diff --git a/control/controlclient/auto.go b/control/controlclient/auto.go
index 40b02a598..50248a647 100644
--- a/control/controlclient/auto.go
+++ b/control/controlclient/auto.go
@@ -117,7 +117,7 @@ type Auto struct {
 	logf          logger.Logf
 	closed        bool
 	updateCh      chan struct{} // readable when we should inform the server of a change
-	observer      Observer      // called to update Client status; always non-nil
+	observer      Observer      // if non-nil, called to update Client status
 	observerQueue execqueue.ExecQueue
 	shutdownFn    func() // to be called prior to shutdown or nil
 
@@ -170,9 +170,6 @@ func NewNoStart(opts Options) (_ *Auto, err error) {
 		}
 	}()
 
-	if opts.Observer == nil {
-		return nil, errors.New("missing required Options.Observer")
-	}
 	if opts.Logf == nil {
 		opts.Logf = func(fmt string, args ...any) {}
 	}
@@ -609,6 +606,11 @@ func (c *Auto) sendStatus(who string, err error, url string, nm *netmap.NetworkM
 		Err:     err,
 		state:   state,
 	}
+
+	if c.observer == nil {
+		return
+	}
+
 	c.lastStatus.Store(newSt)
 
 	// Launch a new goroutine to avoid blocking the caller while the observer
diff --git a/control/controlclient/direct.go b/control/controlclient/direct.go
index 63a12b249..d30db6191 100644
--- a/control/controlclient/direct.go
+++ b/control/controlclient/direct.go
@@ -115,6 +115,9 @@ type Direct struct {
 
 // Observer is implemented by users of the control client (such as LocalBackend)
 // to get notified of changes in the control client's status.
+//
+// If an implementation of Observer also implements [NetmapDeltaUpdater], they get
+// delta updates as well as full netmap updates.
 type Observer interface {
 	// SetControlClientStatus is called when the client has a new status to
 	// report. The Client is provided to allow the Observer to track which
@@ -145,6 +148,7 @@ type Options struct {
 
 	// Observer is called when there's a change in status to report
 	// from the control client.
+	// If nil, no status updates are reported.
 	Observer Observer
 
 	// SkipIPForwardingCheck declares that the host's IP
diff --git a/ipn/ipnlocal/network-lock_test.go b/ipn/ipnlocal/network-lock_test.go
index c7c4c905f..17040fef3 100644
--- a/ipn/ipnlocal/network-lock_test.go
+++ b/ipn/ipnlocal/network-lock_test.go
@@ -41,12 +41,6 @@ import (
 	"tailscale.com/util/set"
 )
 
-type observerFunc func(controlclient.Status)
-
-func (f observerFunc) SetControlClientStatus(_ controlclient.Client, s controlclient.Status) {
-	f(s)
-}
-
 func fakeControlClient(t *testing.T, c *http.Client) (*controlclient.Auto, *eventbus.Bus) {
 	hi := hostinfo.New()
 	ni := tailcfg.NetInfo{LinkType: "wired"}
@@ -64,7 +58,6 @@ func fakeControlClient(t *testing.T, c *http.Client) (*controlclient.Auto, *even
 		},
 		HTTPTestClient:  c,
 		NoiseTestClient: c,
-		Observer:        observerFunc(func(controlclient.Status) {}),
 		Dialer:          dialer,
 		Bus:             bus,
 	}