Set up basic deterministic lockstep

server/src/main.cpp

@@ -1,4 +1,5 @@
 #include "game_server/InternalGameServer.h"
+#include "game_server/NetworkProtocol.h"
 #if defined(NETWORK)
 #include "game_server/WebsocketGameServer.h"
 #endif
@@ -15,6 +16,7 @@
 #include <memory>
 #include <string>
 #include <thread>
+#include <vector>
 
 namespace {
 
@@ -44,7 +46,7 @@ std::int64_t parsePositiveNumber(const char* value, const char* option)
 
 int main(int argc, char** argv)
 {
-	std::int64_t tickMs = 500;
+	std::int64_t tickMs = FRG::kSimulationTickMs;
 	std::int64_t maxTicks = (std::numeric_limits<std::int64_t>::max)();
 	bool sleepBetweenTicks = true;
 	std::string campaignId;
@@ -89,14 +91,18 @@ int main(int argc, char** argv)
 		return EXIT_FAILURE;
 	}
 
-	//Temporary override:
-	campaignId = "battle_zone_multiplayer";
-	locationId = "uni_exterior";
+	if (tickMs != FRG::kSimulationTickMs) {
+		std::cerr << "Network lockstep requires --tick-ms "
+			<< FRG::kSimulationTickMs << '\n';
+		return EXIT_FAILURE;
+	}
 
 	std::signal(SIGINT, requestStop);
 	std::signal(SIGTERM, requestStop);
 
 	FRG::InternalGameServer server;
+	std::vector<std::string> playerSlots;
+	std::string compatibilityFingerprint = "lockstep-v2";
 	if (!campaignId.empty()) {
 		try {
 			FRG::CampaignRegistry::instance().loadFromJson(campaignsPath);
@@ -138,6 +144,17 @@ int main(int argc, char** argv)
 				}
 			}
 			server.activateLocation(selectedLocation);
+			playerSlots = campaign->networkPlayerSlots;
+			for (const std::string& slot : playerSlots) {
+				if (server.snapshot()->players.count(slot) == 0)
+					throw std::runtime_error(
+						"Multiplayer slot '" + slot +
+						"' is missing from the initial state");
+			}
+			compatibilityFingerprint =
+				campaign->networkCompatibility.empty()
+					? "lockstep-v2:" + campaignId
+					: campaign->networkCompatibility;
 			if (!campaign->tutorial) {
 				server.submit(FRG::SetTutorialStepCommand{
 					FRG::TutorialStep::Completed});
@@ -158,7 +175,8 @@ int main(int argc, char** argv)
 	std::unique_ptr<FRG::WebsocketGameServer> websocketServer;
 	try {
 		websocketServer = std::make_unique<FRG::WebsocketGameServer>(
-			server, listenAddress, static_cast<std::uint16_t>(listenPort));
+			server, playerSlots, compatibilityFingerprint,
+			listenAddress, static_cast<std::uint16_t>(listenPort));
 	} catch (const std::exception& error) {
 		std::cerr << "WebSocket listener setup failed: "
 			<< error.what() << '\n';
@@ -174,7 +192,7 @@ int main(int argc, char** argv)
 		tick < maxTicks && !stopRequested.load(); ++tick) {
 		nextTick += tickDuration;
 #if defined(NETWORK)
-		websocketServer->update(tickMs);
+		websocketServer->update();
 #else
 		server.update(tickMs);
 #endif