feat: rebuild CSP practice workflow, UX and automation

backend/tests/problem_workspace_service_test.cc

@@ -0,0 +1,48 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "csp/db/sqlite_db.h"
+#include "csp/services/problem_workspace_service.h"
+
+#include <sqlite3.h>
+
+TEST_CASE("problem workspace service drafts and solution jobs") {
+  auto db = csp::db::SqliteDb::OpenMemory();
+  csp::db::ApplyMigrations(db);
+  csp::db::SeedDemoData(db);
+  REQUIRE(sqlite3_exec(
+              db.raw(),
+              "INSERT INTO users(username,password_salt,password_hash,created_at)"
+              " VALUES('tester','salt','hash',0)",
+              nullptr,
+              nullptr,
+              nullptr) == SQLITE_OK);
+
+  sqlite3_stmt* stmt = nullptr;
+  REQUIRE(sqlite3_prepare_v2(db.raw(), "SELECT id FROM problems ORDER BY id LIMIT 1",
+                             -1, &stmt, nullptr) == SQLITE_OK);
+  REQUIRE(sqlite3_step(stmt) == SQLITE_ROW);
+  const int64_t pid = sqlite3_column_int64(stmt, 0);
+  sqlite3_finalize(stmt);
+  REQUIRE(pid > 0);
+
+  csp::services::ProblemWorkspaceService svc(db);
+  REQUIRE(svc.ProblemExists(pid));
+
+  svc.SaveDraft(1, pid, "cpp", "int main(){return 0;}", "1 2\n");
+  const auto draft = svc.GetDraft(1, pid);
+  REQUIRE(draft.has_value());
+  REQUIRE(draft->language == "cpp");
+  REQUIRE(draft->code.find("main") != std::string::npos);
+
+  const auto job_id = svc.CreateSolutionJob(pid, 1, 3);
+  REQUIRE(job_id > 0);
+
+  const auto latest = svc.GetLatestSolutionJob(pid);
+  REQUIRE(latest.has_value());
+  REQUIRE(latest->id == job_id);
+  REQUIRE(latest->status == "queued");
+  REQUIRE(latest->max_solutions == 3);
+
+  const auto solutions = svc.ListSolutions(pid);
+  REQUIRE(solutions.empty());
+}