Function DrawModsTab

engine/Poseidon/Dev/Debug/DebugOverlay.cpp:1054–1127

Live mod picker + in-process reload. Lists the @ folders actually present in the user's mods folder, lets you tick a set, and re-mounts the game with exactly that set — only from the main menu (re-mounting mid-mission would evict assets the simulation still references).

// in the user's mods folder, lets you tick a set, and re-mounts the game with
// exactly that set — only from the main menu (re-mounting mid-mission would evict
// assets the simulation still references).
void DrawModsTab()
{
    namespace fs = std::filesystem;
    const std::string modsRoot = GamePaths::Instance().ModsDir();

    ImGui::TextUnformatted("Mods folder (scanned live):");
    ImGui::TextWrapped("%s", modsRoot.c_str());
    ImGui::Separator();

    // Checkbox state persists across frames: modId ("@foo") -> checked.
    static std::map<std::string, bool> s_modChecked;

    // Live scan for @<mod> folders each frame.
    std::vector<std::string> mods;
    std::error_code ec;
    if (fs::is_directory(modsRoot, ec))
    {
        for (const auto& entry : fs::directory_iterator(modsRoot, ec))
        {
            std::error_code dirEc;
            if (!entry.is_directory(dirEc))
                continue;
            const std::string name = entry.path().filename().string();
            if (!name.empty() && name[0] == '@')
                mods.push_back(name);
        }
    }
    std::sort(mods.begin(), mods.end());

    if (mods.empty())
        ImGui::TextDisabled("(no @<mod> folders here yet — drop one in and it shows up)");

    for (const std::string& modId : mods)
    {
        auto it = s_modChecked.find(modId);
        bool checked = (it != s_modChecked.end()) ? it->second : false;
        if (ImGui::Checkbox(modId.c_str(), &checked) || it == s_modChecked.end())
            s_modChecked[modId] = checked;
    }

    // Build the mod path from the checked set — semicolon-separated absolute
    // mod-folder paths (empty string = base game only). modsRoot ends with a sep.
    std::string modPath;
    for (const std::string& modId : mods)
    {
        auto it = s_modChecked.find(modId);
        if (it != s_modChecked.end() && it->second)
        {
            if (!modPath.empty())
                modPath += ';';
            modPath += modsRoot + modId;
        }
    }

    ImGui::Spacing();
    ImGui::Separator();
    ImGui::TextWrapped("Apply set: %s", modPath.empty() ? "(none — base game only)" : modPath.c_str());