feat(codex-skills): surface built-in .system skills as read-only

Scan ~/.codex/skills/.system so Codex CLI's bundled skills (imagegen,
skill-creator, etc.) appear in the $ autocomplete and Skills settings.
Mark them read_only on the API; the save/delete handlers refuse writes
to that path, and the UI shows a system badge with a tooltip and
disables edit/delete/save for those entries.

src/components/settings/skills-settings.tsx

@@ -990,6 +990,15 @@ export function SkillsSettings() {
                                 >
                                   {skill.scope}
                                 </Badge>
+                                {skill.read_only && (
+                                  <Badge
+                                    variant="outline"
+                                    title={t("systemHint")}
+                                    className="h-6 px-2 inline-flex items-center gap-1 text-xs leading-none shrink-0 border-amber-500/40 bg-amber-500/10 text-amber-600 dark:text-amber-400"
+                                  >
+                                    {t("systemBadge")}
+                                  </Badge>
+                                )}
                               </div>
                               <div className="text-[11px] text-muted-foreground truncate mt-1">
                                 {skill.path}
@@ -1010,6 +1019,7 @@ export function SkillsSettings() {
                               {t("actions.preview")}
                             </ContextMenuItem>
                             <ContextMenuItem
+                              disabled={skill.read_only}
                               onSelect={() => {
                                 handleEditSkill(skill).catch((err) => {
                                   console.error(
@@ -1034,7 +1044,12 @@ export function SkillsSettings() {
                               {t("actions.openInWindow")}
                             </ContextMenuItem>
                             <ContextMenuItem
-                              disabled={skillSaving || skillReading || deleting}
+                              disabled={
+                                skillSaving ||
+                                skillReading ||
+                                deleting ||
+                                skill.read_only
+                              }
                               onSelect={() => {
                                 handleRequestDeleteSkill(skill)
                               }}
@@ -1097,10 +1112,19 @@ export function SkillsSettings() {
                   selectedSkillId || isDrafting ? (
                     <div className="h-full flex flex-col">
                       <div className="border-b px-4 py-3 flex items-center justify-between gap-3">
-                        <div className="min-w-0">
+                        <div className="min-w-0 flex items-center gap-2">
                           <h3 className="text-sm font-semibold truncate">
                             {skillDraftId.trim() || t("newSkillTitle")}
                           </h3>
+                          {selectedSkill?.read_only && (
+                            <Badge
+                              variant="outline"
+                              title={t("systemHint")}
+                              className="h-5 px-1.5 text-[10px] leading-none shrink-0 border-amber-500/40 bg-amber-500/10 text-amber-600 dark:text-amber-400"
+                            >
+                              {t("systemBadge")}
+                            </Badge>
+                          )}
                         </div>
 
                         <div className="flex items-center gap-1.5 shrink-0">
@@ -1123,7 +1147,11 @@ export function SkillsSettings() {
                                 )
                               })
                             }}
-                            disabled={skillSaving || skillReading}
+                            disabled={
+                              skillSaving ||
+                              skillReading ||
+                              Boolean(selectedSkill?.read_only)
+                            }
                           >
                             {skillSaving ? (
                               <>
@@ -1189,7 +1217,10 @@ export function SkillsSettings() {
                                 onClick={() => {
                                   setIsContentEditing((prev) => !prev)
                                 }}
-                                disabled={skillReading}
+                                disabled={
+                                  skillReading ||
+                                  Boolean(selectedSkill?.read_only)
+                                }
                               >
                                 {isContentEditing ? (
                                   <>

src/i18n/messages/ar.json

@@ -302,6 +302,8 @@
     "loadingSkill": "جارٍ تحميل Skill...",
     "emptyNoAgents": "لا يوجد وكيل متاح.",
     "noSelectionHint": "اختر Skill من اليسار، أو انقر على \"Skill جديد\" لإنشاء واحد.",
+    "systemBadge": "نظام",
+    "systemHint": "Skill مدمج في CLI · للقراءة فقط",
     "scope": {
       "global": "عام",
       "folder": "مجلد",

src/i18n/messages/de.json

@@ -302,6 +302,8 @@
     "loadingSkill": "Skill wird geladen...",
     "emptyNoAgents": "Kein verfügbarer Agent.",
     "noSelectionHint": "Wählen Sie links einen Skill oder klicken Sie auf „Neuer Skill“, um einen zu erstellen.",
+    "systemBadge": "System",
+    "systemHint": "Integrierter CLI-Skill · schreibgeschützt",
     "scope": {
       "global": "Global",
       "folder": "Ordner",

src/i18n/messages/en.json

@@ -302,6 +302,8 @@
     "loadingSkill": "Loading skill...",
     "emptyNoAgents": "No available agent.",
     "noSelectionHint": "Select a skill on the left, or click \"New Skill\" to create one.",
+    "systemBadge": "System",
+    "systemHint": "Built-in CLI skill · read-only",
     "scope": {
       "global": "Global",
       "folder": "Folder",

src/i18n/messages/es.json

@@ -302,6 +302,8 @@
     "loadingSkill": "Cargando Skill...",
     "emptyNoAgents": "No hay agentes disponibles.",
     "noSelectionHint": "Selecciona un Skill a la izquierda o haz clic en \"Nuevo Skill\" para crear uno.",
+    "systemBadge": "Sistema",
+    "systemHint": "Skill integrado del CLI · solo lectura",
     "scope": {
       "global": "Global",
       "folder": "Carpeta",

src/i18n/messages/fr.json

@@ -302,6 +302,8 @@
     "loadingSkill": "Chargement de la Skill...",
     "emptyNoAgents": "Aucun agent disponible.",
     "noSelectionHint": "Sélectionnez un Skill à gauche ou cliquez sur « Nouveau Skill » pour en créer un.",
+    "systemBadge": "Système",
+    "systemHint": "Skill intégré du CLI · lecture seule",
     "scope": {
       "global": "Global",
       "folder": "Dossier",

src/i18n/messages/ja.json

@@ -302,6 +302,8 @@
     "loadingSkill": "Skillを読み込み中...",
     "emptyNoAgents": "利用可能なエージェントがありません。",
     "noSelectionHint": "左側から Skill を選択するか、「新規 Skill」をクリックして作成してください。",
+    "systemBadge": "システム",
+    "systemHint": "CLI 組み込み Skill・読み取り専用",
     "scope": {
       "global": "グローバル",
       "folder": "フォルダ",

src/i18n/messages/ko.json

@@ -302,6 +302,8 @@
     "loadingSkill": "Skill 불러오는 중...",
     "emptyNoAgents": "사용 가능한 에이전트가 없습니다.",
     "noSelectionHint": "왼쪽에서 Skill을 선택하거나 \"새 Skill\"을 클릭하여 만드세요.",
+    "systemBadge": "시스템",
+    "systemHint": "CLI 내장 Skill · 읽기 전용",
     "scope": {
       "global": "전역",
       "folder": "폴더",

src/i18n/messages/pt.json

@@ -302,6 +302,8 @@
     "loadingSkill": "Carregando Skill...",
     "emptyNoAgents": "Nenhum agente disponível.",
     "noSelectionHint": "Selecione um Skill à esquerda ou clique em \"Novo Skill\" para criar um.",
+    "systemBadge": "Sistema",
+    "systemHint": "Skill integrado do CLI · somente leitura",
     "scope": {
       "global": "Global",
       "folder": "Pasta",

src/i18n/messages/zh-CN.json

@@ -302,6 +302,8 @@
     "loadingSkill": "正在加载 Skill...",
     "emptyNoAgents": "暂无可用 Agent。",
     "noSelectionHint": "从左侧选择一个 Skill，或点击“新建 Skill”创建。",
+    "systemBadge": "系统",
+    "systemHint": "CLI 内置 Skill · 只读",
     "scope": {
       "global": "全局",
       "folder": "文件夹",

src/i18n/messages/zh-TW.json

@@ -302,6 +302,8 @@
     "loadingSkill": "正在載入 Skill...",
     "emptyNoAgents": "暫無可用 Agent。",
     "noSelectionHint": "從左側選擇一個 Skill，或點擊「新建 Skill」建立。",
+    "systemBadge": "系統",
+    "systemHint": "CLI 內建 Skill · 唯讀",
     "scope": {
       "global": "全域",
       "folder": "資料夾",

src/lib/types.ts

@@ -557,6 +557,7 @@ export interface AgentSkillItem {
   scope: AgentSkillScope
   layout: AgentSkillLayout
   path: string
+  read_only: boolean
 }
 
 export interface AgentSkillsListResult {