feat(session): every reconnect starts a fresh session

SOCKS5 Reconnect re-attached to the session the device already held. It
was the only path where a session began without an ad and without a
nonce binding it to one, and supporting it cost three parameters -
resume, release, resetSupportClaim - plus a carve-out in rule 4 that let
_fetchActiveSession accept whatever nonce the server happened to return.

It also wasn't the kindness it looked like. _handle_main calls
create_or_replace with a fresh full window, so a new session hands the
user *more* time, not less; re-attaching only preserved the remainder of
a session whose proxy had just died.

Reconnect now disconnects and connects again exactly as the button does,
ad included. All four special cases are deleted and the nonce check is
unconditional.

Costs one rewarded ad to repair an orphaned proxy once ads are enabled.
esef's call, and it buys a single way to start a session.

Also fixes the 3.3.7 regression where Reconnect released the session and
then asked for it back: there is no longer a path that does either.

Co-Authored-By: Claude Opus 5 <[email protected]>

test/session_lifecycle_regression_test.dart

@@ -116,7 +116,7 @@ void main() {
     // /session/stop takes a device_id as its only proof of ownership, so it
     // must never be reachable from an error path. disconnect() is called only
     // by the connect button; _doDisconnect is every other ending.
-    final disconnectEntry = timer.indexOf('Future<void> disconnect(');
+    final disconnectEntry = timer.indexOf('Future<void> disconnect({');
     final doDisconnect = timer.indexOf('Future<void> _doDisconnect(');
     final release = timer.indexOf('HivemindService.releaseSession()');
     expect(release, greaterThan(disconnectEntry));
@@ -132,21 +132,36 @@ void main() {
     );
   });
 
-  test('SOCKS5 Reconnect re-attaches instead of handing the session back', () {
-    final timer = File('lib/logic/session_timer.dart').readAsStringSync();
+  test('every session starts the same way - no re-attach path', () {
     final mode =
         File('lib/screens/settings/in_settings/connection_mode.dart')
             .readAsStringSync();
+    final hivemind = File('lib/logic/hivemind_service.dart').readAsStringSync();
+    final vpn = File('lib/logic/vpn_connection.dart').readAsStringSync();
+    final timer = File('lib/logic/session_timer.dart').readAsStringSync();
 
-    // Reconnect repairs an orphaned proxy by re-attaching to the session the
-    // device already holds. Releasing it on the way out would destroy the very
-    // session the follow-up connect(resume: true) then asks for.
-    expect(timer, contains('bool release = true'));
-    expect(timer, contains('if (release) unawaited(HivemindService.releaseSession())'));
-    expect(mode, contains('timer.disconnect(release: false)'));
-    expect(mode, contains('vpn.connect(resume: true)'));
+    // SOCKS5 Reconnect used to re-attach to the session already held. It was
+    // the only place a session began without an ad and without a nonce binding
+    // it, and it needed three parameters and a carve-out in rule 4 to support.
+    // Reconnect now ends the session and starts a fresh one, like the button.
+    expect(mode, contains("ad.showAd('main')"));
+    expect(mode, contains('vpn.connect(adNonce: adNonce)'));
+    expect(mode, isNot(contains('resume: true')));
+    expect(mode, isNot(contains('release: false')));
+    expect(mode, isNot(contains('resetSupportClaim')));
 
-    // And it must not hand back a second support top-up for the same session.
-    expect(mode, contains('timer.start(resetSupportClaim: false)'));
+    // The special cases that only existed for it are gone.
+    expect(hivemind, isNot(contains('bool resume')));
+    expect(vpn, isNot(contains('bool resume')));
+    expect(timer, isNot(contains('bool release')));
+    expect(timer, isNot(contains('resetSupportClaim')));
+
+    // So the nonce is now unconditional: no path accepts whatever the server
+    // happens to hold.
+    expect(
+      hivemind,
+      contains('if (serverNonce is! String || serverNonce != nonce) return null;'),
+      reason: 'the nonce check must not be skippable',
+    );
   });
 }