diff --git a/backend/internal/lifecycle/manager.go b/backend/internal/lifecycle/manager.go
index 925af553..360f17b3 100644
--- a/backend/internal/lifecycle/manager.go
+++ b/backend/internal/lifecycle/manager.go
@@ -37,7 +37,11 @@ type Manager struct {
 
 // New builds a Lifecycle Manager over the session store it writes and the messenger it uses for agent nudges.
 func New(store sessionStore, messenger ports.AgentMessenger) *Manager {
-	return &Manager{store: store, messenger: messenger, window: defaultRecentActivityWindow, clock: time.Now, react: newReactionState()}
+	// UTC so activity-driven LastActivityAt/UpdatedAt match spawn-stamped
+	// timestamps (the session manager clock is UTC too); a local clock here left
+	// `ao session get` showing created in UTC but updated in local time.
+	clock := func() time.Time { return time.Now().UTC() }
+	return &Manager{store: store, messenger: messenger, window: defaultRecentActivityWindow, clock: clock, react: newReactionState()}
 }
 
 func (m *Manager) mutate(ctx context.Context, id domain.SessionID, fn func(domain.SessionRecord, time.Time) (domain.SessionRecord, bool)) error {
diff --git a/backend/internal/lifecycle/manager_test.go b/backend/internal/lifecycle/manager_test.go
index e739fa01..4190de5e 100644
--- a/backend/internal/lifecycle/manager_test.go
+++ b/backend/internal/lifecycle/manager_test.go
@@ -138,6 +138,21 @@ func TestMarkSpawnedStoresRuntimeMetadata(t *testing.T) {
 	}
 }
 
+// TestMarkSpawned_StampsUTCActivity locks the lifecycle clock to UTC so
+// activity-driven timestamps match the session manager's spawn timestamps. A
+// local clock here left `ao session get` showing created in UTC but updated in
+// local time.
+func TestMarkSpawned_StampsUTCActivity(t *testing.T) {
+	m, st, _ := newManager()
+	st.sessions["mer-1"] = domain.SessionRecord{ID: "mer-1", ProjectID: "mer", IsTerminated: true}
+	if err := m.MarkSpawned(ctx, "mer-1", domain.SessionMetadata{RuntimeHandleID: "h1"}); err != nil {
+		t.Fatal(err)
+	}
+	if loc := st.sessions["mer-1"].Activity.LastActivityAt.Location(); loc != time.UTC {
+		t.Fatalf("LastActivityAt location = %v, want UTC", loc)
+	}
+}
+
 func TestPRObservation_CIFailingNudgesAgentWithLogs(t *testing.T) {
 	m, st, msg := newManager()
 	st.sessions["mer-1"] = working("mer-1")
diff --git a/backend/internal/session_manager/manager.go b/backend/internal/session_manager/manager.go
index 9a563e96..49bbcaea 100644
--- a/backend/internal/session_manager/manager.go
+++ b/backend/internal/session_manager/manager.go
@@ -136,7 +136,10 @@ func New(d Deps) *Manager {
 		logger:     d.Logger,
 	}
 	if m.clock == nil {
-		m.clock = time.Now
+		// UTC so spawn-stamped CreatedAt/UpdatedAt match every other session
+		// write (rename, activity) — all of which use time.Now().UTC(). A local
+		// default produced mixed-timezone timestamps in `ao session get`.
+		m.clock = func() time.Time { return time.Now().UTC() }
 	}
 	if m.lookPath == nil {
 		m.lookPath = exec.LookPath
diff --git a/backend/internal/session_manager/manager_test.go b/backend/internal/session_manager/manager_test.go
index cc7832e2..a877469d 100644
--- a/backend/internal/session_manager/manager_test.go
+++ b/backend/internal/session_manager/manager_test.go
@@ -293,6 +293,25 @@ func TestSpawn_AssignsIDAndGoesIdle(t *testing.T) {
 		t.Fatal("handle not folded")
 	}
 }
+
+// TestSpawn_StampsUTCTimestamps locks the default clock to UTC so spawn-stamped
+// CreatedAt/UpdatedAt match every other session write (rename, activity), which
+// all use time.Now().UTC(). A local default produced mixed-timezone timestamps
+// in `ao session get` (created in local time, updated in UTC).
+func TestSpawn_StampsUTCTimestamps(t *testing.T) {
+	m, st, _, _ := newManager()
+	if _, err := m.Spawn(ctx, ports.SpawnConfig{ProjectID: "mer", Kind: domain.KindWorker}); err != nil {
+		t.Fatal(err)
+	}
+	rec := st.sessions["mer-1"]
+	if loc := rec.CreatedAt.Location(); loc != time.UTC {
+		t.Fatalf("CreatedAt location = %v, want UTC", loc)
+	}
+	if loc := rec.UpdatedAt.Location(); loc != time.UTC {
+		t.Fatalf("UpdatedAt location = %v, want UTC", loc)
+	}
+}
+
 func TestSpawn_RollsBackOnRuntimeFailure(t *testing.T) {
 	m, st, _, ws := newManager()
 	m.runtime = &fakeRuntime{createErr: errors.New("boom")}