diff --git a/sdk/cliproxy/auth/conductor.go b/sdk/cliproxy/auth/conductor.go
index 3434b7a7..ae5b745c 100644
--- a/sdk/cliproxy/auth/conductor.go
+++ b/sdk/cliproxy/auth/conductor.go
@@ -463,9 +463,14 @@ func (m *Manager) Update(ctx context.Context, auth *Auth) (*Auth, error) {
 		return nil, nil
 	}
 	m.mu.Lock()
-	if existing, ok := m.auths[auth.ID]; ok && existing != nil && !auth.indexAssigned && auth.Index == "" {
-		auth.Index = existing.Index
-		auth.indexAssigned = existing.indexAssigned
+	if existing, ok := m.auths[auth.ID]; ok && existing != nil {
+		if !auth.indexAssigned && auth.Index == "" {
+			auth.Index = existing.Index
+			auth.indexAssigned = existing.indexAssigned
+		}
+		if len(auth.ModelStates) == 0 && len(existing.ModelStates) > 0 {
+			auth.ModelStates = existing.ModelStates
+		}
 	}
 	auth.EnsureIndex()
 	m.auths[auth.ID] = auth.Clone()
diff --git a/sdk/cliproxy/auth/conductor_update_test.go b/sdk/cliproxy/auth/conductor_update_test.go
new file mode 100644
index 00000000..f058f517
--- /dev/null
+++ b/sdk/cliproxy/auth/conductor_update_test.go
@@ -0,0 +1,49 @@
+package auth
+
+import (
+	"context"
+	"testing"
+)
+
+func TestManager_Update_PreservesModelStates(t *testing.T) {
+	m := NewManager(nil, nil, nil)
+
+	model := "test-model"
+	backoffLevel := 7
+
+	if _, errRegister := m.Register(context.Background(), &Auth{
+		ID:       "auth-1",
+		Provider: "claude",
+		Metadata: map[string]any{"k": "v"},
+		ModelStates: map[string]*ModelState{
+			model: {
+				Quota: QuotaState{BackoffLevel: backoffLevel},
+			},
+		},
+	}); errRegister != nil {
+		t.Fatalf("register auth: %v", errRegister)
+	}
+
+	if _, errUpdate := m.Update(context.Background(), &Auth{
+		ID:       "auth-1",
+		Provider: "claude",
+		Metadata: map[string]any{"k": "v2"},
+	}); errUpdate != nil {
+		t.Fatalf("update auth: %v", errUpdate)
+	}
+
+	updated, ok := m.GetByID("auth-1")
+	if !ok || updated == nil {
+		t.Fatalf("expected auth to be present")
+	}
+	if len(updated.ModelStates) == 0 {
+		t.Fatalf("expected ModelStates to be preserved")
+	}
+	state := updated.ModelStates[model]
+	if state == nil {
+		t.Fatalf("expected model state to be present")
+	}
+	if state.Quota.BackoffLevel != backoffLevel {
+		t.Fatalf("expected BackoffLevel to be %d, got %d", backoffLevel, state.Quota.BackoffLevel)
+	}
+}
diff --git a/sdk/cliproxy/service.go b/sdk/cliproxy/service.go
index 4be83816..9952e7b2 100644
--- a/sdk/cliproxy/service.go
+++ b/sdk/cliproxy/service.go
@@ -290,6 +290,9 @@ func (s *Service) applyCoreAuthAddOrUpdate(ctx context.Context, auth *coreauth.A
 		auth.CreatedAt = existing.CreatedAt
 		auth.LastRefreshedAt = existing.LastRefreshedAt
 		auth.NextRefreshAfter = existing.NextRefreshAfter
+		if len(auth.ModelStates) == 0 && len(existing.ModelStates) > 0 {
+			auth.ModelStates = existing.ModelStates
+		}
 		op = "update"
 		_, err = s.coreManager.Update(ctx, auth)
 	} else {