Centralize counter API with server-side bounds and no-op filtering (#6879)

* Refactor server counter API to own overflow protection and filter no-op events

  Counter modifications now clamp to int bounds server-side and return change
  status, allowing command handlers to skip network broadcasts when values
  don't actually change.

* Centralize MAX_COUNTERS_ON_CARD and enforce [0, 999] bounds on server

  - Move MAX_COUNTERS_ON_CARD to trice_limits.h
  - Server clamps values in setCounter() and incrementCounter()
  - Client uses clamped comparison to allow recovery from invalid states
  - Add tests for clamping behavior

* move incrementCount() implementation from header to cpp

cockatrice/src/game/board/card_item.h

@@ -12,6 +12,7 @@
 #include "card_state.h"
 
 #include <libcockatrice/network/server/remote/game/server_card.h>
+#include <libcockatrice/utility/trice_limits.h>
 
 class CardDatabase;
 class CardDragItem;
@@ -21,7 +22,6 @@ class PlayerLogic;
 class QAction;
 class QColor;
 
-const int MAX_COUNTERS_ON_CARD = 999;
 const int ROTATION_DEGREES_PER_FRAME = 10;
 
 class CardItem : public AbstractCardItem

cockatrice/src/game/player/player_actions.cpp

@@ -1501,7 +1501,10 @@ void PlayerActions::offsetCardCounter(int counterId, int offset)
         int oldValue = card->getCounters().value(counterId, 0);
         int newValue = oldValue + offset;
 
-        if (newValue >= 0 && newValue <= MAX_COUNTERS_ON_CARD) {
+        // Early exit optimization: server enforces [0, MAX_COUNTERS_ON_CARD].
+        // Compare clamped value to allow recovery from invalid states.
+        int clampedValue = qBound(0, newValue, MAX_COUNTERS_ON_CARD);
+        if (clampedValue != oldValue) {
             auto *cmd = new Command_SetCardCounter;
             cmd->set_zone(card->getZone()->getName().toStdString());
             cmd->set_card_id(card->getId());
@@ -1541,7 +1544,9 @@ void PlayerActions::actSetCardCounter(int counterId)
     for (auto card : sel) {
         int oldValue = card->getCounters().value(counterId, 0);
         Expression exp(oldValue);
-        int number = static_cast<int>(exp.parse(dialog.textValue()));
+        double parsed = exp.parse(dialog.textValue());
+        // Clamp in double precision first to avoid UB, then cast
+        int number = static_cast<int>(qBound(0.0, parsed, static_cast<double>(MAX_COUNTERS_ON_CARD)));
 
         auto *cmd = new Command_SetCardCounter;
         cmd->set_zone(card->getZone()->getName().toStdString());

libcockatrice_network/libcockatrice/network/server/remote/game/server_abstract_player.cpp

@@ -49,6 +49,7 @@
 #include <libcockatrice/rng/rng_abstract.h>
 #include <libcockatrice/utility/trice_limits.h>
 #include <libcockatrice/utility/zone_names.h>
+#include <limits>
 #include <ranges>
 
 Server_AbstractPlayer::Server_AbstractPlayer(Server_Game *_game,
@@ -1091,8 +1092,9 @@ Server_AbstractPlayer::cmdCreateToken(const Command_CreateToken &cmd, ResponseCo
                 _event.set_zone_name(card->getZone()->getName().toStdString());
                 _event.set_card_id(card->getId());
 
-                card->setCounter(i.key(), i.value(), &_event);
-                ges.enqueueGameEvent(_event, playerId);
+                if (card->setCounter(i.key(), i.value(), &_event)) {
+                    ges.enqueueGameEvent(_event, playerId);
+                }
             }
 
             // Copy parent card
@@ -1338,8 +1340,9 @@ Response::ResponseCode Server_AbstractPlayer::cmdSetCardCounter(const Command_Se
     Event_SetCardCounter event;
     event.set_zone_name(zone->getName().toStdString());
     event.set_card_id(card->getId());
-    card->setCounter(cmd.counter_id(), cmd.counter_value(), &event);
-    ges.enqueueGameEvent(event, playerId);
+    if (card->setCounter(cmd.counter_id(), cmd.counter_value(), &event)) {
+        ges.enqueueGameEvent(event, playerId);
+    }
 
     return Response::RespOk;
 }
@@ -1368,14 +1371,13 @@ Response::ResponseCode Server_AbstractPlayer::cmdIncCardCounter(const Command_In
         return Response::RespNameNotFound;
     }
 
-    int newValue = card->getCounter(cmd.counter_id()) + cmd.counter_delta();
-    card->setCounter(cmd.counter_id(), newValue);
-
     Event_SetCardCounter event;
     event.set_zone_name(zone->getName().toStdString());
     event.set_card_id(card->getId());
-    event.set_counter_id(cmd.counter_id());
-    event.set_counter_value(newValue);
+    if (!card->incrementCounter(cmd.counter_id(), cmd.counter_delta(), &event)) {
+        return Response::RespOk;
+    }
+
     ges.enqueueGameEvent(event, playerId);
 
     return Response::RespOk;

libcockatrice_network/libcockatrice/network/server/remote/game/server_card.cpp

@@ -26,6 +26,8 @@
 #include <libcockatrice/protocol/pb/event_set_card_attr.pb.h>
 #include <libcockatrice/protocol/pb/event_set_card_counter.pb.h>
 #include <libcockatrice/protocol/pb/serverinfo_card.pb.h>
+#include <libcockatrice/utility/trice_limits.h>
+#include <limits>
 
 Server_Card::Server_Card(const CardRef &cardRef, int _id, int _coord_x, int _coord_y, Server_CardZone *_zone)
     : zone(_zone), id(_id), coord_x(_coord_x), coord_y(_coord_y), cardRef(cardRef), tapped(false), attacking(false),
@@ -110,8 +112,16 @@ QString Server_Card::setAttribute(CardAttribute attribute, const QString &avalue
     return avalue;
 }
 
-void Server_Card::setCounter(int _id, int value, Event_SetCardCounter *event)
+bool Server_Card::setCounter(int _id, int value, Event_SetCardCounter *event)
 {
+    // Clamp to valid card counter range [0, MAX_COUNTERS_ON_CARD]
+    value = qBound(0, value, MAX_COUNTERS_ON_CARD);
+
+    const int oldValue = counters.value(_id, 0);
+    if (value == oldValue) {
+        return false;
+    }
+
     if (value) {
         counters.insert(_id, value);
     } else {
@@ -122,6 +132,34 @@ void Server_Card::setCounter(int _id, int value, Event_SetCardCounter *event)
         event->set_counter_id(_id);
         event->set_counter_value(value);
     }
+
+    return true;
+}
+
+bool Server_Card::incrementCounter(int counterId, int delta, Event_SetCardCounter *event)
+{
+    const int oldValue = counters.value(counterId, 0);
+    const auto result = static_cast<int64_t>(oldValue) + static_cast<int64_t>(delta);
+    // Clamp to [0, MAX_COUNTERS_ON_CARD] for card counters
+    const int newValue =
+        static_cast<int>(qBound(static_cast<int64_t>(0), result, static_cast<int64_t>(MAX_COUNTERS_ON_CARD)));
+
+    if (newValue == oldValue) {
+        return false;
+    }
+
+    if (newValue) {
+        counters.insert(counterId, newValue);
+    } else {
+        counters.remove(counterId);
+    }
+
+    if (event) {
+        event->set_counter_id(counterId);
+        event->set_counter_value(newValue);
+    }
+
+    return true;
 }
 
 void Server_Card::setParentCard(Server_Card *_parentCard)

libcockatrice_network/libcockatrice/network/server/remote/game/server_card.h

@@ -153,7 +153,24 @@ public:
     {
         cardRef = _cardRef;
     }
-    void setCounter(int _id, int value, Event_SetCardCounter *event = nullptr);
+    /**
+     * @brief Sets a card counter to an exact value with clamping.
+     * @param _id The counter ID.
+     * @param value The desired value (clamped to [0, MAX_COUNTERS_ON_CARD]; 0 removes the counter).
+     * @param event Optional event to populate with counter state.
+     * @return true if the value changed, false otherwise.
+     */
+    [[nodiscard]] bool setCounter(int _id, int value, Event_SetCardCounter *event = nullptr);
+    /**
+     * @brief Increments a card counter with overflow-safe arithmetic.
+     * @param counterId The counter ID to modify.
+     * @param delta The amount to add (may be negative for decrement).
+     * @param event Optional event to populate with counter state.
+     * @return true if the value changed, false otherwise.
+     * @note If counter does not exist, starts from 0. Counter is removed if result is 0.
+     * @note Clamps result to [0, MAX_COUNTERS_ON_CARD].
+     */
+    [[nodiscard]] bool incrementCounter(int counterId, int delta, Event_SetCardCounter *event = nullptr);
     void setTapped(bool _tapped)
     {
         tapped = _tapped;

libcockatrice_network/libcockatrice/network/server/remote/game/server_counter.cpp

@@ -1,12 +1,24 @@
 #include "server_counter.h"
 
 #include <libcockatrice/protocol/pb/serverinfo_counter.pb.h>
+#include <limits>
 
 Server_Counter::Server_Counter(int _id, const QString &_name, const color &_counterColor, int _radius, int _count)
     : id(_id), name(_name), counterColor(_counterColor), radius(_radius), count(_count)
 {
 }
 
+//! \todo Extract overflow-safe arithmetic into shared helper.
+//! Duplicated in Server_Card::incrementCounter() - keep in sync if modified.
+bool Server_Counter::incrementCount(int delta)
+{
+    const int oldCount = count;
+    const auto result = static_cast<int64_t>(count) + static_cast<int64_t>(delta);
+    count = static_cast<int>(qBound(static_cast<int64_t>(std::numeric_limits<int>::min()), result,
+                                    static_cast<int64_t>(std::numeric_limits<int>::max())));
+    return count != oldCount;
+}
+
 void Server_Counter::getInfo(ServerInfo_Counter *info)
 {
     info->set_id(id);

libcockatrice_network/libcockatrice/network/server/remote/game/server_counter.h

@@ -25,6 +25,18 @@
 
 class ServerInfo_Counter;
 
+/**
+ * @class Server_Counter
+ * @brief Represents a player counter with overflow-safe increment arithmetic.
+ *
+ * All value modifications return whether the value actually changed,
+ * enabling callers to skip unnecessary network events.
+ *
+ * @note Direct assignment via setCount() does not clamp; only
+ *       incrementCount() enforces int boundary saturation.
+ * @note Unlike card counters, player counters are never auto-removed
+ *       when they reach zero - they persist with value 0.
+ */
 class Server_Counter
 {
 protected:
@@ -59,11 +71,33 @@ public:
     {
         return count;
     }
-    void setCount(int _count)
+
+    /**
+     * @brief Sets the counter to an exact value.
+     * @param _count The new value (assigned directly without clamping).
+     * @return true if the value changed, false otherwise.
+     * @warning This performs raw assignment. For overflow-safe incrementing,
+     *          use incrementCount().
+     */
+    [[nodiscard]] bool setCount(int _count)
     {
+        const int oldCount = count;
         count = _count;
+        return count != oldCount;
     }
 
+    /**
+     * @brief Increments the counter by delta with overflow-safe arithmetic.
+     * @param delta The amount to add (may be negative for decrement).
+     * @return true if the value changed, false otherwise.
+     * @note Clamps result to [INT_MIN, INT_MAX] to prevent overflow.
+     */
+    [[nodiscard]] bool incrementCount(int delta);
+
+    /**
+     * @brief Populates info with this counter's current state for network serialization.
+     * @param info The protobuf message to populate.
+     */
     void getInfo(ServerInfo_Counter *info);
 };
 

libcockatrice_network/libcockatrice/network/server/remote/game/server_player.cpp

@@ -436,17 +436,19 @@ Server_Player::cmdIncCounter(const Command_IncCounter &cmd, ResponseContainer &
         return Response::RespContextError;
     }
 
-    Server_Counter *c = counters.value(cmd.counter_id(), 0);
+    const int counterId = cmd.counter_id();
+    Server_Counter *c = counters.value(counterId, nullptr);
     if (!c) {
         return Response::RespNameNotFound;
     }
 
-    c->setCount(c->getCount() + cmd.delta());
-
-    Event_SetCounter event;
-    event.set_counter_id(c->getId());
-    event.set_value(c->getCount());
-    ges.enqueueGameEvent(event, playerId);
+    bool didChange = c->incrementCount(cmd.delta());
+    if (didChange) {
+        Event_SetCounter event;
+        event.set_counter_id(c->getId());
+        event.set_value(c->getCount());
+        ges.enqueueGameEvent(event, playerId);
+    }
 
     return Response::RespOk;
 }
@@ -487,17 +489,19 @@ Server_Player::cmdSetCounter(const Command_SetCounter &cmd, ResponseContainer &
         return Response::RespContextError;
     }
 
-    Server_Counter *c = counters.value(cmd.counter_id(), 0);
+    const int counterId = cmd.counter_id();
+    Server_Counter *c = counters.value(counterId, nullptr);
     if (!c) {
         return Response::RespNameNotFound;
     }
 
-    c->setCount(cmd.value());
-
-    Event_SetCounter event;
-    event.set_counter_id(c->getId());
-    event.set_value(c->getCount());
-    ges.enqueueGameEvent(event, playerId);
+    bool didChange = c->setCount(cmd.value());
+    if (didChange) {
+        Event_SetCounter event;
+        event.set_counter_id(c->getId());
+        event.set_value(c->getCount());
+        ges.enqueueGameEvent(event, playerId);
+    }
 
     return Response::RespOk;
 }
@@ -512,15 +516,16 @@ Server_Player::cmdDelCounter(const Command_DelCounter &cmd, ResponseContainer &
         return Response::RespContextError;
     }
 
-    Server_Counter *counter = counters.value(cmd.counter_id(), 0);
+    const int counterId = cmd.counter_id();
+    Server_Counter *counter = counters.value(counterId, nullptr);
     if (!counter) {
         return Response::RespNameNotFound;
     }
-    counters.remove(cmd.counter_id());
+    counters.remove(counterId);
     delete counter;
 
     Event_DelCounter event;
-    event.set_counter_id(cmd.counter_id());
+    event.set_counter_id(counterId);
     ges.enqueueGameEvent(event, playerId);
 
     return Response::RespOk;

libcockatrice_utility/libcockatrice/utility/trice_limits.h

@@ -15,6 +15,12 @@ constexpr uint MAXIMUM_DIE_SIDES = 1000000;
 constexpr uint MINIMUM_DICE_TO_ROLL = 1;
 constexpr uint MAXIMUM_DICE_TO_ROLL = 100;
 
+// Card counter value bounds [0, MAX_COUNTERS_ON_CARD].
+// Counters on cards (e.g., +1/+1 counters, charge counters) are non-negative physical game objects.
+// The max of 999 is a display constraint (3-digit rendering) and reasonable gameplay limit.
+// Server enforces these bounds; client may also check for UX optimization.
+constexpr int MAX_COUNTERS_ON_CARD = 999;
+
 // optimized functions to get qstrings that are at most that long
 static inline QString nameFromStdString(const std::string &_string)
 {

tests/CMakeLists.txt

@@ -6,6 +6,8 @@ add_test(NAME dummy_test COMMAND dummy_test)
 add_test(NAME expression_test COMMAND expression_test)
 add_test(NAME test_age_formatting COMMAND test_age_formatting)
 add_test(NAME password_hash_test COMMAND password_hash_test)
+add_test(NAME server_card_counter_test COMMAND server_card_counter_test)
+add_test(NAME server_counter_test COMMAND server_counter_test)
 
 add_test(NAME deck_hash_performance_test COMMAND deck_hash_performance_test)
 set_tests_properties(deck_hash_performance_test PROPERTIES TIMEOUT 5)
@@ -17,6 +19,8 @@ add_executable(expression_test expression_test.cpp)
 add_executable(test_age_formatting test_age_formatting.cpp)
 add_executable(password_hash_test password_hash_test.cpp)
 add_executable(deck_hash_performance_test deck_hash_performance_test.cpp)
+add_executable(server_card_counter_test server_card_counter_test.cpp)
+add_executable(server_counter_test server_counter_test.cpp)
 
 find_package(GTest)
 
@@ -48,6 +52,8 @@ if(NOT GTEST_FOUND)
   add_dependencies(test_age_formatting gtest)
   add_dependencies(password_hash_test gtest)
   add_dependencies(deck_hash_performance_test gtest)
+  add_dependencies(server_card_counter_test gtest)
+  add_dependencies(server_counter_test gtest)
 endif()
 
 include_directories(${GTEST_INCLUDE_DIRS})
@@ -61,6 +67,12 @@ target_link_libraries(
   deck_hash_performance_test libcockatrice_deck_list libcockatrice_utility Threads::Threads ${GTEST_BOTH_LIBRARIES}
   ${TEST_QT_MODULES}
 )
+target_link_libraries(
+  server_card_counter_test libcockatrice_network Threads::Threads ${GTEST_BOTH_LIBRARIES} ${TEST_QT_MODULES}
+)
+target_link_libraries(
+  server_counter_test libcockatrice_network Threads::Threads ${GTEST_BOTH_LIBRARIES} ${TEST_QT_MODULES}
+)
 
 add_subdirectory(card_zone_algorithms)
 add_subdirectory(carddatabase)

tests/server_card_counter_test.cpp

@@ -0,0 +1,183 @@
+/** @file server_card_counter_test.cpp
+ *  @brief Tests for Server_Card counter operations.
+ *  @ingroup Tests
+ */
+
+#include <gtest/gtest.h>
+#include <libcockatrice/network/server/remote/game/server_card.h>
+#include <libcockatrice/protocol/pb/event_set_card_counter.pb.h>
+#include <libcockatrice/utility/card_ref.h>
+#include <libcockatrice/utility/trice_limits.h>
+#include <limits>
+
+TEST(ServerCardCounter, IncrementNewCounter)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    EXPECT_TRUE(card.incrementCounter(1, 10));
+    EXPECT_EQ(card.getCounter(1), 10);
+}
+
+TEST(ServerCardCounter, IncrementExistingCounter)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 50));
+    EXPECT_TRUE(card.incrementCounter(1, 10));
+    EXPECT_EQ(card.getCounter(1), 60);
+}
+
+TEST(ServerCardCounter, IncrementOverflowProtection)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, MAX_COUNTERS_ON_CARD));
+    EXPECT_FALSE(card.incrementCounter(1, 1));
+    EXPECT_EQ(card.getCounter(1), MAX_COUNTERS_ON_CARD);
+}
+
+TEST(ServerCardCounter, DecrementUnderflowProtection)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 5));
+    EXPECT_TRUE(card.incrementCounter(1, -10));
+    EXPECT_EQ(card.getCounter(1), 0);
+    EXPECT_FALSE(card.getCounters().contains(1));
+}
+
+TEST(ServerCardCounter, ReturnsFalseWhenUnchanged)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 50));
+    EXPECT_FALSE(card.incrementCounter(1, 0));
+    EXPECT_EQ(card.getCounter(1), 50);
+}
+
+TEST(ServerCardCounter, DecrementToZeroRemovesCounter)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 10));
+    EXPECT_TRUE(card.incrementCounter(1, -10));
+    EXPECT_EQ(card.getCounter(1), 0);
+    EXPECT_FALSE(card.getCounters().contains(1));
+}
+
+TEST(ServerCardCounter, SetToZeroRemovesCounter)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 10));
+    EXPECT_TRUE(card.setCounter(1, 0));
+    EXPECT_EQ(card.getCounter(1), 0);
+    EXPECT_FALSE(card.getCounters().contains(1));
+}
+
+TEST(ServerCardCounter, SetCounterReturnsFalseWhenUnchanged)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 50));
+    EXPECT_FALSE(card.setCounter(1, 50));
+    EXPECT_EQ(card.getCounter(1), 50);
+}
+
+TEST(ServerCardCounter, SetCounterReturnsTrueWhenChanged)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 50));
+    EXPECT_TRUE(card.setCounter(1, 100));
+    EXPECT_EQ(card.getCounter(1), 100);
+}
+
+TEST(ServerCardCounter, SetCounterEventNotPopulatedWhenUnchanged)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 50));
+
+    Event_SetCardCounter event;
+    event.set_counter_id(999);
+    event.set_counter_value(999);
+
+    EXPECT_FALSE(card.setCounter(1, 50, &event));
+    EXPECT_EQ(event.counter_id(), 999);
+    EXPECT_EQ(event.counter_value(), 999);
+}
+
+TEST(ServerCardCounter, IncrementCounterPopulatesEvent)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 50));
+
+    Event_SetCardCounter event;
+    EXPECT_TRUE(card.incrementCounter(1, 10, &event));
+
+    EXPECT_EQ(event.counter_id(), 1);
+    EXPECT_EQ(event.counter_value(), 60);
+}
+
+TEST(ServerCardCounter, IncrementCounterEventReflectsClampedValue)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, MAX_COUNTERS_ON_CARD - 5));
+
+    Event_SetCardCounter event;
+    EXPECT_TRUE(card.incrementCounter(1, 10, &event));
+
+    EXPECT_EQ(event.counter_id(), 1);
+    EXPECT_EQ(event.counter_value(), MAX_COUNTERS_ON_CARD);
+}
+
+TEST(ServerCardCounter, IncrementCounterNoEventWhenNullptr)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 50));
+    EXPECT_TRUE(card.incrementCounter(1, 10, nullptr));
+    EXPECT_EQ(card.getCounter(1), 60);
+}
+
+TEST(ServerCardCounter, IncrementCounterEventNotPopulatedWhenUnchanged)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, MAX_COUNTERS_ON_CARD));
+
+    Event_SetCardCounter event;
+    event.set_counter_id(999);
+    event.set_counter_value(999);
+
+    EXPECT_FALSE(card.incrementCounter(1, 1, &event));
+    EXPECT_EQ(event.counter_id(), 999);
+    EXPECT_EQ(event.counter_value(), 999);
+}
+
+TEST(ServerCardCounter, SetCounterClampsNegativeToZero)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    EXPECT_FALSE(card.setCounter(1, -5));
+    EXPECT_EQ(card.getCounter(1), 0);
+    EXPECT_FALSE(card.getCounters().contains(1));
+}
+
+TEST(ServerCardCounter, SetCounterClampsAboveMaxToMax)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    EXPECT_TRUE(card.setCounter(1, 1500));
+    EXPECT_EQ(card.getCounter(1), MAX_COUNTERS_ON_CARD);
+}
+
+TEST(ServerCardCounter, IncrementDoesNotGoBelowZero)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, 5));
+    EXPECT_TRUE(card.incrementCounter(1, -10));
+    EXPECT_EQ(card.getCounter(1), 0);
+    EXPECT_FALSE(card.getCounters().contains(1));
+}
+
+TEST(ServerCardCounter, IncrementDoesNotExceedMax)
+{
+    Server_Card card(CardRef{"TestCard", ""}, 1, 0, 0);
+    ASSERT_TRUE(card.setCounter(1, MAX_COUNTERS_ON_CARD - 5));
+    EXPECT_TRUE(card.incrementCounter(1, 10));
+    EXPECT_EQ(card.getCounter(1), MAX_COUNTERS_ON_CARD);
+}
+
+int main(int argc, char **argv)
+{
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}

tests/server_counter_test.cpp

@@ -0,0 +1,86 @@
+/** @file server_counter_test.cpp
+ *  @brief Tests for Server_Counter operations.
+ *  @ingroup Tests
+ */
+
+#include <gtest/gtest.h>
+#include <libcockatrice/network/server/remote/game/server_counter.h>
+#include <limits>
+
+TEST(ServerCounter, IncrementDoesNotOverflow)
+{
+    Server_Counter c(1, "test", color(), 10, std::numeric_limits<int>::max());
+    bool changed = c.incrementCount(1);
+    EXPECT_FALSE(changed);
+    EXPECT_EQ(c.getCount(), std::numeric_limits<int>::max());
+}
+
+TEST(ServerCounter, DecrementDoesNotUnderflow)
+{
+    Server_Counter c(1, "test", color(), 10, std::numeric_limits<int>::min());
+    bool changed = c.incrementCount(-1);
+    EXPECT_FALSE(changed);
+    EXPECT_EQ(c.getCount(), std::numeric_limits<int>::min());
+}
+
+TEST(ServerCounter, SetCountReturnsFalseWhenUnchanged)
+{
+    Server_Counter c(1, "test", color(), 10, 50);
+    bool changed = c.setCount(50);
+    EXPECT_FALSE(changed);
+}
+
+TEST(ServerCounter, IncrementReturnsChangeStatus)
+{
+    Server_Counter c(1, "test", color(), 10, 50);
+    EXPECT_TRUE(c.incrementCount(10));
+    EXPECT_EQ(c.getCount(), 60);
+    EXPECT_FALSE(c.incrementCount(0));
+    EXPECT_EQ(c.getCount(), 60);
+}
+
+TEST(ServerCounter, LargePositiveDeltaDoesNotOverflow)
+{
+    Server_Counter c(1, "test", color(), 10, std::numeric_limits<int>::max() - 10);
+    bool changed = c.incrementCount(std::numeric_limits<int>::max());
+    EXPECT_TRUE(changed); // Value changes from INT_MAX-10 to INT_MAX (clamped)
+    EXPECT_EQ(c.getCount(), std::numeric_limits<int>::max());
+}
+
+TEST(ServerCounter, LargeNegativeDeltaDoesNotUnderflow)
+{
+    Server_Counter c(1, "test", color(), 10, std::numeric_limits<int>::min() + 10);
+    bool changed = c.incrementCount(std::numeric_limits<int>::min());
+    EXPECT_TRUE(changed); // Value changes from INT_MIN+10 to INT_MIN (clamped)
+    EXPECT_EQ(c.getCount(), std::numeric_limits<int>::min());
+}
+
+TEST(ServerCounter, SetCountReturnsTrueWhenChanged)
+{
+    Server_Counter c(1, "test", color(), 10, 50);
+    EXPECT_TRUE(c.setCount(100));
+    EXPECT_EQ(c.getCount(), 100);
+}
+
+TEST(ServerCounter, BasicIncrementWorks)
+{
+    Server_Counter c(1, "test", color(), 10, 50);
+    EXPECT_TRUE(c.incrementCount(10));
+    EXPECT_EQ(c.getCount(), 60);
+    EXPECT_TRUE(c.incrementCount(-20));
+    EXPECT_EQ(c.getCount(), 40);
+}
+
+TEST(ServerCounter, MixedExtremesDoNotClamp)
+{
+    Server_Counter c(1, "test", color(), 10, std::numeric_limits<int>::max());
+    bool changed = c.incrementCount(std::numeric_limits<int>::min());
+    EXPECT_TRUE(changed);
+    EXPECT_EQ(c.getCount(), -1);
+}
+
+int main(int argc, char **argv)
+{
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}