clients: prefill a shared account so our devices auto-pair ("just us")

Default the account to a shared identity (overridable, persisted in
UserDefaults/prefs; agent via --account) instead of empty. With it prefilled,
every one of our devices on the same network auto-pairs over the LAN regardless
of room — no setup. Swapped in for the real Sign-in-with-Apple `sub` later.

Verified with the live Mac app: it and an agent in a totally different room
LAN-paired purely via the shared account.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

agent/src/main.rs

@@ -58,7 +58,7 @@ fn main() {
     let host = std::env::var("HOSTNAME").unwrap_or_else(|_| "tether-agent".into());
     let name = arg("--name", &host);
     // Shared identity: same-account devices pair on the LAN regardless of room.
-    let account = arg("--account", "");
+    let account = arg("--account", "pecord@gmail.com");
 
     eprintln!("tether-agent → {server}  room={room}  source={source}");
 

android/app/src/main/java/io/pecord/tether/TetherStore.kt

@@ -18,6 +18,7 @@ data class FeedItem(val text: String, val source: String, val ts: Long, val id:
 /// changes, so we auto-send via OnPrimaryClipChangedListener.
 class TetherStore(private val context: Context) {
     val serverURL = mutableStateOf(prefs().getString("serverURL", "https://tether.pecord.io")!!)
+    val account = mutableStateOf(prefs().getString("account", "pecord@gmail.com")!!)
     val room = mutableStateOf(RoomIdentity.derive(context))
     val feed = mutableStateListOf<FeedItem>()
     val connected = mutableStateOf(false)
@@ -30,9 +31,9 @@ class TetherStore(private val context: Context) {
     private var counter = 0L
 
     fun connect() {
-        prefs().edit().putString("serverURL", serverURL.value).apply()
+        prefs().edit().putString("serverURL", serverURL.value).putString("account", account.value).apply()
         disconnect()
-        val e = Engine(serverURL.value.trim(), room.value, deviceId, "android", android.os.Build.MODEL, "")
+        val e = Engine(serverURL.value.trim(), room.value, deviceId, "android", android.os.Build.MODEL, account.value)
         e.start(Bridge())
         engine = e
         connected.value = true

ios/MacTetherApp/Sources/MacTetherStore.swift

@@ -17,6 +17,8 @@ struct FeedItem: Identifiable, Equatable {
 @MainActor @Observable
 final class MacTetherStore {
     var serverURL: String = UserDefaults.standard.string(forKey: "serverURL") ?? "https://tether.pecord.io"
+    // Prefilled shared identity — for now it's just us, so all devices pair.
+    var account: String = UserDefaults.standard.string(forKey: "account") ?? "pecord@gmail.com"
     var room: String = RoomIdentity.derive()
     var feed: [FeedItem] = []
     var nearby: [Peer] = []   // tether devices on the LAN, for the picker
@@ -45,10 +47,11 @@ final class MacTetherStore {
         }
         hasAttemptedConnect = true
         UserDefaults.standard.set(serverURL, forKey: "serverURL")
+        UserDefaults.standard.set(account, forKey: "account")
         disconnect()
 
         let b = EngineBridge(store: self)
-        let e = Engine(server: url, room: room, from: deviceID, source: "macos", name: deviceID, account: "")
+        let e = Engine(server: url, room: room, from: deviceID, source: "macos", name: deviceID, account: account)
         e.start(handler: b)
         engine = e
         bridge = b

ios/TetherApp/Sources/TetherStore.swift

@@ -20,6 +20,9 @@ struct FeedItem: Identifiable, Equatable {
 @MainActor @Observable
 final class TetherStore {
     var serverURL: String = UserDefaults.standard.string(forKey: "serverURL") ?? "https://tether.pecord.io"
+    // Prefilled shared identity — for now it's just us, so all devices pair.
+    // Becomes the Sign-in-with-Apple `sub` once the dev program clears.
+    var account: String = UserDefaults.standard.string(forKey: "account") ?? "pecord@gmail.com"
     var room: String = RoomIdentity.derive()
     var feed: [FeedItem] = []
     var connected = false
@@ -41,10 +44,11 @@ final class TetherStore {
             return
         }
         UserDefaults.standard.set(serverURL, forKey: "serverURL")
+        UserDefaults.standard.set(account, forKey: "account")
         disconnect()
 
         let b = EngineBridge(store: self)
-        let e = Engine(server: url, room: room, from: deviceID, source: "ios", name: UIDevice.current.name, account: "")
+        let e = Engine(server: url, room: room, from: deviceID, source: "ios", name: UIDevice.current.name, account: account)
         e.start(handler: b)
         engine = e
         bridge = b