diff --git a/sdk/cliproxy/service.go b/sdk/cliproxy/service.go
index dd22987fd7..54ba7dbb17 100644
--- a/sdk/cliproxy/service.go
+++ b/sdk/cliproxy/service.go
@@ -879,6 +879,11 @@ func (s *Service) registerModelsForAuth(a *coreauth.Auth) {
 		if a.Attributes != nil {
 			codexPlanType = strings.TrimSpace(a.Attributes["plan_type"])
 		}
+		if authKind != "apikey" {
+			if override := codexOAuthPlanOverride(); override != "" {
+				codexPlanType = override
+			}
+		}
 		switch strings.ToLower(codexPlanType) {
 		case "pro":
 			models = registry.GetCodexProModels()
@@ -1180,6 +1185,20 @@ func (s *Service) resolveConfigCodexKey(auth *coreauth.Auth) *config.CodexKey {
 	return nil
 }
 
+func codexOAuthPlanOverride() string {
+	raw := strings.TrimSpace(os.Getenv("CODEX_OAUTH_PLAN_OVERRIDE"))
+	if raw == "" {
+		return ""
+	}
+	switch strings.ToLower(raw) {
+	case "free", "plus", "pro", "team", "business", "go":
+		return raw
+	default:
+		log.Warnf("ignoring invalid CODEX_OAUTH_PLAN_OVERRIDE value: %q", raw)
+		return ""
+	}
+}
+
 func (s *Service) oauthExcludedModels(provider, authKind string) []string {
 	cfg := s.cfg
 	if cfg == nil {
diff --git a/sdk/cliproxy/service_codex_plan_override_test.go b/sdk/cliproxy/service_codex_plan_override_test.go
new file mode 100644
index 0000000000..3359a46f7e
--- /dev/null
+++ b/sdk/cliproxy/service_codex_plan_override_test.go
@@ -0,0 +1,51 @@
+package cliproxy
+
+import (
+	"testing"
+
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
+	coreauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
+)
+
+func TestRegisterModelsForAuth_CodexOAuthPlanOverride(t *testing.T) {
+	t.Setenv("CODEX_OAUTH_PLAN_OVERRIDE", "pro")
+
+	service := &Service{}
+	auth := &coreauth.Auth{
+		ID:       "auth-codex-override",
+		Provider: "codex",
+		Status:   coreauth.StatusActive,
+		Attributes: map[string]string{
+			"auth_kind": "oauth",
+			"plan_type": "free",
+		},
+	}
+
+	modelRegistry := registry.GetGlobalRegistry()
+	modelRegistry.UnregisterClient(auth.ID)
+	t.Cleanup(func() {
+		modelRegistry.UnregisterClient(auth.ID)
+	})
+
+	service.registerModelsForAuth(auth)
+
+	models := modelRegistry.GetModelsForClient(auth.ID)
+	if len(models) == 0 {
+		t.Fatal("expected codex models to be registered")
+	}
+
+	has54 := false
+	for _, model := range models {
+		if model == nil {
+			continue
+		}
+		if model.ID == "gpt-5.4" {
+			has54 = true
+			break
+		}
+	}
+
+	if !has54 {
+		t.Fatal("expected CODEX_OAUTH_PLAN_OVERRIDE=pro to expose gpt-5.4")
+	}
+}