diff --git a/internal/daemon/daemon.go b/internal/daemon/daemon.go
index c755412..83f51ad 100644
--- a/internal/daemon/daemon.go
+++ b/internal/daemon/daemon.go
@@ -419,6 +419,14 @@ func (d *Daemon) routeMessages() {
 
 				d.logger.Info("Delivered message %s from %s to %s/%s", msg.ID, msg.From, repoName, agentName)
 			}
+
+			// Clean up acknowledged messages to prevent pile-up
+			count, err := msgMgr.DeleteAcked(repoName, agentName)
+			if err != nil {
+				d.logger.Error("Failed to clean up acked messages for %s/%s: %v", repoName, agentName, err)
+			} else if count > 0 {
+				d.logger.Debug("Cleaned up %d acked messages for %s/%s", count, repoName, agentName)
+			}
 		}
 	}
 }
diff --git a/internal/daemon/daemon_test.go b/internal/daemon/daemon_test.go
index a882edb..d814d59 100644
--- a/internal/daemon/daemon_test.go
+++ b/internal/daemon/daemon_test.go
@@ -1182,6 +1182,82 @@ func TestMessageRoutingWithRealTmux(t *testing.T) {
 	}
 }
 
+func TestMessageRoutingCleansUpAckedMessages(t *testing.T) {
+	tmuxClient := tmux.NewClient()
+	if !tmuxClient.IsTmuxAvailable() {
+		t.Fatal("tmux is required for this test but not available")
+	}
+
+	d, cleanup := setupTestDaemon(t)
+	defer cleanup()
+
+	// Create a real tmux session
+	sessionName := "mc-test-cleanup"
+	if err := tmuxClient.CreateSession(context.Background(), sessionName, true); err != nil {
+		t.Fatalf("tmux is required for this test but cannot create sessions in this environment: %v", err)
+	}
+	defer tmuxClient.KillSession(context.Background(), sessionName)
+
+	// Create window for worker
+	if err := tmuxClient.CreateWindow(context.Background(), sessionName, "worker1"); err != nil {
+		t.Fatalf("Failed to create worker window: %v", err)
+	}
+
+	// Add repo and agent
+	repo := &state.Repository{
+		GithubURL:   "https://github.com/test/repo",
+		TmuxSession: sessionName,
+		Agents:      make(map[string]state.Agent),
+	}
+	if err := d.state.AddRepo("test-repo", repo); err != nil {
+		t.Fatalf("Failed to add repo: %v", err)
+	}
+
+	worker := state.Agent{
+		Type:       state.AgentTypeWorker,
+		TmuxWindow: "worker1",
+		Task:       "Test task",
+		CreatedAt:  time.Now(),
+	}
+	if err := d.state.AddAgent("test-repo", "worker1", worker); err != nil {
+		t.Fatalf("Failed to add worker: %v", err)
+	}
+
+	// Create messages and immediately ack them
+	msgMgr := messages.NewManager(d.paths.MessagesDir)
+	for i := 0; i < 5; i++ {
+		msg, err := msgMgr.Send("test-repo", "supervisor", "worker1", "Test message")
+		if err != nil {
+			t.Fatalf("Failed to send message: %v", err)
+		}
+		// Mark as acked
+		if err := msgMgr.Ack("test-repo", "worker1", msg.ID); err != nil {
+			t.Fatalf("Failed to ack message: %v", err)
+		}
+	}
+
+	// Verify we have 5 acked messages
+	allMsgs, err := msgMgr.List("test-repo", "worker1")
+	if err != nil {
+		t.Fatalf("Failed to list messages: %v", err)
+	}
+	if len(allMsgs) != 5 {
+		t.Fatalf("Expected 5 messages, got %d", len(allMsgs))
+	}
+
+	// Trigger message routing which should clean up acked messages
+	d.TriggerMessageRouting()
+
+	// Verify acked messages were deleted
+	remainingMsgs, err := msgMgr.List("test-repo", "worker1")
+	if err != nil {
+		t.Fatalf("Failed to list messages after cleanup: %v", err)
+	}
+	if len(remainingMsgs) != 0 {
+		t.Errorf("Expected 0 messages after cleanup, got %d", len(remainingMsgs))
+	}
+}
+
 func TestWakeLoopUpdatesNudgeTime(t *testing.T) {
 	tmuxClient := tmux.NewClient()
 	if !tmuxClient.IsTmuxAvailable() {