{% set nav_style = theme_nav_style | default('header') %}
{% set show_nav_level = meta['html_theme.show_nav_level'] if (meta is defined and meta is not none and 'html_theme.show_nav_level' in meta) else theme_show_nav_level %}

{% if nav_style == 'header' %}
  {# ==========================================
     模式 A: PyData 默认 (仅显示当前上下文子树)
     ========================================== #}
  <nav class="bd-docs-nav bd-links" aria-label="{{ _('Section Navigation') }}">
    <p class="bd-links__title" role="heading" aria-level="1">{{ _("Section Navigation") }}</p>
    <div class="bd-toc-item navbar-nav">
      {{- generate_toctree_html(
        "sidebar",
        show_nav_level=show_nav_level | int,
        maxdepth=theme_navigation_depth | int,
        collapse=theme_collapse_navigation | tobool,
        includehidden=theme_sidebar_includehidden | tobool,
        titles_only=True
        )
      -}}
    </div>
  </nav>

{% elif nav_style == 'sidebar' %}
  {# ==========================================
     模式 B: Book-Theme 风格 (显示全局树)
     ========================================== #}
  <nav class="bd-docs-nav bd-links" aria-label="{{ _('Main Navigation') }}">
    <div class="bd-toc-item navbar-nav active">

      {# 可选的 Home 链接增强 #}
      {% if theme_home_page_in_toc | default(False) | tobool %}
        <ul class="nav bd-sidenav bd-sidenav__home-link">
            <li class="toctree-l1{% if pagename == root_doc %} current active{% endif %}">
                <a class="reference internal" href="{{ pathto(root_doc) }}">
                    {{ root_title | default('Home') }}
                </a>
            </li>
        </ul>
      {% endif %}

      {# 核心差异点：传入 startdepth=0 渲染全量树 #}
      {{- generate_toctree_html(
            "sidebar",
            startdepth=0,
            maxdepth=theme_navigation_depth | int,
            collapse=theme_collapse_navigation | tobool,
            includehidden=theme_sidebar_includehidden | tobool,
            titles_only=True,
            show_nav_level=show_nav_level | int
        )
      -}}
    </div>
  </nav>
{% endif %}