Add atomic account Boss Card checkpoints and preserve cards in legacy saves (#7)

server/server.mjs

@@ -209,7 +209,7 @@ export function createGameServer(options = {}) {
       response.writeHead(204, {
         ...cors,
         "Access-Control-Allow-Headers": "Authorization, Content-Type",
-        "Access-Control-Allow-Methods": "GET, HEAD, POST, PUT, DELETE, OPTIONS",
+        "Access-Control-Allow-Methods": "GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS",
         "Access-Control-Max-Age": "86400",
       });
       response.end();
@@ -445,6 +445,15 @@ export function createGameServer(options = {}) {
         json(response, 200, gameDatabase.putCloudSave(account.id, body.data));
         return;
       }
+      if (url.pathname === "/api/cloud-save" && request.method === "PATCH") {
+        const account = gameDatabase.authenticate(bearerToken(request));
+        const body = await readJson(request, bodyLimit);
+        if (!body || typeof body !== "object" || Array.isArray(body) || !Object.hasOwn(body, "bossCards")) {
+          throw new GameDatabaseError("Boss Card collection is required.", 400, "invalid_boss_cards");
+        }
+        json(response, 200, gameDatabase.patchCloudSaveBossCards(account.id, body.bossCards, body.expectedRevision));
+        return;
+      }
       if (url.pathname === "/api/online-group" && request.method === "GET") {
         const account = gameDatabase.authenticate(bearerToken(request));
         json(response, 200, gameDatabase.onlineGroupState(account.id));