@* A collapsible sidebar nav section. The header is a full-width button that
   toggles ChildContent visibility. Pattern lifted from ScadaLink CentralUI
   (Components/Layout/NavSection.razor) — see [[project-deployed-service]]. *@

<li class="nav-item">
    <button type="button"
            class="nav-section-toggle"
            @onclick="OnToggle"
            aria-expanded="@(Expanded ? "true" : "false")">
        <span class="chevron" aria-hidden="true">@(Expanded ? "▾" : "▸")</span>
        <span>@Title</span>
    </button>
</li>
@if (Expanded)
{
    @ChildContent
}

@code {
    /// <summary>Section label shown in the header (e.g. "Runtime").</summary>
    [Parameter, EditorRequired]
    public string Title { get; set; } = string.Empty;

    /// <summary>Whether the section is expanded — its items rendered.</summary>
    [Parameter]
    public bool Expanded { get; set; }

    /// <summary>Raised when the header button is clicked.</summary>
    [Parameter]
    public EventCallback OnToggle { get; set; }

    /// <summary>The section's nav items, rendered only while expanded.</summary>
    [Parameter]
    public RenderFragment? ChildContent { get; set; }
}