{#- chirp-ui: Panel component
    Reusable titled pane for inspectors, activity feeds, file trees, and embedded work surfaces.

    Usage:
        {% from "chirpui/panel.html" import panel %}

        {% call panel(title="Tool Activity", scroll_body=true) %}
        {% slot actions %}{{ btn("Clear", variant="ghost", size="sm") }}{% end %}
        <div>Activity rows...</div>
        {% slot footer %}<span class="chirpui-text-muted chirpui-ui-sm">Connected</span>{% end %}
        {% end %}
-#}

{% def panel(title=none, subtitle=none, surface_variant="muted", scroll_body=false, cls="") %}
{% set surface_variant = surface_variant | validate_variant_block("surface", default="muted") %}
{% set panel_cls = "chirpui-panel" ~ (" chirpui-panel--scroll" if scroll_body else "") ~ (" " ~ cls if cls else "") %}
<section class="chirpui-surface chirpui-surface--{{ surface_variant }} chirpui-surface--no-padding {{ panel_cls }}">
    {% if title or subtitle %}
    <header class="chirpui-panel__header">
        <div class="chirpui-panel__heading">
            {% if title %}
            <h2 class="chirpui-panel__title">{{ title }}</h2>
            {% end %}
            {% if subtitle %}
            <p class="chirpui-panel__subtitle">{{ subtitle }}</p>
            {% end %}
        </div>
        <div class="chirpui-panel__actions">{% slot actions %}</div>
    </header>
    {% end %}
    <div class="chirpui-panel__body{{ " chirpui-panel__body--scroll" if scroll_body else "" }}">
        {% slot %}
    </div>
    <footer class="chirpui-panel__footer">{% slot footer %}</footer>
</section>
{% end %}