Improve Shardok C++ safety checks (#7345)

.bazelrc

@@ -22,6 +22,32 @@ common --per_file_copt=src/test/cpp/.*@-Wno-sign-compare
 common --per_file_copt=src/test/cpp/.*@-Wno-unknown-warning-option
 common --host_cxxopt="--std=c++23"
 
+# C++ sanitizer configs for targeted Shardok safety checks.
+# Example: bazel test --config=asan //src/test/cpp/net/eagle0/shardok/library/...
+build:asan --compilation_mode=dbg
+build:asan --strip=never
+build:asan --copt=-fno-omit-frame-pointer
+build:asan --copt=-Wno-macro-redefined
+build:asan --copt=-fsanitize=address
+build:asan --linkopt=-fsanitize=address
+test:asan --test_env=ASAN_OPTIONS=detect_leaks=0:strict_init_order=1
+
+build:ubsan --compilation_mode=dbg
+build:ubsan --strip=never
+build:ubsan --copt=-fno-omit-frame-pointer
+build:ubsan --copt=-Wno-macro-redefined
+build:ubsan --copt=-fsanitize=undefined
+build:ubsan --linkopt=-fsanitize=undefined
+test:ubsan --test_env=UBSAN_OPTIONS=print_stacktrace=1:halt_on_error=1
+
+build:tsan --compilation_mode=dbg
+build:tsan --strip=never
+build:tsan --copt=-fno-omit-frame-pointer
+build:tsan --copt=-Wno-macro-redefined
+build:tsan --copt=-fsanitize=thread
+build:tsan --linkopt=-fsanitize=thread
+test:tsan --test_env=TSAN_OPTIONS=halt_on_error=1
+
 common --javacopt="-Xlint:-options"
 
 # Prefer protobuf's prebuilt protoc toolchain instead of building protoc from

.clang-tidy

@@ -0,0 +1,32 @@
+Checks: >
+  -*,
+  bugprone-*,
+  performance-*,
+  readability-*,
+  modernize-*,
+  cppcoreguidelines-*,
+  -bugprone-easily-swappable-parameters,
+  -cppcoreguidelines-avoid-magic-numbers,
+  -cppcoreguidelines-macro-usage,
+  -cppcoreguidelines-owning-memory,
+  -cppcoreguidelines-pro-bounds-array-to-pointer-decay,
+  -cppcoreguidelines-pro-bounds-constant-array-index,
+  -cppcoreguidelines-pro-bounds-pointer-arithmetic,
+  -cppcoreguidelines-pro-type-const-cast,
+  -cppcoreguidelines-pro-type-reinterpret-cast,
+  -cppcoreguidelines-pro-type-union-access,
+  -cppcoreguidelines-pro-type-vararg,
+  -modernize-use-trailing-return-type,
+  -readability-convert-member-functions-to-static,
+  -readability-function-cognitive-complexity,
+  -readability-identifier-length,
+  -readability-magic-numbers
+WarningsAsErrors: ''
+HeaderFilterRegex: 'src/(main|test)/cpp/net/eagle0/(shardok|common)/.*'
+FormatStyle: file
+CheckOptions:
+  readability-braces-around-statements.ShortStatementLines: '1'
+  readability-function-size.LineThreshold: '160'
+  readability-function-size.StatementThreshold: '80'
+  readability-function-size.BranchThreshold: '20'
+  modernize-use-nullptr.NullMacros: 'NULL'

src/main/cpp/net/eagle0/shardok/server/ShardokGamesManager.cpp

@@ -9,6 +9,7 @@
 #include "ShardokGamesManager.hpp"
 
 #include <memory>
+#include <mutex>
 #include <shared_mutex>
 #include <utility>
 
@@ -68,7 +69,7 @@ auto ShardokGamesManager::UnlockedCreateFromGameStateBytes(
         const byte_vector &gameStateBytes,
         int32_t startingHistoryCount,
         const string &mapName) -> GameId {
-    std::shared_lock<std::shared_mutex> lk(runningControllersLock);
+    std::unique_lock<std::shared_mutex> lk(runningControllersLock);
 
     auto gs = GameStateW::FromByteVector(gameStateBytes);
 
@@ -90,7 +91,7 @@ auto ShardokGamesManager::UnlockedCreateSpecifiedGame(
         const string &serializedRequest,
         const std::vector<std::pair<int32_t, std::vector<PlayerId>>> &watcherAllies) -> GameId {
     // Check for existing game with this ID and early-exit
-    std::shared_lock<std::shared_mutex> lk(runningControllersLock);
+    std::unique_lock<std::shared_mutex> lk(runningControllersLock);
     const auto existingGame = runningControllers.find(gameId);
 
     // If it exists, register new handlers and early-exit