fix(ads): pass the rewarded ad's nonce through to connect

With ads enabled the SSV nonce and the nonce the connect flow waited for
were minted separately, so the client rejected the very session the ad had
just created and failed with "Session not activated".

- showAd() returns the nonce it put in the SSV custom_data (null on no reward)
- fetchConfigDirectly({adNonce, resume}) replaces skipAdBypass: a real ad
  waits for exactly that nonce and polls ~36 s for Google's callback, the
  bypass path mints its own, and resume re-attaches to the session the
  device already owns
- SOCKS5 "Reconnect" uses resume: true instead of requesting a new session

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

lib/logic/hivemind_service.dart

@@ -81,13 +81,19 @@ class HivemindService {
     _expectedNonce = null;
   }
 
-  static void setExpectedNonce(String nonce) {
-    _expectedNonce = nonce;
-  }
-
+  // Fetches this device's VLESS URL. Three ways in:
+  //   adNonce != null — a real rewarded ad was watched; its SSV custom_data
+  //                     carried this nonce, so wait for a session holding it.
+  //                     Google's SSV callback can lag, so poll longer.
+  //   resume == true  — re-attach to the session already granted (mode-switch
+  //                     reconnect in connection_mode.dart). No ad, no bypass,
+  //                     any nonce accepted — device_id already owns it.
+  //   neither         — ads disabled: mint a nonce and fire the server-gated
+  //                     ADMOB_BYPASS callback (rule 87).
   static Future<String> fetchConfigDirectly({
     void Function(int attempt, int total)? onAttempt,
-    bool skipAdBypass = false,
+    String? adNonce,
+    bool resume = false,
   }) async {
     // Capture the generation before the first await. Otherwise a disconnect
     // that lands while secure storage is resolving the device ID can be lost
@@ -96,15 +102,15 @@ class HivemindService {
     final deviceId = await CryptoService.getDeviceId();
     _throwIfCancelled(callId);
 
-    final nonce = _newNonce();
+    final nonce = resume ? null : (adNonce ?? newNonce());
     _expectedNonce = nonce;
 
-    if (!skipAdBypass) {
-      await _runConfiguredBypass(deviceId, nonce);
+    if (!resume && adNonce == null) {
+      await _runConfiguredBypass(deviceId, nonce!);
       _throwIfCancelled(callId);
     }
 
-    const maxAttempts = 5;
+    final maxAttempts = adNonce != null ? 10 : 5;
     for (var attempt = 1; attempt <= maxAttempts; attempt++) {
       _throwIfCancelled(callId);
       onAttempt?.call(attempt, maxAttempts);
@@ -122,7 +128,9 @@ class HivemindService {
       }
 
       if (attempt < maxAttempts) {
-        await Future.delayed(_pollBackoff[attempt - 1]);
+        await Future.delayed(
+          _pollBackoff[min(attempt - 1, _pollBackoff.length - 1)],
+        );
         _throwIfCancelled(callId);
       }
     }
@@ -142,7 +150,7 @@ class HivemindService {
     }
   }
 
-  static String _newNonce() {
+  static String newNonce() {
     final random = Random.secure();
     final high = random.nextInt(0x7FFFFFFF);
     final low = random.nextInt(0x7FFFFFFF);
@@ -161,9 +169,10 @@ class HivemindService {
     }
   }
 
+  // nonce == null accepts whatever nonce the server holds (resume path).
   static Future<_HivemindSessionConfig?> _fetchActiveSession(
     String deviceId,
-    String nonce,
+    String? nonce,
   ) async {
     final statusUri = _publicUrl('/session/status').replace(
       queryParameters: {'device_id': deviceId},
@@ -175,9 +184,8 @@ class HivemindService {
     if (decoded is! Map<String, dynamic>) return null;
 
     final serverNonce = decoded['nonce'];
-    if (_expectedNonce != nonce ||
-        serverNonce is! String ||
-        serverNonce != nonce) {
+    if (_expectedNonce != nonce) return null;
+    if (nonce != null && (serverNonce is! String || serverNonce != nonce)) {
       return null;
     }