Restructure step 1: lasting identity, presence and protocol 16

Server and core: version ranges on both sides with a coded refusal; a
client id maps to the same member and token for the server's life; a
drop is `gone` for a 10-minute grace keeping ready, presence, queue
items, relay and avatar; `bye` leaves at once; ordered takeover (seq,
replaced/stale); presence joining/in/away/gone with one PresencePolicy;
joiners never pause playback and hold a held gate at most ~15 s;
state.hold; feed ids, seq and replay; the relay lives through its
source's grace and continues on re-dial; queue `by` lasting, auto
items and cancel; MediaRef carried; client ids never logged.

App: persisted client id and seq; Connection with unstable/lost/
replaced states, backoff with jitter, no lost/back pair per flap; a drop
keeps the session (state, player, media, relay source); presence in the
strip and members card; sit out = away intent; feed matched by id;
auto sit-out (idle when not playing, minimised for a while; never when
alone) replaces auto-unready; bye on close and Leave, not on update
restart; relay source re-dials through its grace.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/desktop/lib/src/state/session_state.dart

@@ -19,6 +19,7 @@ import '../sfx/synth_sfx.dart';
 import '../session/health.dart';
 import '../session/notifier.dart';
 import '../session/connection.dart' show Connection;
+import '../session/identity.dart' show ClientIdentity;
 import '../session/session_coordinator.dart';
 import '../widgets/avatar_pipeline.dart';
 import 'connect_prefs.dart';
@@ -175,7 +176,9 @@ class SessionState {
   /// Every toast, sound and activity-log line goes through it.
   late final Notifier notifier = Notifier(sfx: sfx, attention: ports.shell.requestAttention);
   /// The link to the server; lost/back go to the notifier.
-  late final Connection connection = Connection(notify: notifier.notify);
+  /// The link to the server, with this install's stored identity
+  /// (`hello.client` / `seq`); lost/back go to the notifier.
+  late final Connection connection = Connection(notify: notifier.notify, identity: ClientIdentity.stored());
   late final SessionCoordinator coordinator =
       SessionCoordinator(notifier: notifier, connection: connection, ytDlp: ports.links);
   final lastForm = ConnectForm();
@@ -513,8 +516,10 @@ class SessionState {
     await server?.stop();
   }
 
-  Future<void> leave() async {
-    await coordinator.leave();
+  /// Out of the session (Leave, the app closing). [bye] false: Update
+  /// and restart, the restarted app takes the member back within its grace.
+  Future<void> leave({bool bye = true}) async {
+    await coordinator.leave(bye: bye);
     await stopServer();
     solo.value = false;
     coordinator.solo = false;

apps/desktop/lib/src/state/settings.dart

@@ -37,7 +37,7 @@ const _keySoundPreset = 'soundPreset';
 const _keyWelcomeDismissed = 'welcomeDismissed';
 const _keySoundPresetFor = 'soundPresetFor';
 const _keyUnreadyOnSwap = 'unreadyOnSwap';
-const _keyIdleSitsOut = 'idleSitsOut';
+const keyAutoSitOut = 'autoSitOut';
 const _keyChatPopups = 'chatPopups';
 const _keyShareDiagnostics = 'shareDiagnostics';
 
@@ -77,8 +77,9 @@ class AppSettings {
   /// Session: send ready=false when the video changes (a swap keeps the
   /// server's ready flags).
   final unreadyOnSwap = signal(false);
-  /// Session: the idle auto-unready sits this member out instead.
-  final idleSitsOut = signal(false);
+  /// Session: auto sit-out (idle while nothing plays, or minimised for a
+  /// while, sets you away; coming back sets you in).
+  final autoSitOut = signal(true);
   /// The player controls' skin (`controls/`). Applies live.
   final controlsSkin = signal(ControlsSkin.standard);
   /// The bar's clock: elapsed / total or the time left.
@@ -151,8 +152,8 @@ class AppSettings {
       if (advance is bool) autoAdvance.value = advance;
       final unready = box.get(_keyUnreadyOnSwap);
       if (unready is bool) unreadyOnSwap.value = unready;
-      final idleOut = box.get(_keyIdleSitsOut);
-      if (idleOut is bool) idleSitsOut.value = idleOut;
+      final autoOut = box.get(keyAutoSitOut);
+      if (autoOut is bool) autoSitOut.value = autoOut;
       controlsSkin.value =
           ControlsSkin.fromStored(box.get(_keyControlsSkin), legacyMpvControls: box.get(_keyMpvControls));
       final time = box.get(_keyTimeDisplay);
@@ -230,9 +231,9 @@ class AppSettings {
     _put(_keyUnreadyOnSwap, on);
   }
 
-  void setIdleSitsOut(bool on) {
-    idleSitsOut.value = on;
-    _put(_keyIdleSitsOut, on);
+  void setAutoSitOut(bool on) {
+    autoSitOut.value = on;
+    _put(keyAutoSitOut, on);
   }
 
   void setControlsSkin(ControlsSkin skin) {

apps/desktop/lib/src/state/settings_schema.dart

@@ -5,8 +5,9 @@ import 'package:hive_ce/hive.dart';
 // changed formats); the restructure steps add theirs here.
 
 /// The layout this build reads. 1: the layout of 1.2.x, where versioning
-/// starts (a box without a version is at 1).
-const settingsSchemaVersion = 1;
+/// starts (a box without a version is at 1). 2: auto sit-out replaces the
+/// idle switch.
+const settingsSchemaVersion = 2;
 
 /// The box key holding the stored version.
 const settingsSchemaKey = 'schemaVersion';
@@ -20,9 +21,19 @@ class SettingsMigration {
   const SettingsMigration(this.to, this.what, this.apply);
 }
 
-/// Every step in order of [SettingsMigration.to] (2, 3, ...); empty while
-/// version 1 is current.
-const settingsMigrations = <SettingsMigration>[];
+/// Every step in order of [SettingsMigration.to] (2, 3, ...).
+const settingsMigrations = <SettingsMigration>[
+  SettingsMigration(2, 'auto sit-out replaces "when idle, sit out instead of just unready"', _autoSitOut),
+];
+
+/// 2: `idleSitsOut` only chose between two automatic steps after 10 idle
+/// minutes (unready, or sit out); both are auto sit-out now, on unless
+/// switched off (`autoSitOut`).
+Future<void> _autoSitOut(Box box) async {
+  if (!box.containsKey('idleSitsOut')) return;
+  await box.delete('idleSitsOut');
+  if (!box.containsKey('autoSitOut')) await box.put('autoSitOut', true);
+}
 
 /// Runs the [steps] past the box's stored version up to [current], in
 /// order, storing the version after each, then stores [current]. A box