fmtlib.fmt

// Core executor/timer behavior over the module surface: strand FIFO order,
// work-guard-driven run loop, thread_pool, and timer cancellation mapping to
// asio::error::operation_aborted. Module consumers pair `import asio;` with
// `import std;` (no text #include mixing).
import std;
import asio;

int main() {
    using namespace std::chrono_literals;

    asio::io_context io;
    auto guard = asio::make_work_guard(io);
    auto serial = asio::make_strand(io);
    asio::steady_timer timer(io, 2ms);

    std::atomic<int> posted{0};
    std::mutex order_mutex;
    std::vector<int> order;
    bool timer_called = false;

    asio::post(serial, [&] {
        std::lock_guard lock(order_mutex);
// …