diff --git a/agent/probe.go b/agent/probe.go
index b5285947..e39c854c 100644
--- a/agent/probe.go
+++ b/agent/probe.go
@@ -199,7 +199,6 @@ func (pm *ProbeManager) GetResults(durationMs uint16) map[string]probe.Result {
 	for key, task := range pm.probes {
 		task.mu.Lock()
 		agg := task.aggregateLocked(duration, now)
-		// The live request window still controls avg/loss, but the range fields are always 1h.
 		hourAgg := task.aggregateLocked(time.Hour, now)
 		task.mu.Unlock()
 
diff --git a/agent/probe_test.go b/agent/probe_test.go
index 865a4b24..92a2a94e 100644
--- a/agent/probe_test.go
+++ b/agent/probe_test.go
@@ -1,9 +1,13 @@
 package agent
 
 import (
+	"net"
+	"net/http"
+	"net/http/httptest"
 	"testing"
 	"time"
 
+	"github.com/henrygd/beszel/internal/entities/probe"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -87,3 +91,107 @@ func TestProbeManagerGetResultsIncludesHourResponseRange(t *testing.T) {
 	assert.Equal(t, 40.0, result[3])
 	assert.Equal(t, 20.0, result[4])
 }
+
+func TestProbeManagerGetResultsIncludesLossOnlyHourData(t *testing.T) {
+	now := time.Now().UTC()
+	task := &probeTask{}
+	task.addSampleLocked(probeSample{responseMs: -1, timestamp: now.Add(-30 * time.Second)})
+	task.addSampleLocked(probeSample{responseMs: -1, timestamp: now.Add(-10 * time.Second)})
+
+	pm := &ProbeManager{probes: map[string]*probeTask{"icmp:example.com": task}}
+
+	results := pm.GetResults(uint16(time.Minute / time.Millisecond))
+	result, ok := results["icmp:example.com"]
+	require.True(t, ok)
+	require.Len(t, result, 5)
+	assert.Equal(t, 0.0, result[0])
+	assert.Equal(t, 0.0, result[1])
+	assert.Equal(t, 0.0, result[2])
+	assert.Equal(t, 0.0, result[3])
+	assert.Equal(t, 100.0, result[4])
+}
+
+func TestProbeManagerSyncProbesStopsRemovedTasksButKeepsExisting(t *testing.T) {
+	keepCfg := probe.Config{Target: "https://example.com", Protocol: "http", Interval: 10}
+	removeCfg := probe.Config{Target: "1.1.1.1", Protocol: "icmp", Interval: 10}
+
+	keptTask := &probeTask{config: keepCfg, cancel: make(chan struct{})}
+	removedTask := &probeTask{config: removeCfg, cancel: make(chan struct{})}
+	pm := &ProbeManager{
+		probes: map[string]*probeTask{
+			keepCfg.Key():   keptTask,
+			removeCfg.Key(): removedTask,
+		},
+	}
+
+	pm.SyncProbes([]probe.Config{keepCfg})
+
+	assert.Same(t, keptTask, pm.probes[keepCfg.Key()])
+	_, exists := pm.probes[removeCfg.Key()]
+	assert.False(t, exists)
+
+	select {
+	case <-removedTask.cancel:
+	default:
+		t.Fatal("expected removed probe task to be cancelled")
+	}
+
+	select {
+	case <-keptTask.cancel:
+		t.Fatal("expected existing probe task to remain active")
+	default:
+	}
+}
+
+func TestProbeHTTP(t *testing.T) {
+	t.Run("success", func(t *testing.T) {
+		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusNoContent)
+		}))
+		defer server.Close()
+
+		responseMs := probeHTTP(server.Client(), server.URL)
+		assert.GreaterOrEqual(t, responseMs, 0.0)
+	})
+
+	t.Run("server error", func(t *testing.T) {
+		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			http.Error(w, "boom", http.StatusInternalServerError)
+		}))
+		defer server.Close()
+
+		assert.Equal(t, -1.0, probeHTTP(server.Client(), server.URL))
+	})
+}
+
+func TestProbeTCP(t *testing.T) {
+	t.Run("success", func(t *testing.T) {
+		listener, err := net.Listen("tcp", "127.0.0.1:0")
+		require.NoError(t, err)
+		defer listener.Close()
+
+		accepted := make(chan struct{})
+		go func() {
+			defer close(accepted)
+			conn, err := listener.Accept()
+			if err == nil {
+				_ = conn.Close()
+			}
+		}()
+
+		port := uint16(listener.Addr().(*net.TCPAddr).Port)
+		responseMs := probeTCP("127.0.0.1", port)
+		assert.GreaterOrEqual(t, responseMs, 0.0)
+		<-accepted
+	})
+
+	t.Run("connection failure", func(t *testing.T) {
+		listener, err := net.Listen("tcp", "127.0.0.1:0")
+		require.NoError(t, err)
+
+		port := uint16(listener.Addr().(*net.TCPAddr).Port)
+		require.NoError(t, listener.Close())
+
+		assert.Equal(t, -1.0, probeTCP("127.0.0.1", port))
+	})
+}