Manifest for Linux; connect as Background app where Utility is refused

- manifest.vrmanifest: binary_path_linux and binary_path_linux_arm. The
  Steam Frame's SteamVR reads only binary_path_linux_arm.
- handleManifests(): connect as Utility app first (works without a running
  SteamVR, e.g. from the Windows installer); if SteamVR refuses Utility apps,
  as on the Steam Frame, connect as Background app. Fail right away on other
  errors instead of going through initializeOpenVR()'s retry loop.
- main(): check --graphics-api before connecting to OpenVR, so a wrong value
  fails right away.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/steamframe/PROGRESS.md

@@ -102,3 +102,23 @@
 - `MyTextField` opens the SteamVR keyboard on `activeFocus`. The template had to send the
   offscreen window an explicit `FocusIn`, otherwise `activeFocusItem` stayed null. The `qt6`
   branch doesn't send it. If text fields don't respond on the Frame, that is the cause (R4).
+
+### Step 4: manifest and installation (2026-10-07)
+
+**Changes:**
+- **`manifest.vrmanifest`:** `binary_path_linux` and `binary_path_linux_arm` →
+  `AdvancedSettings_app`.
+- **`manifest::handleManifests`:**
+  - `VR_Init(Utility)`; on `VRInitError_Init_NotAvailableToUtilityApps`,
+    `VR_Init(Background)`.
+  - Other errors: message and exit code `OPENVR_INIT_ERROR`, instead of
+    `initializeOpenVR`'s retry loop.
+- **`main.cpp`:** `--graphics-api` is checked before connecting to OpenVR. A wrong value
+  used to fail only after `initializeOpenVR`'s retry loop.
+
+**Results (x86_64, without SteamVR):**
+- `--force-install-manifest` exits right away with `OPENVR_INIT_ERROR` (−2).
+- `--graphics-api foo` exits right away with `GENERAL_FAILURE` (−1).
+- The build tree contains the binary, `libopenvr_api.so`, both manifests,
+  `default_action_manifests/` and `res/`.
+- Not tested yet: `Background` on the Frame (step 5).

src/main.cpp

@@ -45,14 +45,8 @@ int main( int argc, char* argv[] )
                                    commandLineArgs.forceRemoveManifest );
     }
 
-    openvr_init::initializeOpenVR(
-        openvr_init::OpenVrInitializationType::Overlay );
-
-    // Render backend (render/RenderBackend.h). Created after OpenVR, because
-    // the Vulkan backend needs SteamVR's device requirements
-    // (openvr_init::renderInterop()), and before OverlayController, because
-    // QQuickWindow::setGraphicsApi() must run before any QQuickWindow exists
-    // (OverlayController owns one).
+    // Render backend (render/RenderBackend.h). Chosen before connecting to
+    // OpenVR, so a wrong --graphics-api fails right away.
     GraphicsApi graphicsApi = GraphicsApi::OpenGL;
     if ( !parseGraphicsApi( commandLineArgs.graphicsApi, &graphicsApi ) )
     {
@@ -68,6 +62,14 @@ int main( int argc, char* argv[] )
                     << "is not compiled into this build";
         return ReturnErrorCode::GENERAL_FAILURE;
     }
+
+    openvr_init::initializeOpenVR(
+        openvr_init::OpenVrInitializationType::Overlay );
+
+    // Initialized after OpenVR, because the Vulkan backend needs SteamVR's
+    // device requirements (openvr_init::renderInterop()), and before
+    // OverlayController, because QQuickWindow::setGraphicsApi() must run
+    // before any QQuickWindow exists (OverlayController owns one).
     QString renderBackendError;
     if ( !renderBackend->initialize( openvr_init::renderInterop(),
                                      &renderBackendError ) )

src/package_files/manifest.vrmanifest

@@ -4,6 +4,8 @@
 		"app_key": "steam.overlay.1009850",
 		"launch_type": "binary",
 		"binary_path_windows": "AdvancedSettings.exe",
+		"binary_path_linux": "AdvancedSettings_app",
+		"binary_path_linux_arm": "AdvancedSettings_app",
 		"is_dashboard_overlay": true,
 
 		"strings": {

src/utils/setup.cpp

@@ -262,8 +262,26 @@ void forceRemoveApplicationManifest()
 [[noreturn]] void handleManifests( const bool installManifest,
                                    const bool removeManifest )
 {
-    openvr_init::initializeOpenVR(
-        openvr_init::OpenVrInitializationType::Utility );
+    // Connect as Utility app first: it works without a running SteamVR (e.g.
+    // from the Windows installer). The Steam Frame's SteamVR refuses Utility
+    // apps (VRInitError_Init_NotAvailableToUtilityApps); there, connect as
+    // Background app, which needs a running SteamVR and never starts it.
+    // VR_Init is called directly: initializeOpenVR() retries every error with
+    // waits, including the one expected here.
+    vr::EVRInitError initError = vr::VRInitError_None;
+    vr::VR_Init( &initError, vr::VRApplication_Utility );
+    if ( initError == vr::VRInitError_Init_NotAvailableToUtilityApps )
+    {
+        qInfo() << "SteamVR refuses Utility apps, connecting as Background "
+                   "app.";
+        vr::VR_Init( &initError, vr::VRApplication_Background );
+    }
+    if ( initError != vr::VRInitError_None )
+    {
+        qCritical() << "Failed to connect to SteamVR for manifest handling:"
+                    << vr::VR_GetVRInitErrorAsEnglishDescription( initError );
+        exit( ReturnErrorCode::OPENVR_INIT_ERROR );
+    }
 
     int exit_code = ReturnErrorCode::SUCCESS;
     try