Let the user name the iPhone in Settings

TODO.md

@@ -1,6 +1,4 @@
 # Bugs
-- Enable the iPhone device-name entitlement
-  Once Apple grants User Assigned Device Name to the App ID `run.fc.byre.ios` (Certificates, Identifiers & Profiles, Capability Requests), turn it on there and add `com.apple.developer.device-information.user-assigned-device-name` to `mac/phone/byre.entitlements`. Until then `UIDevice.current.name` returns `iPhone` on a real phone. Check on a TestFlight build that the Status tab lists the phone by its own name.
 
 # M1 — One agent end to end
 

docs/iphone.md

@@ -17,5 +17,5 @@ The simulator's window (Xcode's Device Hub) lists the app's own accessibility el
 ## Platform facts
 
 - CloudKit on iOS requires the `remote-notification` background mode in `Info.plist`, even though the app sets up no push of its own.
-- The phone's tailnet node is always `byre-app-iphone`; the phone's own name stays inside byre. `Byre-Host`, which the server shows for the phone, takes its name from `UIDevice.current.name`, which iOS reads only on the main actor (so the app delegate reads it first) and returns as just `iPhone` unless the app has the `com.apple.developer.device-information.user-assigned-device-name` entitlement. Apple grants that entitlement on request (developer.apple.com/contact/request/user-assigned-device-name); it then has to be enabled on the App ID and added to `mac/phone/byre.entitlements`. The simulator returns the simulator device's own name without it.
+- The phone's name is the one typed in Settings, kept in the phone's own `UserDefaults` (not synced through iCloud, since each phone has its own), and `iPhone` until one is typed. It goes in `Byre-Host` and the tailnet node's name, both fixed when the app starts. `UIDevice.current.name` returns just `iPhone` without Apple's `com.apple.developer.device-information.user-assigned-device-name` entitlement, which Apple refused because byre shows the name to other people and sends it to Tailscale and to the agents' model vendors.
 - SwiftTerm's iOS `TerminalViewDelegate` requires `requestOpenLink`, which its macOS one provides a default for.

mac/Sources/Byre/API.swift

@@ -107,7 +107,8 @@ private let clientID = newID("cli")
 #if os(macOS)
 let deviceName = Host.current().localizedName ?? ProcessInfo.processInfo.hostName
 #else
-let deviceName = MainActor.assumeIsolated { UIDevice.current.name }
+let deviceNameKey = "deviceName"
+let deviceName = UserDefaults.standard.string(forKey: deviceNameKey) ?? deviceKind
 #endif
 
 final class API: Sendable {

mac/Sources/Byre/Phone.swift

@@ -3,8 +3,6 @@ import SwiftUI
 
 final class PhoneDelegate: NSObject, UIApplicationDelegate {
     func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil) -> Bool {
-        // deviceName reads UIDevice, which is main-actor only, so it must first be read here.
-        _ = deviceName
         Notifier.shared.install()
         UITextView.appearance().textContainerInset = .zero
         return true

mac/Sources/Byre/Settings.swift

@@ -22,6 +22,13 @@ struct SettingsView: View {
     var body: some View {
         ScrollView {
             VStack(alignment: .leading, spacing: 0) {
+                #if os(iOS)
+                heading("This iPhone's name")
+                Text("byre shows this iPhone by this name, and names its tailnet node after it. A new name takes effect the next time byre opens.")
+                    .foregroundStyle(Palette.muted)
+                    .fixedSize(horizontal: false, vertical: true)
+                DeviceNameField()
+                #endif
                 heading("Window color")
                 Text("Windows for this server have a border in this color, on every device you use.")
                     .foregroundStyle(Palette.muted)
@@ -79,6 +86,40 @@ struct SettingsView: View {
     }
 }
 
+#if os(iOS)
+private struct DeviceNameField: View {
+    @ViewState private var name = UserDefaults.standard.string(forKey: deviceNameKey) ?? deviceKind
+    @ViewState private var saved = UserDefaults.standard.string(forKey: deviceNameKey) ?? deviceKind
+
+    var body: some View {
+        let trimmed = name.trimmingCharacters(in: .whitespaces)
+        let valid = !slug(trimmed).isEmpty && trimmed != saved
+        HStack(spacing: 6) {
+            TextField("Name", text: $name)
+                .modifier(FieldStyle())
+                .onSubmit {
+                    save(trimmed, valid)
+                }
+            Button("Save") {
+                save(trimmed, valid)
+            }
+            .buttonStyle(WebButtonStyle())
+            .disabled(!valid)
+        }
+        .padding(.top, 8)
+    }
+
+    private func save(_ trimmed: String, _ valid: Bool) {
+        if !valid {
+            return
+        }
+        UserDefaults.standard.set(trimmed, forKey: deviceNameKey)
+        saved = trimmed
+        name = trimmed
+    }
+}
+#endif
+
 private struct ServerColorPicker: View {
     @Environment(Store.self) private var store
 

mac/Sources/Byre/Tailnet.swift

@@ -26,11 +26,7 @@ func slug(_ text: String) -> String {
 
 final class TailnetNode: Sendable {
     let sd: tailscale
-    #if os(macOS)
     let hostname = "byre-app-\(slug(deviceName))"
-    #else
-    let hostname = "byre-app-\(slug(deviceKind))"
-    #endif
     private let socks = TailnetProxy()
 
     init() {