fix: canonicalize hidden system metadata

src/utils/systemMetadata.ts

@@ -0,0 +1,39 @@
+const SYSTEM_METADATA_ALIAS_GROUPS = {
+  _icon: ['_icon', 'icon'],
+  _order: ['_order', 'order'],
+  _sidebar_label: ['_sidebar_label', 'sidebar_label', 'sidebar label'],
+  _sort: ['_sort', 'sort'],
+} as const
+
+const CANONICAL_SYSTEM_METADATA_KEYS = Object.keys(SYSTEM_METADATA_ALIAS_GROUPS)
+
+const CANONICAL_BY_ALIAS = new Map<string, string>()
+
+for (const canonical of CANONICAL_SYSTEM_METADATA_KEYS) {
+  for (const alias of SYSTEM_METADATA_ALIAS_GROUPS[canonical as keyof typeof SYSTEM_METADATA_ALIAS_GROUPS]) {
+    CANONICAL_BY_ALIAS.set(alias, canonical)
+  }
+}
+
+export function normalizePropertyKey(key: string): string {
+  return key.trim().toLowerCase().replace(/\s+/g, '_')
+}
+
+export function canonicalSystemMetadataKey(key: string): string {
+  const normalized = normalizePropertyKey(key)
+  return CANONICAL_BY_ALIAS.get(normalized) ?? normalized
+}
+
+export function isSystemMetadataKey(key: string): boolean {
+  const normalized = normalizePropertyKey(key)
+  return normalized.startsWith('_') || CANONICAL_BY_ALIAS.has(normalized)
+}
+
+export function hasSystemMetadataKey(keys: Iterable<string>, canonicalKey: keyof typeof SYSTEM_METADATA_ALIAS_GROUPS): boolean {
+  for (const key of keys) {
+    if (canonicalSystemMetadataKey(key) === canonicalKey) {
+      return true
+    }
+  }
+  return false
+}