Remove legacy polling wait and add exponential backoff to reconnect

Changes:
- Remove 5-second wait in GetUpdates that was used for long-polling.
  With streaming, WaitForUpdatesAndPush already waits for updates before
  calling GetUpdates, making this redundant. GetGameStatus is deprecated.
- Add exponential backoff to Eagle's stream reconnection logic, starting
  at 1 second and doubling up to 30 seconds max.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/main/cpp/net/eagle0/shardok/controller/ShardokGameController.cpp

@@ -24,9 +24,6 @@ using std::scoped_lock;
 using std::string;
 using std::unique_lock;
 using std::weak_ptr;
-using std::chrono::duration;
-
-static constexpr duration kWaitForUpdatesDuration = std::chrono::milliseconds(5000);
 
 using net::eagle0::shardok::common::GameStatus;
 
@@ -278,15 +275,9 @@ auto ShardokGameController::GetUpdates(const int64_t startingActionId) -> AllUpd
         awrs = engine->GetGameHistory(startingActionId);
         incomingRegistrations--;
 
-        // If the current player is an AI, wait for some results to post. Otherwise go ahead and
-        // return, we might be telling the caller about available commands.
-        if (awrs.empty() && !engine->GameIsOver() &&
-            engine->GetPlayerInfos()[engine->GetCurrentPlayerId()].is_ai()) {
-            updateCondition.wait_for(guard, kWaitForUpdatesDuration);
-            incomingRegistrations++;
-            awrs = engine->GetGameHistory(startingActionId);
-            incomingRegistrations--;
-        }
+        // Note: Previously this had a 5-second wait for AI players to support long-polling.
+        // With streaming (WaitForUpdatesAndPush), the caller already waits for updates,
+        // so this wait is no longer needed. GetGameStatus is deprecated in favor of streaming.
 
         updates.mainResults.reserve(awrs.size());
         std::ranges::transform(

src/main/scala/net/eagle0/eagle/shardok_interface/ShardokInterfaceGrpcClient.scala

@@ -123,7 +123,7 @@ class ShardokInterfaceGrpcClient(
     grpcClient.subscribeToGame(request, responseObserver)
   }
 
-  /** Schedules a reconnection attempt after stream disconnection. */
+  /** Schedules a reconnection attempt after stream disconnection with exponential backoff. */
   private def scheduleReconnect(
       eagleGameId: GameId,
       shardokGameId: ShardokGameId,
@@ -133,8 +133,15 @@ class ShardokInterfaceGrpcClient(
       Thread.sleep(delayMs)
       pendingBattles.synchronized {
         if pendingBattles.contains(shardokGameId) then
-          println(s"Reconnecting stream for $shardokGameId")
-          subscribeToGame(eagleGameId, shardokGameId, None)
+          println(s"Reconnecting stream for $shardokGameId (delay was ${delayMs}ms)")
+          try subscribeToGame(eagleGameId, shardokGameId, None)
+          catch {
+            case e: Exception =>
+              println(s"Reconnect failed for $shardokGameId: $e")
+              // Exponential backoff with max 30 seconds
+              val nextDelay = Math.min(delayMs * 2, 30000)
+              scheduleReconnect(eagleGameId, shardokGameId, nextDelay)
+          }
       }
     }