diff --git a/sds/sds.go b/sds/sds.go
index b1ed01c..8d77e82 100644
--- a/sds/sds.go
+++ b/sds/sds.go
@@ -257,7 +257,7 @@ func (rm *ReliabilityManager) RegisterCallbacks(callbacks EventCallbacks) {
 
 func (rm *ReliabilityManager) OnEvent(eventStr string) {
 
-	fmt.Println("------------------- received event: ", eventStr)
+	fmt.Println("------------------- received event: ", eventStr) // TODO: remove after debugging
 
 	jsonEvent := jsonEvent{}
 	err := json.Unmarshal([]byte(eventStr), &jsonEvent)
@@ -385,7 +385,7 @@ func (rm *ReliabilityManager) WrapOutgoingMessage(message []byte, messageId Mess
 		return nil, err
 	}
 
-	Debug("Wraping outgoing message %v", messageId)
+	Debug("Wrapping outgoing message %v", messageId)
 
 	wg := sync.WaitGroup{}
 	var resp = C.allocResp(unsafe.Pointer(&wg))
diff --git a/sds/sds_test.go b/sds/sds_test.go
index cab0155..7407fd3 100644
--- a/sds/sds_test.go
+++ b/sds/sds_test.go
@@ -1,7 +1,10 @@
 package sds
 
 import (
+	"fmt"
+	"sync"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 )
@@ -89,3 +92,124 @@ func TestDependencies(t *testing.T) {
 	err = rm2.MarkDependenciesMet([]MessageID{msgID1})
 	require.NoError(t, err)
 }
+
+// Test callbacks
+func TestCallbacks(t *testing.T) {
+	channelID := "test-callbacks"
+	rm, err := NewReliabilityManager(channelID)
+	require.NoError(t, err)
+	defer rm.Cleanup()
+
+	var wg sync.WaitGroup
+	receivedReady := make(map[MessageID]bool)
+	receivedSent := make(map[MessageID]bool)
+	receivedMissing := make(map[MessageID][]MessageID)
+	syncRequested := false
+	var cbMutex sync.Mutex // Protect access to callback tracking maps/vars
+
+	callbacks := EventCallbacks{
+		OnMessageReady: func(messageId MessageID) {
+			fmt.Printf("Test: OnMessageReady received: %s\n", messageId)
+			cbMutex.Lock()
+			receivedReady[messageId] = true
+			cbMutex.Unlock()
+			wg.Done()
+		},
+		OnMessageSent: func(messageId MessageID) {
+			fmt.Printf("Test: OnMessageSent received: %s\n", messageId)
+			cbMutex.Lock()
+			receivedSent[messageId] = true
+			cbMutex.Unlock()
+			wg.Done()
+		},
+		OnMissingDependencies: func(messageId MessageID, missingDeps []MessageID) {
+			fmt.Printf("Test: OnMissingDependencies received for %s: %v\n", messageId, missingDeps)
+			cbMutex.Lock()
+			receivedMissing[messageId] = missingDeps
+			cbMutex.Unlock()
+			wg.Done()
+		},
+		OnPeriodicSync: func() {
+			fmt.Println("Test: OnPeriodicSync received")
+			cbMutex.Lock()
+			syncRequested = true
+			cbMutex.Unlock()
+			// Don't wg.Done() here, it might be called multiple times
+		},
+	}
+
+	rm.RegisterCallbacks(callbacks)
+
+	// Start tasks AFTER registering callbacks
+	err = rm.StartPeriodicTasks()
+	require.NoError(t, err)
+
+	// --- Test Scenario ---
+
+	// 1. Send msg1
+	wg.Add(1) // Expect OnMessageSent for msg1 eventually
+	payload1 := []byte("callback test 1")
+	msgID1 := MessageID("cb-msg-1")
+	wrappedMsg1, err := rm.WrapOutgoingMessage(payload1, msgID1)
+	require.NoError(t, err)
+
+	// 2. Receive msg1 (triggers OnMessageReady for msg1, OnMessageSent for msg1 via causal history)
+	wg.Add(1) // Expect OnMessageReady for msg1
+	_, err = rm.UnwrapReceivedMessage(wrappedMsg1)
+	require.NoError(t, err)
+
+	// 3. Send msg2 (depends on msg1)
+	wg.Add(1) // Expect OnMessageSent for msg2 eventually
+	payload2 := []byte("callback test 2")
+	msgID2 := MessageID("cb-msg-2")
+	wrappedMsg2, err := rm.WrapOutgoingMessage(payload2, msgID2)
+	require.NoError(t, err)
+
+	// 4. Receive msg2 (triggers OnMessageReady for msg2, OnMessageSent for msg2)
+	wg.Add(1) // Expect OnMessageReady for msg2
+	_, err = rm.UnwrapReceivedMessage(wrappedMsg2)
+	require.NoError(t, err)
+
+	// --- Verification ---
+	// Wait for expected callbacks with a timeout
+	waitTimeout(&wg, 5*time.Second, t)
+
+	cbMutex.Lock()
+	defer cbMutex.Unlock()
+
+	if !receivedReady[msgID1] {
+		t.Errorf("OnMessageReady not called for %s", msgID1)
+	}
+	if !receivedReady[msgID2] {
+		t.Errorf("OnMessageReady not called for %s", msgID2)
+	}
+	if !receivedSent[msgID1] {
+		t.Errorf("OnMessageSent not called for %s", msgID1)
+	}
+	if !receivedSent[msgID2] {
+		t.Errorf("OnMessageSent not called for %s", msgID2)
+	}
+	// We didn't explicitly test missing deps in this path
+	if len(receivedMissing) > 0 {
+		t.Errorf("Unexpected OnMissingDependencies calls: %v", receivedMissing)
+	}
+	// Periodic sync is harder to guarantee in a short test, just check if it was ever true
+	if !syncRequested {
+		t.Logf("Warning: OnPeriodicSync might not have been called within the test timeout")
+	}
+}
+
+// Helper function to wait for WaitGroup with a timeout
+func waitTimeout(wg *sync.WaitGroup, timeout time.Duration, t *testing.T) {
+	c := make(chan struct{})
+	go func() {
+		defer close(c)
+		wg.Wait()
+	}()
+	select {
+	case <-c:
+		// Completed normally
+	case <-time.After(timeout):
+		t.Fatalf("Timed out waiting for callbacks")
+	}
+}