feat(kick-system): add translated kick reasons with error codes

- Add kickReason field to ServerErrorMessage schema with enum values
- Display translated kick messages instead of generic "Kicked from game"
- Include error codes (KICK_ADMIN, KICK_MULTI_TAB, KICK_LOBBY_CREATOR) for debugging
- Update kick handlers in GameServer, PostJoinHandler, and Worker to pass reasons
- Modify showErrorModal to handle kick-specific formatting without duplication

resources/lang/en.json

@@ -545,7 +545,11 @@
     "copy_clipboard": "Copy to clipboard",
     "copied": "Copied!",
     "failed_copy": "Failed to copy",
-    "desync_notice": "You are desynced from other players. What you see might differ from other players."
+    "desync_notice": "You are desynced from other players. What you see might differ from other players.",
+    "kicked_message": "You have been kicked from the game.",
+    "kicked_reason_admin": "An administrator removed you from the game.",
+    "kicked_reason_lobby_creator": "The lobby host removed you from the game.",
+    "kicked_reason_multi_tab": "You may be playing on another tab or browser window."
   },
   "heads_up_message": {
     "choose_spawn": "Choose a starting location"

src/client/ClientGameRunner.ts

@@ -105,15 +105,31 @@ export function joinLobby(
       ).then((r) => r.start());
     }
     if (message.type === "error") {
-      showErrorModal(
-        message.error,
-        message.message,
-        lobbyConfig.gameID,
-        lobbyConfig.clientID,
-        true,
-        false,
-        "error_modal.connection_error",
-      );
+      if (message.kickReason) {
+        const kickMessage = translateText("error_modal.kicked_message");
+        const reasonKey = `error_modal.kicked_reason_${message.kickReason.replace("kick_", "")}`;
+        const reasonMessage = translateText(reasonKey);
+
+        showErrorModal(
+          kickMessage,
+          `${reasonMessage}\nError Code: ${message.kickReason.toUpperCase()}`,
+          lobbyConfig.gameID,
+          lobbyConfig.clientID,
+          true,
+          false,
+          "error_modal.connection_error",
+        );
+      } else {
+        showErrorModal(
+          message.error,
+          message.message,
+          lobbyConfig.gameID,
+          lobbyConfig.clientID,
+          true,
+          false,
+          "error_modal.connection_error",
+        );
+      }
     }
   };
   transport.connect(onconnect, onmessage);
@@ -336,15 +352,31 @@ export class ClientGameRunner {
         );
       }
       if (message.type === "error") {
-        showErrorModal(
-          message.error,
-          message.message,
-          this.lobby.gameID,
-          this.lobby.clientID,
-          true,
-          false,
-          "error_modal.connection_error",
-        );
+        if (message.kickReason) {
+          const kickMessage = translateText("error_modal.kicked_message");
+          const reasonKey = `error_modal.kicked_reason_${message.kickReason.replace("kick_", "")}`;
+          const reasonMessage = translateText(reasonKey);
+
+          showErrorModal(
+            kickMessage,
+            `${reasonMessage}\nError Code: ${message.kickReason.toUpperCase()}`,
+            this.lobby.gameID,
+            this.lobby.clientID,
+            true,
+            false,
+            "error_modal.connection_error",
+          );
+        } else {
+          showErrorModal(
+            message.error,
+            message.message,
+            this.lobby.gameID,
+            this.lobby.clientID,
+            true,
+            false,
+            "error_modal.connection_error",
+          );
+        }
       }
       if (message.type === "turn") {
         if (!this.hasJoined) {

src/core/Schemas.ts

@@ -465,6 +465,7 @@ export const ServerDesyncSchema = z.object({
 
 export const ServerErrorSchema = z.object({
   error: z.string(),
+  kickReason: z.enum(["kick_admin", "kick_multi_tab", "kick_lobby_creator"]).optional(),
   message: z.string().optional(),
   type: z.literal("error"),
 });

src/server/GameServer.ts

@@ -175,7 +175,7 @@ export class GameServer {
         });
         // Kick the existing client instead of the new one, because this was causing issues when
         // a client wanted to replay the game afterwards.
-        this.kickClient(conflicting.clientID);
+        this.kickClient(conflicting.clientID, "kick_multi_tab");
       }
     }
 
@@ -502,7 +502,8 @@ export class GameServer {
     return this.gameConfig.gameType === GameType.Public;
   }
 
-  public kickClient(clientID: ClientID): void {
+
+  public kickClient(clientID: ClientID, kickReason?: "kick_admin" | "kick_multi_tab" | "kick_lobby_creator"): void {
     if (this.kickedClients.has(clientID)) {
       this.log.warn(`cannot kick client, already kicked`, {
         clientID,
@@ -513,11 +514,13 @@ export class GameServer {
     if (client) {
       this.log.info("Kicking client from game", {
         clientID: client.clientID,
+        kickReason,
         persistentID: client.persistentID,
       });
       client.ws.send(
         JSON.stringify({
-          error: "Kicked from game (you may have been playing on another tab)",
+          error: "Kicked from game",
+          kickReason,
           type: "error",
         } satisfies ServerErrorMessage),
       );

src/server/Worker.ts

@@ -294,7 +294,7 @@ export async function startWorker() {
         return;
       }
 
-      game.kickClient(clientID);
+      game.kickClient(clientID, "kick_admin");
       res.status(200).send("Player kicked successfully");
     }),
   );

src/server/worker/websocket/handler/message/PostJoinHandler.ts

@@ -77,7 +77,7 @@ export async function postJoinMessageHandler(
               target: clientMsg.intent.target,
             });
 
-            gs.kickClient(clientMsg.intent.target);
+            gs.kickClient(clientMsg.intent.target, "kick_lobby_creator");
             return;
           }