diff --git a/docs/DEV_PLUGINS.md b/docs/DEV_PLUGINS.md
index 216bddc..909558f 100644
--- a/docs/DEV_PLUGINS.md
+++ b/docs/DEV_PLUGINS.md
@@ -85,11 +85,12 @@ Frontend bundles are mounted with a plugin-scoped API created by
 - `capabilities.list/get/has`
 - `commands.register/execute` for handlers declared in `contributes.commands`
 - `events.publish/subscribe` using the bundled frontend event bus
-- `files.list/metadata/readText/writeText/createFolder/move/trash` for
-  canonical vault-relative slash paths guarded by `files.read`, `files.write`,
-  and `files.delete`. Backslashes, Windows absolute paths, UNC paths,
-  traversal, `.verstak` variants, and symlink read/write/move/trash operations
-  are rejected. Text read/write is UTF-8 only and limited to 2 MB for reads.
+- `files.list/metadata/readText/writeText/createFolder/move/trash/openExternal/showInFolder`
+  for canonical vault-relative slash paths guarded by `files.read`,
+  `files.write`, `files.delete`, and `files.openExternal`. Backslashes,
+  Windows absolute paths, UNC paths, traversal, `.verstak` variants, and
+  symlink read/write/move/trash/external-open operations are rejected. Text
+  read/write is UTF-8 only and limited to 2 MB for reads.
 - `workbench.openResource/editResource` for routing vault resources to
   contributed `openProviders`. Plugins must declare `workbench.open`; this is a
   policy/contract check. Files and Notes plugins call this API and do not import
diff --git a/docs/PLUGIN_RUNTIME.md b/docs/PLUGIN_RUNTIME.md
index 1ed58cb..38c54d7 100644
--- a/docs/PLUGIN_RUNTIME.md
+++ b/docs/PLUGIN_RUNTIME.md
@@ -426,8 +426,13 @@ contributions summary.
   folder into itself and conflicts unless `options.overwrite` is true.
 - `files.trash(relativePath)` — moves a file/folder into internal
   `.verstak/trash/files/<trashId>/...` and returns trash metadata.
+- `files.openExternal(relativePath)` — opens a vault-relative file/folder in
+  the OS default application.
+- `files.showInFolder(relativePath)` — reveals a vault-relative file/folder in
+  the OS file manager where the platform supports it.
 - Backend requires plugin exists, enabled, status `loaded`/`degraded`, open
-  vault, and `files.read`, `files.write`, or `files.delete`.
+  vault, and `files.read`, `files.write`, `files.delete`, or
+  `files.openExternal`.
 - All paths are canonical vault-relative slash paths. Backslashes, POSIX
   absolute paths, Windows drive paths, UNC/network paths, `..`, null bytes,
   symlink traversal, and public access to `.verstak/` are rejected.
@@ -511,6 +516,8 @@ bundled runtime. Это реальный runtime contract для cooperative bun
 | `api.files.createFolder(relativePath)` | ✅ Работает | Создаёт vault-relative folder |
 | `api.files.move(from, to, options)` | ✅ Работает | Move file/folder с conflict и path-policy checks |
 | `api.files.trash(relativePath)` | ✅ Работает | Перемещает в internal trash, permanent delete нет |
+| `api.files.openExternal(relativePath)` | ✅ Работает | Открывает vault file/folder во внешнем приложении, требует `files.openExternal` |
+| `api.files.showInFolder(relativePath)` | ✅ Работает | Показывает vault file/folder в системном файловом менеджере, требует `files.openExternal` |
 | `api.workbench.openResource(request)` | ✅ Работает | Routes vault resources to `openProviders` |
 | `api.workbench.editResource(request)` | ✅ Работает | Same routing, forcing `mode: "edit"` |
 | `api.dispose()` | ✅ Работает | Очищает command handlers и event subscriptions текущего API instance |
diff --git a/frontend/src/lib/plugin-host/VerstakPluginAPI.js b/frontend/src/lib/plugin-host/VerstakPluginAPI.js
index fd00e16..22ffe30 100644
--- a/frontend/src/lib/plugin-host/VerstakPluginAPI.js
+++ b/frontend/src/lib/plugin-host/VerstakPluginAPI.js
@@ -245,6 +245,18 @@ export function createPluginAPI(pluginId) {
         return callBackend(pluginId, 'files.trash(' + relativePath + ')', function() {
           return App.TrashVaultPath(pluginId, relativePath);
         });
+      },
+      openExternal: function(relativePath) {
+        assertActive('files.openExternal(' + relativePath + ')');
+        return callBackendErrorString(pluginId, 'files.openExternal(' + relativePath + ')', function() {
+          return App.OpenVaultPathExternal(pluginId, relativePath);
+        });
+      },
+      showInFolder: function(relativePath) {
+        assertActive('files.showInFolder(' + relativePath + ')');
+        return callBackendErrorString(pluginId, 'files.showInFolder(' + relativePath + ')', function() {
+          return App.ShowVaultPathInFolder(pluginId, relativePath);
+        });
       }
     },
 
diff --git a/frontend/src/lib/test/wails-mock.js b/frontend/src/lib/test/wails-mock.js
index 4e2f18a..c3a599f 100644
--- a/frontend/src/lib/test/wails-mock.js
+++ b/frontend/src/lib/test/wails-mock.js
@@ -24,7 +24,7 @@
         provides: ['verstak/platform-test/v1', 'verstak/diagnostics/v1'],
         requires: ['verstak/core/plugin-manager/v1', 'verstak/core/capability-registry/v1'],
         optionalRequires: ['verstak/core/vault/v1', 'verstak/core/sync/v1', 'verstak/core/files/v1', 'verstak/core/workbench/v1'],
-        permissions: ['vault.read', 'events.publish', 'events.subscribe', 'ui.register', 'commands.register', 'storage.namespace', 'files.read', 'files.write', 'files.delete', 'workbench.open'],
+        permissions: ['vault.read', 'events.publish', 'events.subscribe', 'ui.register', 'commands.register', 'storage.namespace', 'files.read', 'files.write', 'files.delete', 'files.openExternal', 'workbench.open'],
         frontend: { entry: 'frontend/dist/index.js' },
         contributes: {
           views: [
@@ -124,7 +124,7 @@
         icon: 'folder',
         provides: ['verstak/files/v1'],
         requires: ['verstak/core/files/v1', 'verstak/core/workbench/v1'],
-        permissions: ['files.read', 'files.write', 'files.delete', 'workbench.open', 'ui.register'],
+        permissions: ['files.read', 'files.write', 'files.delete', 'files.openExternal', 'workbench.open', 'ui.register'],
         frontend: { entry: 'frontend/dist/index.js' },
     contributes: {
       views: [{ id: 'verstak.files.view', title: 'Files', icon: 'folder', component: 'FilesView' }],
@@ -145,6 +145,8 @@
     'verstak.platform-test': { savedText: 'initial value' }
   };
   var vaultFiles = makeDefaultVaultFiles();
+  var externalOpens = [];
+  window.__wailsMockExternalOpens = [];
   var workspaceTree = makeDefaultWorkspaceTree();
   var reloadResponseMode = 'tuple';
 
@@ -293,6 +295,7 @@
       { name: 'files.read', description: 'Read vault files', dangerous: false },
       { name: 'files.write', description: 'Write vault files', dangerous: true },
       { name: 'files.delete', description: 'Trash vault files', dangerous: true },
+      { name: 'files.openExternal', description: 'Open vault files and folders externally', dangerous: true },
       { name: 'workbench.open', description: 'Request Workbench open/edit routing', dangerous: false }
     ];
   }
@@ -1125,6 +1128,26 @@
       moving.forEach(function (path) { delete vaultFiles[path]; });
       return Promise.resolve([{ originalPath: norm.path, trashPath: trashPath, trashId: trashId, deletedAt: new Date().toISOString() }, '']);
     },
+    OpenVaultPathExternal: function (pluginId, relativePath) {
+      var err = requirePluginPermission(pluginId, 'files.openExternal');
+      if (err) return Promise.resolve(err);
+      var norm = normalizeVaultPath(relativePath, false);
+      if (norm.error) return Promise.resolve(norm.error);
+      if (!vaultFiles[norm.path]) return Promise.resolve('not-found: ' + norm.path);
+      externalOpens.push({ action: 'open', path: norm.path });
+      window.__wailsMockExternalOpens = externalOpens.slice();
+      return Promise.resolve('');
+    },
+    ShowVaultPathInFolder: function (pluginId, relativePath) {
+      var err = requirePluginPermission(pluginId, 'files.openExternal');
+      if (err) return Promise.resolve(err);
+      var norm = normalizeVaultPath(relativePath, false);
+      if (norm.error) return Promise.resolve(norm.error);
+      if (!vaultFiles[norm.path]) return Promise.resolve('not-found: ' + norm.path);
+      externalOpens.push({ action: 'show', path: norm.path });
+      window.__wailsMockExternalOpens = externalOpens.slice();
+      return Promise.resolve('');
+    },
     ListWorkspaces: function () {
       return Promise.resolve(listWorkspacesFromTree());
     },
@@ -1281,7 +1304,7 @@
             provides: ['verstak/platform-test/v1', 'verstak/diagnostics/v1'],
             requires: ['verstak/core/plugin-manager/v1', 'verstak/core/capability-registry/v1'],
             optionalRequires: ['verstak/core/vault/v1', 'verstak/core/sync/v1', 'verstak/core/files/v1', 'verstak/core/workbench/v1'],
-            permissions: ['vault.read', 'events.publish', 'events.subscribe', 'ui.register', 'commands.register', 'storage.namespace', 'files.read', 'files.write', 'files.delete', 'workbench.open'],
+            permissions: ['vault.read', 'events.publish', 'events.subscribe', 'ui.register', 'commands.register', 'storage.namespace', 'files.read', 'files.write', 'files.delete', 'files.openExternal', 'workbench.open'],
             frontend: { entry: 'frontend/dist/index.js' },
             contributes: {
               views: [
@@ -1381,7 +1404,7 @@
             icon: 'folder',
             provides: ['verstak/files/v1'],
             requires: ['verstak/core/files/v1', 'verstak/core/workbench/v1'],
-            permissions: ['files.read', 'files.write', 'files.delete', 'workbench.open', 'ui.register'],
+            permissions: ['files.read', 'files.write', 'files.delete', 'files.openExternal', 'workbench.open', 'ui.register'],
             frontend: { entry: 'frontend/dist/index.js' },
             contributes: {
               views: [{ id: 'verstak.files.view', title: 'Files', icon: 'folder', component: 'FilesView' }],
@@ -1399,6 +1422,8 @@
       openedResources = [];
       pluginSettings = { 'verstak.platform-test': { savedText: 'initial value' } };
       vaultFiles = makeDefaultVaultFiles();
+      externalOpens = [];
+      window.__wailsMockExternalOpens = [];
       workspaceTree = makeDefaultWorkspaceTree();
       reloadResponseMode = 'tuple';
     },
diff --git a/frontend/wailsjs/go/api/App.d.ts b/frontend/wailsjs/go/api/App.d.ts
index 4f5191f..9e8c0fc 100755
--- a/frontend/wailsjs/go/api/App.d.ts
+++ b/frontend/wailsjs/go/api/App.d.ts
@@ -74,6 +74,8 @@ export function MoveWorkspaceNode(arg1:string,arg2:string):Promise<string>;
 
 export function OpenVault(arg1:string):Promise<void>;
 
+export function OpenVaultPathExternal(arg1:string,arg2:string):Promise<string>;
+
 export function OpenWorkbenchResource(arg1:string,arg2:Record<string, any>):Promise<workbench.OpenResourceResult|string>;
 
 export function PluginSyncConfigure(arg1:string,arg2:string,arg3:string,arg4:string):Promise<string>;
@@ -116,6 +118,8 @@ export function SetCurrentWorkspace(arg1:string):Promise<string>;
 
 export function SetCurrentWorkspaceNode(arg1:string):Promise<string>;
 
+export function ShowVaultPathInFolder(arg1:string,arg2:string):Promise<string>;
+
 export function SubscribePluginEvent(arg1:string,arg2:string):Promise<string>;
 
 export function TrashVaultPath(arg1:string,arg2:string):Promise<files.TrashResult|string>;
diff --git a/frontend/wailsjs/go/api/App.js b/frontend/wailsjs/go/api/App.js
index a2c0dd5..07d9ada 100755
--- a/frontend/wailsjs/go/api/App.js
+++ b/frontend/wailsjs/go/api/App.js
@@ -134,6 +134,10 @@ export function OpenVault(arg1) {
   return window['go']['api']['App']['OpenVault'](arg1);
 }
 
+export function OpenVaultPathExternal(arg1, arg2) {
+  return window['go']['api']['App']['OpenVaultPathExternal'](arg1, arg2);
+}
+
 export function OpenWorkbenchResource(arg1, arg2) {
   return window['go']['api']['App']['OpenWorkbenchResource'](arg1, arg2);
 }
@@ -218,6 +222,10 @@ export function SetCurrentWorkspaceNode(arg1) {
   return window['go']['api']['App']['SetCurrentWorkspaceNode'](arg1);
 }
 
+export function ShowVaultPathInFolder(arg1, arg2) {
+  return window['go']['api']['App']['ShowVaultPathInFolder'](arg1, arg2);
+}
+
 export function SubscribePluginEvent(arg1, arg2) {
   return window['go']['api']['App']['SubscribePluginEvent'](arg1, arg2);
 }
diff --git a/internal/api/app.go b/internal/api/app.go
index 37755bd..3228b02 100644
--- a/internal/api/app.go
+++ b/internal/api/app.go
@@ -17,6 +17,7 @@ import (
 	"github.com/verstak/verstak-desktop/internal/core/capability"
 	"github.com/verstak/verstak-desktop/internal/core/contribution"
 	"github.com/verstak/verstak-desktop/internal/core/events"
+	"github.com/verstak/verstak-desktop/internal/core/externalopen"
 	corefiles "github.com/verstak/verstak-desktop/internal/core/files"
 	"github.com/verstak/verstak-desktop/internal/core/permissions"
 	"github.com/verstak/verstak-desktop/internal/core/plugin"
@@ -40,6 +41,7 @@ type App struct {
 	vault           *vault.Vault
 	storage         *storage.Storage
 	files           *corefiles.Service
+	externalOpen    externalOpenService
 	appSettings     *appsettings.Manager
 	pluginState     *pluginstate.Manager
 	workbench       *coreworkbench.Router
@@ -48,6 +50,11 @@ type App struct {
 	debug           bool
 }
 
+type externalOpenService interface {
+	OpenPath(path string) error
+	ShowInFolder(path string, isDir bool) error
+}
+
 // NewApp creates a new App instance.
 func NewApp(
 	capReg *capability.Registry,
@@ -73,6 +80,7 @@ func NewApp(
 		vault:           vaultService,
 		storage:         storageService,
 		files:           filesService,
+		externalOpen:    externalopen.NewService(),
 		appSettings:     appSettingsMgr,
 		pluginState:     pluginStateMgr,
 		workbench:       coreworkbench.NewRouter(workbenchPrefsFromSettings(appSettingsMgr)),
@@ -749,6 +757,50 @@ func (a *App) TrashVaultPath(pluginID, relativePath string) (corefiles.TrashResu
 	return result, ""
 }
 
+// OpenVaultPathExternal opens a vault-relative file or folder in the OS default app.
+func (a *App) OpenVaultPathExternal(pluginID, relativePath string) string {
+	if _, err := a.requirePluginAccess(pluginID, "files.openExternal"); err != nil {
+		return err.Error()
+	}
+	if a.files == nil {
+		return "files service not initialized"
+	}
+	target, err := a.files.ResolveExternalOpenTarget(relativePath)
+	if err != nil {
+		return err.Error()
+	}
+	if err := a.externalOpenService().OpenPath(target.AbsolutePath); err != nil {
+		return err.Error()
+	}
+	return ""
+}
+
+// ShowVaultPathInFolder reveals a vault-relative file or folder in the OS file manager.
+func (a *App) ShowVaultPathInFolder(pluginID, relativePath string) string {
+	if _, err := a.requirePluginAccess(pluginID, "files.openExternal"); err != nil {
+		return err.Error()
+	}
+	if a.files == nil {
+		return "files service not initialized"
+	}
+	target, err := a.files.ResolveExternalOpenTarget(relativePath)
+	if err != nil {
+		return err.Error()
+	}
+	isDir := target.Metadata.Type == corefiles.FileTypeFolder
+	if err := a.externalOpenService().ShowInFolder(target.AbsolutePath, isDir); err != nil {
+		return err.Error()
+	}
+	return ""
+}
+
+func (a *App) externalOpenService() externalOpenService {
+	if a.externalOpen != nil {
+		return a.externalOpen
+	}
+	return externalopen.NewService()
+}
+
 func (a *App) recordFileSyncOp(entityType, entityID, opType string, payload interface{}) error {
 	if a.syncSvc == nil {
 		return nil
diff --git a/internal/api/app_test.go b/internal/api/app_test.go
index 5cd30ea..1795590 100644
--- a/internal/api/app_test.go
+++ b/internal/api/app_test.go
@@ -82,6 +82,22 @@ func newFilesTestApp(t *testing.T, perms []string) (*App, string) {
 	}, v.GetVaultPath()
 }
 
+type testExternalOpenService struct {
+	open func(path string) error
+}
+
+func newTestExternalOpenService(open func(path string) error) *testExternalOpenService {
+	return &testExternalOpenService{open: open}
+}
+
+func (s *testExternalOpenService) OpenPath(path string) error {
+	return s.open(path)
+}
+
+func (s *testExternalOpenService) ShowInFolder(path string, _ bool) error {
+	return s.open(path)
+}
+
 func newSyncFilesTestApp(t *testing.T, perms []string, deviceID string) (*App, string) {
 	t.Helper()
 	app, root := newFilesTestApp(t, perms)
@@ -358,6 +374,61 @@ func TestFilesBridgeReadWriteListMoveTrash(t *testing.T) {
 	}
 }
 
+func TestFilesBridgeOpenExternalUsesVaultPathPolicyAndPermission(t *testing.T) {
+	app, root := newFilesTestApp(t, []string{"files.openExternal"})
+	filePath := filepath.Join(root, "Docs", "one.txt")
+	if err := os.MkdirAll(filepath.Dir(filePath), 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := os.WriteFile(filePath, []byte("hello"), 0o644); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+
+	var opened []string
+	app.externalOpen = newTestExternalOpenService(func(path string) error {
+		opened = append(opened, path)
+		return nil
+	})
+
+	if errStr := app.OpenVaultPathExternal("files.plugin", "Docs/one.txt"); errStr != "" {
+		t.Fatalf("OpenVaultPathExternal: %s", errStr)
+	}
+	if len(opened) != 1 || opened[0] != filePath {
+		t.Fatalf("opened = %#v, want %q", opened, filePath)
+	}
+
+	if errStr := app.OpenVaultPathExternal("files.plugin", ".verstak/vault.json"); errStr == "" || !strings.Contains(errStr, "reserved-path") {
+		t.Fatalf("reserved path error = %q, want reserved-path", errStr)
+	}
+	if len(opened) != 1 {
+		t.Fatalf("reserved path should not open, opened = %#v", opened)
+	}
+}
+
+func TestFilesBridgeShowInFolderUsesVaultPathPolicyAndPermission(t *testing.T) {
+	app, root := newFilesTestApp(t, []string{"files.openExternal"})
+	filePath := filepath.Join(root, "Docs", "one.txt")
+	if err := os.MkdirAll(filepath.Dir(filePath), 0o755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := os.WriteFile(filePath, []byte("hello"), 0o644); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+
+	var shown []string
+	app.externalOpen = newTestExternalOpenService(func(path string) error {
+		shown = append(shown, path)
+		return nil
+	})
+
+	if errStr := app.ShowVaultPathInFolder("files.plugin", "Docs/one.txt"); errStr != "" {
+		t.Fatalf("ShowVaultPathInFolder: %s", errStr)
+	}
+	if len(shown) != 1 || shown[0] != filePath {
+		t.Fatalf("shown = %#v, want %q", shown, filePath)
+	}
+}
+
 func TestFilesBridgePermissions(t *testing.T) {
 	cases := []struct {
 		name       string
@@ -411,6 +482,18 @@ func TestFilesBridgePermissions(t *testing.T) {
 			call:       func(app *App) string { _, errStr := app.TrashVaultPath("files.plugin", "one.txt"); return errStr },
 			wantPhrase: "files.delete",
 		},
+		{
+			name:       "open external requires openExternal",
+			perms:      []string{"files.read", "files.write", "files.delete"},
+			call:       func(app *App) string { return app.OpenVaultPathExternal("files.plugin", "one.txt") },
+			wantPhrase: "files.openExternal",
+		},
+		{
+			name:       "show in folder requires openExternal",
+			perms:      []string{"files.read", "files.write", "files.delete"},
+			call:       func(app *App) string { return app.ShowVaultPathInFolder("files.plugin", "one.txt") },
+			wantPhrase: "files.openExternal",
+		},
 	}
 
 	for _, tc := range cases {
diff --git a/internal/core/externalopen/service.go b/internal/core/externalopen/service.go
new file mode 100644
index 0000000..a92372b
--- /dev/null
+++ b/internal/core/externalopen/service.go
@@ -0,0 +1,62 @@
+package externalopen
+
+import (
+	"os/exec"
+	"path/filepath"
+	"runtime"
+)
+
+type Runner func(name string, args ...string) error
+
+type Service struct {
+	goos   string
+	runner Runner
+}
+
+func NewService() *Service {
+	return NewServiceFor(runtime.GOOS, func(name string, args ...string) error {
+		return exec.Command(name, args...).Start()
+	})
+}
+
+func NewServiceFor(goos string, runner Runner) *Service {
+	return &Service{goos: goos, runner: runner}
+}
+
+func (s *Service) OpenPath(path string) error {
+	name, args := s.openCommand(path)
+	return s.runner(name, args...)
+}
+
+func (s *Service) ShowInFolder(path string, isDir bool) error {
+	name, args := s.showCommand(path, isDir)
+	return s.runner(name, args...)
+}
+
+func (s *Service) openCommand(path string) (string, []string) {
+	switch s.goos {
+	case "darwin":
+		return "open", []string{path}
+	case "windows":
+		return "rundll32", []string{"url.dll,FileProtocolHandler", path}
+	default:
+		return "xdg-open", []string{path}
+	}
+}
+
+func (s *Service) showCommand(path string, isDir bool) (string, []string) {
+	switch s.goos {
+	case "darwin":
+		return "open", []string{"-R", path}
+	case "windows":
+		if isDir {
+			return "explorer", []string{path}
+		}
+		return "explorer", []string{"/select," + path}
+	default:
+		if isDir {
+			return "xdg-open", []string{path}
+		}
+		return "xdg-open", []string{filepath.Dir(path)}
+	}
+}
diff --git a/internal/core/externalopen/service_test.go b/internal/core/externalopen/service_test.go
new file mode 100644
index 0000000..c295888
--- /dev/null
+++ b/internal/core/externalopen/service_test.go
@@ -0,0 +1,71 @@
+package externalopen
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestOpenPathCommands(t *testing.T) {
+	cases := []struct {
+		goos string
+		path string
+		want commandCall
+	}{
+		{goos: "linux", path: "/vault/file.txt", want: commandCall{name: "xdg-open", args: []string{"/vault/file.txt"}}},
+		{goos: "darwin", path: "/vault/file.txt", want: commandCall{name: "open", args: []string{"/vault/file.txt"}}},
+		{goos: "windows", path: `C:\Vault\file.txt`, want: commandCall{name: "rundll32", args: []string{"url.dll,FileProtocolHandler", `C:\Vault\file.txt`}}},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.goos, func(t *testing.T) {
+			var got commandCall
+			svc := NewServiceFor(tc.goos, func(name string, args ...string) error {
+				got = commandCall{name: name, args: args}
+				return nil
+			})
+			if err := svc.OpenPath(tc.path); err != nil {
+				t.Fatalf("OpenPath: %v", err)
+			}
+			if !reflect.DeepEqual(got, tc.want) {
+				t.Fatalf("command = %#v, want %#v", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestShowInFolderCommands(t *testing.T) {
+	cases := []struct {
+		name  string
+		goos  string
+		path  string
+		isDir bool
+		want  commandCall
+	}{
+		{name: "linux file opens parent", goos: "linux", path: "/vault/Docs/file.txt", want: commandCall{name: "xdg-open", args: []string{"/vault/Docs"}}},
+		{name: "linux dir opens dir", goos: "linux", path: "/vault/Docs", isDir: true, want: commandCall{name: "xdg-open", args: []string{"/vault/Docs"}}},
+		{name: "darwin reveal", goos: "darwin", path: "/vault/file.txt", want: commandCall{name: "open", args: []string{"-R", "/vault/file.txt"}}},
+		{name: "windows select file", goos: "windows", path: `C:\Vault\file.txt`, want: commandCall{name: "explorer", args: []string{`/select,C:\Vault\file.txt`}}},
+		{name: "windows open dir", goos: "windows", path: `C:\Vault\Docs`, isDir: true, want: commandCall{name: "explorer", args: []string{`C:\Vault\Docs`}}},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			var got commandCall
+			svc := NewServiceFor(tc.goos, func(name string, args ...string) error {
+				got = commandCall{name: name, args: args}
+				return nil
+			})
+			if err := svc.ShowInFolder(tc.path, tc.isDir); err != nil {
+				t.Fatalf("ShowInFolder: %v", err)
+			}
+			if !reflect.DeepEqual(got, tc.want) {
+				t.Fatalf("command = %#v, want %#v", got, tc.want)
+			}
+		})
+	}
+}
+
+type commandCall struct {
+	name string
+	args []string
+}
diff --git a/internal/core/files/service.go b/internal/core/files/service.go
index c1e6b7c..980202d 100644
--- a/internal/core/files/service.go
+++ b/internal/core/files/service.go
@@ -88,6 +88,31 @@ func (s *Service) GetVaultFileMetadata(relativePath string) (FileMetadata, error
 	return makeMetadata(rel, info), nil
 }
 
+func (s *Service) ResolveExternalOpenTarget(relativePath string) (ExternalOpenTarget, error) {
+	root, rel, full, err := s.resolveFile(relativePath)
+	if err != nil {
+		return ExternalOpenTarget{}, err
+	}
+	if err := rejectSymlinkPath(root, rel, true); err != nil {
+		return ExternalOpenTarget{}, err
+	}
+	info, err := os.Lstat(full)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return ExternalOpenTarget{}, fmt.Errorf("not-found: %s", rel)
+		}
+		return ExternalOpenTarget{}, err
+	}
+	if info.Mode()&os.ModeSymlink != 0 {
+		return ExternalOpenTarget{}, fmt.Errorf("symlink-not-allowed: %s", rel)
+	}
+	return ExternalOpenTarget{
+		RelativePath: rel,
+		AbsolutePath: full,
+		Metadata:     makeMetadata(rel, info),
+	}, nil
+}
+
 func (s *Service) ReadVaultTextFile(relativePath string) (string, error) {
 	root, rel, full, err := s.resolveFile(relativePath)
 	if err != nil {
diff --git a/internal/core/files/types.go b/internal/core/files/types.go
index 4f7af71..622b7aa 100644
--- a/internal/core/files/types.go
+++ b/internal/core/files/types.go
@@ -39,6 +39,12 @@ type FileMetadata struct {
 	CanWrite     bool     `json:"canWrite"`
 }
 
+type ExternalOpenTarget struct {
+	RelativePath string       `json:"relativePath"`
+	AbsolutePath string       `json:"absolutePath"`
+	Metadata     FileMetadata `json:"metadata"`
+}
+
 type WriteOptions struct {
 	CreateIfMissing bool `json:"createIfMissing"`
 	Overwrite       bool `json:"overwrite"`
diff --git a/internal/core/permissions/registry.go b/internal/core/permissions/registry.go
index 3868fcf..d3deb8d 100644
--- a/internal/core/permissions/registry.go
+++ b/internal/core/permissions/registry.go
@@ -36,6 +36,7 @@ func (r *Registry) registerDefaults() {
 		{Name: "files.read", Description: "List files and read text files through the vault Files API", Dangerous: false},
 		{Name: "files.write", Description: "Create folders, write text files, and move paths through the vault Files API", Dangerous: true},
 		{Name: "files.delete", Description: "Trash vault files and folders through the vault Files API", Dangerous: true},
+		{Name: "files.openExternal", Description: "Open vault files and folders in external OS applications", Dangerous: true},
 		{Name: "storage.namespace", Description: "Read/write plugin's own storage namespace", Dangerous: false},
 		{Name: "storage.migrations", Description: "Run database migrations in plugin namespace", Dangerous: false},
 		{Name: "events.publish", Description: "Publish events to the event bus", Dangerous: false},