[ci skip] more codex 5.3 improvements

server/handler/legacy_gate.go

@@ -0,0 +1,23 @@
+package handler
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+	"strings"
+)
+
+const legacyAPIEnvVar = "VCTP_ENABLE_LEGACY_API"
+
+func legacyAPIEnabled() bool {
+	return strings.TrimSpace(os.Getenv(legacyAPIEnvVar)) == "1"
+}
+
+func (h *Handler) denyLegacyAPI(w http.ResponseWriter, endpoint string) bool {
+	if legacyAPIEnabled() {
+		return false
+	}
+	h.Logger.Warn("legacy endpoint request blocked", "endpoint", endpoint, "env_var", legacyAPIEnvVar)
+	writeJSONError(w, http.StatusGone, fmt.Sprintf("%s is deprecated and disabled; set %s=1 to temporarily re-enable", endpoint, legacyAPIEnvVar))
+	return true
+}