diff --git a/cmd/goupkeep/main.go b/cmd/goupkeep/main.go
index 0ae9cb0..26c01b3 100644
--- a/cmd/goupkeep/main.go
+++ b/cmd/goupkeep/main.go
@@ -112,6 +112,7 @@ func main() {
 		fmt.Printf("Imported %d monitors and %d alerts from Uptime Kuma v%s\n", len(backup.Sites), len(backup.Alerts), kb.Version)
 	}
 
+	monitor.InitHistoryFromStore()
 	monitor.StartEngine()
 
 	server.Start(server.ServerConfig{
diff --git a/internal/models/models.go b/internal/models/models.go
index 467fd33..cdf4c68 100644
--- a/internal/models/models.go
+++ b/internal/models/models.go
@@ -50,7 +50,13 @@ type User struct {
 	Role      string
 }
 
-// Phase 5: Backup Structure
+type CheckRecord struct {
+	SiteID    int
+	LatencyNs int64
+	IsUp      bool
+	CheckedAt time.Time
+}
+
 type Backup struct {
 	Sites  []Site        `json:"sites"`
 	Alerts []AlertConfig `json:"alerts"`
diff --git a/internal/monitor/history.go b/internal/monitor/history.go
index c6fbcbe..8642255 100644
--- a/internal/monitor/history.go
+++ b/internal/monitor/history.go
@@ -1,6 +1,7 @@
 package monitor
 
 import (
+	"go-upkeep/internal/store"
 	"sync"
 	"time"
 )
@@ -19,6 +20,31 @@ var (
 	historyMu sync.RWMutex
 )
 
+func InitHistoryFromStore() {
+	s := store.Get()
+	if s == nil {
+		return
+	}
+	all := s.LoadAllHistory(maxHistoryLen)
+	historyMu.Lock()
+	defer historyMu.Unlock()
+	for siteID, records := range all {
+		h := &SiteHistory{}
+		for _, r := range records {
+			h.TotalChecks++
+			if r.IsUp {
+				h.UpChecks++
+			}
+			h.Latencies = append(h.Latencies, time.Duration(r.LatencyNs))
+			h.Statuses = append(h.Statuses, r.IsUp)
+		}
+		histories[siteID] = h
+	}
+	if len(all) > 0 {
+		AddLog("Loaded check history from database")
+	}
+}
+
 func RecordCheck(siteID int, latency time.Duration, isUp bool) {
 	historyMu.Lock()
 	defer historyMu.Unlock()
@@ -43,6 +69,10 @@ func RecordCheck(siteID int, latency time.Duration, isUp bool) {
 	if len(h.Statuses) > maxHistoryLen {
 		h.Statuses = h.Statuses[len(h.Statuses)-maxHistoryLen:]
 	}
+
+	if s := store.Get(); s != nil {
+		go s.SaveCheck(siteID, latency.Nanoseconds(), isUp)
+	}
 }
 
 func GetHistory(siteID int) (SiteHistory, bool) {
diff --git a/internal/monitor/monitor.go b/internal/monitor/monitor.go
index 76a55bb..1bb02fe 100644
--- a/internal/monitor/monitor.go
+++ b/internal/monitor/monitor.go
@@ -243,7 +243,7 @@ func checkByID(id int) {
 	case "dns":
 		checkDNS(site)
 	case "group":
-		// groups don't perform checks
+		checkGroup(site)
 	}
 }
 
@@ -437,6 +437,44 @@ func checkPort(site models.Site) {
 	handleStatusChange(updatedSite, "UP", 0, latency)
 }
 
+func checkGroup(site models.Site) {
+	Mutex.RLock()
+	status := "UP"
+	hasChildren := false
+	allPaused := true
+	for _, child := range LiveState {
+		if child.ParentID != site.ID || child.Type == "group" {
+			continue
+		}
+		hasChildren = true
+		if !child.Paused {
+			allPaused = false
+		}
+		if child.Paused {
+			continue
+		}
+		if child.Status == "DOWN" || child.Status == "SSL EXP" {
+			status = "DOWN"
+		} else if child.Status == "PENDING" && status != "DOWN" {
+			status = "PENDING"
+		}
+	}
+	Mutex.RUnlock()
+
+	if !hasChildren {
+		status = "PENDING"
+	}
+
+	Mutex.Lock()
+	s := LiveState[site.ID]
+	s.Status = status
+	if hasChildren && allPaused {
+		s.Paused = true
+	}
+	LiveState[site.ID] = s
+	Mutex.Unlock()
+}
+
 func checkDNS(site models.Site) {
 	host := site.Hostname
 	if host == "" {
diff --git a/internal/server/server.go b/internal/server/server.go
index 89460ed..f814cc3 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -185,6 +185,12 @@ func renderStatusPage(w http.ResponseWriter, title string) {
 		<script>
 			var lastUpdate = null;
 
+			function esc(s) {
+				var d = document.createElement('div');
+				d.appendChild(document.createTextNode(s));
+				return d.innerHTML;
+			}
+
 			function cssClass(status) {
 				return status.replace(/\s+/g, '-');
 			}
@@ -234,13 +240,13 @@ func renderStatusPage(w http.ResponseWriter, title string) {
 					var s = sites[i];
 					var st = s.Paused ? 'PAUSED' : s.Status;
 					var cls = cssClass(st);
-					var meta = s.Type + ' | ' + (s.Type === 'http' ? s.URL : 'Heartbeat Monitor');
+					var meta = esc(s.Type) + ' | ' + (s.Type === 'http' ? esc(s.URL) : 'Heartbeat Monitor');
 					var lc = s.LastCheck ? new Date(s.LastCheck).toLocaleTimeString('en-GB', {hour12: false}) : '—';
 					html += '<div class="card"><div class="info">' +
-						'<div class="name">' + s.Name + '</div>' +
+						'<div class="name">' + esc(s.Name) + '</div>' +
 						'<div class="meta">' + meta + '</div>' +
 						'<div class="meta" style="margin-top:4px;">Last Check: ' + lc + '</div>' +
-						'</div><div class="status ' + cls + '">' + st + '</div></div>';
+						'</div><div class="status ' + cls + '">' + esc(st) + '</div></div>';
 				}
 				c.innerHTML = html;
 			}
diff --git a/internal/store/postgres.go b/internal/store/postgres.go
index ea7f58b..c5201d0 100644
--- a/internal/store/postgres.go
+++ b/internal/store/postgres.go
@@ -56,6 +56,13 @@ func (p *PostgresStore) Init() error {
 			public_key TEXT NOT NULL,
 			role TEXT DEFAULT 'user'
 		);`,
+		`CREATE TABLE IF NOT EXISTS check_history (
+			id SERIAL PRIMARY KEY,
+			site_id INTEGER NOT NULL,
+			latency_ns BIGINT,
+			is_up BOOLEAN,
+			checked_at TIMESTAMP DEFAULT NOW()
+		);`,
 	}
 	for _, q := range queries {
 		if _, err := p.db.Exec(q); err != nil {
@@ -63,6 +70,8 @@ func (p *PostgresStore) Init() error {
 		}
 	}
 
+	p.db.Exec("CREATE INDEX IF NOT EXISTS idx_check_history_site ON check_history(site_id, checked_at DESC)")
+
 	migrations := []string{
 		"ALTER TABLE sites ADD COLUMN IF NOT EXISTS hostname TEXT DEFAULT ''",
 		"ALTER TABLE sites ADD COLUMN IF NOT EXISTS port INTEGER DEFAULT 0",
@@ -184,7 +193,38 @@ func (p *PostgresStore) DeleteUser(id int) error {
 	return err
 }
 
-// --- PHASE 5 ---
+func (p *PostgresStore) SaveCheck(siteID int, latencyNs int64, isUp bool) {
+	p.db.Exec("INSERT INTO check_history (site_id, latency_ns, is_up) VALUES ($1, $2, $3)", siteID, latencyNs, isUp)
+	p.db.Exec(`DELETE FROM check_history WHERE site_id = $1 AND id NOT IN (
+		SELECT id FROM check_history WHERE site_id = $1 ORDER BY checked_at DESC LIMIT 1000
+	)`, siteID)
+}
+
+func (p *PostgresStore) LoadAllHistory(limit int) map[int][]models.CheckRecord {
+	result := make(map[int][]models.CheckRecord)
+	rows, err := p.db.Query(`
+		SELECT site_id, latency_ns, is_up FROM (
+			SELECT site_id, latency_ns, is_up,
+				ROW_NUMBER() OVER (PARTITION BY site_id ORDER BY checked_at DESC) AS rn
+			FROM check_history
+		) sub WHERE rn <= $1`, limit)
+	if err != nil {
+		return result
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var r models.CheckRecord
+		rows.Scan(&r.SiteID, &r.LatencyNs, &r.IsUp)
+		result[r.SiteID] = append(result[r.SiteID], r)
+	}
+	for id, records := range result {
+		for i, j := 0, len(records)-1; i < j; i, j = i+1, j-1 {
+			records[i], records[j] = records[j], records[i]
+		}
+		result[id] = records
+	}
+	return result
+}
 
 func (p *PostgresStore) ExportData() models.Backup {
 	return models.Backup{
diff --git a/internal/store/sqlite.go b/internal/store/sqlite.go
index a0331cd..e83d96e 100644
--- a/internal/store/sqlite.go
+++ b/internal/store/sqlite.go
@@ -57,7 +57,15 @@ func (s *SQLiteStore) Init() error {
 		username TEXT NOT NULL,
 		public_key TEXT NOT NULL,
 		role TEXT DEFAULT 'user'
-	);`
+	);
+	CREATE TABLE IF NOT EXISTS check_history (
+		id INTEGER PRIMARY KEY AUTOINCREMENT,
+		site_id INTEGER NOT NULL,
+		latency_ns INTEGER,
+		is_up BOOLEAN,
+		checked_at DATETIME DEFAULT CURRENT_TIMESTAMP
+	);
+	CREATE INDEX IF NOT EXISTS idx_check_history_site ON check_history(site_id, checked_at DESC);`
 	_, err = s.db.Exec(createTables)
 	if err != nil {
 		return err
@@ -204,7 +212,38 @@ func (s *SQLiteStore) DeleteUser(id int) error {
 	return err
 }
 
-// --- PHASE 5 ---
+func (s *SQLiteStore) SaveCheck(siteID int, latencyNs int64, isUp bool) {
+	s.db.Exec("INSERT INTO check_history (site_id, latency_ns, is_up) VALUES (?, ?, ?)", siteID, latencyNs, isUp)
+	s.db.Exec(`DELETE FROM check_history WHERE site_id = ? AND id NOT IN (
+		SELECT id FROM check_history WHERE site_id = ? ORDER BY checked_at DESC LIMIT 1000
+	)`, siteID, siteID)
+}
+
+func (s *SQLiteStore) LoadAllHistory(limit int) map[int][]models.CheckRecord {
+	result := make(map[int][]models.CheckRecord)
+	rows, err := s.db.Query(`
+		SELECT site_id, latency_ns, is_up FROM (
+			SELECT site_id, latency_ns, is_up,
+				ROW_NUMBER() OVER (PARTITION BY site_id ORDER BY checked_at DESC) AS rn
+			FROM check_history
+		) WHERE rn <= ?`, limit)
+	if err != nil {
+		return result
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var r models.CheckRecord
+		rows.Scan(&r.SiteID, &r.LatencyNs, &r.IsUp)
+		result[r.SiteID] = append(result[r.SiteID], r)
+	}
+	for id, records := range result {
+		for i, j := 0, len(records)-1; i < j; i, j = i+1, j-1 {
+			records[i], records[j] = records[j], records[i]
+		}
+		result[id] = records
+	}
+	return result
+}
 
 func (s *SQLiteStore) ExportData() models.Backup {
 	return models.Backup{
diff --git a/internal/store/store.go b/internal/store/store.go
index 85b47f6..af3cd71 100644
--- a/internal/store/store.go
+++ b/internal/store/store.go
@@ -27,7 +27,11 @@ type Store interface {
 	UpdateUser(id int, username, publicKey, role string) error
 	DeleteUser(id int) error
 
-	// Phase 5: Backup & Restore
+	// History
+	SaveCheck(siteID int, latencyNs int64, isUp bool)
+	LoadAllHistory(limit int) map[int][]models.CheckRecord
+
+	// Backup & Restore
 	ExportData() models.Backup
 	ImportData(data models.Backup) error
 }
diff --git a/internal/tui/tab_alerts.go b/internal/tui/tab_alerts.go
index 4aa9c54..8a0447b 100644
--- a/internal/tui/tab_alerts.go
+++ b/internal/tui/tab_alerts.go
@@ -108,7 +108,7 @@ func (m Model) viewAlertsTab() string {
 	for i := m.tableOffset; i < end; i++ {
 		alert := m.alerts[i]
 		rows = append(rows, []string{
-			fmt.Sprintf("%d", alert.ID),
+			fmt.Sprintf("%d", i+1),
 			m.zones.Mark(fmt.Sprintf("alert-%d", i), limitStr(alert.Name, 15)),
 			fmtAlertType(alert.Type),
 			fmtAlertConfig(struct {
@@ -127,7 +127,7 @@ func (m Model) viewAlertsTab() string {
 		Border(lipgloss.RoundedBorder()).
 		BorderStyle(alertBorderStyle).
 		Width(tableWidth).
-		Headers("ID", "NAME", "TYPE", "CONFIG").
+		Headers("#", "NAME", "TYPE", "CONFIG").
 		Rows(rows...).
 		StyleFunc(func(row, col int) lipgloss.Style {
 			if row == table.HeaderRow {
diff --git a/internal/tui/tab_sites.go b/internal/tui/tab_sites.go
index 8d7a6dc..3a590a0 100644
--- a/internal/tui/tab_sites.go
+++ b/internal/tui/tab_sites.go
@@ -34,6 +34,11 @@ var (
 
 	siteBorderStyle = lipgloss.NewStyle().
 			Foreground(lipgloss.Color("#444"))
+
+	siteGroupStyle = lipgloss.NewStyle().
+			Padding(0, 1).
+			Bold(true).
+			Foreground(lipgloss.Color("#7D56F4"))
 )
 
 type siteFormData struct {
@@ -50,6 +55,7 @@ type siteFormData struct {
 	Timeout     string
 	Description string
 	IgnoreTLS   bool
+	GroupID     string
 }
 
 func latencySparkline(latencies []time.Duration, width int) string {
@@ -222,10 +228,42 @@ func (m Model) viewSitesTab() string {
 	selectedVisual := m.cursor - m.tableOffset
 
 	var rows [][]string
+	var groupRows []int
 	for i := m.tableOffset; i < end; i++ {
 		site := m.sites[i]
-		hist, _ := monitor.GetHistory(site.ID)
 
+		if site.Type == "group" {
+			groupRows = append(groupRows, i-m.tableOffset)
+			arrow := "▾"
+			if m.collapsed[site.ID] {
+				arrow = "▸"
+			}
+			rows = append(rows, []string{
+				strconv.Itoa(i + 1),
+				m.zones.Mark(fmt.Sprintf("site-%d", i), arrow+" "+limitStr(site.Name, 11)),
+				"group",
+				fmtStatus(site.Status, site.Paused),
+				subtleStyle.Render("—"),
+				subtleStyle.Render("—"),
+				subtleStyle.Render(strings.Repeat("·", sparkWidth)),
+				subtleStyle.Render("-"),
+				subtleStyle.Render("—"),
+			})
+			continue
+		}
+
+		name := site.Name
+		if site.ParentID > 0 {
+			prefix := "├"
+			if i+1 >= len(m.sites) || m.sites[i+1].ParentID != site.ParentID {
+				prefix = "└"
+			}
+			name = prefix + " " + limitStr(name, 11)
+		} else {
+			name = limitStr(name, 13)
+		}
+
+		hist, _ := monitor.GetHistory(site.ID)
 		var spark string
 		if site.Type == "push" {
 			spark = heartbeatSparkline(hist.Statuses, sparkWidth)
@@ -234,8 +272,8 @@ func (m Model) viewSitesTab() string {
 		}
 
 		rows = append(rows, []string{
-			strconv.Itoa(site.ID),
-			m.zones.Mark(fmt.Sprintf("site-%d", i), limitStr(site.Name, 13)),
+			strconv.Itoa(i + 1),
+			m.zones.Mark(fmt.Sprintf("site-%d", i), name),
 			site.Type,
 			fmtStatus(site.Status, site.Paused),
 			fmtLatency(site.Latency),
@@ -246,6 +284,15 @@ func (m Model) viewSitesTab() string {
 		})
 	}
 
+	isGroupRow := func(row int) bool {
+		for _, g := range groupRows {
+			if g == row {
+				return true
+			}
+		}
+		return false
+	}
+
 	tableWidth := m.termWidth - 6
 	if tableWidth < 40 {
 		tableWidth = 40
@@ -255,7 +302,7 @@ func (m Model) viewSitesTab() string {
 		Border(lipgloss.RoundedBorder()).
 		BorderStyle(siteBorderStyle).
 		Width(tableWidth).
-		Headers("ID", "NAME", "TYPE", "STATUS", "LATENCY", "UPTIME", "HISTORY", "SSL", "RETRY").
+		Headers("#", "NAME", "TYPE", "STATUS", "LATENCY", "UPTIME", "HISTORY", "SSL", "RETRY").
 		Rows(rows...).
 		StyleFunc(func(row, col int) lipgloss.Style {
 			if row == table.HeaderRow {
@@ -264,6 +311,9 @@ func (m Model) viewSitesTab() string {
 			if row == selectedVisual {
 				return siteSelectedStyle
 			}
+			if isGroupRow(row) {
+				return siteGroupStyle
+			}
 			return siteCellStyle
 		})
 
@@ -278,6 +328,7 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 		Retries:   "0",
 		Timeout:   "5",
 		Port:      "0",
+		GroupID:   "0",
 	}
 
 	if m.editID > 0 {
@@ -296,6 +347,7 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 				m.siteFormData.Timeout = strconv.Itoa(site.Timeout)
 				m.siteFormData.Description = site.Description
 				m.siteFormData.IgnoreTLS = site.IgnoreTLS
+				m.siteFormData.GroupID = strconv.Itoa(site.ParentID)
 				break
 			}
 		}
@@ -311,6 +363,13 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 		}
 	}
 
+	groupOpts := []huh.Option[string]{huh.NewOption("None", "0")}
+	for _, s := range m.sites {
+		if s.Type == "group" && s.ID != m.editID {
+			groupOpts = append(groupOpts, huh.NewOption(s.Name, strconv.Itoa(s.ID)))
+		}
+	}
+
 	m.huhForm = huh.NewForm(
 		huh.NewGroup(
 			huh.NewInput().Title("Monitor Name").
@@ -331,12 +390,17 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 					huh.NewOption("DNS", "dns"),
 					huh.NewOption("Group", "group"),
 				).Value(&m.siteFormData.SiteType),
+			huh.NewSelect[string]().Title("Alert Channel").
+				Options(alertOpts...).
+				Value(&m.siteFormData.AlertID),
+		).Title("Monitor Settings"),
+		huh.NewGroup(
 			huh.NewInput().Title("URL").
 				Placeholder("https://example.com").
 				Description("Required for HTTP monitors").
 				Value(&m.siteFormData.URL).
 				Validate(func(s string) error {
-					if m.siteFormData.SiteType == "push" {
+					if m.siteFormData.SiteType == "push" || m.siteFormData.SiteType == "group" {
 						return nil
 					}
 					if s == "" {
@@ -356,12 +420,23 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 				}),
 			huh.NewInput().Title("Check Interval (seconds)").
 				Placeholder("60").
-				Value(&m.siteFormData.Interval),
-			huh.NewSelect[string]().Title("Alert Channel").
-				Options(alertOpts...).
-				Value(&m.siteFormData.AlertID),
-		).Title("Monitor Settings"),
-		huh.NewGroup(
+				Value(&m.siteFormData.Interval).
+				Validate(func(s string) error {
+					if m.siteFormData.SiteType == "group" {
+						return nil
+					}
+					v, err := strconv.Atoi(s)
+					if err != nil {
+						return fmt.Errorf("must be a number")
+					}
+					if v < 5 {
+						return fmt.Errorf("minimum interval is 5 seconds")
+					}
+					return nil
+				}),
+			huh.NewSelect[string]().Title("Parent Group").
+				Options(groupOpts...).
+				Value(&m.siteFormData.GroupID),
 			huh.NewInput().Title("Hostname / IP").
 				Placeholder("10.0.0.1").
 				Description("Target for ping/port/DNS monitors").
@@ -369,26 +444,73 @@ func (m *Model) initSiteHuhForm() tea.Cmd {
 			huh.NewInput().Title("Port").
 				Placeholder("0").
 				Description("Target port for TCP port monitors").
-				Value(&m.siteFormData.Port),
+				Value(&m.siteFormData.Port).
+				Validate(func(s string) error {
+					v, err := strconv.Atoi(s)
+					if err != nil {
+						return fmt.Errorf("must be a number")
+					}
+					if v < 0 || v > 65535 {
+						return fmt.Errorf("port must be 0-65535")
+					}
+					return nil
+				}),
 			huh.NewInput().Title("Timeout (seconds)").
 				Placeholder("5").
-				Value(&m.siteFormData.Timeout),
+				Value(&m.siteFormData.Timeout).
+				Validate(func(s string) error {
+					if m.siteFormData.SiteType == "group" {
+						return nil
+					}
+					v, err := strconv.Atoi(s)
+					if err != nil {
+						return fmt.Errorf("must be a number")
+					}
+					if v < 1 || v > 300 {
+						return fmt.Errorf("timeout must be 1-300 seconds")
+					}
+					return nil
+				}),
 			huh.NewInput().Title("Description").
 				Placeholder("Optional description").
 				Value(&m.siteFormData.Description),
-		).Title("Connection"),
+		).Title("Connection").WithHideFunc(func() bool {
+			return m.siteFormData.SiteType == "group"
+		}),
 		huh.NewGroup(
 			huh.NewConfirm().Title("Monitor SSL Certificate?").
 				Value(&m.siteFormData.CheckSSL),
 			huh.NewInput().Title("SSL Warning Threshold (days)").
 				Placeholder("7").
-				Value(&m.siteFormData.Threshold),
+				Value(&m.siteFormData.Threshold).
+				Validate(func(s string) error {
+					v, err := strconv.Atoi(s)
+					if err != nil {
+						return fmt.Errorf("must be a number")
+					}
+					if v < 1 {
+						return fmt.Errorf("threshold must be at least 1 day")
+					}
+					return nil
+				}),
 			huh.NewInput().Title("Max Retries Before Alert").
 				Placeholder("0").
-				Value(&m.siteFormData.Retries),
+				Value(&m.siteFormData.Retries).
+				Validate(func(s string) error {
+					v, err := strconv.Atoi(s)
+					if err != nil {
+						return fmt.Errorf("must be a number")
+					}
+					if v < 0 {
+						return fmt.Errorf("retries cannot be negative")
+					}
+					return nil
+				}),
 			huh.NewConfirm().Title("Ignore TLS Errors?").
 				Value(&m.siteFormData.IgnoreTLS),
-		).Title("Advanced"),
+		).Title("Advanced").WithHideFunc(func() bool {
+			return m.siteFormData.SiteType == "group"
+		}),
 	).WithTheme(huh.ThemeDracula())
 
 	return m.huhForm.Init()
@@ -402,6 +524,7 @@ func (m *Model) submitSiteForm() {
 	retries, _ := strconv.Atoi(d.Retries)
 	port, _ := strconv.Atoi(d.Port)
 	timeout, _ := strconv.Atoi(d.Timeout)
+	groupID, _ := strconv.Atoi(d.GroupID)
 	if interval < 1 {
 		interval = 60
 	}
@@ -424,6 +547,7 @@ func (m *Model) submitSiteForm() {
 		Timeout:         timeout,
 		Description:     d.Description,
 		IgnoreTLS:       d.IgnoreTLS,
+		ParentID:        groupID,
 	}
 
 	if m.editID > 0 {
diff --git a/internal/tui/tab_users.go b/internal/tui/tab_users.go
index 14f9a93..4858b7c 100644
--- a/internal/tui/tab_users.go
+++ b/internal/tui/tab_users.go
@@ -64,7 +64,7 @@ func (m Model) viewUsersTab() string {
 	for i := m.tableOffset; i < end; i++ {
 		u := m.users[i]
 		rows = append(rows, []string{
-			fmt.Sprintf("%d", u.ID),
+			fmt.Sprintf("%d", i+1),
 			m.zones.Mark(fmt.Sprintf("user-%d", i), limitStr(u.Username, 15)),
 			fmtRole(u.Role),
 			fmtKey(u.PublicKey),
@@ -80,7 +80,7 @@ func (m Model) viewUsersTab() string {
 		Border(lipgloss.RoundedBorder()).
 		BorderStyle(userBorderStyle).
 		Width(tableWidth).
-		Headers("ID", "USERNAME", "ROLE", "PUBLIC KEY").
+		Headers("#", "USERNAME", "ROLE", "PUBLIC KEY").
 		Rows(rows...).
 		StyleFunc(func(row, col int) lipgloss.Style {
 			if row == table.HeaderRow {
diff --git a/internal/tui/tui.go b/internal/tui/tui.go
index 6f9c5ed..4972a3a 100644
--- a/internal/tui/tui.go
+++ b/internal/tui/tui.go
@@ -40,6 +40,7 @@ const (
 	stateFormSite
 	stateFormAlert
 	stateFormUser
+	stateConfirmDelete
 )
 
 type Model struct {
@@ -62,6 +63,12 @@ type Model struct {
 	isAdmin     bool
 	zones       *zone.Manager
 
+	deleteID   int
+	deleteName string
+	deleteTab  int
+
+	collapsed map[int]bool
+
 	// harmonica animation state
 	pulseSpring harmonica.Spring
 	pulsePos    float64
@@ -85,6 +92,7 @@ func InitialModel(isAdmin bool) Model {
 		isAdmin:      isAdmin,
 		zones:        z,
 		pulseSpring:  spring,
+		collapsed:    make(map[int]bool),
 	}
 }
 
@@ -95,6 +103,41 @@ func (m Model) Init() tea.Cmd {
 func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	var cmd tea.Cmd
 
+	if m.state == stateConfirmDelete {
+		if keyMsg, ok := msg.(tea.KeyMsg); ok {
+			switch keyMsg.String() {
+			case "y", "Y":
+				if store.Get() != nil {
+					switch m.deleteTab {
+					case 0:
+						store.Get().DeleteSite(m.deleteID)
+						monitor.RemoveSite(m.deleteID)
+						m.adjustCursor(len(m.sites) - 1)
+					case 1:
+						store.Get().DeleteAlert(m.deleteID)
+						m.adjustCursor(len(m.alerts) - 1)
+					case 3:
+						store.Get().DeleteUser(m.deleteID)
+						m.adjustCursor(len(m.users) - 1)
+					}
+				}
+				m.refreshData()
+				m.state = stateDashboard
+				if m.deleteTab == 3 {
+					m.state = stateUsers
+				}
+			case "n", "N", "esc":
+				m.state = stateDashboard
+				if m.deleteTab == 3 {
+					m.state = stateUsers
+				}
+			case "ctrl+c":
+				return m, tea.Quit
+			}
+		}
+		return m, nil
+	}
+
 	// Form state: forward ALL messages to huh (keys, timers, resize, etc.)
 	if m.state == stateFormSite || m.state == stateFormAlert || m.state == stateFormUser {
 		if keyMsg, ok := msg.(tea.KeyMsg); ok {
@@ -259,6 +302,12 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 					m.state = stateFormUser
 					return m, m.initUserHuhForm()
 				}
+			case " ":
+				if m.currentTab == 0 && len(m.sites) > 0 && m.sites[m.cursor].Type == "group" {
+					gid := m.sites[m.cursor].ID
+					m.collapsed[gid] = !m.collapsed[gid]
+					m.refreshData()
+				}
 			case "p":
 				if m.currentTab == 0 && len(m.sites) > 0 {
 					site := m.sites[m.cursor]
@@ -270,19 +319,22 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 					m.refreshData()
 				}
 			case "d", "backspace":
-				if m.currentTab == 1 && len(m.alerts) > 0 {
-					store.Get().DeleteAlert(m.alerts[m.cursor].ID)
-					m.adjustCursor(len(m.alerts) - 1)
-				} else if m.currentTab == 0 && len(m.sites) > 0 {
-					id := m.sites[m.cursor].ID
-					store.Get().DeleteSite(id)
-					monitor.RemoveSite(id)
-					m.adjustCursor(len(m.sites) - 1)
+				if m.currentTab == 0 && len(m.sites) > 0 {
+					m.deleteID = m.sites[m.cursor].ID
+					m.deleteName = m.sites[m.cursor].Name
+					m.deleteTab = 0
+					m.state = stateConfirmDelete
+				} else if m.currentTab == 1 && len(m.alerts) > 0 {
+					m.deleteID = m.alerts[m.cursor].ID
+					m.deleteName = m.alerts[m.cursor].Name
+					m.deleteTab = 1
+					m.state = stateConfirmDelete
 				} else if m.currentTab == 3 && m.isAdmin && len(m.users) > 0 {
-					store.Get().DeleteUser(m.users[m.cursor].ID)
-					m.adjustCursor(len(m.users) - 1)
+					m.deleteID = m.users[m.cursor].ID
+					m.deleteName = m.users[m.cursor].Username
+					m.deleteTab = 3
+					m.state = stateConfirmDelete
 				}
-				m.refreshData()
 			}
 		}
 	}
@@ -378,13 +430,40 @@ func (m *Model) adjustCursor(newLen int) {
 
 func (m *Model) refreshData() {
 	monitor.Mutex.RLock()
-	var sites []models.Site
+	var allSites []models.Site
 	for _, s := range monitor.LiveState {
-		sites = append(sites, s)
+		allSites = append(allSites, s)
 	}
 	monitor.Mutex.RUnlock()
-	sort.Slice(sites, func(i, j int) bool { return sites[i].ID < sites[j].ID })
-	m.sites = sites
+
+	var groups, ungrouped []models.Site
+	children := make(map[int][]models.Site)
+	for _, s := range allSites {
+		if s.Type == "group" {
+			groups = append(groups, s)
+		} else if s.ParentID > 0 {
+			children[s.ParentID] = append(children[s.ParentID], s)
+		} else {
+			ungrouped = append(ungrouped, s)
+		}
+	}
+	sort.Slice(groups, func(i, j int) bool { return groups[i].ID < groups[j].ID })
+	for pid := range children {
+		c := children[pid]
+		sort.Slice(c, func(i, j int) bool { return c[i].ID < c[j].ID })
+		children[pid] = c
+	}
+	sort.Slice(ungrouped, func(i, j int) bool { return ungrouped[i].ID < ungrouped[j].ID })
+
+	var ordered []models.Site
+	for _, g := range groups {
+		ordered = append(ordered, g)
+		if !m.collapsed[g.ID] {
+			ordered = append(ordered, children[g.ID]...)
+		}
+	}
+	ordered = append(ordered, ungrouped...)
+	m.sites = ordered
 	if store.Get() != nil {
 		m.alerts = store.Get().GetAllAlerts()
 		if m.isAdmin {
@@ -426,6 +505,16 @@ func (m Model) pulseIndicator() string {
 
 func (m Model) View() string {
 	switch m.state {
+	case stateConfirmDelete:
+		kind := "monitor"
+		if m.deleteTab == 1 {
+			kind = "alert"
+		} else if m.deleteTab == 3 {
+			kind = "user"
+		}
+		msg := dangerStyle.Render(fmt.Sprintf("Delete %s \"%s\"?", kind, m.deleteName))
+		hint := subtleStyle.Render("[y] Confirm  [n] Cancel")
+		return lipgloss.NewStyle().Padding(2, 4).Render(msg + "\n\n" + hint)
 	case stateFormSite, stateFormAlert, stateFormUser:
 		if m.huhForm != nil {
 			title := ""
@@ -490,7 +579,7 @@ func (m Model) viewDashboard() string {
 		}
 	}
 
-	footer := subtleStyle.Render("\n[n] New  [e/Enter] Edit  [d] Delete  [p] Pause  [Tab/Click] Switch  [Ctrl+L] Clear  [q] Quit")
+	footer := subtleStyle.Render("\n[n] New  [e/Enter] Edit  [d] Delete  [p] Pause  [Space] Collapse  [Tab/Click] Switch  [q] Quit")
 	if m.currentTab == 3 {
 		footer = subtleStyle.Render("\n[n] Add User  [d] Revoke  [Tab/Click] Switch  [Ctrl+L] Clear  [q] Quit")
 	}