ([]models.StateChange, error) {
 	return nil, nil
 }

internal/server/server_test.go

@@ -74,14 +74,15 @@ func (m *mockStore) LoadLogs(int) ([]string, error)                 { return nil
 func (m *mockStore) GetAllMaintenanceWindows(int) ([]models.MaintenanceWindow, error) {
 	return nil, nil
 }
-func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error    { return nil }
+func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error         { return nil }
-func (m *mockStore) EndMaintenanceWindow(int) error                         { return nil }
+func (m *mockStore) EndMaintenanceWindow(int) error                              { return nil }
-func (m *mockStore) DeleteMaintenanceWindow(int) error                      { return nil }
+func (m *mockStore) DeleteMaintenanceWindow(int) error                           { return nil }
-func (m *mockStore) IsMonitorInMaintenance(int) (bool, error)               { return false, nil }
+func (m *mockStore) PruneExpiredMaintenanceWindows(time.Duration) (int64, error) { return 0, nil }
-func (m *mockStore) GetPreference(string) (string, error)                   { return "", nil }
+func (m *mockStore) IsMonitorInMaintenance(int) (bool, error)                    { return false, nil }
-func (m *mockStore) SetPreference(string, string) error                     { return nil }
+func (m *mockStore) GetPreference(string) (string, error)                        { return "", nil }
-func (m *mockStore) SaveStateChange(int, string, string, string) error      { return nil }
+func (m *mockStore) SetPreference(string, string) error                          { return nil }
-func (m *mockStore) GetStateChanges(int, int) ([]models.StateChange, error) { return nil, nil }
+func (m *mockStore) SaveStateChange(int, string, string, string) error           { return nil }
+func (m *mockStore) GetStateChanges(int, int) ([]models.StateChange, error)      { return nil, nil }
 func (m *mockStore) GetStateChangesSince(int, time.Time) ([]models.StateChange, error) {
 	return nil, nil
 }

internal/store/sqlstore.go

@@ -619,6 +619,18 @@ func (s *SQLStore) DeleteMaintenanceWindow(id int) error {
 	return nil
 }
 
+func (s *SQLStore) PruneExpiredMaintenanceWindows(retention time.Duration) (int64, error) {
+	cutoff := time.Now().Add(-retention)
+	result, err := s.db.Exec(
+		s.q("DELETE FROM maintenance_windows WHERE end_time IS NOT NULL AND end_time < ?"),
+		cutoff,
+	)
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}
+
 func (s *SQLStore) IsMonitorInMaintenance(monitorID int) (bool, error) {
 	var count int
 	err := s.db.QueryRow(s.q(`SELECT COUNT(*) FROM maintenance_windows

internal/store/sqlstore_test.go

@@ -315,3 +315,65 @@ func TestDeleteSiteCascade(t *testing.T) {
 		}
 	}
 }
+
+func TestPruneExpiredMaintenanceWindows(t *testing.T) {
+	s := newTestStore(t)
+
+	now := time.Now()
+
+	// Expired 10 days ago — should be pruned with 7d retention.
+	old := models.MaintenanceWindow{
+		MonitorID: 0,
+		Title:     "Old Window",
+		Type:      "maintenance",
+		StartTime: now.Add(-11 * 24 * time.Hour),
+		EndTime:   now.Add(-10 * 24 * time.Hour),
+	}
+	if err := s.AddMaintenanceWindow(old); err != nil {
+		t.Fatalf("AddMaintenanceWindow (old): %v", err)
+	}
+
+	// Expired 1 day ago — within 7d retention, should survive.
+	recent := models.MaintenanceWindow{
+		MonitorID: 0,
+		Title:     "Recent Window",
+		Type:      "maintenance",
+		StartTime: now.Add(-2 * 24 * time.Hour),
+		EndTime:   now.Add(-1 * 24 * time.Hour),
+	}
+	if err := s.AddMaintenanceWindow(recent); err != nil {
+		t.Fatalf("AddMaintenanceWindow (recent): %v", err)
+	}
+
+	// Ongoing — no end time, should survive.
+	ongoing := models.MaintenanceWindow{
+		MonitorID: 0,
+		Title:     "Ongoing Window",
+		Type:      "maintenance",
+		StartTime: now.Add(-1 * time.Hour),
+	}
+	if err := s.AddMaintenanceWindow(ongoing); err != nil {
+		t.Fatalf("AddMaintenanceWindow (ongoing): %v", err)
+	}
+
+	pruned, err := s.PruneExpiredMaintenanceWindows(7 * 24 * time.Hour)
+	if err != nil {
+		t.Fatalf("PruneExpiredMaintenanceWindows: %v", err)
+	}
+	if pruned != 1 {
+		t.Errorf("expected 1 pruned, got %d", pruned)
+	}
+
+	all, err := s.GetAllMaintenanceWindows(100)
+	if err != nil {
+		t.Fatalf("GetAllMaintenanceWindows: %v", err)
+	}
+	if len(all) != 2 {
+		t.Fatalf("expected 2 remaining windows, got %d", len(all))
+	}
+	for _, w := range all {
+		if w.Title == "Old Window" {
+			t.Error("old window should have been pruned")
+		}
+	}
+}

internal/store/store.go

@@ -66,6 +66,7 @@ type Store interface {
 	AddMaintenanceWindow(mw models.MaintenanceWindow) error
 	EndMaintenanceWindow(id int) error
 	DeleteMaintenanceWindow(id int) error
+	PruneExpiredMaintenanceWindows(retention time.Duration) (int64, error)
 	IsMonitorInMaintenance(monitorID int) (bool, error)
 
 	// Preferences