Keyboard and trackpad for the Frame, through its own KDE Connect

Home → Keyboard and trackpad, in every version of Frame Control (Mac,
Windows, Linux, iPhone, iPad) with nothing to install on the device in
your hand. On a phone: a trackpad (drag, tap, two-finger scroll and
right-click) and a field that types on the Frame. On a computer: click
the pad to pass the mouse and keyboard through; Esc to stop.

First-party route: ui/frame_input_agent.py runs on the Frame and talks
KDE Connect's LAN protocol (v7) to kdeconnectd as if it were a phone.
KDE Connect isn't on the image, but Valve's package repository has it;
the agent fetches it and four libraries into ~ (no root, survives
updates), starts it, pairs by itself (accepting over D-Bus), and stops
it again when the last device disconnects. Each device has its own
identity; a stuck KDE Connect is restarted once.

Verified against the real Frame (SteamOS 0.4.1): first-time install,
pairing, pointer moves from the Mac's server and the iPhone app
(Simulator), Mac and iPhone at once, two installs at once, a frozen
daemon replaced, and the daemon stopping when the app quits.

Reviewed by GPT-6 Astra (xhigh) over seven rounds; all findings fixed
except per-event delivery acknowledgement (documented known limit).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

ios/FrameControl/App/AppModel.swift

@@ -1,4 +1,5 @@
 import Citadel
+import CryptoKit
 import Foundation
 import SwiftUI
 import UIKit
@@ -33,6 +34,11 @@ final class AppModel: ObservableObject {
     }
 
     var deviceName: String { UIDevice.current.userInterfaceIdiom == .pad ? "iPad" : "iPhone" }
+    /// Stable per install: a hash of this device's SSH key, which is made once and kept in the Keychain.
+    var clientID: String {
+        let digest = SHA256.hash(data: Data(authorizedKeysLine.utf8))
+        return deviceName.lowercased() + "-" + digest.prefix(6).map { String(format: "%02x", $0) }.joined()
+    }
     private var hostKey: String? { UserDefaults.standard.string(forKey: Self.hostKeyKey) }
 
     // MARK: pairing
@@ -167,7 +173,7 @@ final class AppModel: ObservableObject {
             guard current() else { throw CancellationError() }
             step("Starting Frame Control on the headset")
             let key = Self.randomKey()
-            let server = try await HeadsetServer.start(in: dir, over: l, key: key, device: deviceName)
+            let server = try await HeadsetServer.start(in: dir, over: l, key: key, device: deviceName, client: clientID)
             guard current() else { throw CancellationError() }
             let f = try await PortForwarder.start(over: l, to: server.port)
             forwarder = f