diff --git a/packages/ui/src/components/sections/skills/SkillsPage.tsx b/packages/ui/src/components/sections/skills/SkillsPage.tsx
index bf346d51..9f91f047 100644
--- a/packages/ui/src/components/sections/skills/SkillsPage.tsx
+++ b/packages/ui/src/components/sections/skills/SkillsPage.tsx
@@ -1,7 +1,9 @@
 import React from 'react';
+import { parse as parseYaml, stringify as stringifyYaml } from 'yaml';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Textarea } from '@/components/ui/textarea';
+import { CodeMirrorEditor } from '@/components/ui/CodeMirrorEditor';
 import { toast } from '@/components/ui';
 import { useSkillsStore, type SkillConfig, type SkillScope, type SupportingFile, type PendingFile } from '@/stores/useSkillsStore';
 import { useShallow } from 'zustand/react/shallow';
@@ -21,6 +23,8 @@ import {
   DialogTitle,
 } from '@/components/ui/dialog';
 import { Icon } from "@/components/icon/Icon";
+import { SimpleMarkdownRenderer } from '@/components/chat/MarkdownRenderer';
+import { PreviewToggleButton } from '@/components/views/PreviewToggleButton';
 import { SkillsCatalogPage } from './catalog/SkillsCatalogPage';
 import {
   SKILL_LOCATION_OPTIONS,
@@ -29,6 +33,12 @@ import {
   type SkillLocationValue,
 } from './skillLocations';
 import { useI18n } from '@/lib/i18n';
+import { languageByExtension } from '@/lib/codemirror/languageByExtension';
+import { createFlexokiCodeMirrorTheme } from '@/lib/codemirror/flexokiTheme';
+import { useThemeSystem } from '@/contexts/useThemeSystem';
+import { cn } from '@/lib/utils';
+import { EditorView } from '@codemirror/view';
+import type { Extension } from '@codemirror/state';
 
 export interface SkillsPageProps {
   view?: 'installed' | 'catalog';
@@ -38,8 +48,57 @@ const SkillsCatalogStandalone: React.FC = () => (
   <SkillsCatalogPage mode="external" onModeChange={() => {}} showModeTabs={false} />
 );
 
+type SkillDocumentParseResult = {
+  description: string | null;
+  instructions: string;
+};
+
+const SKILL_DOCUMENT_PATH = 'SKILL.md';
+const SKILL_EDITOR_HEIGHT_CLASS = 'h-[clamp(320px,58dvh,680px)] min-h-[260px] max-h-[calc(100dvh-220px)]';
+
+const buildSkillMarkdown = (description: string, instructions: string): string => {
+  const frontmatter = stringifyYaml({ description }).trimEnd();
+  const body = instructions.trimStart();
+  return `---\n${frontmatter}\n---${body ? `\n\n${body}` : '\n'}`;
+};
+
+const isRecord = (value: unknown): value is Record<string, unknown> => (
+  typeof value === 'object' && value !== null && !Array.isArray(value)
+);
+
+const parseSkillMarkdown = (value: string): SkillDocumentParseResult => {
+  const match = value.match(/^---\r?\n([\s\S]*?)\r?\n---(?:\r?\n|$)([\s\S]*)$/);
+  if (!match) {
+    return { description: null, instructions: value };
+  }
+
+  let description: string | null = null;
+  try {
+    const frontmatter: unknown = parseYaml(match[1]);
+    if (isRecord(frontmatter)) {
+      const candidate = frontmatter.description;
+      if (typeof candidate === 'string') {
+        description = candidate;
+      }
+    }
+  } catch {
+    description = null;
+  }
+
+  return {
+    description,
+    instructions: match[2].replace(/^\r?\n/, ''),
+  };
+};
+
+const replaceSkillMarkdownDescription = (value: string, description: string): string => {
+  const parsed = parseSkillMarkdown(value);
+  return buildSkillMarkdown(description, parsed.instructions);
+};
+
 const SkillsInstalledPage: React.FC = () => {
   const { t } = useI18n();
+  const { currentTheme } = useThemeSystem();
   const {
     selectedSkillName,
     getSkillByName,
@@ -65,6 +124,7 @@ const SkillsInstalledPage: React.FC = () => {
   const selectedSkill = selectedSkillName ? getSkillByName(selectedSkillName) : null;
   const isNewSkill = Boolean(skillDraft && skillDraft.name === selectedSkillName && !selectedSkill);
   const hasStaleSelection = Boolean(selectedSkillName && !selectedSkill && !skillDraft);
+  const isReadOnlySkill = selectedSkill?.path === '<built-in>';
 
   React.useEffect(() => {
     if (!hasStaleSelection) {
@@ -79,6 +139,8 @@ const SkillsInstalledPage: React.FC = () => {
   const [draftSource, setDraftSource] = React.useState<'opencode' | 'agents'>('opencode');
   const [description, setDescription] = React.useState('');
   const [instructions, setInstructions] = React.useState('');
+  const [skillMarkdown, setSkillMarkdown] = React.useState(() => buildSkillMarkdown('', ''));
+  const [skillEditorMode, setSkillEditorMode] = React.useState<'edit' | 'preview'>('edit');
   const [supportingFiles, setSupportingFiles] = React.useState<SupportingFile[]>([]);
   const [pendingFiles, setPendingFiles] = React.useState<PendingFile[]>([]);
   const [isSaving, setIsSaving] = React.useState(false);
@@ -141,11 +203,14 @@ const SkillsInstalledPage: React.FC = () => {
   React.useEffect(() => {
     const loadSkillDetails = async () => {
       if (isNewSkill && skillDraft) {
+        const nextDescription = skillDraft.description || '';
+        const nextInstructions = skillDraft.instructions || '';
         setDraftName(skillDraft.name || '');
         setDraftScope(skillDraft.scope || 'user');
         setDraftSource(skillDraft.source === 'agents' ? 'agents' : 'opencode');
-        setDescription(skillDraft.description || '');
-        setInstructions(skillDraft.instructions || '');
+        setDescription(nextDescription);
+        setInstructions(nextInstructions);
+        setSkillMarkdown(buildSkillMarkdown(nextDescription, nextInstructions));
         setOriginalDescription('');
         setOriginalInstructions('');
         setSupportingFiles([]);
@@ -156,10 +221,13 @@ const SkillsInstalledPage: React.FC = () => {
           const detail = await getSkillDetail(selectedSkillName);
           if (detail) {
             const md = detail.sources.md;
-            setDescription(md.description || '');
-            setInstructions(md.instructions || '');
-            setOriginalDescription(md.description || '');
-            setOriginalInstructions(md.instructions || '');
+            const nextDescription = md.description || '';
+            const nextInstructions = md.instructions || '';
+            setDescription(nextDescription);
+            setInstructions(nextInstructions);
+            setSkillMarkdown(buildSkillMarkdown(nextDescription, nextInstructions));
+            setOriginalDescription(nextDescription);
+            setOriginalInstructions(nextInstructions);
             setSupportingFiles(md.supportingFiles || []);
           }
         } catch (error) {
@@ -173,6 +241,39 @@ const SkillsInstalledPage: React.FC = () => {
     loadSkillDetails();
   }, [selectedSkill, isNewSkill, selectedSkillName, skills, skillDraft, getSkillDetail]);
 
+  const skillEditorExtensions = React.useMemo<Extension[]>(() => {
+    const extensions: Extension[] = [createFlexokiCodeMirrorTheme(currentTheme)];
+    const markdownExtension = languageByExtension(SKILL_DOCUMENT_PATH);
+    if (markdownExtension) {
+      extensions.push(markdownExtension);
+    }
+    extensions.push(EditorView.lineWrapping);
+    return extensions;
+  }, [currentTheme]);
+
+  const supportingFileEditorExtensions = React.useMemo<Extension[]>(() => {
+    const filePath = newFileName.trim() || 'supporting-file.md';
+    const extensions: Extension[] = [createFlexokiCodeMirrorTheme(currentTheme)];
+    const languageExtension = languageByExtension(filePath);
+    if (languageExtension) {
+      extensions.push(languageExtension);
+    }
+    extensions.push(EditorView.lineWrapping);
+    return extensions;
+  }, [currentTheme, newFileName]);
+
+  const handleDescriptionChange = React.useCallback((nextDescription: string) => {
+    setDescription(nextDescription);
+    setSkillMarkdown((current) => replaceSkillMarkdownDescription(current, nextDescription));
+  }, []);
+
+  const handleSkillMarkdownChange = React.useCallback((nextMarkdown: string) => {
+    setSkillMarkdown(nextMarkdown);
+    const parsed = parseSkillMarkdown(nextMarkdown);
+    setDescription(parsed.description ?? '');
+    setInstructions(parsed.instructions);
+  }, []);
+
   const handleSave = async () => {
     const skillName = isNewSkill ? draftName.trim().replace(/\s+/g, '-').toLowerCase() : selectedSkillName?.trim();
 
@@ -469,10 +570,11 @@ const SkillsInstalledPage: React.FC = () => {
               <div className="mt-1.5">
                 <Textarea
                   value={description}
-                  onChange={(e) => setDescription(e.target.value)}
+                  onChange={(e) => handleDescriptionChange(e.target.value)}
                   placeholder={t('settings.skills.page.field.descriptionPlaceholder')}
                   rows={2}
                   className="w-full resize-none min-h-[60px] max-h-32 bg-transparent"
+                  disabled={isReadOnlySkill}
                 />
               </div>
             </div>
@@ -482,19 +584,44 @@ const SkillsInstalledPage: React.FC = () => {
 
         {/* Instructions */}
         <div className="mb-8">
-          <div className="mb-1 px-1">
+          <div className="mb-1 px-1 flex items-center justify-between gap-2">
             <h3 className="typography-ui-header font-medium text-foreground">
               {t('settings.skills.page.section.instructions')}
             </h3>
+            <PreviewToggleButton
+              currentMode={skillEditorMode === 'preview' ? 'preview' : 'edit'}
+              onToggle={() => setSkillEditorMode((mode) => mode === 'preview' ? 'edit' : 'preview')}
+            />
           </div>
 
           <section className="px-2 pb-2 pt-0">
-            <Textarea
-              value={instructions}
-              onChange={(e) => setInstructions(e.target.value)}
-              placeholder={t('settings.skills.page.field.instructionsPlaceholder')}
-              className="min-h-[220px] max-h-[60vh] font-mono typography-meta"
-            />
+            <div
+              className={cn(
+                'overflow-hidden rounded-md border border-[var(--surface-subtle)] bg-background',
+                SKILL_EDITOR_HEIGHT_CLASS,
+              )}
+            >
+              {skillEditorMode === 'preview' ? (
+                <ScrollableOverlay outerClassName="h-full" className="h-full">
+                  <div className="min-h-full px-4 py-3">
+                    <SimpleMarkdownRenderer
+                      content={skillMarkdown}
+                      className="typography-markdown-body"
+                      stripFrontmatter
+                    />
+                  </div>
+                </ScrollableOverlay>
+              ) : (
+                <CodeMirrorEditor
+                  value={skillMarkdown}
+                  onChange={handleSkillMarkdownChange}
+                  readOnly={isReadOnlySkill}
+                  extensions={skillEditorExtensions}
+                  className="h-full"
+                  enableSearch
+                />
+              )}
+            </div>
           </section>
         </div>
 
@@ -504,7 +631,7 @@ const SkillsInstalledPage: React.FC = () => {
             <h3 className="typography-ui-header font-medium text-foreground">
               {t('settings.skills.page.section.supportingFiles')}
             </h3>
-            <Button variant="outline" size="xs" className="!font-normal gap-1" onClick={handleAddFile}>
+            <Button variant="outline" size="xs" className="!font-normal gap-1" onClick={handleAddFile} disabled={isReadOnlySkill}>
               <Icon name="add" className="h-3.5 w-3.5" /> {t('settings.skills.page.actions.addFile')}
             </Button>
           </div>
@@ -536,16 +663,18 @@ const SkillsInstalledPage: React.FC = () => {
                           {t('settings.skills.page.badge.pending')}
                         </span>
                       )}
-                      <Button size="sm"
-                        variant="ghost"
-                        className="h-5 w-5 px-0 flex-shrink-0 text-muted-foreground hover:text-[var(--status-error)] opacity-0 group-hover:opacity-100 transition-opacity"
-                        onClick={(e) => {
-                          e.stopPropagation();
-                          handleDeleteFile(file.path);
-                        }}
-                      >
-                        <Icon name="delete-bin" className="h-3 w-3" />
-                      </Button>
+                      {!isReadOnlySkill && (
+                        <Button size="sm"
+                          variant="ghost"
+                          className="h-5 w-5 px-0 flex-shrink-0 text-muted-foreground hover:text-[var(--status-error)] opacity-0 group-hover:opacity-100 transition-opacity"
+                          onClick={(e) => {
+                            e.stopPropagation();
+                            handleDeleteFile(file.path);
+                          }}
+                        >
+                          <Icon name="delete-bin" className="h-3 w-3" />
+                        </Button>
+                      )}
                     </div>
                   ))}
                 </div>
@@ -558,7 +687,7 @@ const SkillsInstalledPage: React.FC = () => {
         <div className="px-2 py-1">
           <Button
             onClick={handleSave}
-            disabled={isSaving || !hasSkillChanges}
+            disabled={isReadOnlySkill || isSaving || !hasSkillChanges}
             size="xs"
             className="!font-normal"
           >
@@ -638,13 +767,15 @@ const SkillsInstalledPage: React.FC = () => {
                 <label className="typography-ui-label font-medium text-foreground flex-shrink-0">
                   {t('settings.skills.page.fileDialog.field.content')}
                 </label>
-                <Textarea
-                  value={newFileContent}
-                  onChange={(e) => setNewFileContent(e.target.value)}
-                  placeholder={t('settings.skills.page.fileDialog.field.contentPlaceholder')}
-                  outerClassName="h-[45vh] min-h-[250px] max-h-[55vh]"
-                  className="h-full min-h-0 font-mono typography-meta"
-                />
+                <div className="h-[45vh] min-h-[250px] max-h-[55vh] overflow-hidden rounded-md border border-[var(--surface-subtle)] bg-background">
+                  <CodeMirrorEditor
+                    value={newFileContent}
+                    onChange={setNewFileContent}
+                    extensions={supportingFileEditorExtensions}
+                    className="h-full"
+                    enableSearch
+                  />
+                </div>
               </div>
             </div>
           )}
diff --git a/packages/ui/src/components/sections/skills/SkillsSidebar.tsx b/packages/ui/src/components/sections/skills/SkillsSidebar.tsx
index cf4b0296..4dbd0e6f 100644
--- a/packages/ui/src/components/sections/skills/SkillsSidebar.tsx
+++ b/packages/ui/src/components/sections/skills/SkillsSidebar.tsx
@@ -30,6 +30,10 @@ interface SkillsSidebarProps {
   onItemSelect?: () => void;
 }
 
+const BUILT_IN_SKILL_LOCATION = '<built-in>';
+
+const isBuiltInSkill = (skill: DiscoveredSkill | null | undefined): boolean => skill?.path === BUILT_IN_SKILL_LOCATION;
+
 export const SkillsSidebar: React.FC<SkillsSidebarProps> = ({ onItemSelect }) => {
   const { t } = useI18n();
   const [renameDialogSkill, setRenameDialogSkill] = React.useState<DiscoveredSkill | null>(null);
@@ -78,6 +82,7 @@ export const SkillsSidebar: React.FC<SkillsSidebarProps> = ({ onItemSelect }) =>
   };
 
   const handleDeleteSkill = async (skill: DiscoveredSkill) => {
+    if (isBuiltInSkill(skill)) return;
     setDeleteDialogSkill(skill);
   };
 
@@ -85,6 +90,10 @@ export const SkillsSidebar: React.FC<SkillsSidebarProps> = ({ onItemSelect }) =>
     if (!deleteDialogSkill) {
       return;
     }
+    if (isBuiltInSkill(deleteDialogSkill)) {
+      setDeleteDialogSkill(null);
+      return;
+    }
 
     setIsDeletePending(true);
     const success = await deleteSkill(deleteDialogSkill.name);
@@ -98,6 +107,8 @@ export const SkillsSidebar: React.FC<SkillsSidebarProps> = ({ onItemSelect }) =>
   };
 
   const handleDuplicateSkill = async (skill: DiscoveredSkill) => {
+    if (isBuiltInSkill(skill)) return;
+
     const baseName = skill.name;
     let copyNumber = 1;
     let newName = `${baseName}-copy`;
@@ -127,12 +138,17 @@ export const SkillsSidebar: React.FC<SkillsSidebarProps> = ({ onItemSelect }) =>
   };
 
   const handleOpenRenameDialog = (skill: DiscoveredSkill) => {
+    if (isBuiltInSkill(skill)) return;
     setRenameNewName(skill.name);
     setRenameDialogSkill(skill);
   };
 
   const handleRenameSkill = async () => {
     if (!renameDialogSkill) return;
+    if (isBuiltInSkill(renameDialogSkill)) {
+      setRenameDialogSkill(null);
+      return;
+    }
 
     const sanitizedName = renameNewName.trim().replace(/\s+/g, '-').toLowerCase();
 
@@ -443,6 +459,7 @@ const SkillListItem: React.FC<SkillListItemProps> = ({
       ? t('settings.skills.sidebar.badge.agents')
       : t('settings.skills.sidebar.badge.opencode');
   const badgeClassName = 'typography-micro text-muted-foreground bg-[var(--surface-muted)] px-1 rounded flex-shrink-0 leading-none pb-px border border-[var(--interactive-border)]/50';
+  const isBuiltIn = isBuiltInSkill(skill);
   return (
     <div
       className={cn(
@@ -471,7 +488,7 @@ const SkillListItem: React.FC<SkillListItemProps> = ({
           </div>
         </button>
 
-        <DropdownMenu open={isMenuOpen} onOpenChange={onMenuOpenChange}>
+        {!isBuiltIn ? <DropdownMenu open={isMenuOpen} onOpenChange={onMenuOpenChange}>
           <DropdownMenuTrigger asChild>
             <Button size="sm"
               variant="ghost"
@@ -512,7 +529,7 @@ const SkillListItem: React.FC<SkillListItemProps> = ({
               {t('settings.common.actions.delete')}
             </DropdownMenuItem>
           </DropdownMenuContent>
-        </DropdownMenu>
+        </DropdownMenu> : null}
       </div>
     </div>
   );
diff --git a/packages/ui/src/components/views/SettingsView.tsx b/packages/ui/src/components/views/SettingsView.tsx
index 93489fbf..f4091319 100644
--- a/packages/ui/src/components/views/SettingsView.tsx
+++ b/packages/ui/src/components/views/SettingsView.tsx
@@ -53,12 +53,17 @@ import {
 const SETTINGS_NAV_MIN_WIDTH = 176;
 const SETTINGS_NAV_MAX_WIDTH = 280;
 const SETTINGS_NAV_RESIZE_STEP = 8;
+const SETTINGS_DETAIL_HISTORY_KEY = '__openchamberSettingsDetail';
 
 function clampSettingsNavWidth(width: number): number {
   return Math.min(SETTINGS_NAV_MAX_WIDTH, Math.max(SETTINGS_NAV_MIN_WIDTH, width));
 }
 
 type MobileStage = 'nav' | 'page-sidebar' | 'page-content';
+type SettingsDetailHistoryEntry = {
+  page: SettingsPageSlug;
+  stage: 'page-content';
+};
 
 interface SettingsViewProps {
   onClose?: () => void;
@@ -106,6 +111,37 @@ function isPageAvailable(page: SettingsPageMeta, ctx: SettingsRuntimeContext): b
   return page.isAvailable(ctx);
 }
 
+function isObjectRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
+function getSettingsDetailHistoryEntry(state: unknown): SettingsDetailHistoryEntry | null {
+  if (!isObjectRecord(state)) {
+    return null;
+  }
+
+  const detail = state[SETTINGS_DETAIL_HISTORY_KEY];
+  if (!isObjectRecord(detail)) {
+    return null;
+  }
+
+  const page = detail.page;
+  const stage = detail.stage;
+  if (typeof page !== 'string' || stage !== 'page-content') {
+    return null;
+  }
+
+  const resolvedPage = resolveSettingsSlug(page);
+  return { page: resolvedPage, stage };
+}
+
+function getCurrentHistoryState(): Record<string, unknown> {
+  if (typeof window === 'undefined' || !isObjectRecord(window.history.state)) {
+    return {};
+  }
+  return window.history.state;
+}
+
 // eslint-disable-next-line react-refresh/only-export-components
 export function getSettingsNavIcon(slug: SettingsPageSlug): IconName | null {
   switch (slug) {
@@ -559,11 +595,84 @@ export const SettingsView: React.FC<SettingsViewProps> = ({ onClose, forceMobile
   }, [isMobile, mobileStage, settingsSlug]);
 
   const showBackButton = isMobile && mobileStage !== 'nav';
+  const backButtonTargetsPageSidebar = isMobile && mobileStage === 'page-content' && settingsSlug === 'skills.installed';
+  const showOpenPageSidebarButton = mobileStage === 'page-content'
+    && activePageMeta?.kind === 'split'
+    && !backButtonTargetsPageSidebar;
+  const mobileBackButtonLabel = backButtonTargetsPageSidebar
+    ? t('settings.view.actions.back')
+    : showBackButton
+      ? t('settings.view.actions.backToSettings')
+      : t('settings.view.actions.closeSettings');
   const shortcutKey = getModifierLabel();
 
+  const pushMobileSplitDetailHistory = React.useCallback((slug: SettingsPageSlug) => {
+    if (typeof window === 'undefined' || runtimeCtx.isVSCode) {
+      return;
+    }
+
+    const currentDetail = getSettingsDetailHistoryEntry(window.history.state);
+    if (currentDetail?.page === slug && currentDetail.stage === 'page-content') {
+      return;
+    }
+
+    window.history.pushState(
+      {
+        ...getCurrentHistoryState(),
+        [SETTINGS_DETAIL_HISTORY_KEY]: { page: slug, stage: 'page-content' },
+      },
+      '',
+      window.location.href,
+    );
+  }, [runtimeCtx.isVSCode]);
+
+  const handleMobilePageSidebarItemSelect = React.useCallback(() => {
+    setMobileStage('page-content');
+    if (settingsSlug === 'skills.installed') {
+      pushMobileSplitDetailHistory(settingsSlug);
+    }
+  }, [pushMobileSplitDetailHistory, settingsSlug]);
+
   const handleBack = React.useCallback(() => {
+    if (backButtonTargetsPageSidebar) {
+      const currentDetail = typeof window !== 'undefined'
+        ? getSettingsDetailHistoryEntry(window.history.state)
+        : null;
+      if (currentDetail?.page === settingsSlug && !runtimeCtx.isVSCode) {
+        window.history.back();
+        return;
+      }
+      setMobileStage('page-sidebar');
+      return;
+    }
+
     setMobileStage('nav');
-  }, []);
+  }, [backButtonTargetsPageSidebar, runtimeCtx.isVSCode, settingsSlug]);
+
+  React.useEffect(() => {
+    if (!isMobile || runtimeCtx.isVSCode) {
+      return;
+    }
+
+    const handlePopState = (event: PopStateEvent) => {
+      if (settingsSlug !== 'skills.installed') {
+        return;
+      }
+
+      const detail = getSettingsDetailHistoryEntry(event.state);
+      if (detail?.page === 'skills.installed') {
+        setMobileStage('page-content');
+        return;
+      }
+
+      setMobileStage((stage) => stage === 'page-content' ? 'page-sidebar' : stage);
+    };
+
+    window.addEventListener('popstate', handlePopState);
+    return () => {
+      window.removeEventListener('popstate', handlePopState);
+    };
+  }, [isMobile, runtimeCtx.isVSCode, settingsSlug]);
 
   const handleOpenPageSidebar = React.useCallback(() => {
     setMobileStage('page-sidebar');
@@ -670,7 +779,7 @@ export const SettingsView: React.FC<SettingsViewProps> = ({ onClose, forceMobile
       return (
         <div className={cn('flex-1 min-h-0 overflow-hidden', runtimeCtx.isVSCode ? 'bg-background' : 'bg-sidebar')}>
           <ErrorBoundary>
-            {renderPageSidebar(settingsSlug, { onItemSelect: () => setMobileStage('page-content') })}
+            {renderPageSidebar(settingsSlug, { onItemSelect: handleMobilePageSidebarItemSelect })}
           </ErrorBoundary>
         </div>
       );
@@ -724,7 +833,7 @@ export const SettingsView: React.FC<SettingsViewProps> = ({ onClose, forceMobile
           <button
             type="button"
             onClick={showBackButton ? handleBack : onClose}
-            aria-label={showBackButton ? t('settings.view.actions.backToSettings') : t('settings.view.actions.closeSettings')}
+            aria-label={mobileBackButtonLabel}
             className="inline-flex h-9 w-9 flex-shrink-0 items-center justify-center rounded-lg p-2 text-muted-foreground hover:text-foreground hover:bg-interactive-hover/50 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-primary"
           >
             <Icon name="arrow-left-s" className="h-5 w-5" />
@@ -736,7 +845,7 @@ export const SettingsView: React.FC<SettingsViewProps> = ({ onClose, forceMobile
               : (activePageMeta ? getPageTitle(activePageMeta.slug) : t('settings.view.home.title'))}
           </div>
 
-          {mobileStage === 'page-content' && activePageMeta?.kind === 'split' && (
+          {showOpenPageSidebarButton && (
             <button
               type="button"
               onClick={handleOpenPageSidebar}
diff --git a/packages/ui/src/lib/opencode/client.ts b/packages/ui/src/lib/opencode/client.ts
index f642acaa..b35e49ad 100644
--- a/packages/ui/src/lib/opencode/client.ts
+++ b/packages/ui/src/lib/opencode/client.ts
@@ -1415,7 +1415,7 @@ class OpencodeService {
       for (const item of data as Array<Record<string, unknown>>) {
           const name = typeof item.name === 'string' ? item.name.trim() : '';
           const location = typeof item.location === 'string' ? item.location : '';
-          if (!name || !location || location === '<built-in>') {
+          if (!name || !location) {
             continue;
           }
           const skill: { name: string; description?: string; location: string; content?: string } = { name, location };
diff --git a/packages/vscode/src/bridge-config-runtime.ts b/packages/vscode/src/bridge-config-runtime.ts
index aa6cfdbd..8523fad3 100644
--- a/packages/vscode/src/bridge-config-runtime.ts
+++ b/packages/vscode/src/bridge-config-runtime.ts
@@ -16,6 +16,7 @@ import {
   AGENT_SCOPE,
   COMMAND_SCOPE,
   discoverSkills,
+  mergeDiscoveredSkills,
   getSkillSources,
   createSkill,
   updateSkill,
@@ -93,6 +94,15 @@ const parseSkillsCatalogSources = (settings: Record<string, unknown>): SkillsCat
     .filter((value): value is SkillsCatalogSourceConfig => value !== null);
 };
 
+const resolveDiscoveredSkills = async (
+  deps: ConfigRuntimeDeps,
+  ctx: BridgeContext | undefined,
+  workingDirectory?: string,
+): Promise<DiscoveredSkill[]> => mergeDiscoveredSkills(
+  (await deps.fetchOpenCodeSkillsFromApi(ctx, workingDirectory)) || [],
+  discoverSkills(workingDirectory),
+);
+
 export async function handleConfigBridgeMessage(
   message: BridgeMessageInput,
   ctx: BridgeContext | undefined,
@@ -458,7 +468,7 @@ export async function handleConfigBridgeMessage(
       const normalizedMethod = typeof method === 'string' && method.trim() ? method.trim().toUpperCase() : 'GET';
 
       if (!name && normalizedMethod === 'GET') {
-        const skills = (await deps.fetchOpenCodeSkillsFromApi(ctx, workingDirectory)) || discoverSkills(workingDirectory);
+        const skills = await resolveDiscoveredSkills(deps, ctx, workingDirectory);
         return { id, type, success: true, data: { skills } };
       }
 
@@ -468,7 +478,7 @@ export async function handleConfigBridgeMessage(
       }
 
       if (normalizedMethod === 'GET') {
-        const discoveredSkill = ((await deps.fetchOpenCodeSkillsFromApi(ctx, workingDirectory)) || [])
+        const discoveredSkill = (await resolveDiscoveredSkills(deps, ctx, workingDirectory))
           .find((skill) => skill.name === skillName);
         const sources = getSkillSources(skillName, workingDirectory, discoveredSkill || null);
         return {
@@ -539,7 +549,7 @@ export async function handleConfigBridgeMessage(
       const workingDirectory = ctx?.manager?.getWorkingDirectory() || vscode.workspace.workspaceFolders?.[0]?.uri.fsPath;
       const settings = deps.readSettings(ctx);
       const additionalSources = parseSkillsCatalogSources(settings);
-      const installedSkills = (await deps.fetchOpenCodeSkillsFromApi(ctx, workingDirectory)) || undefined;
+      const installedSkills = await resolveDiscoveredSkills(deps, ctx, workingDirectory);
       const data = await getSkillsCatalog(workingDirectory, refresh, additionalSources, installedSkills);
       return { id, type, success: true, data };
     }
@@ -623,7 +633,7 @@ export async function handleConfigBridgeMessage(
         return { id, type, success: false, error: 'File path is required' };
       }
 
-      const discoveredSkill = ((await deps.fetchOpenCodeSkillsFromApi(ctx, workingDirectory)) || [])
+      const discoveredSkill = (await resolveDiscoveredSkills(deps, ctx, workingDirectory))
         .find((skill) => skill.name === skillName);
       const sources = getSkillSources(skillName, workingDirectory, discoveredSkill || null);
       if (!sources.md.dir) {
diff --git a/packages/vscode/src/bridge-settings-runtime.ts b/packages/vscode/src/bridge-settings-runtime.ts
index cfe7d688..7a95e508 100644
--- a/packages/vscode/src/bridge-settings-runtime.ts
+++ b/packages/vscode/src/bridge-settings-runtime.ts
@@ -2,7 +2,7 @@ import * as fs from 'fs';
 import * as os from 'os';
 import * as path from 'path';
 import * as vscode from 'vscode';
-import { type DiscoveredSkill, type SkillScope, type SkillSource } from './opencodeConfig';
+import { BUILT_IN_SKILL_LOCATION, type DiscoveredSkill, type SkillScope, type SkillSource } from './opencodeConfig';
 import type { BridgeContext } from './bridge';
 
 const SETTINGS_KEY = 'openchamber.settings';
@@ -129,9 +129,20 @@ export const fetchOpenCodeSkillsFromApi = async (
         const name = typeof item?.name === 'string' ? item.name.trim() : '';
         const location = typeof item?.location === 'string' ? item.location : '';
         const description = typeof item?.description === 'string' ? item.description : '';
+        const content = typeof item?.content === 'string' ? item.content : '';
         if (!name || !location) {
           return null;
         }
+        if (location === BUILT_IN_SKILL_LOCATION) {
+          return {
+            name,
+            path: location,
+            scope: 'user',
+            source: 'opencode',
+            description,
+            content,
+          } as DiscoveredSkill;
+        }
         const inferred = inferSkillScopeAndSourceFromLocation(location, workingDirectory);
         return {
           name,
@@ -139,6 +150,7 @@ export const fetchOpenCodeSkillsFromApi = async (
           scope: inferred.scope,
           source: inferred.source,
           description,
+          content,
         } as DiscoveredSkill;
       })
       .filter((item): item is DiscoveredSkill => item !== null);
diff --git a/packages/vscode/src/opencodeConfig.skills.test.js b/packages/vscode/src/opencodeConfig.skills.test.js
new file mode 100644
index 00000000..6f45ff6b
--- /dev/null
+++ b/packages/vscode/src/opencodeConfig.skills.test.js
@@ -0,0 +1,46 @@
+import { describe, expect, test } from 'bun:test';
+
+import {
+  BUILT_IN_SKILL_LOCATION,
+  getSkillSources,
+  mergeDiscoveredSkills,
+} from './opencodeConfig';
+
+describe('VS Code skill discovery parity', () => {
+  test('merges OpenCode API skills with locally discovered fallback skills', () => {
+    const merged = mergeDiscoveredSkills(
+      [
+        { name: 'built-in', path: BUILT_IN_SKILL_LOCATION, scope: 'user', source: 'opencode' },
+        { name: 'local-first', path: '/tmp/local-first/SKILL.md', scope: 'user', source: 'agents' },
+      ],
+      [
+        { name: 'local-first', path: '/tmp/local-first/SKILL.md', scope: 'user', source: 'agents' },
+        { name: 'local-only', path: '/tmp/local-only/SKILL.md', scope: 'project', source: 'claude' },
+      ],
+    );
+
+    expect(merged.map((skill) => skill.name)).toEqual(['built-in', 'local-first', 'local-only']);
+  });
+
+  test('resolves built-in skills without treating the virtual location as a file', () => {
+    const discoveredSkill = {
+      name: 'customize-opencode',
+      path: BUILT_IN_SKILL_LOCATION,
+      scope: 'user',
+      source: 'opencode',
+      description: 'Customize opencode',
+      content: '# Customize opencode\n\nUse for config work.',
+    };
+
+    const sources = getSkillSources('customize-opencode', '/tmp/openchamber-vscode-skills-test', discoveredSkill);
+
+    expect(sources.md.exists).toBe(true);
+    expect(sources.md.path).toBeNull();
+    expect(sources.md.dir).toBeNull();
+    expect(sources.md.scope).toBe('user');
+    expect(sources.md.source).toBe('opencode');
+    expect(sources.md.description).toBe('Customize opencode');
+    expect(sources.md.instructions).toBe('# Customize opencode\n\nUse for config work.');
+    expect(sources.md.fields).toEqual(['description', 'instructions']);
+  });
+});
diff --git a/packages/vscode/src/opencodeConfig.ts b/packages/vscode/src/opencodeConfig.ts
index d174e513..8a2853eb 100644
--- a/packages/vscode/src/opencodeConfig.ts
+++ b/packages/vscode/src/opencodeConfig.ts
@@ -1311,6 +1311,9 @@ export type SkillConfigSources = {
     scope?: SkillScope | null;
     source?: SkillSource | null;
     supportingFiles: SupportingFile[];
+    name?: string;
+    description?: string;
+    instructions?: string;
   };
   projectMd?: { exists: boolean; path: string | null };
   claudeMd?: { exists: boolean; path: string | null };
@@ -1323,6 +1326,34 @@ export type DiscoveredSkill = {
   scope: SkillScope;
   source: SkillSource;
   description?: string;
+  content?: string;
+};
+
+export const BUILT_IN_SKILL_LOCATION = '<built-in>';
+
+export const mergeDiscoveredSkills = (
+  primarySkills: DiscoveredSkill[] = [],
+  fallbackSkills: DiscoveredSkill[] = []
+): DiscoveredSkill[] => {
+  const merged: DiscoveredSkill[] = [];
+  const seenNames = new Set<string>();
+
+  const appendSkill = (skill: DiscoveredSkill | null | undefined) => {
+    if (!skill) {
+      return;
+    }
+    const name = typeof skill?.name === 'string' ? skill.name.trim() : '';
+    if (!name || seenNames.has(name)) {
+      return;
+    }
+    seenNames.add(name);
+    merged.push(skill);
+  };
+
+  for (const skill of primarySkills || []) appendSkill(skill);
+  for (const skill of fallbackSkills || []) appendSkill(skill);
+
+  return merged;
 };
 
 const addSkillFromMdFile = (
@@ -1562,6 +1593,14 @@ export const getSkillSources = (
   discoveredSkill?: DiscoveredSkill | null
 ): SkillConfigSources => {
   ensureSkillDirs();
+  const isReadableFile = (filePath: string | null): boolean => {
+    if (!filePath) return false;
+    try {
+      return fs.statSync(filePath).isFile();
+    } catch {
+      return false;
+    }
+  };
   
   // Check all possible locations
   const projectPath = workingDirectory ? getProjectSkillPath(workingDirectory, skillName) : null;
@@ -1579,6 +1618,8 @@ export const getSkillSources = (
   const matchedDiscovered = discoveredSkill?.name === skillName
     ? discoveredSkill
     : discoverSkills(workingDirectory).find((skill) => skill.name === skillName);
+  const discoveredPath = typeof matchedDiscovered?.path === 'string' ? matchedDiscovered.path : null;
+  const isBuiltInDiscovered = discoveredPath === BUILT_IN_SKILL_LOCATION;
   
   // Determine which md file to use (priority: project > claude > user)
   let mdPath: string | null = null;
@@ -1586,7 +1627,15 @@ export const getSkillSources = (
   let mdSource: SkillSource | null = null;
   let mdDir: string | null = null;
   
-  if (projectExists) {
+  if (isBuiltInDiscovered) {
+    mdScope = matchedDiscovered?.scope || SKILL_SCOPE.USER;
+    mdSource = matchedDiscovered?.source || 'opencode';
+  } else if (discoveredPath && isReadableFile(discoveredPath)) {
+    mdPath = discoveredPath;
+    mdScope = matchedDiscovered?.scope || null;
+    mdSource = matchedDiscovered?.source || null;
+    mdDir = path.dirname(discoveredPath);
+  } else if (projectExists) {
     mdPath = projectPath;
     mdScope = SKILL_SCOPE.PROJECT;
     mdSource = 'opencode';
@@ -1601,21 +1650,20 @@ export const getSkillSources = (
     mdScope = SKILL_SCOPE.USER;
     mdSource = 'opencode';
     mdDir = userDir;
-  } else if (matchedDiscovered?.path) {
-    mdPath = matchedDiscovered.path;
-    mdScope = matchedDiscovered.scope;
-    mdSource = matchedDiscovered.source;
-    mdDir = path.dirname(matchedDiscovered.path);
   }
   
-  const mdExists = !!mdPath;
-  let mdFields: string[] = [];
+  const mdExists = isBuiltInDiscovered || !!mdPath;
+  let mdFields: string[] = isBuiltInDiscovered ? ['description', 'instructions'] : [];
   let supportingFiles: SupportingFile[] = [];
+  let mdDescription = typeof matchedDiscovered?.description === 'string' ? matchedDiscovered.description : '';
+  let mdInstructions = isBuiltInDiscovered && typeof matchedDiscovered?.content === 'string' ? matchedDiscovered.content : '';
   
   if (mdExists && mdPath) {
     const { frontmatter, body } = parseMdFile(mdPath);
     mdFields = Object.keys(frontmatter);
+    mdDescription = typeof frontmatter.description === 'string' ? frontmatter.description : '';
     if (body) mdFields.push('instructions');
+    mdInstructions = body || '';
     if (mdDir) {
       supportingFiles = listSupportingFiles(mdDir);
     }
@@ -1629,7 +1677,10 @@ export const getSkillSources = (
       fields: mdFields,
       scope: mdScope,
       source: mdSource,
-      supportingFiles
+      supportingFiles,
+      name: matchedDiscovered?.name || skillName,
+      description: mdDescription,
+      instructions: mdInstructions,
     },
     projectMd: { exists: projectExists, path: projectPath },
     claudeMd: { exists: claudeExists, path: claudePath },
diff --git a/packages/web/server/lib/opencode/feature-routes-runtime.js b/packages/web/server/lib/opencode/feature-routes-runtime.js
index 6e6b173f..5aaf5ae4 100644
--- a/packages/web/server/lib/opencode/feature-routes-runtime.js
+++ b/packages/web/server/lib/opencode/feature-routes-runtime.js
@@ -161,6 +161,7 @@ export const createFeatureRoutesRuntime = (dependencies) => {
     const {
       getSkillSources,
       discoverSkills,
+      mergeDiscoveredSkills,
       createSkill,
       updateSkill,
       deleteSkill,
@@ -201,6 +202,7 @@ export const createFeatureRoutesRuntime = (dependencies) => {
       getOpenCodePort,
       getSkillSources,
       discoverSkills,
+      mergeDiscoveredSkills,
       createSkill,
       updateSkill,
       deleteSkill,
diff --git a/packages/web/server/lib/opencode/index.js b/packages/web/server/lib/opencode/index.js
index ee57bb96..5df3159f 100644
--- a/packages/web/server/lib/opencode/index.js
+++ b/packages/web/server/lib/opencode/index.js
@@ -35,6 +35,7 @@ export {
   getSkillSources,
   getSkillScope,
   discoverSkills,
+  mergeDiscoveredSkills,
   createSkill,
   updateSkill,
   deleteSkill,
diff --git a/packages/web/server/lib/opencode/skill-routes.js b/packages/web/server/lib/opencode/skill-routes.js
index 3490f77a..b66680a5 100644
--- a/packages/web/server/lib/opencode/skill-routes.js
+++ b/packages/web/server/lib/opencode/skill-routes.js
@@ -16,6 +16,8 @@ export const registerSkillRoutes = (app, dependencies) => {
     getOpenCodeAuthHeaders,
     getOpenCodePort,
     getSkillSources,
+    discoverSkills,
+    mergeDiscoveredSkills,
     createSkill,
     updateSkill,
     deleteSkill,
@@ -139,17 +141,32 @@ export const registerSkillRoutes = (app, dependencies) => {
           const name = typeof item?.name === 'string' ? item.name.trim() : '';
           const location = typeof item?.location === 'string' ? item.location : '';
           const description = typeof item?.description === 'string' ? item.description : '';
-          if (!name || !location || location === '<built-in>') {
+          const content = typeof item?.content === 'string' ? item.content : '';
+          if (!name || !location) {
             return null;
           }
+          if (location === '<built-in>') {
+            return {
+              name,
+              path: location,
+              scope: SKILL_SCOPE.USER,
+              source: 'opencode',
+              description,
+              content,
+            };
+          }
           const inferred = inferSkillScopeAndSourceFromPath(location, workingDirectory);
-          return {
+          const skill = {
             name,
             path: location,
             scope: inferred.scope,
             source: inferred.source,
             description,
           };
+          if (content) {
+            skill.content = content;
+          }
+          return skill;
         })
         .filter(Boolean);
     } catch (error) {
@@ -189,7 +206,9 @@ export const registerSkillRoutes = (app, dependencies) => {
       if (error) {
         return res.status(400).json({ error });
       }
-      const skills = await fetchOpenCodeDiscoveredSkills(directory);
+      const openCodeSkills = await fetchOpenCodeDiscoveredSkills(directory);
+      const localSkills = discoverSkills(directory);
+      const skills = mergeDiscoveredSkills(openCodeSkills, localSkills);
 
       const enrichedSkills = skills.map((skill) => {
         const sources = getSkillSources(skill.name, directory, skill);
@@ -271,8 +290,11 @@ export const registerSkillRoutes = (app, dependencies) => {
         return res.status(404).json({ ok: false, error: { kind: 'invalidSource', message: 'Unknown source' } });
       }
 
-      const discovered = await fetchOpenCodeDiscoveredSkills(directory);
-      const installedByName = new Map(discovered.map((s) => [s.name, s]));
+      const resolvedDiscovered = mergeDiscoveredSkills(
+        await fetchOpenCodeDiscoveredSkills(directory),
+        discoverSkills(directory),
+      );
+      const installedByName = new Map(resolvedDiscovered.map((s) => [s.name, s]));
 
       if (src.sourceType === 'clawdhub' || isClawdHubSource(src.source)) {
         const scanned = await scanClawdHubPage({ cursor: cursor || null });
diff --git a/packages/web/server/lib/opencode/skills.js b/packages/web/server/lib/opencode/skills.js
index 23161b2e..30dfd558 100644
--- a/packages/web/server/lib/opencode/skills.js
+++ b/packages/web/server/lib/opencode/skills.js
@@ -21,6 +21,8 @@ import {
   findWorktreeRoot,
 } from './shared.js';
 
+const BUILT_IN_SKILL_LOCATION = '<built-in>';
+
 function ensureProjectSkillDir(workingDirectory) {
   const projectSkillDir = path.join(workingDirectory, '.opencode', 'skills');
   if (!fs.existsSync(projectSkillDir)) {
@@ -236,7 +238,39 @@ function discoverSkills(workingDirectory) {
   return Array.from(skills.values());
 }
 
+function mergeDiscoveredSkills(primarySkills = [], fallbackSkills = []) {
+  const merged = [];
+  const seenNames = new Set();
+
+  const appendSkill = (skill) => {
+    const name = typeof skill?.name === 'string' ? skill.name.trim() : '';
+    if (!name || seenNames.has(name)) {
+      return;
+    }
+    seenNames.add(name);
+    merged.push(skill);
+  };
+
+  for (const skill of primarySkills || []) {
+    appendSkill(skill);
+  }
+  for (const skill of fallbackSkills || []) {
+    appendSkill(skill);
+  }
+
+  return merged;
+}
+
 function getSkillSources(skillName, workingDirectory, discoveredSkill = null) {
+  const isReadableFile = (filePath) => {
+    if (!filePath) return false;
+    try {
+      return fs.statSync(filePath).isFile();
+    } catch {
+      return false;
+    }
+  };
+
   const projectPath = workingDirectory ? getProjectSkillPath(workingDirectory, skillName) : null;
   const projectExists = projectPath && fs.existsSync(projectPath);
   const projectDir = projectExists ? path.dirname(projectPath) : null;
@@ -259,17 +293,33 @@ function getSkillSources(skillName, workingDirectory, discoveredSkill = null) {
   const matchedDiscovered = discoveredSkill && discoveredSkill.name === skillName
     ? discoveredSkill
     : discoverSkills(workingDirectory).find((skill) => skill.name === skillName);
+  const discoveredDescription =
+    matchedDiscovered && typeof matchedDiscovered.description === 'string'
+      ? matchedDiscovered.description
+      : '';
+  const discoveredContent =
+    matchedDiscovered && typeof matchedDiscovered.content === 'string'
+      ? matchedDiscovered.content
+      : '';
+  const discoveredPath =
+    matchedDiscovered && typeof matchedDiscovered.path === 'string'
+      ? matchedDiscovered.path
+      : null;
+  const isBuiltInDiscovered = discoveredPath === BUILT_IN_SKILL_LOCATION;
   
   let mdPath = null;
   let mdScope = null;
   let mdSource = null;
   let mdDir = null;
   
-  if (matchedDiscovered?.path) {
-    mdPath = matchedDiscovered.path;
+  if (isBuiltInDiscovered) {
+    mdScope = matchedDiscovered.scope || SKILL_SCOPE.USER;
+    mdSource = matchedDiscovered.source || 'opencode';
+  } else if (discoveredPath) {
+    mdPath = discoveredPath;
     mdScope = matchedDiscovered.scope || null;
     mdSource = matchedDiscovered.source || null;
-    mdDir = path.dirname(matchedDiscovered.path);
+    mdDir = isReadableFile(discoveredPath) ? path.dirname(discoveredPath) : null;
   } else if (projectExists) {
     mdPath = projectPath;
     mdScope = SKILL_SCOPE.PROJECT;
@@ -297,10 +347,12 @@ function getSkillSources(skillName, workingDirectory, discoveredSkill = null) {
     mdDir = userAgentsDir;
   }
   
-  const mdExists = !!mdPath && fs.existsSync(mdPath);
+  const mdExists = isBuiltInDiscovered || isReadableFile(mdPath);
   if (!mdExists) {
     mdPath = null;
     mdDir = null;
+    mdScope = null;
+    mdSource = null;
   }
 
   const sources = {
@@ -310,8 +362,11 @@ function getSkillSources(skillName, workingDirectory, discoveredSkill = null) {
       dir: mdDir,
       scope: mdScope,
       source: mdSource,
-      fields: [],
-      supportingFiles: []
+      fields: isBuiltInDiscovered ? ['description', 'instructions'] : [],
+      supportingFiles: [],
+      name: matchedDiscovered?.name || skillName,
+      description: discoveredDescription,
+      instructions: isBuiltInDiscovered ? discoveredContent : ''
     },
     projectMd: {
       exists: projectExists,
@@ -542,6 +597,7 @@ export {
   getSkillScope,
   getSkillWritePath,
   discoverSkills,
+  mergeDiscoveredSkills,
   createSkill,
   updateSkill,
   deleteSkill,
diff --git a/packages/web/server/lib/opencode/skills.test.js b/packages/web/server/lib/opencode/skills.test.js
new file mode 100644
index 00000000..95f9c722
--- /dev/null
+++ b/packages/web/server/lib/opencode/skills.test.js
@@ -0,0 +1,113 @@
+import { describe, expect, it } from 'vitest';
+import fsPromises from 'fs/promises';
+import os from 'os';
+import path from 'path';
+import { getSkillSources, mergeDiscoveredSkills } from './skills.js';
+
+describe('skills', () => {
+  it('merges locally discovered skills missing from OpenCode live discovery', () => {
+    const merged = mergeDiscoveredSkills(
+      [
+        { name: 'existing-opencode-skill', path: '/home/jkker/.config/opencode/skills/existing-opencode-skill/SKILL.md', source: 'opencode' },
+        { name: 'existing-agent-skill', path: '/home/jkker/.agents/skills/existing-agent-skill/SKILL.md', source: 'agents' },
+      ],
+      [
+        { name: 'existing-agent-skill', path: '/home/jkker/.agents/skills/existing-agent-skill/SKILL.md', source: 'agents' },
+        { name: 'new-agent-skill', path: '/home/jkker/.agents/skills/new-agent-skill/SKILL.md', source: 'agents' },
+      ],
+    );
+
+    expect(merged.map((skill) => skill.name)).toEqual([
+      'existing-opencode-skill',
+      'existing-agent-skill',
+      'new-agent-skill',
+    ]);
+  });
+
+  it('resolves built-in OpenCode skill content without parsing virtual locations as files', () => {
+    const sources = getSkillSources(
+      'customize-opencode',
+      '/tmp/openchamber-skills-test-missing-project',
+      {
+        name: 'customize-opencode',
+        path: '<built-in>',
+        scope: 'user',
+        source: 'opencode',
+        description: 'Customize opencode',
+        content: '# Customizing opencode\n\nUse this skill when updating config.',
+      },
+    );
+
+    expect(sources.md.exists).toBe(true);
+    expect(sources.md.path).toBe(null);
+    expect(sources.md.dir).toBe(null);
+    expect(sources.md.scope).toBe('user');
+    expect(sources.md.source).toBe('opencode');
+    expect(sources.md.description).toBe('Customize opencode');
+    expect(sources.md.instructions).toBe('# Customizing opencode\n\nUse this skill when updating config.');
+    expect(sources.md.fields).toEqual(['description', 'instructions']);
+  });
+
+  it('clears file metadata when a discovered skill path is unreadable', () => {
+    const missingPath = path.join(os.tmpdir(), 'openchamber-skills-test-missing-file', 'SKILL.md');
+    const sources = getSkillSources(
+      'missing-agent-skill',
+      '/tmp/openchamber-skills-test-missing-project',
+      {
+        name: 'missing-agent-skill',
+        path: missingPath,
+        scope: 'user',
+        source: 'agents',
+        description: 'Missing skill',
+      },
+    );
+
+    expect(sources.md.exists).toBe(false);
+    expect(sources.md.path).toBe(null);
+    expect(sources.md.dir).toBe(null);
+    expect(sources.md.scope).toBe(null);
+    expect(sources.md.source).toBe(null);
+    expect(sources.md.description).toBe('Missing skill');
+    expect(sources.md.instructions).toBe('');
+  });
+
+  it('enriches discovered skills when their location is a real markdown file', async () => {
+    const tempRoot = await fsPromises.mkdtemp(path.join(os.tmpdir(), 'oc-skills-'));
+    const skillDir = path.join(tempRoot, 'example-skill');
+    const skillPath = path.join(skillDir, 'SKILL.md');
+
+    try {
+      await fsPromises.mkdir(skillDir, { recursive: true });
+      await fsPromises.writeFile(
+        skillPath,
+        [
+          '---',
+          'name: example-skill',
+          'description: Example from agents',
+          '---',
+          '',
+          'Use this skill for examples.',
+          '',
+        ].join('\n'),
+        'utf8',
+      );
+
+      const sources = getSkillSources('example-skill', tempRoot, {
+        name: 'example-skill',
+        path: skillPath,
+        scope: 'user',
+        source: 'agents',
+        description: 'Fallback description',
+      });
+
+      expect(sources.md.exists).toBe(true);
+      expect(sources.md.path).toBe(skillPath);
+      expect(sources.md.scope).toBe('user');
+      expect(sources.md.source).toBe('agents');
+      expect(sources.md.description).toBe('Example from agents');
+      expect(sources.md.instructions).toBe('Use this skill for examples.');
+    } finally {
+      await fsPromises.rm(tempRoot, { recursive: true, force: true });
+    }
+  });
+});