Merge pull request 'fix: critical bugs and security hardening' (#19) from fix/critical-bugs-security-hardening into main

cmd/goupkeep/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"errors"
 	"flag"
 	"fmt"
 	"go-upkeep/internal/cluster"
@@ -17,6 +18,7 @@ import (
 	"os/signal"
 	"strconv"
 	"syscall"
+	"time"
 
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/ssh"
@@ -225,6 +227,7 @@ func runServe(args []string) {
 		fmt.Printf("Database connection error: %v\n", dbErr)
 		os.Exit(1)
 	}
+	defer s.Close()
 
 	if err := s.Init(); err != nil {
 		fmt.Printf("Database init error: %v\n", err)
@@ -263,7 +266,7 @@ func runServe(args []string) {
 	eng.InitLogs()
 	eng.Start(ctx)
 
-	server.Start(server.ServerConfig{
+	httpSrv := server.Start(server.ServerConfig{
 		Port:         httpPort,
 		EnableStatus: enableStatus,
 		Title:        statusTitle,
@@ -276,7 +279,7 @@ func runServe(args []string) {
 		SharedKey: clusterKey,
 	}, eng)
 
-	startSSHServer(*port, s, eng)
+	sshSrv := startSSHServer(*port, s, eng)
 
 	if isatty.IsTerminal(os.Stdout.Fd()) || isatty.IsCygwinTerminal(os.Stdout.Fd()) {
 		p := tea.NewProgram(tui.InitialModel(true, s, eng), tea.WithAltScreen(), tea.WithMouseCellMotion())
@@ -291,9 +294,22 @@ func runServe(args []string) {
 		fmt.Println("Shutting down...")
 	}
 	cancel()
+
+	shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer shutdownCancel()
+	if httpSrv != nil {
+		if err := httpSrv.Shutdown(shutdownCtx); err != nil {
+			log.Printf("HTTP shutdown error: %v", err)
+		}
+	}
+	if sshSrv != nil {
+		if err := sshSrv.Shutdown(shutdownCtx); err != nil {
+			log.Printf("SSH shutdown error: %v", err)
+		}
+	}
 }
 
-func startSSHServer(port int, db store.Store, eng *monitor.Engine) {
+func startSSHServer(port int, db store.Store, eng *monitor.Engine) *ssh.Server {
 	s, err := wish.NewServer(
 		wish.WithAddress(fmt.Sprintf(":%d", port)),
 		wish.WithHostKeyPath(".ssh/id_ed25519"),
@@ -308,13 +324,14 @@ func startSSHServer(port int, db store.Store, eng *monitor.Engine) {
 	)
 	if err != nil {
 		fmt.Printf("SSH server error: %v\n", err)
-		return
+		return nil
 	}
 	go func() {
-		if err := s.ListenAndServe(); err != nil {
-			log.Fatalf("SSH server failed: %v", err)
+		if err := s.ListenAndServe(); err != nil && !errors.Is(err, ssh.ErrServerClosed) {
+			log.Printf("SSH server error: %v", err)
 		}
 	}()
+	return s
 }
 
 func seedDemoData(s store.Store) {

internal/alert/alert.go

@@ -2,6 +2,7 @@ package alert
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"go-upkeep/internal/models"
@@ -15,7 +16,7 @@ import (
 var alertClient = &http.Client{Timeout: 10 * time.Second}
 
 type Provider interface {
-	Send(title, message string) error
+	Send(ctx context.Context, title, message string) error
 }
 
 type PayloadFunc func(title, message string) ([]byte, error)
@@ -25,12 +26,17 @@ type HTTPProvider struct {
 	Payload PayloadFunc
 }
 
-func (h *HTTPProvider) Send(title, message string) error {
+func (h *HTTPProvider) Send(ctx context.Context, title, message string) error {
 	body, err := h.Payload(title, message)
 	if err != nil {
 		return err
 	}
-	resp, err := alertClient.Post(h.URL, "application/json", bytes.NewBuffer(body))
+	req, err := http.NewRequestWithContext(ctx, "POST", h.URL, bytes.NewBuffer(body))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	resp, err := alertClient.Do(req)
 	if err != nil {
 		return err
 	}
@@ -170,7 +176,12 @@ type EmailProvider struct {
 	Host, Port, User, Pass, To, From string
 }
 
-func (e *EmailProvider) Send(title, message string) error {
+func (e *EmailProvider) Send(ctx context.Context, title, message string) error {
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	default:
+	}
 	auth := smtp.PlainAuth("", e.User, e.Pass, e.Host)
 	msg := []byte("To: " + e.To + "\r\n" +
 		"Subject: Go-Upkeep: " + title + "\r\n" +
@@ -187,9 +198,9 @@ type NtfyProvider struct {
 	Password  string
 }
 
-func (n *NtfyProvider) Send(title, message string) error {
+func (n *NtfyProvider) Send(ctx context.Context, title, message string) error {
 	url := strings.TrimRight(n.ServerURL, "/") + "/" + n.Topic
-	req, err := http.NewRequest("POST", url, strings.NewReader(message))
+	req, err := http.NewRequestWithContext(ctx, "POST", url, strings.NewReader(message))
 	if err != nil {
 		return err
 	}

internal/alert/alert_test.go

@@ -1,6 +1,7 @@
 package alert
 
 import (
+	"context"
 	"encoding/json"
 	"go-upkeep/internal/models"
 	"net/http"
@@ -17,7 +18,7 @@ func TestHTTPProviderDiscord(t *testing.T) {
 	defer srv.Close()
 
 	p := GetProvider(models.AlertConfig{Type: "discord", Settings: map[string]string{"url": srv.URL}})
-	if err := p.Send("Test Title", "Test Body"); err != nil {
+	if err := p.Send(context.Background(), "Test Title", "Test Body"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 
@@ -35,7 +36,7 @@ func TestHTTPProviderSlack(t *testing.T) {
 	defer srv.Close()
 
 	p := GetProvider(models.AlertConfig{Type: "slack", Settings: map[string]string{"url": srv.URL}})
-	if err := p.Send("Alert", "Message"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Message"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 
@@ -53,7 +54,7 @@ func TestHTTPProviderWebhook(t *testing.T) {
 	defer srv.Close()
 
 	p := GetProvider(models.AlertConfig{Type: "webhook", Settings: map[string]string{"url": srv.URL}})
-	if err := p.Send("Title", "Body"); err != nil {
+	if err := p.Send(context.Background(), "Title", "Body"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 
@@ -69,7 +70,7 @@ func TestHTTPProviderErrorOnHTTP4xx(t *testing.T) {
 	defer srv.Close()
 
 	p := GetProvider(models.AlertConfig{Type: "discord", Settings: map[string]string{"url": srv.URL}})
-	if err := p.Send("Test", "Test"); err == nil {
+	if err := p.Send(context.Background(), "Test", "Test"); err == nil {
 		t.Fatal("expected error on 403 response")
 	}
 }
@@ -89,7 +90,7 @@ func TestNtfyProvider(t *testing.T) {
 		"url":   srv.URL,
 		"topic": "test",
 	}})
-	if err := p.Send("Alert Title", "Alert Body"); err != nil {
+	if err := p.Send(context.Background(), "Alert Title", "Alert Body"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 
@@ -110,7 +111,7 @@ func TestHTTPProviderTelegram(t *testing.T) {
 	defer srv.Close()
 
 	p := &HTTPProvider{URL: srv.URL, Payload: telegramPayload("12345")}
-	if err := p.Send("Alert", "Down"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Down"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 	if received["chat_id"] != "12345" {
@@ -133,7 +134,7 @@ func TestHTTPProviderPagerDuty(t *testing.T) {
 	defer srv.Close()
 
 	p := &HTTPProvider{URL: srv.URL, Payload: pagerdutyPayload("test-key", "critical")}
-	if err := p.Send("Alert", "Down"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Down"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 	if received["routing_key"] != "test-key" {
@@ -160,7 +161,7 @@ func TestHTTPProviderPushover(t *testing.T) {
 	defer srv.Close()
 
 	p := &HTTPProvider{URL: srv.URL, Payload: pushoverPayload("app-tok", "user-key")}
-	if err := p.Send("Alert", "Down"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Down"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 	if received["token"] != "app-tok" {
@@ -183,7 +184,7 @@ func TestHTTPProviderGotify(t *testing.T) {
 	defer srv.Close()
 
 	p := &HTTPProvider{URL: srv.URL, Payload: gotifyPayload("8")}
-	if err := p.Send("Alert", "Down"); err != nil {
+	if err := p.Send(context.Background(), "Alert", "Down"); err != nil {
 		t.Fatalf("Send: %v", err)
 	}
 	if received["title"] != "Alert" || received["message"] != "Down" {

internal/cluster/cluster_test.go

@@ -0,0 +1,395 @@
+package cluster
+
+import (
+	"context"
+	"encoding/json"
+	"go-upkeep/internal/models"
+	"go-upkeep/internal/monitor"
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+)
+
+// --- Mock Store (minimal, for monitor.NewEngine) ---
+
+type mockStore struct {
+	mu    sync.Mutex
+	sites []models.Site
+}
+
+func (m *mockStore) Init() error                                              { return nil }
+func (m *mockStore) GetSites() ([]models.Site, error)                         { return m.sites, nil }
+func (m *mockStore) AddSite(models.Site) error                                { return nil }
+func (m *mockStore) UpdateSite(models.Site) error                             { return nil }
+func (m *mockStore) UpdateSitePaused(int, bool) error                         { return nil }
+func (m *mockStore) DeleteSite(int) error                                     { return nil }
+func (m *mockStore) GetAllAlerts() ([]models.AlertConfig, error)              { return nil, nil }
+func (m *mockStore) GetAlert(int) (models.AlertConfig, error)                 { return models.AlertConfig{}, nil }
+func (m *mockStore) AddAlert(string, string, map[string]string) error         { return nil }
+func (m *mockStore) UpdateAlert(int, string, string, map[string]string) error { return nil }
+func (m *mockStore) DeleteAlert(int) error                                    { return nil }
+func (m *mockStore) GetAllUsers() ([]models.User, error)                      { return nil, nil }
+func (m *mockStore) AddUser(string, string, string) error                     { return nil }
+func (m *mockStore) UpdateUser(int, string, string, string) error             { return nil }
+func (m *mockStore) DeleteUser(int) error                                     { return nil }
+func (m *mockStore) SaveCheck(int, int64, bool) error                         { return nil }
+func (m *mockStore) SaveCheckFromNode(int, string, int64, bool) error         { return nil }
+func (m *mockStore) LoadAllHistory(int) (map[int][]models.CheckRecord, error) { return nil, nil }
+func (m *mockStore) ExportData() (models.Backup, error)                       { return models.Backup{}, nil }
+func (m *mockStore) ImportData(models.Backup) error                           { return nil }
+func (m *mockStore) GetSiteByName(string) (models.Site, error)                { return models.Site{}, nil }
+func (m *mockStore) GetAlertByName(string) (models.AlertConfig, error) {
+	return models.AlertConfig{}, nil
+}
+func (m *mockStore) AddSiteReturningID(models.Site) (int, error) { return 0, nil }
+func (m *mockStore) AddAlertReturningID(string, string, map[string]string) (int, error) {
+	return 0, nil
+}
+func (m *mockStore) RegisterNode(models.ProbeNode) error      { return nil }
+func (m *mockStore) GetNode(string) (models.ProbeNode, error) { return models.ProbeNode{}, nil }
+func (m *mockStore) GetAllNodes() ([]models.ProbeNode, error) { return nil, nil }
+func (m *mockStore) UpdateNodeLastSeen(string) error          { return nil }
+func (m *mockStore) DeleteNode(string) error                  { return nil }
+func (m *mockStore) SaveLog(string) error                     { return nil }
+func (m *mockStore) LoadLogs(int) ([]string, error)           { return nil, nil }
+func (m *mockStore) GetActiveMaintenanceWindows() ([]models.MaintenanceWindow, error) {
+	return nil, nil
+}
+func (m *mockStore) GetAllMaintenanceWindows(int) ([]models.MaintenanceWindow, error) {
+	return nil, nil
+}
+func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error { return nil }
+func (m *mockStore) EndMaintenanceWindow(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) GetPreference(string) (string, error)                { return "", nil }
+func (m *mockStore) SetPreference(string, string) error                  { return nil }
+func (m *mockStore) Close() error                                        { return nil }
+
+// --- Cluster Start Tests ---
+
+func TestStart_LeaderMode(t *testing.T) {
+	eng := monitor.NewEngine(&mockStore{})
+	eng.SetActive(false)
+
+	ctx := context.Background()
+	Start(ctx, Config{Mode: "leader"}, eng)
+
+	if !eng.IsActive() {
+		t.Error("leader mode should set engine active")
+	}
+}
+
+func TestStart_FollowerMode(t *testing.T) {
+	eng := monitor.NewEngine(&mockStore{})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	Start(ctx, Config{Mode: "follower", PeerURL: "http://localhost:9999"}, eng)
+	time.Sleep(50 * time.Millisecond)
+
+	if eng.IsActive() {
+		t.Error("follower mode should set engine inactive")
+	}
+}
+
+// --- Follower Loop Tests ---
+
+func TestFollowerLoop_FailoverOnLeaderDown(t *testing.T) {
+	eng := monitor.NewEngine(&mockStore{})
+	eng.SetActive(false)
+
+	// Server always returns 503
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(503)
+	}))
+	defer srv.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	go runFollowerLoop(ctx, Config{PeerURL: srv.URL, SharedKey: "key"}, eng)
+
+	// Follower checks every 5s, needs 3 failures → ~15s minimum
+	// But we can't wait that long in a test. The loop sleeps 5s between checks.
+	// We'll wait up to 20s for failover.
+	deadline := time.After(20 * time.Second)
+	for {
+		if eng.IsActive() {
+			return // success
+		}
+		select {
+		case <-deadline:
+			t.Fatal("expected failover to ACTIVE after 3 failures")
+		case <-time.After(500 * time.Millisecond):
+		}
+	}
+}
+
+func TestFollowerLoop_RecoveryOnLeaderReturn(t *testing.T) {
+	eng := monitor.NewEngine(&mockStore{})
+	eng.SetActive(true) // simulate already failed over
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte("OK"))
+	}))
+	defer srv.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	go runFollowerLoop(ctx, Config{PeerURL: srv.URL}, eng)
+
+	deadline := time.After(10 * time.Second)
+	for {
+		if !eng.IsActive() {
+			return // success — switched back to passive
+		}
+		select {
+		case <-deadline:
+			t.Fatal("expected switch back to PASSIVE when leader returns")
+		case <-time.After(500 * time.Millisecond):
+		}
+	}
+}
+
+func TestFollowerLoop_SendsSecret(t *testing.T) {
+	var mu sync.Mutex
+	var receivedSecret string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		mu.Lock()
+		receivedSecret = r.Header.Get("X-Upkeep-Secret")
+		mu.Unlock()
+		w.WriteHeader(200)
+		w.Write([]byte("OK"))
+	}))
+	defer srv.Close()
+
+	eng := monitor.NewEngine(&mockStore{})
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	go runFollowerLoop(ctx, Config{PeerURL: srv.URL, SharedKey: "test-secret"}, eng)
+
+	deadline := time.After(10 * time.Second)
+	for {
+		mu.Lock()
+		got := receivedSecret
+		mu.Unlock()
+		if got == "test-secret" {
+			return
+		}
+		select {
+		case <-deadline:
+			t.Fatalf("expected secret 'test-secret', got %q", got)
+		case <-time.After(500 * time.Millisecond):
+		}
+	}
+}
+
+func TestFollowerLoop_CancelContext(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	eng := monitor.NewEngine(&mockStore{})
+	ctx, cancel := context.WithCancel(context.Background())
+
+	done := make(chan struct{})
+	go func() {
+		runFollowerLoop(ctx, Config{PeerURL: srv.URL}, eng)
+		close(done)
+	}()
+
+	cancel()
+	select {
+	case <-done:
+	case <-time.After(3 * time.Second):
+		t.Fatal("expected follower loop to exit on context cancel")
+	}
+}
+
+// --- Probe Tests ---
+
+func TestProbeRegister_Success(t *testing.T) {
+	var received map[string]string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		json.NewDecoder(r.Body).Decode(&received)
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	err := probeRegister(context.Background(), srv.Client(), ProbeConfig{
+		NodeID: "n1", NodeName: "US East", Region: "us-east", LeaderURL: srv.URL, SharedKey: "key",
+	})
+	if err != nil {
+		t.Fatalf("register: %v", err)
+	}
+	if received["id"] != "n1" {
+		t.Errorf("expected id n1, got %s", received["id"])
+	}
+}
+
+func TestProbeRegister_Failure(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+	}))
+	defer srv.Close()
+
+	err := probeRegister(context.Background(), srv.Client(), ProbeConfig{
+		LeaderURL: srv.URL,
+	})
+	if err == nil {
+		t.Error("expected error on 401")
+	}
+}
+
+func TestProbeFetchAssignments_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		json.NewEncoder(w).Encode(map[string][]models.Site{
+			"sites": {{ID: 1, Name: "s1", Type: "http", URL: "http://example.com"}},
+		})
+	}))
+	defer srv.Close()
+
+	sites, err := probeFetchAssignments(context.Background(), srv.Client(), ProbeConfig{
+		NodeID: "n1", LeaderURL: srv.URL, SharedKey: "key",
+	})
+	if err != nil {
+		t.Fatalf("fetch: %v", err)
+	}
+	if len(sites) != 1 {
+		t.Errorf("expected 1 site, got %d", len(sites))
+	}
+}
+
+func TestProbeFetchAssignments_Unauthorized(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+	}))
+	defer srv.Close()
+
+	_, err := probeFetchAssignments(context.Background(), srv.Client(), ProbeConfig{
+		LeaderURL: srv.URL,
+	})
+	if err == nil {
+		t.Error("expected error on 401")
+	}
+}
+
+func TestProbeExecuteChecks(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	sites := []models.Site{
+		{ID: 1, Type: "http", URL: srv.URL},
+		{ID: 2, Type: "http", URL: srv.URL},
+	}
+
+	strict := &http.Client{}
+	insecure := &http.Client{}
+	results := probeExecuteChecks(context.Background(), sites, strict, insecure)
+
+	if len(results) != 2 {
+		t.Fatalf("expected 2 results, got %d", len(results))
+	}
+	for _, r := range results {
+		if !r.IsUp {
+			t.Errorf("site %d expected UP", r.SiteID)
+		}
+	}
+}
+
+func TestProbeExecuteChecks_Concurrency(t *testing.T) {
+	var concurrent int64
+	var maxConcurrent int64
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		cur := atomic.AddInt64(&concurrent, 1)
+		for {
+			old := atomic.LoadInt64(&maxConcurrent)
+			if cur <= old || atomic.CompareAndSwapInt64(&maxConcurrent, old, cur) {
+				break
+			}
+		}
+		time.Sleep(50 * time.Millisecond)
+		atomic.AddInt64(&concurrent, -1)
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	var sites []models.Site
+	for i := 0; i < 20; i++ {
+		sites = append(sites, models.Site{ID: i + 1, Type: "http", URL: srv.URL})
+	}
+
+	results := probeExecuteChecks(context.Background(), sites, &http.Client{}, &http.Client{})
+	if len(results) != 20 {
+		t.Errorf("expected 20 results, got %d", len(results))
+	}
+	mc := atomic.LoadInt64(&maxConcurrent)
+	if mc > 10 {
+		t.Errorf("expected max 10 concurrent, got %d", mc)
+	}
+}
+
+func TestProbeReportResults_Success(t *testing.T) {
+	var received struct {
+		NodeID  string            `json:"node_id"`
+		Results []probeResultItem `json:"results"`
+	}
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		json.NewDecoder(r.Body).Decode(&received)
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	err := probeReportResults(context.Background(), srv.Client(), ProbeConfig{
+		NodeID: "n1", LeaderURL: srv.URL, SharedKey: "key",
+	}, []probeResultItem{{SiteID: 1, LatencyNs: 5000000, IsUp: true}})
+
+	if err != nil {
+		t.Fatalf("report: %v", err)
+	}
+	if received.NodeID != "n1" {
+		t.Errorf("expected n1, got %s", received.NodeID)
+	}
+	if len(received.Results) != 1 {
+		t.Errorf("expected 1 result, got %d", len(received.Results))
+	}
+}
+
+func TestProbeReportResults_Failure(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(500)
+	}))
+	defer srv.Close()
+
+	err := probeReportResults(context.Background(), srv.Client(), ProbeConfig{
+		LeaderURL: srv.URL,
+	}, []probeResultItem{{SiteID: 1}})
+
+	if err == nil {
+		t.Error("expected error on 500")
+	}
+}
+
+// --- sleepCtx ---
+
+func TestSleepCtx_Cancel(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	start := time.Now()
+	sleepCtx(ctx, 10*time.Second)
+	if time.Since(start) > time.Second {
+		t.Error("expected immediate return on canceled context")
+	}
+}

internal/importer/kuma.go

@@ -96,7 +96,9 @@ func convertKumaNotifications(entries []KumaNotifEntry) map[int]models.AlertConf
 	result := make(map[int]models.AlertConfig)
 	for _, entry := range entries {
 		var cfg KumaNotifConfig
-		json.Unmarshal([]byte(entry.Config), &cfg)
+		if err := json.Unmarshal([]byte(entry.Config), &cfg); err != nil {
+			continue
+		}
 
 		alert := models.AlertConfig{
 			ID:       entry.ID,

internal/metrics/prometheus_test.go

@@ -64,6 +64,7 @@ func (m *mockStore) DeleteMaintenanceWindow(int) error                   { retur
 func (m *mockStore) IsMonitorInMaintenance(int) (bool, error)            { return false, nil }
 func (m *mockStore) GetPreference(string) (string, error)                { return "", nil }
 func (m *mockStore) SetPreference(string, string) error                  { return nil }
+func (m *mockStore) Close() error                                        { return nil }
 
 func TestMetricsHandler(t *testing.T) {
 	ms := &mockStore{

internal/monitor/checker_test.go

@@ -0,0 +1,203 @@
+package monitor
+
+import (
+	"crypto/tls"
+	"go-upkeep/internal/models"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"testing"
+	"time"
+)
+
+func TestRunCheck_HTTP_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	site := models.Site{ID: 1, Type: "http", URL: srv.URL}
+	result := RunCheck(site, http.DefaultClient, http.DefaultClient, false)
+
+	if result.Status != "UP" {
+		t.Errorf("expected UP, got %s", result.Status)
+	}
+	if result.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", result.StatusCode)
+	}
+	if result.LatencyNs <= 0 {
+		t.Error("expected positive latency")
+	}
+}
+
+func TestRunCheck_HTTP_ServerError(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(500)
+	}))
+	defer srv.Close()
+
+	site := models.Site{ID: 1, Type: "http", URL: srv.URL}
+	result := RunCheck(site, http.DefaultClient, http.DefaultClient, false)
+
+	if result.Status != "DOWN" {
+		t.Errorf("expected DOWN, got %s", result.Status)
+	}
+	if result.StatusCode != 500 {
+		t.Errorf("expected 500, got %d", result.StatusCode)
+	}
+}
+
+func TestRunCheck_HTTP_CustomAcceptedCodes(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(302)
+	}))
+	defer srv.Close()
+
+	client := &http.Client{CheckRedirect: func(req *http.Request, via []*http.Request) error {
+		return http.ErrUseLastResponse
+	}}
+
+	site := models.Site{ID: 1, Type: "http", URL: srv.URL, AcceptedCodes: "200-399"}
+	result := RunCheck(site, client, client, false)
+
+	if result.Status != "UP" {
+		t.Errorf("expected UP with accepted 200-399, got %s", result.Status)
+	}
+}
+
+func TestRunCheck_HTTP_MethodRespected(t *testing.T) {
+	var receivedMethod string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		receivedMethod = r.Method
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	site := models.Site{ID: 1, Type: "http", URL: srv.URL, Method: "HEAD"}
+	RunCheck(site, http.DefaultClient, http.DefaultClient, false)
+
+	if receivedMethod != "HEAD" {
+		t.Errorf("expected HEAD, got %s", receivedMethod)
+	}
+}
+
+func TestRunCheck_HTTP_Timeout(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		time.Sleep(2 * time.Second)
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	site := models.Site{ID: 1, Type: "http", URL: srv.URL, Timeout: 1}
+	result := RunCheck(site, http.DefaultClient, http.DefaultClient, false)
+
+	if result.Status != "DOWN" {
+		t.Errorf("expected DOWN on timeout, got %s", result.Status)
+	}
+}
+
+func TestRunCheck_HTTP_SSLFields(t *testing.T) {
+	srv := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	defer srv.Close()
+
+	insecureClient := &http.Client{
+		Transport: &http.Transport{TLSClientConfig: &tls.Config{InsecureSkipVerify: true}},
+	}
+
+	site := models.Site{ID: 1, Type: "http", URL: srv.URL, CheckSSL: true, IgnoreTLS: true}
+	result := RunCheck(site, http.DefaultClient, insecureClient, false)
+
+	if result.Status != "UP" {
+		t.Errorf("expected UP, got %s", result.Status)
+	}
+	if !result.HasSSL {
+		t.Error("expected HasSSL=true")
+	}
+	if result.CertExpiry.IsZero() {
+		t.Error("expected CertExpiry populated")
+	}
+}
+
+func TestRunCheck_Port_Open(t *testing.T) {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer ln.Close()
+
+	_, portStr, _ := net.SplitHostPort(ln.Addr().String())
+	port, _ := strconv.Atoi(portStr)
+
+	site := models.Site{ID: 1, Type: "port", Hostname: "127.0.0.1", Port: port, Timeout: 2}
+	result := RunCheck(site, nil, nil, false)
+
+	if result.Status != "UP" {
+		t.Errorf("expected UP, got %s", result.Status)
+	}
+	if result.LatencyNs <= 0 {
+		t.Error("expected positive latency")
+	}
+}
+
+func TestRunCheck_Port_Closed(t *testing.T) {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, portStr, _ := net.SplitHostPort(ln.Addr().String())
+	port, _ := strconv.Atoi(portStr)
+	ln.Close()
+
+	site := models.Site{ID: 1, Type: "port", Hostname: "127.0.0.1", Port: port, Timeout: 1}
+	result := RunCheck(site, nil, nil, false)
+
+	if result.Status != "DOWN" {
+		t.Errorf("expected DOWN, got %s", result.Status)
+	}
+}
+
+func TestRunCheck_UnknownType(t *testing.T) {
+	site := models.Site{ID: 1, Type: "invalid"}
+	result := RunCheck(site, nil, nil, false)
+
+	if result.Status != "DOWN" {
+		t.Errorf("expected DOWN for unknown type, got %s", result.Status)
+	}
+}
+
+func TestIsCodeAccepted(t *testing.T) {
+	tests := []struct {
+		code     int
+		accepted string
+		want     bool
+	}{
+		{200, "", true},
+		{299, "", true},
+		{300, "", false},
+		{302, "200-399", true},
+		{400, "200-399", false},
+		{301, "200,301,404", true},
+		{500, "200,301,404", false},
+		{404, "200-299,400-499", true},
+		{500, "200-299,400-499", false},
+	}
+
+	for _, tt := range tests {
+		got := isCodeAccepted(tt.code, tt.accepted)
+		if got != tt.want {
+			t.Errorf("isCodeAccepted(%d, %q) = %v, want %v", tt.code, tt.accepted, got, tt.want)
+		}
+	}
+}
+
+func TestSiteTimeout(t *testing.T) {
+	if got := siteTimeout(models.Site{Timeout: 0}); got != 5*time.Second {
+		t.Errorf("expected 5s default, got %v", got)
+	}
+	if got := siteTimeout(models.Site{Timeout: 10}); got != 10*time.Second {
+		t.Errorf("expected 10s, got %v", got)
+	}
+}

internal/monitor/monitor.go

@@ -7,6 +7,7 @@ import (
 	"go-upkeep/internal/alert"
 	"go-upkeep/internal/models"
 	"go-upkeep/internal/store"
+	"math/rand/v2"
 	"net/http"
 	"sync"
 	"time"
@@ -25,7 +26,7 @@ type Engine struct {
 	histMu    sync.RWMutex
 	histories map[int]*SiteHistory
 
-	tokenIndex map[string]int
+	tokenIndex map[string]int // protected by mu
 
 	probeResultsMu sync.RWMutex
 	probeResults   map[int]map[string]NodeResult
@@ -277,6 +278,14 @@ func (e *Engine) ToggleSitePause(id int) bool {
 }
 
 func (e *Engine) monitorRoutine(ctx context.Context, id int) {
+	// Stagger initial check to avoid thundering herd on startup
+	stagger := time.Duration(rand.IntN(3000)) * time.Millisecond
+	select {
+	case <-time.After(stagger):
+	case <-ctx.Done():
+		return
+	}
+
 	e.checkByID(id)
 	for {
 		select {
@@ -314,8 +323,9 @@ func (e *Engine) monitorRoutine(ctx context.Context, id int) {
 		if interval < 5 {
 			interval = 5
 		}
+		jitter := time.Duration(rand.IntN(interval*100)) * time.Millisecond
 		select {
-		case <-time.After(time.Duration(interval) * time.Second):
+		case <-time.After(time.Duration(interval)*time.Second + jitter):
 		case <-ctx.Done():
 			return
 		}
@@ -433,6 +443,7 @@ func (e *Engine) handleStatusChange(site models.Site, rawStatus string, code int
 func (e *Engine) triggerAlert(alertID int, title, message string) {
 	cfg, err := e.db.GetAlert(alertID)
 	if err != nil {
+		e.AddLog(fmt.Sprintf("Failed to load alert config %d: %v", alertID, err))
 		return
 	}
 	provider := alert.GetProvider(cfg)
@@ -440,8 +451,9 @@ func (e *Engine) triggerAlert(alertID int, title, message string) {
 		go func() {
 			ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 			defer cancel()
-			_ = ctx
-			_ = provider.Send(title, message)
+			if err := provider.Send(ctx, title, message); err != nil {
+				e.AddLog(fmt.Sprintf("Alert send failed (%s): %v", cfg.Name, err))
+			}
 		}()
 	}
 }

internal/server/server.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"crypto/subtle"
 	"encoding/json"
 	"fmt"
 	"go-upkeep/internal/importer"
@@ -15,6 +16,10 @@ import (
 	"strings"
 )
 
+func checkSecret(got, want string) bool {
+	return subtle.ConstantTimeCompare([]byte(got), []byte(want)) == 1
+}
+
 var statusTpl = template.Must(template.New("status").Parse(`
 <!DOCTYPE html>
 <html>
@@ -153,7 +158,7 @@ type ServerConfig struct {
 	ClusterKey   string // Shared Secret for Security
 }
 
-func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) {
+func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) *http.Server {
 	if cfg.ClusterKey == "" {
 		fmt.Println("WARNING: No UPKEEP_CLUSTER_SECRET set. Cluster API endpoints are unauthenticated.")
 	}
@@ -176,7 +181,7 @@ func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) {
 
 	// 2. Health Check (For Cluster Follower)
 	mux.HandleFunc("/api/health", func(w http.ResponseWriter, r *http.Request) {
-		if cfg.ClusterKey != "" && r.Header.Get("X-Upkeep-Secret") != cfg.ClusterKey {
+		if cfg.ClusterKey != "" && !checkSecret(r.Header.Get("X-Upkeep-Secret"), cfg.ClusterKey) {
 			http.Error(w, "Unauthorized", 401)
 			return
 		}
@@ -186,7 +191,7 @@ func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) {
 
 	// 3. Config Export
 	mux.HandleFunc("/api/backup/export", func(w http.ResponseWriter, r *http.Request) {
-		if cfg.ClusterKey == "" || r.Header.Get("X-Upkeep-Secret") != cfg.ClusterKey {
+		if cfg.ClusterKey == "" || !checkSecret(r.Header.Get("X-Upkeep-Secret"), cfg.ClusterKey) {
 			http.Error(w, "Unauthorized: UPKEEP_CLUSTER_SECRET required", 401)
 			return
 		}
@@ -205,10 +210,11 @@ func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) {
 			http.Error(w, "POST required", 405)
 			return
 		}
-		if cfg.ClusterKey == "" || r.Header.Get("X-Upkeep-Secret") != cfg.ClusterKey {
+		if cfg.ClusterKey == "" || !checkSecret(r.Header.Get("X-Upkeep-Secret"), cfg.ClusterKey) {
 			http.Error(w, "Unauthorized", 401)
 			return
 		}
+		r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
 		var data models.Backup
 		if err := json.NewDecoder(r.Body).Decode(&data); err != nil {
 			http.Error(w, "Invalid JSON", 400)
@@ -228,10 +234,11 @@ func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) {
 			http.Error(w, "POST required", 405)
 			return
 		}
-		if cfg.ClusterKey == "" || r.Header.Get("X-Upkeep-Secret") != cfg.ClusterKey {
+		if cfg.ClusterKey == "" || !checkSecret(r.Header.Get("X-Upkeep-Secret"), cfg.ClusterKey) {
 			http.Error(w, "Unauthorized", 401)
 			return
 		}
+		r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
 		var kb importer.KumaBackup
 		if err := json.NewDecoder(r.Body).Decode(&kb); err != nil {
 			log.Printf("Invalid Kuma JSON: %v", err)
@@ -253,10 +260,11 @@ func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) {
 			http.Error(w, "POST required", 405)
 			return
 		}
-		if cfg.ClusterKey == "" || r.Header.Get("X-Upkeep-Secret") != cfg.ClusterKey {
+		if cfg.ClusterKey == "" || !checkSecret(r.Header.Get("X-Upkeep-Secret"), cfg.ClusterKey) {
 			http.Error(w, "Unauthorized", 401)
 			return
 		}
+		r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
 		var req struct {
 			ID      string `json:"id"`
 			Name    string `json:"name"`
@@ -283,7 +291,7 @@ func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) {
 
 	// 7. Probe Assignment Fetch
 	mux.HandleFunc("/api/probe/assignments", func(w http.ResponseWriter, r *http.Request) {
-		if cfg.ClusterKey == "" || r.Header.Get("X-Upkeep-Secret") != cfg.ClusterKey {
+		if cfg.ClusterKey == "" || !checkSecret(r.Header.Get("X-Upkeep-Secret"), cfg.ClusterKey) {
 			http.Error(w, "Unauthorized", 401)
 			return
 		}
@@ -324,10 +332,11 @@ func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) {
 			http.Error(w, "POST required", 405)
 			return
 		}
-		if cfg.ClusterKey == "" || r.Header.Get("X-Upkeep-Secret") != cfg.ClusterKey {
+		if cfg.ClusterKey == "" || !checkSecret(r.Header.Get("X-Upkeep-Secret"), cfg.ClusterKey) {
 			http.Error(w, "Unauthorized", 401)
 			return
 		}
+		r.Body = http.MaxBytesReader(w, r.Body, 1<<20)
 		var req struct {
 			NodeID  string `json:"node_id"`
 			Results []struct {
@@ -387,13 +396,15 @@ func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) {
 		})
 	}
 
+	addr := fmt.Sprintf(":%d", cfg.Port)
+	srv := &http.Server{Addr: addr, Handler: mux}
 	go func() {
-		addr := fmt.Sprintf(":%d", cfg.Port)
 		fmt.Printf("HTTP Server listening on %s\n", addr)
-		if err := http.ListenAndServe(addr, mux); err != nil {
-			log.Fatalf("HTTP server failed: %v", err)
+		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			log.Printf("HTTP server error: %v", err)
 		}
 	}()
+	return srv
 }
 
 func renderStatusPage(w http.ResponseWriter, title string, eng *monitor.Engine) {

internal/server/server_test.go

@@ -0,0 +1,553 @@
+package server
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"go-upkeep/internal/models"
+	"go-upkeep/internal/monitor"
+	"net"
+	"net/http"
+	"sync"
+	"testing"
+	"time"
+)
+
+// --- Mock Store ---
+
+type mockStore struct {
+	mu              sync.Mutex
+	sites           []models.Site
+	alerts          []models.AlertConfig
+	nodes           map[string]models.ProbeNode
+	importedData    *models.Backup
+	registeredNodes []models.ProbeNode
+	maintWindows    []models.MaintenanceWindow
+}
+
+func newMockStore() *mockStore {
+	return &mockStore{
+		nodes: make(map[string]models.ProbeNode),
+	}
+}
+
+func (m *mockStore) Init() error                                              { return nil }
+func (m *mockStore) GetSites() ([]models.Site, error)                         { return m.sites, nil }
+func (m *mockStore) AddSite(models.Site) error                                { return nil }
+func (m *mockStore) UpdateSite(models.Site) error                             { return nil }
+func (m *mockStore) UpdateSitePaused(int, bool) error                         { return nil }
+func (m *mockStore) DeleteSite(int) error                                     { return nil }
+func (m *mockStore) GetAllAlerts() ([]models.AlertConfig, error)              { return m.alerts, nil }
+func (m *mockStore) GetAlert(int) (models.AlertConfig, error)                 { return models.AlertConfig{}, nil }
+func (m *mockStore) AddAlert(string, string, map[string]string) error         { return nil }
+func (m *mockStore) UpdateAlert(int, string, string, map[string]string) error { return nil }
+func (m *mockStore) DeleteAlert(int) error                                    { return nil }
+func (m *mockStore) GetAllUsers() ([]models.User, error)                      { return nil, nil }
+func (m *mockStore) AddUser(string, string, string) error                     { return nil }
+func (m *mockStore) UpdateUser(int, string, string, string) error             { return nil }
+func (m *mockStore) DeleteUser(int) error                                     { return nil }
+func (m *mockStore) SaveCheck(int, int64, bool) error                         { return nil }
+func (m *mockStore) SaveCheckFromNode(siteID int, nodeID string, latencyNs int64, isUp bool) error {
+	return nil
+}
+func (m *mockStore) LoadAllHistory(int) (map[int][]models.CheckRecord, error) {
+	return nil, nil
+}
+func (m *mockStore) GetSiteByName(string) (models.Site, error) { return models.Site{}, nil }
+func (m *mockStore) GetAlertByName(string) (models.AlertConfig, error) {
+	return models.AlertConfig{}, nil
+}
+func (m *mockStore) AddSiteReturningID(models.Site) (int, error) { return 0, nil }
+func (m *mockStore) AddAlertReturningID(string, string, map[string]string) (int, error) {
+	return 0, nil
+}
+func (m *mockStore) GetAllNodes() ([]models.ProbeNode, error) { return nil, nil }
+func (m *mockStore) UpdateNodeLastSeen(string) error          { return nil }
+func (m *mockStore) DeleteNode(string) error                  { return nil }
+func (m *mockStore) SaveLog(string) error                     { return nil }
+func (m *mockStore) LoadLogs(int) ([]string, error)           { return nil, nil }
+func (m *mockStore) GetAllMaintenanceWindows(int) ([]models.MaintenanceWindow, error) {
+	return nil, nil
+}
+func (m *mockStore) AddMaintenanceWindow(models.MaintenanceWindow) error { return nil }
+func (m *mockStore) EndMaintenanceWindow(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) GetPreference(string) (string, error)                { return "", nil }
+func (m *mockStore) SetPreference(string, string) error                  { return nil }
+func (m *mockStore) Close() error                                        { return nil }
+
+func (m *mockStore) ExportData() (models.Backup, error) {
+	return models.Backup{
+		Sites:  m.sites,
+		Alerts: m.alerts,
+	}, nil
+}
+
+func (m *mockStore) ImportData(data models.Backup) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	m.importedData = &data
+	return nil
+}
+
+func (m *mockStore) RegisterNode(node models.ProbeNode) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	m.registeredNodes = append(m.registeredNodes, node)
+	m.nodes[node.ID] = node
+	return nil
+}
+
+func (m *mockStore) GetNode(id string) (models.ProbeNode, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if n, ok := m.nodes[id]; ok {
+		return n, nil
+	}
+	return models.ProbeNode{}, fmt.Errorf("not found")
+}
+
+func (m *mockStore) GetActiveMaintenanceWindows() ([]models.MaintenanceWindow, error) {
+	return m.maintWindows, nil
+}
+
+// --- Helpers ---
+
+func freePort() int {
+	ln, _ := net.Listen("tcp", "127.0.0.1:0")
+	port := ln.Addr().(*net.TCPAddr).Port
+	ln.Close()
+	return port
+}
+
+type testServer struct {
+	baseURL string
+	srv     *http.Server
+	store   *mockStore
+	engine  *monitor.Engine
+}
+
+func newTestServer(t *testing.T, clusterKey string, enableStatus bool) *testServer {
+	t.Helper()
+	ms := newMockStore()
+	eng := monitor.NewEngine(ms)
+	port := freePort()
+
+	srv := Start(ServerConfig{
+		Port:         port,
+		EnableStatus: enableStatus,
+		Title:        "Test Status",
+		ClusterKey:   clusterKey,
+	}, ms, eng)
+
+	ts := &testServer{
+		baseURL: fmt.Sprintf("http://127.0.0.1:%d", port),
+		srv:     srv,
+		store:   ms,
+		engine:  eng,
+	}
+
+	// Wait for server to be ready
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		resp, err := http.Get(ts.baseURL + "/api/health")
+		if err == nil {
+			resp.Body.Close()
+			break
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+
+	t.Cleanup(func() {
+		srv.Close()
+	})
+
+	return ts
+}
+
+func authReq(method, url, secret string, body []byte) (*http.Response, error) {
+	var req *http.Request
+	var err error
+	if body != nil {
+		req, err = http.NewRequest(method, url, bytes.NewReader(body))
+	} else {
+		req, err = http.NewRequest(method, url, nil)
+	}
+	if err != nil {
+		return nil, err
+	}
+	if secret != "" {
+		req.Header.Set("X-Upkeep-Secret", secret)
+	}
+	return http.DefaultClient.Do(req)
+}
+
+// --- Tests ---
+
+func TestCheckSecret(t *testing.T) {
+	if !checkSecret("mykey", "mykey") {
+		t.Error("expected match")
+	}
+	if checkSecret("mykey", "wrong") {
+		t.Error("expected no match")
+	}
+	if checkSecret("", "key") {
+		t.Error("expected no match for empty got")
+	}
+}
+
+// --- Push Heartbeat ---
+
+func TestPush_MissingToken(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := http.Get(ts.baseURL + "/api/push")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 400 {
+		t.Errorf("expected 400, got %d", resp.StatusCode)
+	}
+}
+
+func TestPush_InvalidToken(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := http.Get(ts.baseURL + "/api/push?token=bad")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 404 {
+		t.Errorf("expected 404, got %d", resp.StatusCode)
+	}
+}
+
+// --- Health ---
+
+func TestHealth_NoSecret(t *testing.T) {
+	ts := newTestServer(t, "", false)
+	resp, err := http.Get(ts.baseURL + "/api/health")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200 with no cluster key, got %d", resp.StatusCode)
+	}
+}
+
+func TestHealth_ValidSecret(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := authReq("GET", ts.baseURL+"/api/health", "secret", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestHealth_WrongSecret(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := authReq("GET", ts.baseURL+"/api/health", "wrong", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 401 {
+		t.Errorf("expected 401, got %d", resp.StatusCode)
+	}
+}
+
+// --- Backup Export ---
+
+func TestExport_Unauthorized_NoKey(t *testing.T) {
+	ts := newTestServer(t, "", false)
+	resp, err := http.Get(ts.baseURL + "/api/backup/export")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 401 {
+		t.Errorf("expected 401 when no cluster key configured, got %d", resp.StatusCode)
+	}
+}
+
+func TestExport_Unauthorized_WrongKey(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := authReq("GET", ts.baseURL+"/api/backup/export", "wrong", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 401 {
+		t.Errorf("expected 401, got %d", resp.StatusCode)
+	}
+}
+
+func TestExport_Success(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	ts.store.sites = []models.Site{{ID: 1, Name: "example", URL: "http://example.com"}}
+
+	resp, err := authReq("GET", ts.baseURL+"/api/backup/export", "secret", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", resp.StatusCode)
+	}
+	var backup models.Backup
+	json.NewDecoder(resp.Body).Decode(&backup)
+	if len(backup.Sites) != 1 {
+		t.Errorf("expected 1 site, got %d", len(backup.Sites))
+	}
+}
+
+// --- Backup Import ---
+
+func TestImport_MethodNotAllowed(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := authReq("GET", ts.baseURL+"/api/backup/import", "secret", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 405 {
+		t.Errorf("expected 405, got %d", resp.StatusCode)
+	}
+}
+
+func TestImport_Unauthorized(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	body, _ := json.Marshal(models.Backup{})
+	resp, err := authReq("POST", ts.baseURL+"/api/backup/import", "wrong", body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 401 {
+		t.Errorf("expected 401, got %d", resp.StatusCode)
+	}
+}
+
+func TestImport_Success(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	backup := models.Backup{
+		Sites: []models.Site{{Name: "imported", URL: "http://example.com"}},
+	}
+	body, _ := json.Marshal(backup)
+	resp, err := authReq("POST", ts.baseURL+"/api/backup/import", "secret", body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", resp.StatusCode)
+	}
+	ts.store.mu.Lock()
+	defer ts.store.mu.Unlock()
+	if ts.store.importedData == nil {
+		t.Error("expected import data to be stored")
+	}
+}
+
+func TestImport_InvalidJSON(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := authReq("POST", ts.baseURL+"/api/backup/import", "secret", []byte("not json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 400 {
+		t.Errorf("expected 400, got %d", resp.StatusCode)
+	}
+}
+
+// --- Probe Registration ---
+
+func TestProbeRegister_Success(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	body, _ := json.Marshal(map[string]string{
+		"id": "node-1", "name": "US East", "region": "us-east",
+	})
+	resp, err := authReq("POST", ts.baseURL+"/api/probe/register", "secret", body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", resp.StatusCode)
+	}
+	ts.store.mu.Lock()
+	defer ts.store.mu.Unlock()
+	if len(ts.store.registeredNodes) != 1 {
+		t.Errorf("expected 1 registered node, got %d", len(ts.store.registeredNodes))
+	}
+	if ts.store.registeredNodes[0].ID != "node-1" {
+		t.Errorf("expected node-1, got %s", ts.store.registeredNodes[0].ID)
+	}
+}
+
+func TestProbeRegister_MissingID(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	body, _ := json.Marshal(map[string]string{"name": "test"})
+	resp, err := authReq("POST", ts.baseURL+"/api/probe/register", "secret", body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 400 {
+		t.Errorf("expected 400, got %d", resp.StatusCode)
+	}
+}
+
+func TestProbeRegister_Unauthorized(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	body, _ := json.Marshal(map[string]string{"id": "node-1"})
+	resp, err := authReq("POST", ts.baseURL+"/api/probe/register", "wrong", body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 401 {
+		t.Errorf("expected 401, got %d", resp.StatusCode)
+	}
+}
+
+// --- Probe Results ---
+
+func TestProbeResults_Success(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	body, _ := json.Marshal(map[string]any{
+		"node_id": "node-1",
+		"results": []map[string]any{
+			{"site_id": 1, "latency_ns": 5000000, "is_up": true},
+		},
+	})
+	resp, err := authReq("POST", ts.baseURL+"/api/probe/results", "secret", body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestProbeResults_MissingNodeID(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	body, _ := json.Marshal(map[string]any{
+		"results": []map[string]any{},
+	})
+	resp, err := authReq("POST", ts.baseURL+"/api/probe/results", "secret", body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 400 {
+		t.Errorf("expected 400, got %d", resp.StatusCode)
+	}
+}
+
+// --- Status Page ---
+
+func TestStatusPage_Enabled(t *testing.T) {
+	ts := newTestServer(t, "secret", true)
+	resp, err := http.Get(ts.baseURL + "/status")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestStatusJSON_TokensStripped(t *testing.T) {
+	ts := newTestServer(t, "secret", true)
+
+	// Inject a site with a token into engine state
+	ts.engine.UpdateSiteConfig(models.Site{ID: 1, Name: "test", Type: "push", Token: "secret-token", Status: "UP"})
+	// Need to inject directly since UpdateSiteConfig only updates existing
+	func() {
+		ts.engine.RecordHeartbeat("unused") // just to exercise, won't match
+	}()
+
+	resp, err := http.Get(ts.baseURL + "/status/json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", resp.StatusCode)
+	}
+	var state map[string]models.Site
+	json.NewDecoder(resp.Body).Decode(&state)
+	for _, site := range state {
+		if site.Token != "" {
+			t.Error("expected token stripped from status JSON response")
+		}
+	}
+}
+
+func TestStatusJSON_MaintenanceOverride(t *testing.T) {
+	ts := newTestServer(t, "secret", true)
+	ts.store.maintWindows = []models.MaintenanceWindow{
+		{ID: 1, MonitorID: 0, Type: "maintenance", StartTime: time.Now().Add(-1 * time.Hour)},
+	}
+
+	resp, err := http.Get(ts.baseURL + "/status/json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", resp.StatusCode)
+	}
+}
+
+func TestStatusPage_Disabled(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := http.Get(ts.baseURL + "/status")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 404 {
+		t.Errorf("expected 404 when status disabled, got %d", resp.StatusCode)
+	}
+}
+
+// --- Probe Assignments ---
+
+func TestProbeAssignments_Success(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := authReq("GET", ts.baseURL+"/api/probe/assignments", "secret", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		t.Errorf("expected 200, got %d", resp.StatusCode)
+	}
+	var result map[string][]models.Site
+	json.NewDecoder(resp.Body).Decode(&result)
+	if _, ok := result["sites"]; !ok {
+		t.Error("expected 'sites' key in response")
+	}
+}
+
+func TestProbeAssignments_Unauthorized(t *testing.T) {
+	ts := newTestServer(t, "secret", false)
+	resp, err := authReq("GET", ts.baseURL+"/api/probe/assignments", "wrong", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 401 {
+		t.Errorf("expected 401, got %d", resp.StatusCode)
+	}
+}

internal/store/sqlstore.go

@@ -29,12 +29,16 @@ func (s *SQLStore) q(query string) string {
 	return rewritePlaceholders(query, s.dollar)
 }
 
-func generateToken() string {
+func generateToken() (string, error) {
 	b := make([]byte, 16)
 	if _, err := rand.Read(b); err != nil {
-		panic("crypto/rand failed: " + err.Error())
+		return "", fmt.Errorf("crypto/rand failed: %w", err)
 	}
-	return hex.EncodeToString(b)
+	return hex.EncodeToString(b), nil
+}
+
+func (s *SQLStore) Close() error {
+	return s.db.Close()
 }
 
 func (s *SQLStore) Init() error {
@@ -77,7 +81,11 @@ func (s *SQLStore) GetSites() ([]models.Site, error) {
 func (s *SQLStore) AddSite(site models.Site) error {
 	token := ""
 	if site.Type == "push" {
-		token = generateToken()
+		var err error
+		token, err = generateToken()
+		if err != nil {
+			return fmt.Errorf("generate push token: %w", err)
+		}
 	}
 	_, err := s.db.Exec(s.q("INSERT INTO sites (name, url, type, token, interval, alert_id, check_ssl, threshold, max_retries, hostname, port, timeout, method, description, parent_id, accepted_codes, dns_resolve_type, dns_server, ignore_tls, paused, regions) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)"),
 		site.Name, site.URL, site.Type, token, site.Interval, site.AlertID, site.CheckSSL, site.ExpiryThreshold, site.MaxRetries,
@@ -89,7 +97,11 @@ func (s *SQLStore) UpdateSite(site models.Site) error {
 	var existingToken string
 	s.db.QueryRow(s.q("SELECT token FROM sites WHERE id=?"), site.ID).Scan(&existingToken)
 	if site.Type == "push" && existingToken == "" {
-		existingToken = generateToken()
+		var err error
+		existingToken, err = generateToken()
+		if err != nil {
+			return fmt.Errorf("generate push token: %w", err)
+		}
 	}
 	_, err := s.db.Exec(s.q("UPDATE sites SET name=?, url=?, type=?, token=?, interval=?, alert_id=?, check_ssl=?, threshold=?, max_retries=?, hostname=?, port=?, timeout=?, method=?, description=?, parent_id=?, accepted_codes=?, dns_resolve_type=?, dns_server=?, ignore_tls=?, paused=?, regions=? WHERE id=?"),
 		site.Name, site.URL, site.Type, existingToken, site.Interval, site.AlertID, site.CheckSSL, site.ExpiryThreshold, site.MaxRetries,
@@ -132,7 +144,9 @@ func (s *SQLStore) GetAlertByName(name string) (models.AlertConfig, error) {
 	if err != nil {
 		return a, err
 	}
-	json.Unmarshal([]byte(settingsJSON), &a.Settings)
+	if err := json.Unmarshal([]byte(settingsJSON), &a.Settings); err != nil {
+		return a, fmt.Errorf("unmarshal alert settings: %w", err)
+	}
 	return a, nil
 }
 
@@ -171,7 +185,9 @@ func (s *SQLStore) GetAllAlerts() ([]models.AlertConfig, error) {
 		if err := rows.Scan(&a.ID, &a.Name, &a.Type, &settingsJSON); err != nil {
 			return alerts, err
 		}
-		json.Unmarshal([]byte(settingsJSON), &a.Settings)
+		if err := json.Unmarshal([]byte(settingsJSON), &a.Settings); err != nil {
+			return alerts, fmt.Errorf("unmarshal alert settings for %q: %w", a.Name, err)
+		}
 		alerts = append(alerts, a)
 	}
 	return alerts, rows.Err()
@@ -184,7 +200,9 @@ func (s *SQLStore) GetAlert(id int) (models.AlertConfig, error) {
 	if err != nil {
 		return a, err
 	}
-	json.Unmarshal([]byte(settingsJSON), &a.Settings)
+	if err := json.Unmarshal([]byte(settingsJSON), &a.Settings); err != nil {
+		return a, fmt.Errorf("unmarshal alert settings: %w", err)
+	}
 	return a, nil
 }
 

internal/store/store.go

@@ -64,4 +64,7 @@ type Store interface {
 	// Backup & Restore
 	ExportData() (models.Backup, error)
 	ImportData(data models.Backup) error
+
+	// Lifecycle
+	Close() error
 }