feat: ship minecraft theme updates and platform workflow improvements

backend/include/csp/controllers/admin_controller.h

@@ -13,6 +13,9 @@ class AdminController : public drogon::HttpController<AdminController> {
   ADD_METHOD_TO(AdminController::updateUserRating,
                 "/api/v1/admin/users/{1}/rating",
                 drogon::Patch);
+  ADD_METHOD_TO(AdminController::deleteUser,
+                "/api/v1/admin/users/{1}",
+                drogon::Delete);
   ADD_METHOD_TO(AdminController::listRedeemItems, "/api/v1/admin/redeem-items", drogon::Get);
   ADD_METHOD_TO(AdminController::createRedeemItem, "/api/v1/admin/redeem-items", drogon::Post);
   ADD_METHOD_TO(AdminController::updateRedeemItem,
@@ -32,6 +35,9 @@ class AdminController : public drogon::HttpController<AdminController> {
   void updateUserRating(const drogon::HttpRequestPtr& req,
                         std::function<void(const drogon::HttpResponsePtr&)>&& cb,
                         int64_t user_id);
+  void deleteUser(const drogon::HttpRequestPtr& req,
+                  std::function<void(const drogon::HttpResponsePtr&)>&& cb,
+                  int64_t user_id);
 
   void listRedeemItems(const drogon::HttpRequestPtr& req,
                        std::function<void(const drogon::HttpResponsePtr&)>&& cb);

backend/include/csp/services/user_service.h

@@ -22,6 +22,7 @@ class UserService {
   std::vector<domain::GlobalLeaderboardEntry> GlobalLeaderboard(int limit = 100);
   UserListResult ListUsers(int page, int page_size);
   void SetRating(int64_t user_id, int rating);
+  void DeleteUser(int64_t user_id);
 
  private:
   db::SqliteDb& db_;

backend/src/controllers/admin_controller.cc

@@ -192,6 +192,42 @@ void AdminController::updateUserRating(
   }
 }
 
+void AdminController::deleteUser(
+    const drogon::HttpRequestPtr& req,
+    std::function<void(const drogon::HttpResponsePtr&)>&& cb,
+    int64_t user_id) {
+  try {
+    const auto admin_user_id = RequireAdminUserId(req, cb);
+    if (!admin_user_id.has_value()) return;
+
+    if (*admin_user_id == user_id) {
+      cb(JsonError(drogon::k400BadRequest, "cannot delete current admin user"));
+      return;
+    }
+
+    services::UserService users(csp::AppState::Instance().db());
+    const auto target = users.GetById(user_id);
+    if (!target.has_value()) {
+      cb(JsonError(drogon::k404NotFound, "user not found"));
+      return;
+    }
+    if (target->username == "admin") {
+      cb(JsonError(drogon::k400BadRequest, "cannot delete reserved admin user"));
+      return;
+    }
+
+    users.DeleteUser(user_id);
+
+    Json::Value payload;
+    payload["id"] = Json::Int64(user_id);
+    payload["username"] = target->username;
+    payload["deleted"] = true;
+    cb(JsonOk(payload));
+  } catch (const std::exception& e) {
+    cb(JsonError(drogon::k500InternalServerError, e.what()));
+  }
+}
+
 void AdminController::listRedeemItems(
     const drogon::HttpRequestPtr& req,
     std::function<void(const drogon::HttpResponsePtr&)>&& cb) {

backend/src/controllers/meta_controller.cc

@@ -100,6 +100,7 @@ Json::Value BuildOpenApiSpec() {
   paths["/api/v1/submissions/{id}/analysis"]["post"]["summary"] = "提交评测建议（LLM）";
   paths["/api/v1/admin/users"]["get"]["summary"] = "管理员用户列表";
   paths["/api/v1/admin/users/{id}/rating"]["patch"]["summary"] = "管理员修改用户积分";
+  paths["/api/v1/admin/users/{id}"]["delete"]["summary"] = "管理员删除用户";
   paths["/api/v1/admin/redeem-items"]["get"]["summary"] = "管理员查看积分兑换物品";
   paths["/api/v1/admin/redeem-items"]["post"]["summary"] = "管理员新增积分兑换物品";
   paths["/api/v1/admin/redeem-items/{id}"]["patch"]["summary"] = "管理员修改积分兑换物品";

backend/src/controllers/problem_controller.cc

@@ -138,7 +138,13 @@ void ProblemController::getDraft(
     services::ProblemWorkspaceService svc(csp::AppState::Instance().db());
     const auto draft = svc.GetDraft(*user_id, problem_id);
     if (!draft.has_value()) {
-      cb(JsonError(drogon::k404NotFound, "draft not found"));
+      Json::Value payload;
+      payload["language"] = "cpp";
+      payload["code"] = "";
+      payload["stdin"] = "";
+      payload["updated_at"] = Json::nullValue;
+      payload["exists"] = false;
+      cb(JsonOk(payload));
       return;
     }
 
@@ -147,6 +153,7 @@ void ProblemController::getDraft(
     payload["code"] = draft->code;
     payload["stdin"] = draft->stdin_text;
     payload["updated_at"] = Json::Int64(draft->updated_at);
+    payload["exists"] = true;
     cb(JsonOk(payload));
   } catch (const std::exception& e) {
     cb(JsonError(drogon::k500InternalServerError, e.what()));

backend/src/services/user_service.cc

@@ -126,4 +126,18 @@ void UserService::SetRating(int64_t user_id, int rating) {
   if (sqlite3_changes(db) <= 0) throw std::runtime_error("user not found");
 }
 
+void UserService::DeleteUser(int64_t user_id) {
+  if (user_id <= 0) throw std::runtime_error("invalid user_id");
+
+  sqlite3* db = db_.raw();
+  sqlite3_stmt* stmt = nullptr;
+  const char* sql = "DELETE FROM users WHERE id=?";
+  CheckSqlite(sqlite3_prepare_v2(db, sql, -1, &stmt, nullptr), db,
+              "prepare delete user");
+  CheckSqlite(sqlite3_bind_int64(stmt, 1, user_id), db, "bind user_id");
+  CheckSqlite(sqlite3_step(stmt), db, "exec delete user");
+  sqlite3_finalize(stmt);
+  if (sqlite3_changes(db) <= 0) throw std::runtime_error("user not found");
+}
+
 }  // namespace csp::services