Feature — Loopback Exempt (Tools)

Status: SHIPPED (v1.3.0). Implemented as a dedicated LoopbackExemptWindow accessible from File Explorer. This spec describes the original design.

Goal

Add a Tools tool that applies the Xbox loopback exemption for an installed UWP app so it can reach the console’s Device Portal REST API on itself (https://[::1]:11443). Primary use case: X-Files browsing other apps’ LocalAppData via the portal.

The exemption survives app relaunch but is lost on re-install and console reboot, so the tool is a one-click re-apply (not a watcher).

Background

• X-Files (UWP) cannot reach the portal because Xbox isolates app containers from local loopback.
• The exemption is granted by checknetisolation, which requires elevation — impossible from inside the app, so it must be run over SSH from a PC.
• XB Vault already has every building block: portal REST auth, rotating SSH password fetch, SSH command execution, and installed-package listing.

flowchart LR
    A["XB Vault (PC)"] -->|SSH checknetisolation -a -n=PFN| B["Xbox SSH :22"]
    A -->|REST packages list| C["Portal :11443"]
    C --> D["InstalledPackages[].PackageFamilyName"]
    D -->|PFN| B
    B -->|exemption active| E["X-Files reaches Portal"]
    E --> F["LocalAppData browse"]

Key commands (run over SSH, cmd.exe shell)

PFN example: XFiles.Xbox_jgz7qwhvc5jpc.

Files to create

Files to modify

Icons: create XBVault/Assets/Views/ToolsView/tools-loopback-20.png per the assets guide (docs/ASSETS-GUIDE.md, personal set F:\workspace\icons8-personal-set).

Window UI

┌─────────────────────────────────────────────┐
│ LOOPBACK EXEMPT                            │
│                                             │
│ App:  [ComboBox of installed packages      ]│
│       (pre-selected: package whose Name     │
│        contains "XFiles", else first Dev)   │
│                                             │
│ Package Family Name:  XFiles.Xbox_jgz...    │
│                                             │
│ [Apply exemption]   [Remove exemption]      │
│ [Refresh list]     [Check status]           │
│                                             │
│ Status: Applied ✓ / Already applied / ...   │
└─────────────────────────────────────────────┘

Model: LoopbackExemptViewModel : ObservableObject

• ObservableCollection<InstalledPackage> Packages (reuse existing model — it has Name + PackageFamilyName already)
• InstalledPackage? SelectedPackage
• string StatusText (muted colors via existing brushes/converters)
• bool IsBusy (disable buttons while running)
• Commands: ApplyCommand, RemoveCommand, CheckCommand, RefreshCommand

Flow (Apply / Remove / Check)

1. Ensure SFTP connected — reuse the FileExplorerViewModel.InitializeAsync pattern:

   await _authService.FetchSmbPasswordAsync();
   var creds = _authService.GetSshCredentials();   // DevToolsUser / port 22
   await _sftpService.ConnectAsync(creds.Host, creds.Port, creds.Username, creds.Password);
   

2. Load packages on window open: _packageService.GetInstalledPackagesAsync() → fill Packages, pre-select XFiles match.
3. PFN = SelectedPackage.PackageFamilyName. If empty, show status error.
4. Run over SSH via _sftpService.RunShellCommandAsync:
   • Apply: checknetisolation loopbackexempt -a -n=<PFN>
   • Remove: checknetisolation loopbackexempt -d -n=<PFN>
5. Verify with checknetisolation loopbackexempt -s; check output contains the PFN. Set StatusText accordingly:
   • Applied ✓ / Already applied / Removed ✓ / Not exempted / Command failed: <error>.

Keep all work in Task.Run (SSH.NET is synchronous) — the existing RunShellCommandAsync already wraps it and holds a shell lock; call it with await.

Notes / gotchas

• SSH shell is cmd.exe, not bash. Quotes/escaping follow Windows rules (commands above have no quotes, safe).
• The rotating SSH password comes from FetchSmbPasswordAsync() (portal /ext/smb/developerfolder) — always fetch fresh before connecting; it is different from the portal password.
• Do not add a watcher/auto-re-apply after install in this change. Manual button only. (Auto-hook post-install is a possible follow-up.)
• “Exempt all developer apps” is out of scope (single-app picker only).

Verification

• dotnet build XBVault/XBVault.csproj
• Manual: connect to an Xbox in Dev Mode, open Tools → Loopback Exempt, pick X-Files, Apply → status Applied ✓; close X-Files, relaunch it, open About probe → portal CONNECTED.
• Re-install X-Files (or reboot), Apply again → still works.

Reference

• Scripts (same flow, standalone): x-files-uwp/tools/liberate-loopback.{ps1,sh}
• Technical doc: x-files-uwp/docs/PORTAL-APPDATA.md