README: Rudder, the first plugin that ships as a real desktop app (Linux screenshot)

- documentation/readme-images/deploy5-desktop-rudder.png: the Rudder desktop app running on Linux,
  window content only — the window title bar is cropped (it shows the desktop's theme) and the file is
  rewritten as pixels only: no text, time, software, EXIF, density or colour-profile chunks. Taken with
  RUDDER_PRIVATE_LABELS=1 and a fresh profile, so no device names, volumes or saved drafts show.
- README Output 3: the Rudder desktop app, the screenshot and the two build commands; macOS/Windows
  marked built-but-never-run and the first-run model download as not built yet.
- engine: RUDDER_PRIVATE_LABELS=1 now also hides volume levels and switched-off sound cards (a card's
  name identifies the machine's audio chipset).

README.md

@@ -475,6 +475,20 @@ bun run phone          # builds the app and installs it on a phone or emulator
 
 ![Desktop app (Tauri) — proven, not yet in production](documentation/readme-images/deploy5-desktop.png)
 
+**And the first plugin that ships as a real desktop app: Rudder**, private voice-to-text, built from the
+same `plugin-designs/rudder-voice/` folder that runs in the Plugin Studio. On Linux it installs as a `.deb`,
+starts its own local speech engine, and transcribes offline — no account, no cloud, no telemetry.
+
+![Rudder desktop app on Linux — streaming voice-to-text, offline](documentation/readme-images/deploy5-desktop-rudder.png)
+
+```bash
+# Linux — the full path is in documentation/HOWTO-build-the-desktop-app.md
+bash backend/rudder-engine/setup-runtime.sh   # once: the speech runtime + model, verified by SHA-256
+./node_modules/.bin/tauri build --config deployment/src-tauri/rudder.conf.json   # → Rudder_0.1.0_amd64.deb
+```
+
+<sub>macOS and Windows: built but never run. The 742 MB model is not yet downloaded by the app on first run.</sub>
+
 <details>
 <summary><b>More about the desktop app</b></summary>
 

backend/rudder-engine/devices.go

@@ -117,8 +117,9 @@ func listDevices() DeviceList {
 		if bus, ok := s.Properties["device.bus"].(string); ok {
 			d.Bus = bus
 		}
-		// RUDDER_PRIVATE_LABELS=1: show microphones by KIND, not by name. Device names are often personal
-		// ("Anna's AirPods") — use this for screenshots, screen-sharing and demos.
+		// RUDDER_PRIVATE_LABELS=1: show microphones by KIND, not by name, and hide volume levels and
+		// switched-off sound cards. Device and card names are personal or identify the hardware ("Anna's
+		// AirPods", a laptop's audio chipset) — use this for screenshots, screen-sharing and demos.
 		if os.Getenv("RUDDER_PRIVATE_LABELS") == "1" {
 			d.Label = map[string]string{"bluetooth": "Bluetooth headset", "usb": "USB microphone", "pci": "Built-in microphone"}[d.Bus]
 			if d.Label == "" {
@@ -133,8 +134,14 @@ func listDevices() DeviceList {
 				}
 			}
 		}
+		if os.Getenv("RUDDER_PRIVATE_LABELS") == "1" {
+			d.Volume = "" // a volume level is a detail of this machine's settings
+		}
 		out.Devices = append(out.Devices, d)
 	}
+	if os.Getenv("RUDDER_PRIVATE_LABELS") == "1" {
+		return out // no card names in private mode
+	}
 	// Cards whose active profile is "off" but which offer an input profile.
 	if b, err := runPactl("-f", "json", "list", "cards"); err == nil {
 		var cards []struct {